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![Huang Ying](/assets/img/avatar_default.png)
In theory, the following race is possible for batched TLB flushing. CPU0 CPU1 ---- ---- shrink_page_list() unmap zap_pte_range() flush_tlb_batched_pending() flush_tlb_mm() try_to_unmap() set_tlb_ubc_flush_pending() mm->tlb_flush_batched = true mm->tlb_flush_batched = false After the TLB is flushed on CPU1 via flush_tlb_mm() and before mm->tlb_flush_batched is set to false, some PTE is unmapped on CPU0 and the TLB flushing is pended. Then the pended TLB flushing will be lost. Although both set_tlb_ubc_flush_pending() and flush_tlb_batched_pending() are called with PTL locked, different PTL instances may be used. Because the race window is really small, and the lost TLB flushing will cause problem only if a TLB entry is inserted before the unmapping in the race window, the race is only theoretical. But the fix is simple and cheap too. Syzbot has reported this too as follows: ================================================================== BUG: KCSAN: data-race in flush_tlb_batched_pending / try_to_unmap_one write to 0xffff8881072cfbbc of 1 bytes by task 17406 on cpu 1: flush_tlb_batched_pending+0x5f/0x80 mm/rmap.c:691 madvise_free_pte_range+0xee/0x7d0 mm/madvise.c:594 walk_pmd_range mm/pagewalk.c:128 [inline] walk_pud_range mm/pagewalk.c:205 [inline] walk_p4d_range mm/pagewalk.c:240 [inline] walk_pgd_range mm/pagewalk.c:277 [inline] __walk_page_range+0x981/0x1160 mm/pagewalk.c:379 walk_page_range+0x131/0x300 mm/pagewalk.c:475 madvise_free_single_vma mm/madvise.c:734 [inline] madvise_dontneed_free mm/madvise.c:822 [inline] madvise_vma mm/madvise.c:996 [inline] do_madvise+0xe4a/0x1140 mm/madvise.c:1202 __do_sys_madvise mm/madvise.c:1228 [inline] __se_sys_madvise mm/madvise.c:1226 [inline] __x64_sys_madvise+0x5d/0x70 mm/madvise.c:1226 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae write to 0xffff8881072cfbbc of 1 bytes by task 71 on cpu 0: set_tlb_ubc_flush_pending mm/rmap.c:636 [inline] try_to_unmap_one+0x60e/0x1220 mm/rmap.c:1515 rmap_walk_anon+0x2fb/0x470 mm/rmap.c:2301 try_to_unmap+0xec/0x110 shrink_page_list+0xe91/0x2620 mm/vmscan.c:1719 shrink_inactive_list+0x3fb/0x730 mm/vmscan.c:2394 shrink_list mm/vmscan.c:2621 [inline] shrink_lruvec+0x3c9/0x710 mm/vmscan.c:2940 shrink_node_memcgs+0x23e/0x410 mm/vmscan.c:3129 shrink_node+0x8f6/0x1190 mm/vmscan.c:3252 kswapd_shrink_node mm/vmscan.c:4022 [inline] balance_pgdat+0x702/0xd30 mm/vmscan.c:4213 kswapd+0x200/0x340 mm/vmscan.c:4473 kthread+0x2c7/0x2e0 kernel/kthread.c:327 ret_from_fork+0x1f/0x30 value changed: 0x01 -> 0x00 Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 71 Comm: kswapd0 Not tainted 5.16.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ================================================================== [akpm@linux-foundation.org: tweak comments] Link: https://lkml.kernel.org/r/20211201021104.126469-1-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Reported-by: syzbot+aa5bebed695edaccf0df@syzkaller.appspotmail.com Cc: Nadav Amit <namit@vmware.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Will Deacon <will@kernel.org> Cc: Yu Zhao <yuzhao@google.com> Cc: Marco Elver <elver@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2447 lines
69 KiB
C
2447 lines
69 KiB
C
/*
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* mm/rmap.c - physical to virtual reverse mappings
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*
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* Copyright 2001, Rik van Riel <riel@conectiva.com.br>
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* Released under the General Public License (GPL).
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*
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* Simple, low overhead reverse mapping scheme.
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* Please try to keep this thing as modular as possible.
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*
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* Provides methods for unmapping each kind of mapped page:
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* the anon methods track anonymous pages, and
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* the file methods track pages belonging to an inode.
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*
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* Original design by Rik van Riel <riel@conectiva.com.br> 2001
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* File methods by Dave McCracken <dmccr@us.ibm.com> 2003, 2004
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* Anonymous methods by Andrea Arcangeli <andrea@suse.de> 2004
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* Contributions by Hugh Dickins 2003, 2004
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*/
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/*
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* Lock ordering in mm:
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*
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* inode->i_rwsem (while writing or truncating, not reading or faulting)
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* mm->mmap_lock
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* mapping->invalidate_lock (in filemap_fault)
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* page->flags PG_locked (lock_page) * (see hugetlbfs below)
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* hugetlbfs_i_mmap_rwsem_key (in huge_pmd_share)
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* mapping->i_mmap_rwsem
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* hugetlb_fault_mutex (hugetlbfs specific page fault mutex)
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* anon_vma->rwsem
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* mm->page_table_lock or pte_lock
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* swap_lock (in swap_duplicate, swap_info_get)
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* mmlist_lock (in mmput, drain_mmlist and others)
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* mapping->private_lock (in __set_page_dirty_buffers)
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* lock_page_memcg move_lock (in __set_page_dirty_buffers)
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* i_pages lock (widely used)
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* lruvec->lru_lock (in folio_lruvec_lock_irq)
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* inode->i_lock (in set_page_dirty's __mark_inode_dirty)
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* bdi.wb->list_lock (in set_page_dirty's __mark_inode_dirty)
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* sb_lock (within inode_lock in fs/fs-writeback.c)
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* i_pages lock (widely used, in set_page_dirty,
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* in arch-dependent flush_dcache_mmap_lock,
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* within bdi.wb->list_lock in __sync_single_inode)
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*
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* anon_vma->rwsem,mapping->i_mmap_rwsem (memory_failure, collect_procs_anon)
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* ->tasklist_lock
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* pte map lock
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*
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* * hugetlbfs PageHuge() pages take locks in this order:
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* mapping->i_mmap_rwsem
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* hugetlb_fault_mutex (hugetlbfs specific page fault mutex)
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* page->flags PG_locked (lock_page)
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*/
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#include <linux/mm.h>
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#include <linux/sched/mm.h>
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#include <linux/sched/task.h>
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#include <linux/pagemap.h>
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#include <linux/swap.h>
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#include <linux/swapops.h>
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/ksm.h>
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#include <linux/rmap.h>
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#include <linux/rcupdate.h>
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#include <linux/export.h>
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#include <linux/memcontrol.h>
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#include <linux/mmu_notifier.h>
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#include <linux/migrate.h>
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#include <linux/hugetlb.h>
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#include <linux/huge_mm.h>
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#include <linux/backing-dev.h>
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#include <linux/page_idle.h>
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#include <linux/memremap.h>
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#include <linux/userfaultfd_k.h>
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#include <asm/tlbflush.h>
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#include <trace/events/tlb.h>
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#include "internal.h"
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static struct kmem_cache *anon_vma_cachep;
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static struct kmem_cache *anon_vma_chain_cachep;
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static inline struct anon_vma *anon_vma_alloc(void)
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{
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struct anon_vma *anon_vma;
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anon_vma = kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL);
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if (anon_vma) {
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atomic_set(&anon_vma->refcount, 1);
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anon_vma->degree = 1; /* Reference for first vma */
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anon_vma->parent = anon_vma;
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/*
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* Initialise the anon_vma root to point to itself. If called
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* from fork, the root will be reset to the parents anon_vma.
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*/
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anon_vma->root = anon_vma;
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}
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return anon_vma;
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}
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static inline void anon_vma_free(struct anon_vma *anon_vma)
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{
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VM_BUG_ON(atomic_read(&anon_vma->refcount));
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/*
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* Synchronize against page_lock_anon_vma_read() such that
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* we can safely hold the lock without the anon_vma getting
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* freed.
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*
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* Relies on the full mb implied by the atomic_dec_and_test() from
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* put_anon_vma() against the acquire barrier implied by
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* down_read_trylock() from page_lock_anon_vma_read(). This orders:
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*
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* page_lock_anon_vma_read() VS put_anon_vma()
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* down_read_trylock() atomic_dec_and_test()
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* LOCK MB
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* atomic_read() rwsem_is_locked()
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*
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* LOCK should suffice since the actual taking of the lock must
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* happen _before_ what follows.
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*/
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might_sleep();
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if (rwsem_is_locked(&anon_vma->root->rwsem)) {
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anon_vma_lock_write(anon_vma);
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anon_vma_unlock_write(anon_vma);
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}
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kmem_cache_free(anon_vma_cachep, anon_vma);
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}
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static inline struct anon_vma_chain *anon_vma_chain_alloc(gfp_t gfp)
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{
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return kmem_cache_alloc(anon_vma_chain_cachep, gfp);
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}
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static void anon_vma_chain_free(struct anon_vma_chain *anon_vma_chain)
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{
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kmem_cache_free(anon_vma_chain_cachep, anon_vma_chain);
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}
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static void anon_vma_chain_link(struct vm_area_struct *vma,
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struct anon_vma_chain *avc,
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struct anon_vma *anon_vma)
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{
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avc->vma = vma;
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avc->anon_vma = anon_vma;
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list_add(&avc->same_vma, &vma->anon_vma_chain);
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anon_vma_interval_tree_insert(avc, &anon_vma->rb_root);
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}
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/**
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* __anon_vma_prepare - attach an anon_vma to a memory region
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* @vma: the memory region in question
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*
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* This makes sure the memory mapping described by 'vma' has
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* an 'anon_vma' attached to it, so that we can associate the
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* anonymous pages mapped into it with that anon_vma.
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*
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* The common case will be that we already have one, which
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* is handled inline by anon_vma_prepare(). But if
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* not we either need to find an adjacent mapping that we
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* can re-use the anon_vma from (very common when the only
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* reason for splitting a vma has been mprotect()), or we
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* allocate a new one.
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*
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* Anon-vma allocations are very subtle, because we may have
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* optimistically looked up an anon_vma in page_lock_anon_vma_read()
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* and that may actually touch the rwsem even in the newly
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* allocated vma (it depends on RCU to make sure that the
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* anon_vma isn't actually destroyed).
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*
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* As a result, we need to do proper anon_vma locking even
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* for the new allocation. At the same time, we do not want
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* to do any locking for the common case of already having
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* an anon_vma.
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*
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* This must be called with the mmap_lock held for reading.
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*/
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int __anon_vma_prepare(struct vm_area_struct *vma)
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{
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struct mm_struct *mm = vma->vm_mm;
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struct anon_vma *anon_vma, *allocated;
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struct anon_vma_chain *avc;
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might_sleep();
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avc = anon_vma_chain_alloc(GFP_KERNEL);
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if (!avc)
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goto out_enomem;
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anon_vma = find_mergeable_anon_vma(vma);
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allocated = NULL;
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if (!anon_vma) {
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anon_vma = anon_vma_alloc();
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if (unlikely(!anon_vma))
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goto out_enomem_free_avc;
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allocated = anon_vma;
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}
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anon_vma_lock_write(anon_vma);
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/* page_table_lock to protect against threads */
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spin_lock(&mm->page_table_lock);
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if (likely(!vma->anon_vma)) {
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vma->anon_vma = anon_vma;
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anon_vma_chain_link(vma, avc, anon_vma);
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/* vma reference or self-parent link for new root */
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anon_vma->degree++;
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allocated = NULL;
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avc = NULL;
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}
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spin_unlock(&mm->page_table_lock);
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anon_vma_unlock_write(anon_vma);
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if (unlikely(allocated))
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put_anon_vma(allocated);
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if (unlikely(avc))
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anon_vma_chain_free(avc);
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return 0;
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out_enomem_free_avc:
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anon_vma_chain_free(avc);
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out_enomem:
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return -ENOMEM;
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}
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/*
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* This is a useful helper function for locking the anon_vma root as
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* we traverse the vma->anon_vma_chain, looping over anon_vma's that
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* have the same vma.
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*
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* Such anon_vma's should have the same root, so you'd expect to see
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* just a single mutex_lock for the whole traversal.
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*/
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static inline struct anon_vma *lock_anon_vma_root(struct anon_vma *root, struct anon_vma *anon_vma)
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{
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struct anon_vma *new_root = anon_vma->root;
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if (new_root != root) {
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if (WARN_ON_ONCE(root))
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up_write(&root->rwsem);
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root = new_root;
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down_write(&root->rwsem);
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}
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return root;
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}
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static inline void unlock_anon_vma_root(struct anon_vma *root)
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{
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if (root)
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up_write(&root->rwsem);
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}
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/*
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* Attach the anon_vmas from src to dst.
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* Returns 0 on success, -ENOMEM on failure.
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*
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* anon_vma_clone() is called by __vma_adjust(), __split_vma(), copy_vma() and
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* anon_vma_fork(). The first three want an exact copy of src, while the last
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* one, anon_vma_fork(), may try to reuse an existing anon_vma to prevent
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* endless growth of anon_vma. Since dst->anon_vma is set to NULL before call,
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* we can identify this case by checking (!dst->anon_vma && src->anon_vma).
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*
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* If (!dst->anon_vma && src->anon_vma) is true, this function tries to find
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* and reuse existing anon_vma which has no vmas and only one child anon_vma.
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* This prevents degradation of anon_vma hierarchy to endless linear chain in
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* case of constantly forking task. On the other hand, an anon_vma with more
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* than one child isn't reused even if there was no alive vma, thus rmap
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* walker has a good chance of avoiding scanning the whole hierarchy when it
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* searches where page is mapped.
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*/
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int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src)
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{
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struct anon_vma_chain *avc, *pavc;
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struct anon_vma *root = NULL;
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list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) {
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struct anon_vma *anon_vma;
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avc = anon_vma_chain_alloc(GFP_NOWAIT | __GFP_NOWARN);
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if (unlikely(!avc)) {
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unlock_anon_vma_root(root);
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root = NULL;
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avc = anon_vma_chain_alloc(GFP_KERNEL);
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if (!avc)
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goto enomem_failure;
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}
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anon_vma = pavc->anon_vma;
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root = lock_anon_vma_root(root, anon_vma);
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anon_vma_chain_link(dst, avc, anon_vma);
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/*
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* Reuse existing anon_vma if its degree lower than two,
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* that means it has no vma and only one anon_vma child.
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*
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* Do not chose parent anon_vma, otherwise first child
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* will always reuse it. Root anon_vma is never reused:
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* it has self-parent reference and at least one child.
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*/
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if (!dst->anon_vma && src->anon_vma &&
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anon_vma != src->anon_vma && anon_vma->degree < 2)
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dst->anon_vma = anon_vma;
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}
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if (dst->anon_vma)
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dst->anon_vma->degree++;
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unlock_anon_vma_root(root);
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return 0;
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enomem_failure:
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/*
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* dst->anon_vma is dropped here otherwise its degree can be incorrectly
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* decremented in unlink_anon_vmas().
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* We can safely do this because callers of anon_vma_clone() don't care
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* about dst->anon_vma if anon_vma_clone() failed.
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*/
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dst->anon_vma = NULL;
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unlink_anon_vmas(dst);
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return -ENOMEM;
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}
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/*
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* Attach vma to its own anon_vma, as well as to the anon_vmas that
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* the corresponding VMA in the parent process is attached to.
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* Returns 0 on success, non-zero on failure.
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*/
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int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma)
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{
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struct anon_vma_chain *avc;
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struct anon_vma *anon_vma;
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int error;
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/* Don't bother if the parent process has no anon_vma here. */
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if (!pvma->anon_vma)
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return 0;
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/* Drop inherited anon_vma, we'll reuse existing or allocate new. */
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vma->anon_vma = NULL;
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/*
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* First, attach the new VMA to the parent VMA's anon_vmas,
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* so rmap can find non-COWed pages in child processes.
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*/
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error = anon_vma_clone(vma, pvma);
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if (error)
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return error;
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/* An existing anon_vma has been reused, all done then. */
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if (vma->anon_vma)
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return 0;
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/* Then add our own anon_vma. */
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anon_vma = anon_vma_alloc();
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if (!anon_vma)
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goto out_error;
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avc = anon_vma_chain_alloc(GFP_KERNEL);
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if (!avc)
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goto out_error_free_anon_vma;
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/*
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* The root anon_vma's rwsem is the lock actually used when we
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* lock any of the anon_vmas in this anon_vma tree.
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*/
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anon_vma->root = pvma->anon_vma->root;
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anon_vma->parent = pvma->anon_vma;
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/*
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* With refcounts, an anon_vma can stay around longer than the
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* process it belongs to. The root anon_vma needs to be pinned until
|
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* this anon_vma is freed, because the lock lives in the root.
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*/
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|
get_anon_vma(anon_vma->root);
|
|
/* Mark this anon_vma as the one where our new (COWed) pages go. */
|
|
vma->anon_vma = anon_vma;
|
|
anon_vma_lock_write(anon_vma);
|
|
anon_vma_chain_link(vma, avc, anon_vma);
|
|
anon_vma->parent->degree++;
|
|
anon_vma_unlock_write(anon_vma);
|
|
|
|
return 0;
|
|
|
|
out_error_free_anon_vma:
|
|
put_anon_vma(anon_vma);
|
|
out_error:
|
|
unlink_anon_vmas(vma);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
void unlink_anon_vmas(struct vm_area_struct *vma)
|
|
{
|
|
struct anon_vma_chain *avc, *next;
|
|
struct anon_vma *root = NULL;
|
|
|
|
/*
|
|
* Unlink each anon_vma chained to the VMA. This list is ordered
|
|
* from newest to oldest, ensuring the root anon_vma gets freed last.
|
|
*/
|
|
list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) {
|
|
struct anon_vma *anon_vma = avc->anon_vma;
|
|
|
|
root = lock_anon_vma_root(root, anon_vma);
|
|
anon_vma_interval_tree_remove(avc, &anon_vma->rb_root);
|
|
|
|
/*
|
|
* Leave empty anon_vmas on the list - we'll need
|
|
* to free them outside the lock.
|
|
*/
|
|
if (RB_EMPTY_ROOT(&anon_vma->rb_root.rb_root)) {
|
|
anon_vma->parent->degree--;
|
|
continue;
|
|
}
|
|
|
|
list_del(&avc->same_vma);
|
|
anon_vma_chain_free(avc);
|
|
}
|
|
if (vma->anon_vma) {
|
|
vma->anon_vma->degree--;
|
|
|
|
/*
|
|
* vma would still be needed after unlink, and anon_vma will be prepared
|
|
* when handle fault.
|
|
*/
|
|
vma->anon_vma = NULL;
|
|
}
|
|
unlock_anon_vma_root(root);
|
|
|
|
/*
|
|
* Iterate the list once more, it now only contains empty and unlinked
|
|
* anon_vmas, destroy them. Could not do before due to __put_anon_vma()
|
|
* needing to write-acquire the anon_vma->root->rwsem.
|
|
*/
|
|
list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) {
|
|
struct anon_vma *anon_vma = avc->anon_vma;
|
|
|
|
VM_WARN_ON(anon_vma->degree);
|
|
put_anon_vma(anon_vma);
|
|
|
|
list_del(&avc->same_vma);
|
|
anon_vma_chain_free(avc);
|
|
}
|
|
}
|
|
|
|
static void anon_vma_ctor(void *data)
|
|
{
|
|
struct anon_vma *anon_vma = data;
|
|
|
|
init_rwsem(&anon_vma->rwsem);
|
|
atomic_set(&anon_vma->refcount, 0);
|
|
anon_vma->rb_root = RB_ROOT_CACHED;
|
|
}
|
|
|
|
void __init anon_vma_init(void)
|
|
{
|
|
anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma),
|
|
0, SLAB_TYPESAFE_BY_RCU|SLAB_PANIC|SLAB_ACCOUNT,
|
|
anon_vma_ctor);
|
|
anon_vma_chain_cachep = KMEM_CACHE(anon_vma_chain,
|
|
SLAB_PANIC|SLAB_ACCOUNT);
|
|
}
|
|
|
|
/*
|
|
* Getting a lock on a stable anon_vma from a page off the LRU is tricky!
|
|
*
|
|
* Since there is no serialization what so ever against page_remove_rmap()
|
|
* the best this function can do is return a refcount increased anon_vma
|
|
* that might have been relevant to this page.
|
|
*
|
|
* The page might have been remapped to a different anon_vma or the anon_vma
|
|
* returned may already be freed (and even reused).
|
|
*
|
|
* In case it was remapped to a different anon_vma, the new anon_vma will be a
|
|
* child of the old anon_vma, and the anon_vma lifetime rules will therefore
|
|
* ensure that any anon_vma obtained from the page will still be valid for as
|
|
* long as we observe page_mapped() [ hence all those page_mapped() tests ].
|
|
*
|
|
* All users of this function must be very careful when walking the anon_vma
|
|
* chain and verify that the page in question is indeed mapped in it
|
|
* [ something equivalent to page_mapped_in_vma() ].
|
|
*
|
|
* Since anon_vma's slab is SLAB_TYPESAFE_BY_RCU and we know from
|
|
* page_remove_rmap() that the anon_vma pointer from page->mapping is valid
|
|
* if there is a mapcount, we can dereference the anon_vma after observing
|
|
* those.
|
|
*/
|
|
struct anon_vma *page_get_anon_vma(struct page *page)
|
|
{
|
|
struct anon_vma *anon_vma = NULL;
|
|
unsigned long anon_mapping;
|
|
|
|
rcu_read_lock();
|
|
anon_mapping = (unsigned long)READ_ONCE(page->mapping);
|
|
if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
|
|
goto out;
|
|
if (!page_mapped(page))
|
|
goto out;
|
|
|
|
anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
|
|
if (!atomic_inc_not_zero(&anon_vma->refcount)) {
|
|
anon_vma = NULL;
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* If this page is still mapped, then its anon_vma cannot have been
|
|
* freed. But if it has been unmapped, we have no security against the
|
|
* anon_vma structure being freed and reused (for another anon_vma:
|
|
* SLAB_TYPESAFE_BY_RCU guarantees that - so the atomic_inc_not_zero()
|
|
* above cannot corrupt).
|
|
*/
|
|
if (!page_mapped(page)) {
|
|
rcu_read_unlock();
|
|
put_anon_vma(anon_vma);
|
|
return NULL;
|
|
}
|
|
out:
|
|
rcu_read_unlock();
|
|
|
|
return anon_vma;
|
|
}
|
|
|
|
/*
|
|
* Similar to page_get_anon_vma() except it locks the anon_vma.
|
|
*
|
|
* Its a little more complex as it tries to keep the fast path to a single
|
|
* atomic op -- the trylock. If we fail the trylock, we fall back to getting a
|
|
* reference like with page_get_anon_vma() and then block on the mutex.
|
|
*/
|
|
struct anon_vma *page_lock_anon_vma_read(struct page *page)
|
|
{
|
|
struct anon_vma *anon_vma = NULL;
|
|
struct anon_vma *root_anon_vma;
|
|
unsigned long anon_mapping;
|
|
|
|
rcu_read_lock();
|
|
anon_mapping = (unsigned long)READ_ONCE(page->mapping);
|
|
if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
|
|
goto out;
|
|
if (!page_mapped(page))
|
|
goto out;
|
|
|
|
anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
|
|
root_anon_vma = READ_ONCE(anon_vma->root);
|
|
if (down_read_trylock(&root_anon_vma->rwsem)) {
|
|
/*
|
|
* If the page is still mapped, then this anon_vma is still
|
|
* its anon_vma, and holding the mutex ensures that it will
|
|
* not go away, see anon_vma_free().
|
|
*/
|
|
if (!page_mapped(page)) {
|
|
up_read(&root_anon_vma->rwsem);
|
|
anon_vma = NULL;
|
|
}
|
|
goto out;
|
|
}
|
|
|
|
/* trylock failed, we got to sleep */
|
|
if (!atomic_inc_not_zero(&anon_vma->refcount)) {
|
|
anon_vma = NULL;
|
|
goto out;
|
|
}
|
|
|
|
if (!page_mapped(page)) {
|
|
rcu_read_unlock();
|
|
put_anon_vma(anon_vma);
|
|
return NULL;
|
|
}
|
|
|
|
/* we pinned the anon_vma, its safe to sleep */
|
|
rcu_read_unlock();
|
|
anon_vma_lock_read(anon_vma);
|
|
|
|
if (atomic_dec_and_test(&anon_vma->refcount)) {
|
|
/*
|
|
* Oops, we held the last refcount, release the lock
|
|
* and bail -- can't simply use put_anon_vma() because
|
|
* we'll deadlock on the anon_vma_lock_write() recursion.
|
|
*/
|
|
anon_vma_unlock_read(anon_vma);
|
|
__put_anon_vma(anon_vma);
|
|
anon_vma = NULL;
|
|
}
|
|
|
|
return anon_vma;
|
|
|
|
out:
|
|
rcu_read_unlock();
|
|
return anon_vma;
|
|
}
|
|
|
|
void page_unlock_anon_vma_read(struct anon_vma *anon_vma)
|
|
{
|
|
anon_vma_unlock_read(anon_vma);
|
|
}
|
|
|
|
#ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
|
|
/*
|
|
* Flush TLB entries for recently unmapped pages from remote CPUs. It is
|
|
* important if a PTE was dirty when it was unmapped that it's flushed
|
|
* before any IO is initiated on the page to prevent lost writes. Similarly,
|
|
* it must be flushed before freeing to prevent data leakage.
|
|
*/
|
|
void try_to_unmap_flush(void)
|
|
{
|
|
struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc;
|
|
|
|
if (!tlb_ubc->flush_required)
|
|
return;
|
|
|
|
arch_tlbbatch_flush(&tlb_ubc->arch);
|
|
tlb_ubc->flush_required = false;
|
|
tlb_ubc->writable = false;
|
|
}
|
|
|
|
/* Flush iff there are potentially writable TLB entries that can race with IO */
|
|
void try_to_unmap_flush_dirty(void)
|
|
{
|
|
struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc;
|
|
|
|
if (tlb_ubc->writable)
|
|
try_to_unmap_flush();
|
|
}
|
|
|
|
/*
|
|
* Bits 0-14 of mm->tlb_flush_batched record pending generations.
|
|
* Bits 16-30 of mm->tlb_flush_batched bit record flushed generations.
|
|
*/
|
|
#define TLB_FLUSH_BATCH_FLUSHED_SHIFT 16
|
|
#define TLB_FLUSH_BATCH_PENDING_MASK \
|
|
((1 << (TLB_FLUSH_BATCH_FLUSHED_SHIFT - 1)) - 1)
|
|
#define TLB_FLUSH_BATCH_PENDING_LARGE \
|
|
(TLB_FLUSH_BATCH_PENDING_MASK / 2)
|
|
|
|
static void set_tlb_ubc_flush_pending(struct mm_struct *mm, bool writable)
|
|
{
|
|
struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc;
|
|
int batch, nbatch;
|
|
|
|
arch_tlbbatch_add_mm(&tlb_ubc->arch, mm);
|
|
tlb_ubc->flush_required = true;
|
|
|
|
/*
|
|
* Ensure compiler does not re-order the setting of tlb_flush_batched
|
|
* before the PTE is cleared.
|
|
*/
|
|
barrier();
|
|
batch = atomic_read(&mm->tlb_flush_batched);
|
|
retry:
|
|
if ((batch & TLB_FLUSH_BATCH_PENDING_MASK) > TLB_FLUSH_BATCH_PENDING_LARGE) {
|
|
/*
|
|
* Prevent `pending' from catching up with `flushed' because of
|
|
* overflow. Reset `pending' and `flushed' to be 1 and 0 if
|
|
* `pending' becomes large.
|
|
*/
|
|
nbatch = atomic_cmpxchg(&mm->tlb_flush_batched, batch, 1);
|
|
if (nbatch != batch) {
|
|
batch = nbatch;
|
|
goto retry;
|
|
}
|
|
} else {
|
|
atomic_inc(&mm->tlb_flush_batched);
|
|
}
|
|
|
|
/*
|
|
* If the PTE was dirty then it's best to assume it's writable. The
|
|
* caller must use try_to_unmap_flush_dirty() or try_to_unmap_flush()
|
|
* before the page is queued for IO.
|
|
*/
|
|
if (writable)
|
|
tlb_ubc->writable = true;
|
|
}
|
|
|
|
/*
|
|
* Returns true if the TLB flush should be deferred to the end of a batch of
|
|
* unmap operations to reduce IPIs.
|
|
*/
|
|
static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags)
|
|
{
|
|
bool should_defer = false;
|
|
|
|
if (!(flags & TTU_BATCH_FLUSH))
|
|
return false;
|
|
|
|
/* If remote CPUs need to be flushed then defer batch the flush */
|
|
if (cpumask_any_but(mm_cpumask(mm), get_cpu()) < nr_cpu_ids)
|
|
should_defer = true;
|
|
put_cpu();
|
|
|
|
return should_defer;
|
|
}
|
|
|
|
/*
|
|
* Reclaim unmaps pages under the PTL but do not flush the TLB prior to
|
|
* releasing the PTL if TLB flushes are batched. It's possible for a parallel
|
|
* operation such as mprotect or munmap to race between reclaim unmapping
|
|
* the page and flushing the page. If this race occurs, it potentially allows
|
|
* access to data via a stale TLB entry. Tracking all mm's that have TLB
|
|
* batching in flight would be expensive during reclaim so instead track
|
|
* whether TLB batching occurred in the past and if so then do a flush here
|
|
* if required. This will cost one additional flush per reclaim cycle paid
|
|
* by the first operation at risk such as mprotect and mumap.
|
|
*
|
|
* This must be called under the PTL so that an access to tlb_flush_batched
|
|
* that is potentially a "reclaim vs mprotect/munmap/etc" race will synchronise
|
|
* via the PTL.
|
|
*/
|
|
void flush_tlb_batched_pending(struct mm_struct *mm)
|
|
{
|
|
int batch = atomic_read(&mm->tlb_flush_batched);
|
|
int pending = batch & TLB_FLUSH_BATCH_PENDING_MASK;
|
|
int flushed = batch >> TLB_FLUSH_BATCH_FLUSHED_SHIFT;
|
|
|
|
if (pending != flushed) {
|
|
flush_tlb_mm(mm);
|
|
/*
|
|
* If the new TLB flushing is pending during flushing, leave
|
|
* mm->tlb_flush_batched as is, to avoid losing flushing.
|
|
*/
|
|
atomic_cmpxchg(&mm->tlb_flush_batched, batch,
|
|
pending | (pending << TLB_FLUSH_BATCH_FLUSHED_SHIFT));
|
|
}
|
|
}
|
|
#else
|
|
static void set_tlb_ubc_flush_pending(struct mm_struct *mm, bool writable)
|
|
{
|
|
}
|
|
|
|
static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags)
|
|
{
|
|
return false;
|
|
}
|
|
#endif /* CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH */
|
|
|
|
/*
|
|
* At what user virtual address is page expected in vma?
|
|
* Caller should check the page is actually part of the vma.
|
|
*/
|
|
unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
|
|
{
|
|
if (PageAnon(page)) {
|
|
struct anon_vma *page__anon_vma = page_anon_vma(page);
|
|
/*
|
|
* Note: swapoff's unuse_vma() is more efficient with this
|
|
* check, and needs it to match anon_vma when KSM is active.
|
|
*/
|
|
if (!vma->anon_vma || !page__anon_vma ||
|
|
vma->anon_vma->root != page__anon_vma->root)
|
|
return -EFAULT;
|
|
} else if (!vma->vm_file) {
|
|
return -EFAULT;
|
|
} else if (vma->vm_file->f_mapping != compound_head(page)->mapping) {
|
|
return -EFAULT;
|
|
}
|
|
|
|
return vma_address(page, vma);
|
|
}
|
|
|
|
pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address)
|
|
{
|
|
pgd_t *pgd;
|
|
p4d_t *p4d;
|
|
pud_t *pud;
|
|
pmd_t *pmd = NULL;
|
|
pmd_t pmde;
|
|
|
|
pgd = pgd_offset(mm, address);
|
|
if (!pgd_present(*pgd))
|
|
goto out;
|
|
|
|
p4d = p4d_offset(pgd, address);
|
|
if (!p4d_present(*p4d))
|
|
goto out;
|
|
|
|
pud = pud_offset(p4d, address);
|
|
if (!pud_present(*pud))
|
|
goto out;
|
|
|
|
pmd = pmd_offset(pud, address);
|
|
/*
|
|
* Some THP functions use the sequence pmdp_huge_clear_flush(), set_pmd_at()
|
|
* without holding anon_vma lock for write. So when looking for a
|
|
* genuine pmde (in which to find pte), test present and !THP together.
|
|
*/
|
|
pmde = *pmd;
|
|
barrier();
|
|
if (!pmd_present(pmde) || pmd_trans_huge(pmde))
|
|
pmd = NULL;
|
|
out:
|
|
return pmd;
|
|
}
|
|
|
|
struct page_referenced_arg {
|
|
int mapcount;
|
|
int referenced;
|
|
unsigned long vm_flags;
|
|
struct mem_cgroup *memcg;
|
|
};
|
|
/*
|
|
* arg: page_referenced_arg will be passed
|
|
*/
|
|
static bool page_referenced_one(struct page *page, struct vm_area_struct *vma,
|
|
unsigned long address, void *arg)
|
|
{
|
|
struct page_referenced_arg *pra = arg;
|
|
struct page_vma_mapped_walk pvmw = {
|
|
.page = page,
|
|
.vma = vma,
|
|
.address = address,
|
|
};
|
|
int referenced = 0;
|
|
|
|
while (page_vma_mapped_walk(&pvmw)) {
|
|
address = pvmw.address;
|
|
|
|
if (vma->vm_flags & VM_LOCKED) {
|
|
page_vma_mapped_walk_done(&pvmw);
|
|
pra->vm_flags |= VM_LOCKED;
|
|
return false; /* To break the loop */
|
|
}
|
|
|
|
if (pvmw.pte) {
|
|
if (ptep_clear_flush_young_notify(vma, address,
|
|
pvmw.pte)) {
|
|
/*
|
|
* Don't treat a reference through
|
|
* a sequentially read mapping as such.
|
|
* If the page has been used in another mapping,
|
|
* we will catch it; if this other mapping is
|
|
* already gone, the unmap path will have set
|
|
* PG_referenced or activated the page.
|
|
*/
|
|
if (likely(!(vma->vm_flags & VM_SEQ_READ)))
|
|
referenced++;
|
|
}
|
|
} else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
|
|
if (pmdp_clear_flush_young_notify(vma, address,
|
|
pvmw.pmd))
|
|
referenced++;
|
|
} else {
|
|
/* unexpected pmd-mapped page? */
|
|
WARN_ON_ONCE(1);
|
|
}
|
|
|
|
pra->mapcount--;
|
|
}
|
|
|
|
if (referenced)
|
|
clear_page_idle(page);
|
|
if (test_and_clear_page_young(page))
|
|
referenced++;
|
|
|
|
if (referenced) {
|
|
pra->referenced++;
|
|
pra->vm_flags |= vma->vm_flags;
|
|
}
|
|
|
|
if (!pra->mapcount)
|
|
return false; /* To break the loop */
|
|
|
|
return true;
|
|
}
|
|
|
|
static bool invalid_page_referenced_vma(struct vm_area_struct *vma, void *arg)
|
|
{
|
|
struct page_referenced_arg *pra = arg;
|
|
struct mem_cgroup *memcg = pra->memcg;
|
|
|
|
if (!mm_match_cgroup(vma->vm_mm, memcg))
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
/**
|
|
* page_referenced - test if the page was referenced
|
|
* @page: the page to test
|
|
* @is_locked: caller holds lock on the page
|
|
* @memcg: target memory cgroup
|
|
* @vm_flags: collect encountered vma->vm_flags who actually referenced the page
|
|
*
|
|
* Quick test_and_clear_referenced for all mappings to a page,
|
|
* returns the number of ptes which referenced the page.
|
|
*/
|
|
int page_referenced(struct page *page,
|
|
int is_locked,
|
|
struct mem_cgroup *memcg,
|
|
unsigned long *vm_flags)
|
|
{
|
|
int we_locked = 0;
|
|
struct page_referenced_arg pra = {
|
|
.mapcount = total_mapcount(page),
|
|
.memcg = memcg,
|
|
};
|
|
struct rmap_walk_control rwc = {
|
|
.rmap_one = page_referenced_one,
|
|
.arg = (void *)&pra,
|
|
.anon_lock = page_lock_anon_vma_read,
|
|
};
|
|
|
|
*vm_flags = 0;
|
|
if (!pra.mapcount)
|
|
return 0;
|
|
|
|
if (!page_rmapping(page))
|
|
return 0;
|
|
|
|
if (!is_locked && (!PageAnon(page) || PageKsm(page))) {
|
|
we_locked = trylock_page(page);
|
|
if (!we_locked)
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* If we are reclaiming on behalf of a cgroup, skip
|
|
* counting on behalf of references from different
|
|
* cgroups
|
|
*/
|
|
if (memcg) {
|
|
rwc.invalid_vma = invalid_page_referenced_vma;
|
|
}
|
|
|
|
rmap_walk(page, &rwc);
|
|
*vm_flags = pra.vm_flags;
|
|
|
|
if (we_locked)
|
|
unlock_page(page);
|
|
|
|
return pra.referenced;
|
|
}
|
|
|
|
static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma,
|
|
unsigned long address, void *arg)
|
|
{
|
|
struct page_vma_mapped_walk pvmw = {
|
|
.page = page,
|
|
.vma = vma,
|
|
.address = address,
|
|
.flags = PVMW_SYNC,
|
|
};
|
|
struct mmu_notifier_range range;
|
|
int *cleaned = arg;
|
|
|
|
/*
|
|
* We have to assume the worse case ie pmd for invalidation. Note that
|
|
* the page can not be free from this function.
|
|
*/
|
|
mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_PAGE,
|
|
0, vma, vma->vm_mm, address,
|
|
vma_address_end(page, vma));
|
|
mmu_notifier_invalidate_range_start(&range);
|
|
|
|
while (page_vma_mapped_walk(&pvmw)) {
|
|
int ret = 0;
|
|
|
|
address = pvmw.address;
|
|
if (pvmw.pte) {
|
|
pte_t entry;
|
|
pte_t *pte = pvmw.pte;
|
|
|
|
if (!pte_dirty(*pte) && !pte_write(*pte))
|
|
continue;
|
|
|
|
flush_cache_page(vma, address, pte_pfn(*pte));
|
|
entry = ptep_clear_flush(vma, address, pte);
|
|
entry = pte_wrprotect(entry);
|
|
entry = pte_mkclean(entry);
|
|
set_pte_at(vma->vm_mm, address, pte, entry);
|
|
ret = 1;
|
|
} else {
|
|
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
|
|
pmd_t *pmd = pvmw.pmd;
|
|
pmd_t entry;
|
|
|
|
if (!pmd_dirty(*pmd) && !pmd_write(*pmd))
|
|
continue;
|
|
|
|
flush_cache_page(vma, address, page_to_pfn(page));
|
|
entry = pmdp_invalidate(vma, address, pmd);
|
|
entry = pmd_wrprotect(entry);
|
|
entry = pmd_mkclean(entry);
|
|
set_pmd_at(vma->vm_mm, address, pmd, entry);
|
|
ret = 1;
|
|
#else
|
|
/* unexpected pmd-mapped page? */
|
|
WARN_ON_ONCE(1);
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* No need to call mmu_notifier_invalidate_range() as we are
|
|
* downgrading page table protection not changing it to point
|
|
* to a new page.
|
|
*
|
|
* See Documentation/vm/mmu_notifier.rst
|
|
*/
|
|
if (ret)
|
|
(*cleaned)++;
|
|
}
|
|
|
|
mmu_notifier_invalidate_range_end(&range);
|
|
|
|
return true;
|
|
}
|
|
|
|
static bool invalid_mkclean_vma(struct vm_area_struct *vma, void *arg)
|
|
{
|
|
if (vma->vm_flags & VM_SHARED)
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
int folio_mkclean(struct folio *folio)
|
|
{
|
|
int cleaned = 0;
|
|
struct address_space *mapping;
|
|
struct rmap_walk_control rwc = {
|
|
.arg = (void *)&cleaned,
|
|
.rmap_one = page_mkclean_one,
|
|
.invalid_vma = invalid_mkclean_vma,
|
|
};
|
|
|
|
BUG_ON(!folio_test_locked(folio));
|
|
|
|
if (!folio_mapped(folio))
|
|
return 0;
|
|
|
|
mapping = folio_mapping(folio);
|
|
if (!mapping)
|
|
return 0;
|
|
|
|
rmap_walk(&folio->page, &rwc);
|
|
|
|
return cleaned;
|
|
}
|
|
EXPORT_SYMBOL_GPL(folio_mkclean);
|
|
|
|
/**
|
|
* page_move_anon_rmap - move a page to our anon_vma
|
|
* @page: the page to move to our anon_vma
|
|
* @vma: the vma the page belongs to
|
|
*
|
|
* When a page belongs exclusively to one process after a COW event,
|
|
* that page can be moved into the anon_vma that belongs to just that
|
|
* process, so the rmap code will not search the parent or sibling
|
|
* processes.
|
|
*/
|
|
void page_move_anon_rmap(struct page *page, struct vm_area_struct *vma)
|
|
{
|
|
struct anon_vma *anon_vma = vma->anon_vma;
|
|
|
|
page = compound_head(page);
|
|
|
|
VM_BUG_ON_PAGE(!PageLocked(page), page);
|
|
VM_BUG_ON_VMA(!anon_vma, vma);
|
|
|
|
anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
|
|
/*
|
|
* Ensure that anon_vma and the PAGE_MAPPING_ANON bit are written
|
|
* simultaneously, so a concurrent reader (eg page_referenced()'s
|
|
* PageAnon()) will not see one without the other.
|
|
*/
|
|
WRITE_ONCE(page->mapping, (struct address_space *) anon_vma);
|
|
}
|
|
|
|
/**
|
|
* __page_set_anon_rmap - set up new anonymous rmap
|
|
* @page: Page or Hugepage to add to rmap
|
|
* @vma: VM area to add page to.
|
|
* @address: User virtual address of the mapping
|
|
* @exclusive: the page is exclusively owned by the current process
|
|
*/
|
|
static void __page_set_anon_rmap(struct page *page,
|
|
struct vm_area_struct *vma, unsigned long address, int exclusive)
|
|
{
|
|
struct anon_vma *anon_vma = vma->anon_vma;
|
|
|
|
BUG_ON(!anon_vma);
|
|
|
|
if (PageAnon(page))
|
|
return;
|
|
|
|
/*
|
|
* If the page isn't exclusively mapped into this vma,
|
|
* we must use the _oldest_ possible anon_vma for the
|
|
* page mapping!
|
|
*/
|
|
if (!exclusive)
|
|
anon_vma = anon_vma->root;
|
|
|
|
/*
|
|
* page_idle does a lockless/optimistic rmap scan on page->mapping.
|
|
* Make sure the compiler doesn't split the stores of anon_vma and
|
|
* the PAGE_MAPPING_ANON type identifier, otherwise the rmap code
|
|
* could mistake the mapping for a struct address_space and crash.
|
|
*/
|
|
anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
|
|
WRITE_ONCE(page->mapping, (struct address_space *) anon_vma);
|
|
page->index = linear_page_index(vma, address);
|
|
}
|
|
|
|
/**
|
|
* __page_check_anon_rmap - sanity check anonymous rmap addition
|
|
* @page: the page to add the mapping to
|
|
* @vma: the vm area in which the mapping is added
|
|
* @address: the user virtual address mapped
|
|
*/
|
|
static void __page_check_anon_rmap(struct page *page,
|
|
struct vm_area_struct *vma, unsigned long address)
|
|
{
|
|
/*
|
|
* The page's anon-rmap details (mapping and index) are guaranteed to
|
|
* be set up correctly at this point.
|
|
*
|
|
* We have exclusion against page_add_anon_rmap because the caller
|
|
* always holds the page locked.
|
|
*
|
|
* We have exclusion against page_add_new_anon_rmap because those pages
|
|
* are initially only visible via the pagetables, and the pte is locked
|
|
* over the call to page_add_new_anon_rmap.
|
|
*/
|
|
VM_BUG_ON_PAGE(page_anon_vma(page)->root != vma->anon_vma->root, page);
|
|
VM_BUG_ON_PAGE(page_to_pgoff(page) != linear_page_index(vma, address),
|
|
page);
|
|
}
|
|
|
|
/**
|
|
* page_add_anon_rmap - add pte mapping to an anonymous page
|
|
* @page: the page to add the mapping to
|
|
* @vma: the vm area in which the mapping is added
|
|
* @address: the user virtual address mapped
|
|
* @compound: charge the page as compound or small page
|
|
*
|
|
* The caller needs to hold the pte lock, and the page must be locked in
|
|
* the anon_vma case: to serialize mapping,index checking after setting,
|
|
* and to ensure that PageAnon is not being upgraded racily to PageKsm
|
|
* (but PageKsm is never downgraded to PageAnon).
|
|
*/
|
|
void page_add_anon_rmap(struct page *page,
|
|
struct vm_area_struct *vma, unsigned long address, bool compound)
|
|
{
|
|
do_page_add_anon_rmap(page, vma, address, compound ? RMAP_COMPOUND : 0);
|
|
}
|
|
|
|
/*
|
|
* Special version of the above for do_swap_page, which often runs
|
|
* into pages that are exclusively owned by the current process.
|
|
* Everybody else should continue to use page_add_anon_rmap above.
|
|
*/
|
|
void do_page_add_anon_rmap(struct page *page,
|
|
struct vm_area_struct *vma, unsigned long address, int flags)
|
|
{
|
|
bool compound = flags & RMAP_COMPOUND;
|
|
bool first;
|
|
|
|
if (unlikely(PageKsm(page)))
|
|
lock_page_memcg(page);
|
|
else
|
|
VM_BUG_ON_PAGE(!PageLocked(page), page);
|
|
|
|
if (compound) {
|
|
atomic_t *mapcount;
|
|
VM_BUG_ON_PAGE(!PageLocked(page), page);
|
|
VM_BUG_ON_PAGE(!PageTransHuge(page), page);
|
|
mapcount = compound_mapcount_ptr(page);
|
|
first = atomic_inc_and_test(mapcount);
|
|
} else {
|
|
first = atomic_inc_and_test(&page->_mapcount);
|
|
}
|
|
|
|
if (first) {
|
|
int nr = compound ? thp_nr_pages(page) : 1;
|
|
/*
|
|
* We use the irq-unsafe __{inc|mod}_zone_page_stat because
|
|
* these counters are not modified in interrupt context, and
|
|
* pte lock(a spinlock) is held, which implies preemption
|
|
* disabled.
|
|
*/
|
|
if (compound)
|
|
__mod_lruvec_page_state(page, NR_ANON_THPS, nr);
|
|
__mod_lruvec_page_state(page, NR_ANON_MAPPED, nr);
|
|
}
|
|
|
|
if (unlikely(PageKsm(page))) {
|
|
unlock_page_memcg(page);
|
|
return;
|
|
}
|
|
|
|
/* address might be in next vma when migration races vma_adjust */
|
|
if (first)
|
|
__page_set_anon_rmap(page, vma, address,
|
|
flags & RMAP_EXCLUSIVE);
|
|
else
|
|
__page_check_anon_rmap(page, vma, address);
|
|
}
|
|
|
|
/**
|
|
* page_add_new_anon_rmap - add pte mapping to a new anonymous page
|
|
* @page: the page to add the mapping to
|
|
* @vma: the vm area in which the mapping is added
|
|
* @address: the user virtual address mapped
|
|
* @compound: charge the page as compound or small page
|
|
*
|
|
* Same as page_add_anon_rmap but must only be called on *new* pages.
|
|
* This means the inc-and-test can be bypassed.
|
|
* Page does not have to be locked.
|
|
*/
|
|
void page_add_new_anon_rmap(struct page *page,
|
|
struct vm_area_struct *vma, unsigned long address, bool compound)
|
|
{
|
|
int nr = compound ? thp_nr_pages(page) : 1;
|
|
|
|
VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);
|
|
__SetPageSwapBacked(page);
|
|
if (compound) {
|
|
VM_BUG_ON_PAGE(!PageTransHuge(page), page);
|
|
/* increment count (starts at -1) */
|
|
atomic_set(compound_mapcount_ptr(page), 0);
|
|
if (hpage_pincount_available(page))
|
|
atomic_set(compound_pincount_ptr(page), 0);
|
|
|
|
__mod_lruvec_page_state(page, NR_ANON_THPS, nr);
|
|
} else {
|
|
/* Anon THP always mapped first with PMD */
|
|
VM_BUG_ON_PAGE(PageTransCompound(page), page);
|
|
/* increment count (starts at -1) */
|
|
atomic_set(&page->_mapcount, 0);
|
|
}
|
|
__mod_lruvec_page_state(page, NR_ANON_MAPPED, nr);
|
|
__page_set_anon_rmap(page, vma, address, 1);
|
|
}
|
|
|
|
/**
|
|
* page_add_file_rmap - add pte mapping to a file page
|
|
* @page: the page to add the mapping to
|
|
* @compound: charge the page as compound or small page
|
|
*
|
|
* The caller needs to hold the pte lock.
|
|
*/
|
|
void page_add_file_rmap(struct page *page, bool compound)
|
|
{
|
|
int i, nr = 1;
|
|
|
|
VM_BUG_ON_PAGE(compound && !PageTransHuge(page), page);
|
|
lock_page_memcg(page);
|
|
if (compound && PageTransHuge(page)) {
|
|
int nr_pages = thp_nr_pages(page);
|
|
|
|
for (i = 0, nr = 0; i < nr_pages; i++) {
|
|
if (atomic_inc_and_test(&page[i]._mapcount))
|
|
nr++;
|
|
}
|
|
if (!atomic_inc_and_test(compound_mapcount_ptr(page)))
|
|
goto out;
|
|
if (PageSwapBacked(page))
|
|
__mod_lruvec_page_state(page, NR_SHMEM_PMDMAPPED,
|
|
nr_pages);
|
|
else
|
|
__mod_lruvec_page_state(page, NR_FILE_PMDMAPPED,
|
|
nr_pages);
|
|
} else {
|
|
if (PageTransCompound(page) && page_mapping(page)) {
|
|
struct page *head = compound_head(page);
|
|
|
|
VM_WARN_ON_ONCE(!PageLocked(page));
|
|
|
|
SetPageDoubleMap(head);
|
|
if (PageMlocked(page))
|
|
clear_page_mlock(head);
|
|
}
|
|
if (!atomic_inc_and_test(&page->_mapcount))
|
|
goto out;
|
|
}
|
|
__mod_lruvec_page_state(page, NR_FILE_MAPPED, nr);
|
|
out:
|
|
unlock_page_memcg(page);
|
|
}
|
|
|
|
static void page_remove_file_rmap(struct page *page, bool compound)
|
|
{
|
|
int i, nr = 1;
|
|
|
|
VM_BUG_ON_PAGE(compound && !PageHead(page), page);
|
|
|
|
/* Hugepages are not counted in NR_FILE_MAPPED for now. */
|
|
if (unlikely(PageHuge(page))) {
|
|
/* hugetlb pages are always mapped with pmds */
|
|
atomic_dec(compound_mapcount_ptr(page));
|
|
return;
|
|
}
|
|
|
|
/* page still mapped by someone else? */
|
|
if (compound && PageTransHuge(page)) {
|
|
int nr_pages = thp_nr_pages(page);
|
|
|
|
for (i = 0, nr = 0; i < nr_pages; i++) {
|
|
if (atomic_add_negative(-1, &page[i]._mapcount))
|
|
nr++;
|
|
}
|
|
if (!atomic_add_negative(-1, compound_mapcount_ptr(page)))
|
|
return;
|
|
if (PageSwapBacked(page))
|
|
__mod_lruvec_page_state(page, NR_SHMEM_PMDMAPPED,
|
|
-nr_pages);
|
|
else
|
|
__mod_lruvec_page_state(page, NR_FILE_PMDMAPPED,
|
|
-nr_pages);
|
|
} else {
|
|
if (!atomic_add_negative(-1, &page->_mapcount))
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* We use the irq-unsafe __{inc|mod}_lruvec_page_state because
|
|
* these counters are not modified in interrupt context, and
|
|
* pte lock(a spinlock) is held, which implies preemption disabled.
|
|
*/
|
|
__mod_lruvec_page_state(page, NR_FILE_MAPPED, -nr);
|
|
|
|
if (unlikely(PageMlocked(page)))
|
|
clear_page_mlock(page);
|
|
}
|
|
|
|
static void page_remove_anon_compound_rmap(struct page *page)
|
|
{
|
|
int i, nr;
|
|
|
|
if (!atomic_add_negative(-1, compound_mapcount_ptr(page)))
|
|
return;
|
|
|
|
/* Hugepages are not counted in NR_ANON_PAGES for now. */
|
|
if (unlikely(PageHuge(page)))
|
|
return;
|
|
|
|
if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
|
|
return;
|
|
|
|
__mod_lruvec_page_state(page, NR_ANON_THPS, -thp_nr_pages(page));
|
|
|
|
if (TestClearPageDoubleMap(page)) {
|
|
/*
|
|
* Subpages can be mapped with PTEs too. Check how many of
|
|
* them are still mapped.
|
|
*/
|
|
for (i = 0, nr = 0; i < thp_nr_pages(page); i++) {
|
|
if (atomic_add_negative(-1, &page[i]._mapcount))
|
|
nr++;
|
|
}
|
|
|
|
/*
|
|
* Queue the page for deferred split if at least one small
|
|
* page of the compound page is unmapped, but at least one
|
|
* small page is still mapped.
|
|
*/
|
|
if (nr && nr < thp_nr_pages(page))
|
|
deferred_split_huge_page(page);
|
|
} else {
|
|
nr = thp_nr_pages(page);
|
|
}
|
|
|
|
if (unlikely(PageMlocked(page)))
|
|
clear_page_mlock(page);
|
|
|
|
if (nr)
|
|
__mod_lruvec_page_state(page, NR_ANON_MAPPED, -nr);
|
|
}
|
|
|
|
/**
|
|
* page_remove_rmap - take down pte mapping from a page
|
|
* @page: page to remove mapping from
|
|
* @compound: uncharge the page as compound or small page
|
|
*
|
|
* The caller needs to hold the pte lock.
|
|
*/
|
|
void page_remove_rmap(struct page *page, bool compound)
|
|
{
|
|
lock_page_memcg(page);
|
|
|
|
if (!PageAnon(page)) {
|
|
page_remove_file_rmap(page, compound);
|
|
goto out;
|
|
}
|
|
|
|
if (compound) {
|
|
page_remove_anon_compound_rmap(page);
|
|
goto out;
|
|
}
|
|
|
|
/* page still mapped by someone else? */
|
|
if (!atomic_add_negative(-1, &page->_mapcount))
|
|
goto out;
|
|
|
|
/*
|
|
* We use the irq-unsafe __{inc|mod}_zone_page_stat because
|
|
* these counters are not modified in interrupt context, and
|
|
* pte lock(a spinlock) is held, which implies preemption disabled.
|
|
*/
|
|
__dec_lruvec_page_state(page, NR_ANON_MAPPED);
|
|
|
|
if (unlikely(PageMlocked(page)))
|
|
clear_page_mlock(page);
|
|
|
|
if (PageTransCompound(page))
|
|
deferred_split_huge_page(compound_head(page));
|
|
|
|
/*
|
|
* It would be tidy to reset the PageAnon mapping here,
|
|
* but that might overwrite a racing page_add_anon_rmap
|
|
* which increments mapcount after us but sets mapping
|
|
* before us: so leave the reset to free_unref_page,
|
|
* and remember that it's only reliable while mapped.
|
|
* Leaving it set also helps swapoff to reinstate ptes
|
|
* faster for those pages still in swapcache.
|
|
*/
|
|
out:
|
|
unlock_page_memcg(page);
|
|
}
|
|
|
|
/*
|
|
* @arg: enum ttu_flags will be passed to this argument
|
|
*/
|
|
static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
|
|
unsigned long address, void *arg)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
struct page_vma_mapped_walk pvmw = {
|
|
.page = page,
|
|
.vma = vma,
|
|
.address = address,
|
|
};
|
|
pte_t pteval;
|
|
struct page *subpage;
|
|
bool ret = true;
|
|
struct mmu_notifier_range range;
|
|
enum ttu_flags flags = (enum ttu_flags)(long)arg;
|
|
|
|
/*
|
|
* When racing against e.g. zap_pte_range() on another cpu,
|
|
* in between its ptep_get_and_clear_full() and page_remove_rmap(),
|
|
* try_to_unmap() may return before page_mapped() has become false,
|
|
* if page table locking is skipped: use TTU_SYNC to wait for that.
|
|
*/
|
|
if (flags & TTU_SYNC)
|
|
pvmw.flags = PVMW_SYNC;
|
|
|
|
if (flags & TTU_SPLIT_HUGE_PMD)
|
|
split_huge_pmd_address(vma, address, false, page);
|
|
|
|
/*
|
|
* For THP, we have to assume the worse case ie pmd for invalidation.
|
|
* For hugetlb, it could be much worse if we need to do pud
|
|
* invalidation in the case of pmd sharing.
|
|
*
|
|
* Note that the page can not be free in this function as call of
|
|
* try_to_unmap() must hold a reference on the page.
|
|
*/
|
|
range.end = PageKsm(page) ?
|
|
address + PAGE_SIZE : vma_address_end(page, vma);
|
|
mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
|
|
address, range.end);
|
|
if (PageHuge(page)) {
|
|
/*
|
|
* If sharing is possible, start and end will be adjusted
|
|
* accordingly.
|
|
*/
|
|
adjust_range_if_pmd_sharing_possible(vma, &range.start,
|
|
&range.end);
|
|
}
|
|
mmu_notifier_invalidate_range_start(&range);
|
|
|
|
while (page_vma_mapped_walk(&pvmw)) {
|
|
/*
|
|
* If the page is mlock()d, we cannot swap it out.
|
|
*/
|
|
if (!(flags & TTU_IGNORE_MLOCK) &&
|
|
(vma->vm_flags & VM_LOCKED)) {
|
|
/*
|
|
* PTE-mapped THP are never marked as mlocked: so do
|
|
* not set it on a DoubleMap THP, nor on an Anon THP
|
|
* (which may still be PTE-mapped after DoubleMap was
|
|
* cleared). But stop unmapping even in those cases.
|
|
*/
|
|
if (!PageTransCompound(page) || (PageHead(page) &&
|
|
!PageDoubleMap(page) && !PageAnon(page)))
|
|
mlock_vma_page(page);
|
|
page_vma_mapped_walk_done(&pvmw);
|
|
ret = false;
|
|
break;
|
|
}
|
|
|
|
/* Unexpected PMD-mapped THP? */
|
|
VM_BUG_ON_PAGE(!pvmw.pte, page);
|
|
|
|
subpage = page - page_to_pfn(page) + pte_pfn(*pvmw.pte);
|
|
address = pvmw.address;
|
|
|
|
if (PageHuge(page) && !PageAnon(page)) {
|
|
/*
|
|
* To call huge_pmd_unshare, i_mmap_rwsem must be
|
|
* held in write mode. Caller needs to explicitly
|
|
* do this outside rmap routines.
|
|
*/
|
|
VM_BUG_ON(!(flags & TTU_RMAP_LOCKED));
|
|
if (huge_pmd_unshare(mm, vma, &address, pvmw.pte)) {
|
|
/*
|
|
* huge_pmd_unshare unmapped an entire PMD
|
|
* page. There is no way of knowing exactly
|
|
* which PMDs may be cached for this mm, so
|
|
* we must flush them all. start/end were
|
|
* already adjusted above to cover this range.
|
|
*/
|
|
flush_cache_range(vma, range.start, range.end);
|
|
flush_tlb_range(vma, range.start, range.end);
|
|
mmu_notifier_invalidate_range(mm, range.start,
|
|
range.end);
|
|
|
|
/*
|
|
* The ref count of the PMD page was dropped
|
|
* which is part of the way map counting
|
|
* is done for shared PMDs. Return 'true'
|
|
* here. When there is no other sharing,
|
|
* huge_pmd_unshare returns false and we will
|
|
* unmap the actual page and drop map count
|
|
* to zero.
|
|
*/
|
|
page_vma_mapped_walk_done(&pvmw);
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* Nuke the page table entry. */
|
|
flush_cache_page(vma, address, pte_pfn(*pvmw.pte));
|
|
if (should_defer_flush(mm, flags)) {
|
|
/*
|
|
* We clear the PTE but do not flush so potentially
|
|
* a remote CPU could still be writing to the page.
|
|
* If the entry was previously clean then the
|
|
* architecture must guarantee that a clear->dirty
|
|
* transition on a cached TLB entry is written through
|
|
* and traps if the PTE is unmapped.
|
|
*/
|
|
pteval = ptep_get_and_clear(mm, address, pvmw.pte);
|
|
|
|
set_tlb_ubc_flush_pending(mm, pte_dirty(pteval));
|
|
} else {
|
|
pteval = ptep_clear_flush(vma, address, pvmw.pte);
|
|
}
|
|
|
|
/* Move the dirty bit to the page. Now the pte is gone. */
|
|
if (pte_dirty(pteval))
|
|
set_page_dirty(page);
|
|
|
|
/* Update high watermark before we lower rss */
|
|
update_hiwater_rss(mm);
|
|
|
|
if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) {
|
|
pteval = swp_entry_to_pte(make_hwpoison_entry(subpage));
|
|
if (PageHuge(page)) {
|
|
hugetlb_count_sub(compound_nr(page), mm);
|
|
set_huge_swap_pte_at(mm, address,
|
|
pvmw.pte, pteval,
|
|
vma_mmu_pagesize(vma));
|
|
} else {
|
|
dec_mm_counter(mm, mm_counter(page));
|
|
set_pte_at(mm, address, pvmw.pte, pteval);
|
|
}
|
|
|
|
} else if (pte_unused(pteval) && !userfaultfd_armed(vma)) {
|
|
/*
|
|
* The guest indicated that the page content is of no
|
|
* interest anymore. Simply discard the pte, vmscan
|
|
* will take care of the rest.
|
|
* A future reference will then fault in a new zero
|
|
* page. When userfaultfd is active, we must not drop
|
|
* this page though, as its main user (postcopy
|
|
* migration) will not expect userfaults on already
|
|
* copied pages.
|
|
*/
|
|
dec_mm_counter(mm, mm_counter(page));
|
|
/* We have to invalidate as we cleared the pte */
|
|
mmu_notifier_invalidate_range(mm, address,
|
|
address + PAGE_SIZE);
|
|
} else if (PageAnon(page)) {
|
|
swp_entry_t entry = { .val = page_private(subpage) };
|
|
pte_t swp_pte;
|
|
/*
|
|
* Store the swap location in the pte.
|
|
* See handle_pte_fault() ...
|
|
*/
|
|
if (unlikely(PageSwapBacked(page) != PageSwapCache(page))) {
|
|
WARN_ON_ONCE(1);
|
|
ret = false;
|
|
/* We have to invalidate as we cleared the pte */
|
|
mmu_notifier_invalidate_range(mm, address,
|
|
address + PAGE_SIZE);
|
|
page_vma_mapped_walk_done(&pvmw);
|
|
break;
|
|
}
|
|
|
|
/* MADV_FREE page check */
|
|
if (!PageSwapBacked(page)) {
|
|
if (!PageDirty(page)) {
|
|
/* Invalidate as we cleared the pte */
|
|
mmu_notifier_invalidate_range(mm,
|
|
address, address + PAGE_SIZE);
|
|
dec_mm_counter(mm, MM_ANONPAGES);
|
|
goto discard;
|
|
}
|
|
|
|
/*
|
|
* If the page was redirtied, it cannot be
|
|
* discarded. Remap the page to page table.
|
|
*/
|
|
set_pte_at(mm, address, pvmw.pte, pteval);
|
|
SetPageSwapBacked(page);
|
|
ret = false;
|
|
page_vma_mapped_walk_done(&pvmw);
|
|
break;
|
|
}
|
|
|
|
if (swap_duplicate(entry) < 0) {
|
|
set_pte_at(mm, address, pvmw.pte, pteval);
|
|
ret = false;
|
|
page_vma_mapped_walk_done(&pvmw);
|
|
break;
|
|
}
|
|
if (arch_unmap_one(mm, vma, address, pteval) < 0) {
|
|
set_pte_at(mm, address, pvmw.pte, pteval);
|
|
ret = false;
|
|
page_vma_mapped_walk_done(&pvmw);
|
|
break;
|
|
}
|
|
if (list_empty(&mm->mmlist)) {
|
|
spin_lock(&mmlist_lock);
|
|
if (list_empty(&mm->mmlist))
|
|
list_add(&mm->mmlist, &init_mm.mmlist);
|
|
spin_unlock(&mmlist_lock);
|
|
}
|
|
dec_mm_counter(mm, MM_ANONPAGES);
|
|
inc_mm_counter(mm, MM_SWAPENTS);
|
|
swp_pte = swp_entry_to_pte(entry);
|
|
if (pte_soft_dirty(pteval))
|
|
swp_pte = pte_swp_mksoft_dirty(swp_pte);
|
|
if (pte_uffd_wp(pteval))
|
|
swp_pte = pte_swp_mkuffd_wp(swp_pte);
|
|
set_pte_at(mm, address, pvmw.pte, swp_pte);
|
|
/* Invalidate as we cleared the pte */
|
|
mmu_notifier_invalidate_range(mm, address,
|
|
address + PAGE_SIZE);
|
|
} else {
|
|
/*
|
|
* This is a locked file-backed page, thus it cannot
|
|
* be removed from the page cache and replaced by a new
|
|
* page before mmu_notifier_invalidate_range_end, so no
|
|
* concurrent thread might update its page table to
|
|
* point at new page while a device still is using this
|
|
* page.
|
|
*
|
|
* See Documentation/vm/mmu_notifier.rst
|
|
*/
|
|
dec_mm_counter(mm, mm_counter_file(page));
|
|
}
|
|
discard:
|
|
/*
|
|
* No need to call mmu_notifier_invalidate_range() it has be
|
|
* done above for all cases requiring it to happen under page
|
|
* table lock before mmu_notifier_invalidate_range_end()
|
|
*
|
|
* See Documentation/vm/mmu_notifier.rst
|
|
*/
|
|
page_remove_rmap(subpage, PageHuge(page));
|
|
put_page(page);
|
|
}
|
|
|
|
mmu_notifier_invalidate_range_end(&range);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static bool invalid_migration_vma(struct vm_area_struct *vma, void *arg)
|
|
{
|
|
return vma_is_temporary_stack(vma);
|
|
}
|
|
|
|
static int page_not_mapped(struct page *page)
|
|
{
|
|
return !page_mapped(page);
|
|
}
|
|
|
|
/**
|
|
* try_to_unmap - try to remove all page table mappings to a page
|
|
* @page: the page to get unmapped
|
|
* @flags: action and flags
|
|
*
|
|
* Tries to remove all the page table entries which are mapping this
|
|
* page, used in the pageout path. Caller must hold the page lock.
|
|
*
|
|
* It is the caller's responsibility to check if the page is still
|
|
* mapped when needed (use TTU_SYNC to prevent accounting races).
|
|
*/
|
|
void try_to_unmap(struct page *page, enum ttu_flags flags)
|
|
{
|
|
struct rmap_walk_control rwc = {
|
|
.rmap_one = try_to_unmap_one,
|
|
.arg = (void *)flags,
|
|
.done = page_not_mapped,
|
|
.anon_lock = page_lock_anon_vma_read,
|
|
};
|
|
|
|
if (flags & TTU_RMAP_LOCKED)
|
|
rmap_walk_locked(page, &rwc);
|
|
else
|
|
rmap_walk(page, &rwc);
|
|
}
|
|
|
|
/*
|
|
* @arg: enum ttu_flags will be passed to this argument.
|
|
*
|
|
* If TTU_SPLIT_HUGE_PMD is specified any PMD mappings will be split into PTEs
|
|
* containing migration entries.
|
|
*/
|
|
static bool try_to_migrate_one(struct page *page, struct vm_area_struct *vma,
|
|
unsigned long address, void *arg)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
struct page_vma_mapped_walk pvmw = {
|
|
.page = page,
|
|
.vma = vma,
|
|
.address = address,
|
|
};
|
|
pte_t pteval;
|
|
struct page *subpage;
|
|
bool ret = true;
|
|
struct mmu_notifier_range range;
|
|
enum ttu_flags flags = (enum ttu_flags)(long)arg;
|
|
|
|
/*
|
|
* When racing against e.g. zap_pte_range() on another cpu,
|
|
* in between its ptep_get_and_clear_full() and page_remove_rmap(),
|
|
* try_to_migrate() may return before page_mapped() has become false,
|
|
* if page table locking is skipped: use TTU_SYNC to wait for that.
|
|
*/
|
|
if (flags & TTU_SYNC)
|
|
pvmw.flags = PVMW_SYNC;
|
|
|
|
/*
|
|
* unmap_page() in mm/huge_memory.c is the only user of migration with
|
|
* TTU_SPLIT_HUGE_PMD and it wants to freeze.
|
|
*/
|
|
if (flags & TTU_SPLIT_HUGE_PMD)
|
|
split_huge_pmd_address(vma, address, true, page);
|
|
|
|
/*
|
|
* For THP, we have to assume the worse case ie pmd for invalidation.
|
|
* For hugetlb, it could be much worse if we need to do pud
|
|
* invalidation in the case of pmd sharing.
|
|
*
|
|
* Note that the page can not be free in this function as call of
|
|
* try_to_unmap() must hold a reference on the page.
|
|
*/
|
|
range.end = PageKsm(page) ?
|
|
address + PAGE_SIZE : vma_address_end(page, vma);
|
|
mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
|
|
address, range.end);
|
|
if (PageHuge(page)) {
|
|
/*
|
|
* If sharing is possible, start and end will be adjusted
|
|
* accordingly.
|
|
*/
|
|
adjust_range_if_pmd_sharing_possible(vma, &range.start,
|
|
&range.end);
|
|
}
|
|
mmu_notifier_invalidate_range_start(&range);
|
|
|
|
while (page_vma_mapped_walk(&pvmw)) {
|
|
#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
|
|
/* PMD-mapped THP migration entry */
|
|
if (!pvmw.pte) {
|
|
VM_BUG_ON_PAGE(PageHuge(page) ||
|
|
!PageTransCompound(page), page);
|
|
|
|
set_pmd_migration_entry(&pvmw, page);
|
|
continue;
|
|
}
|
|
#endif
|
|
|
|
/* Unexpected PMD-mapped THP? */
|
|
VM_BUG_ON_PAGE(!pvmw.pte, page);
|
|
|
|
subpage = page - page_to_pfn(page) + pte_pfn(*pvmw.pte);
|
|
address = pvmw.address;
|
|
|
|
if (PageHuge(page) && !PageAnon(page)) {
|
|
/*
|
|
* To call huge_pmd_unshare, i_mmap_rwsem must be
|
|
* held in write mode. Caller needs to explicitly
|
|
* do this outside rmap routines.
|
|
*/
|
|
VM_BUG_ON(!(flags & TTU_RMAP_LOCKED));
|
|
if (huge_pmd_unshare(mm, vma, &address, pvmw.pte)) {
|
|
/*
|
|
* huge_pmd_unshare unmapped an entire PMD
|
|
* page. There is no way of knowing exactly
|
|
* which PMDs may be cached for this mm, so
|
|
* we must flush them all. start/end were
|
|
* already adjusted above to cover this range.
|
|
*/
|
|
flush_cache_range(vma, range.start, range.end);
|
|
flush_tlb_range(vma, range.start, range.end);
|
|
mmu_notifier_invalidate_range(mm, range.start,
|
|
range.end);
|
|
|
|
/*
|
|
* The ref count of the PMD page was dropped
|
|
* which is part of the way map counting
|
|
* is done for shared PMDs. Return 'true'
|
|
* here. When there is no other sharing,
|
|
* huge_pmd_unshare returns false and we will
|
|
* unmap the actual page and drop map count
|
|
* to zero.
|
|
*/
|
|
page_vma_mapped_walk_done(&pvmw);
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* Nuke the page table entry. */
|
|
flush_cache_page(vma, address, pte_pfn(*pvmw.pte));
|
|
pteval = ptep_clear_flush(vma, address, pvmw.pte);
|
|
|
|
/* Move the dirty bit to the page. Now the pte is gone. */
|
|
if (pte_dirty(pteval))
|
|
set_page_dirty(page);
|
|
|
|
/* Update high watermark before we lower rss */
|
|
update_hiwater_rss(mm);
|
|
|
|
if (is_zone_device_page(page)) {
|
|
unsigned long pfn = page_to_pfn(page);
|
|
swp_entry_t entry;
|
|
pte_t swp_pte;
|
|
|
|
/*
|
|
* Store the pfn of the page in a special migration
|
|
* pte. do_swap_page() will wait until the migration
|
|
* pte is removed and then restart fault handling.
|
|
*/
|
|
entry = pte_to_swp_entry(pteval);
|
|
if (is_writable_device_private_entry(entry))
|
|
entry = make_writable_migration_entry(pfn);
|
|
else
|
|
entry = make_readable_migration_entry(pfn);
|
|
swp_pte = swp_entry_to_pte(entry);
|
|
|
|
/*
|
|
* pteval maps a zone device page and is therefore
|
|
* a swap pte.
|
|
*/
|
|
if (pte_swp_soft_dirty(pteval))
|
|
swp_pte = pte_swp_mksoft_dirty(swp_pte);
|
|
if (pte_swp_uffd_wp(pteval))
|
|
swp_pte = pte_swp_mkuffd_wp(swp_pte);
|
|
set_pte_at(mm, pvmw.address, pvmw.pte, swp_pte);
|
|
/*
|
|
* No need to invalidate here it will synchronize on
|
|
* against the special swap migration pte.
|
|
*
|
|
* The assignment to subpage above was computed from a
|
|
* swap PTE which results in an invalid pointer.
|
|
* Since only PAGE_SIZE pages can currently be
|
|
* migrated, just set it to page. This will need to be
|
|
* changed when hugepage migrations to device private
|
|
* memory are supported.
|
|
*/
|
|
subpage = page;
|
|
} else if (PageHWPoison(page)) {
|
|
pteval = swp_entry_to_pte(make_hwpoison_entry(subpage));
|
|
if (PageHuge(page)) {
|
|
hugetlb_count_sub(compound_nr(page), mm);
|
|
set_huge_swap_pte_at(mm, address,
|
|
pvmw.pte, pteval,
|
|
vma_mmu_pagesize(vma));
|
|
} else {
|
|
dec_mm_counter(mm, mm_counter(page));
|
|
set_pte_at(mm, address, pvmw.pte, pteval);
|
|
}
|
|
|
|
} else if (pte_unused(pteval) && !userfaultfd_armed(vma)) {
|
|
/*
|
|
* The guest indicated that the page content is of no
|
|
* interest anymore. Simply discard the pte, vmscan
|
|
* will take care of the rest.
|
|
* A future reference will then fault in a new zero
|
|
* page. When userfaultfd is active, we must not drop
|
|
* this page though, as its main user (postcopy
|
|
* migration) will not expect userfaults on already
|
|
* copied pages.
|
|
*/
|
|
dec_mm_counter(mm, mm_counter(page));
|
|
/* We have to invalidate as we cleared the pte */
|
|
mmu_notifier_invalidate_range(mm, address,
|
|
address + PAGE_SIZE);
|
|
} else {
|
|
swp_entry_t entry;
|
|
pte_t swp_pte;
|
|
|
|
if (arch_unmap_one(mm, vma, address, pteval) < 0) {
|
|
set_pte_at(mm, address, pvmw.pte, pteval);
|
|
ret = false;
|
|
page_vma_mapped_walk_done(&pvmw);
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Store the pfn of the page in a special migration
|
|
* pte. do_swap_page() will wait until the migration
|
|
* pte is removed and then restart fault handling.
|
|
*/
|
|
if (pte_write(pteval))
|
|
entry = make_writable_migration_entry(
|
|
page_to_pfn(subpage));
|
|
else
|
|
entry = make_readable_migration_entry(
|
|
page_to_pfn(subpage));
|
|
|
|
swp_pte = swp_entry_to_pte(entry);
|
|
if (pte_soft_dirty(pteval))
|
|
swp_pte = pte_swp_mksoft_dirty(swp_pte);
|
|
if (pte_uffd_wp(pteval))
|
|
swp_pte = pte_swp_mkuffd_wp(swp_pte);
|
|
set_pte_at(mm, address, pvmw.pte, swp_pte);
|
|
/*
|
|
* No need to invalidate here it will synchronize on
|
|
* against the special swap migration pte.
|
|
*/
|
|
}
|
|
|
|
/*
|
|
* No need to call mmu_notifier_invalidate_range() it has be
|
|
* done above for all cases requiring it to happen under page
|
|
* table lock before mmu_notifier_invalidate_range_end()
|
|
*
|
|
* See Documentation/vm/mmu_notifier.rst
|
|
*/
|
|
page_remove_rmap(subpage, PageHuge(page));
|
|
put_page(page);
|
|
}
|
|
|
|
mmu_notifier_invalidate_range_end(&range);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* try_to_migrate - try to replace all page table mappings with swap entries
|
|
* @page: the page to replace page table entries for
|
|
* @flags: action and flags
|
|
*
|
|
* Tries to remove all the page table entries which are mapping this page and
|
|
* replace them with special swap entries. Caller must hold the page lock.
|
|
*/
|
|
void try_to_migrate(struct page *page, enum ttu_flags flags)
|
|
{
|
|
struct rmap_walk_control rwc = {
|
|
.rmap_one = try_to_migrate_one,
|
|
.arg = (void *)flags,
|
|
.done = page_not_mapped,
|
|
.anon_lock = page_lock_anon_vma_read,
|
|
};
|
|
|
|
/*
|
|
* Migration always ignores mlock and only supports TTU_RMAP_LOCKED and
|
|
* TTU_SPLIT_HUGE_PMD and TTU_SYNC flags.
|
|
*/
|
|
if (WARN_ON_ONCE(flags & ~(TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD |
|
|
TTU_SYNC)))
|
|
return;
|
|
|
|
if (is_zone_device_page(page) && !is_device_private_page(page))
|
|
return;
|
|
|
|
/*
|
|
* During exec, a temporary VMA is setup and later moved.
|
|
* The VMA is moved under the anon_vma lock but not the
|
|
* page tables leading to a race where migration cannot
|
|
* find the migration ptes. Rather than increasing the
|
|
* locking requirements of exec(), migration skips
|
|
* temporary VMAs until after exec() completes.
|
|
*/
|
|
if (!PageKsm(page) && PageAnon(page))
|
|
rwc.invalid_vma = invalid_migration_vma;
|
|
|
|
if (flags & TTU_RMAP_LOCKED)
|
|
rmap_walk_locked(page, &rwc);
|
|
else
|
|
rmap_walk(page, &rwc);
|
|
}
|
|
|
|
/*
|
|
* Walks the vma's mapping a page and mlocks the page if any locked vma's are
|
|
* found. Once one is found the page is locked and the scan can be terminated.
|
|
*/
|
|
static bool page_mlock_one(struct page *page, struct vm_area_struct *vma,
|
|
unsigned long address, void *unused)
|
|
{
|
|
struct page_vma_mapped_walk pvmw = {
|
|
.page = page,
|
|
.vma = vma,
|
|
.address = address,
|
|
};
|
|
|
|
/* An un-locked vma doesn't have any pages to lock, continue the scan */
|
|
if (!(vma->vm_flags & VM_LOCKED))
|
|
return true;
|
|
|
|
while (page_vma_mapped_walk(&pvmw)) {
|
|
/*
|
|
* Need to recheck under the ptl to serialise with
|
|
* __munlock_pagevec_fill() after VM_LOCKED is cleared in
|
|
* munlock_vma_pages_range().
|
|
*/
|
|
if (vma->vm_flags & VM_LOCKED) {
|
|
/*
|
|
* PTE-mapped THP are never marked as mlocked; but
|
|
* this function is never called on a DoubleMap THP,
|
|
* nor on an Anon THP (which may still be PTE-mapped
|
|
* after DoubleMap was cleared).
|
|
*/
|
|
mlock_vma_page(page);
|
|
/*
|
|
* No need to scan further once the page is marked
|
|
* as mlocked.
|
|
*/
|
|
page_vma_mapped_walk_done(&pvmw);
|
|
return false;
|
|
}
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* page_mlock - try to mlock a page
|
|
* @page: the page to be mlocked
|
|
*
|
|
* Called from munlock code. Checks all of the VMAs mapping the page and mlocks
|
|
* the page if any are found. The page will be returned with PG_mlocked cleared
|
|
* if it is not mapped by any locked vmas.
|
|
*/
|
|
void page_mlock(struct page *page)
|
|
{
|
|
struct rmap_walk_control rwc = {
|
|
.rmap_one = page_mlock_one,
|
|
.done = page_not_mapped,
|
|
.anon_lock = page_lock_anon_vma_read,
|
|
|
|
};
|
|
|
|
VM_BUG_ON_PAGE(!PageLocked(page) || PageLRU(page), page);
|
|
VM_BUG_ON_PAGE(PageCompound(page) && PageDoubleMap(page), page);
|
|
|
|
/* Anon THP are only marked as mlocked when singly mapped */
|
|
if (PageTransCompound(page) && PageAnon(page))
|
|
return;
|
|
|
|
rmap_walk(page, &rwc);
|
|
}
|
|
|
|
#ifdef CONFIG_DEVICE_PRIVATE
|
|
struct make_exclusive_args {
|
|
struct mm_struct *mm;
|
|
unsigned long address;
|
|
void *owner;
|
|
bool valid;
|
|
};
|
|
|
|
static bool page_make_device_exclusive_one(struct page *page,
|
|
struct vm_area_struct *vma, unsigned long address, void *priv)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
struct page_vma_mapped_walk pvmw = {
|
|
.page = page,
|
|
.vma = vma,
|
|
.address = address,
|
|
};
|
|
struct make_exclusive_args *args = priv;
|
|
pte_t pteval;
|
|
struct page *subpage;
|
|
bool ret = true;
|
|
struct mmu_notifier_range range;
|
|
swp_entry_t entry;
|
|
pte_t swp_pte;
|
|
|
|
mmu_notifier_range_init_owner(&range, MMU_NOTIFY_EXCLUSIVE, 0, vma,
|
|
vma->vm_mm, address, min(vma->vm_end,
|
|
address + page_size(page)), args->owner);
|
|
mmu_notifier_invalidate_range_start(&range);
|
|
|
|
while (page_vma_mapped_walk(&pvmw)) {
|
|
/* Unexpected PMD-mapped THP? */
|
|
VM_BUG_ON_PAGE(!pvmw.pte, page);
|
|
|
|
if (!pte_present(*pvmw.pte)) {
|
|
ret = false;
|
|
page_vma_mapped_walk_done(&pvmw);
|
|
break;
|
|
}
|
|
|
|
subpage = page - page_to_pfn(page) + pte_pfn(*pvmw.pte);
|
|
address = pvmw.address;
|
|
|
|
/* Nuke the page table entry. */
|
|
flush_cache_page(vma, address, pte_pfn(*pvmw.pte));
|
|
pteval = ptep_clear_flush(vma, address, pvmw.pte);
|
|
|
|
/* Move the dirty bit to the page. Now the pte is gone. */
|
|
if (pte_dirty(pteval))
|
|
set_page_dirty(page);
|
|
|
|
/*
|
|
* Check that our target page is still mapped at the expected
|
|
* address.
|
|
*/
|
|
if (args->mm == mm && args->address == address &&
|
|
pte_write(pteval))
|
|
args->valid = true;
|
|
|
|
/*
|
|
* Store the pfn of the page in a special migration
|
|
* pte. do_swap_page() will wait until the migration
|
|
* pte is removed and then restart fault handling.
|
|
*/
|
|
if (pte_write(pteval))
|
|
entry = make_writable_device_exclusive_entry(
|
|
page_to_pfn(subpage));
|
|
else
|
|
entry = make_readable_device_exclusive_entry(
|
|
page_to_pfn(subpage));
|
|
swp_pte = swp_entry_to_pte(entry);
|
|
if (pte_soft_dirty(pteval))
|
|
swp_pte = pte_swp_mksoft_dirty(swp_pte);
|
|
if (pte_uffd_wp(pteval))
|
|
swp_pte = pte_swp_mkuffd_wp(swp_pte);
|
|
|
|
set_pte_at(mm, address, pvmw.pte, swp_pte);
|
|
|
|
/*
|
|
* There is a reference on the page for the swap entry which has
|
|
* been removed, so shouldn't take another.
|
|
*/
|
|
page_remove_rmap(subpage, false);
|
|
}
|
|
|
|
mmu_notifier_invalidate_range_end(&range);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* page_make_device_exclusive - mark the page exclusively owned by a device
|
|
* @page: the page to replace page table entries for
|
|
* @mm: the mm_struct where the page is expected to be mapped
|
|
* @address: address where the page is expected to be mapped
|
|
* @owner: passed to MMU_NOTIFY_EXCLUSIVE range notifier callbacks
|
|
*
|
|
* Tries to remove all the page table entries which are mapping this page and
|
|
* replace them with special device exclusive swap entries to grant a device
|
|
* exclusive access to the page. Caller must hold the page lock.
|
|
*
|
|
* Returns false if the page is still mapped, or if it could not be unmapped
|
|
* from the expected address. Otherwise returns true (success).
|
|
*/
|
|
static bool page_make_device_exclusive(struct page *page, struct mm_struct *mm,
|
|
unsigned long address, void *owner)
|
|
{
|
|
struct make_exclusive_args args = {
|
|
.mm = mm,
|
|
.address = address,
|
|
.owner = owner,
|
|
.valid = false,
|
|
};
|
|
struct rmap_walk_control rwc = {
|
|
.rmap_one = page_make_device_exclusive_one,
|
|
.done = page_not_mapped,
|
|
.anon_lock = page_lock_anon_vma_read,
|
|
.arg = &args,
|
|
};
|
|
|
|
/*
|
|
* Restrict to anonymous pages for now to avoid potential writeback
|
|
* issues. Also tail pages shouldn't be passed to rmap_walk so skip
|
|
* those.
|
|
*/
|
|
if (!PageAnon(page) || PageTail(page))
|
|
return false;
|
|
|
|
rmap_walk(page, &rwc);
|
|
|
|
return args.valid && !page_mapcount(page);
|
|
}
|
|
|
|
/**
|
|
* make_device_exclusive_range() - Mark a range for exclusive use by a device
|
|
* @mm: mm_struct of assoicated target process
|
|
* @start: start of the region to mark for exclusive device access
|
|
* @end: end address of region
|
|
* @pages: returns the pages which were successfully marked for exclusive access
|
|
* @owner: passed to MMU_NOTIFY_EXCLUSIVE range notifier to allow filtering
|
|
*
|
|
* Returns: number of pages found in the range by GUP. A page is marked for
|
|
* exclusive access only if the page pointer is non-NULL.
|
|
*
|
|
* This function finds ptes mapping page(s) to the given address range, locks
|
|
* them and replaces mappings with special swap entries preventing userspace CPU
|
|
* access. On fault these entries are replaced with the original mapping after
|
|
* calling MMU notifiers.
|
|
*
|
|
* A driver using this to program access from a device must use a mmu notifier
|
|
* critical section to hold a device specific lock during programming. Once
|
|
* programming is complete it should drop the page lock and reference after
|
|
* which point CPU access to the page will revoke the exclusive access.
|
|
*/
|
|
int make_device_exclusive_range(struct mm_struct *mm, unsigned long start,
|
|
unsigned long end, struct page **pages,
|
|
void *owner)
|
|
{
|
|
long npages = (end - start) >> PAGE_SHIFT;
|
|
long i;
|
|
|
|
npages = get_user_pages_remote(mm, start, npages,
|
|
FOLL_GET | FOLL_WRITE | FOLL_SPLIT_PMD,
|
|
pages, NULL, NULL);
|
|
if (npages < 0)
|
|
return npages;
|
|
|
|
for (i = 0; i < npages; i++, start += PAGE_SIZE) {
|
|
if (!trylock_page(pages[i])) {
|
|
put_page(pages[i]);
|
|
pages[i] = NULL;
|
|
continue;
|
|
}
|
|
|
|
if (!page_make_device_exclusive(pages[i], mm, start, owner)) {
|
|
unlock_page(pages[i]);
|
|
put_page(pages[i]);
|
|
pages[i] = NULL;
|
|
}
|
|
}
|
|
|
|
return npages;
|
|
}
|
|
EXPORT_SYMBOL_GPL(make_device_exclusive_range);
|
|
#endif
|
|
|
|
void __put_anon_vma(struct anon_vma *anon_vma)
|
|
{
|
|
struct anon_vma *root = anon_vma->root;
|
|
|
|
anon_vma_free(anon_vma);
|
|
if (root != anon_vma && atomic_dec_and_test(&root->refcount))
|
|
anon_vma_free(root);
|
|
}
|
|
|
|
static struct anon_vma *rmap_walk_anon_lock(struct page *page,
|
|
struct rmap_walk_control *rwc)
|
|
{
|
|
struct anon_vma *anon_vma;
|
|
|
|
if (rwc->anon_lock)
|
|
return rwc->anon_lock(page);
|
|
|
|
/*
|
|
* Note: remove_migration_ptes() cannot use page_lock_anon_vma_read()
|
|
* because that depends on page_mapped(); but not all its usages
|
|
* are holding mmap_lock. Users without mmap_lock are required to
|
|
* take a reference count to prevent the anon_vma disappearing
|
|
*/
|
|
anon_vma = page_anon_vma(page);
|
|
if (!anon_vma)
|
|
return NULL;
|
|
|
|
anon_vma_lock_read(anon_vma);
|
|
return anon_vma;
|
|
}
|
|
|
|
/*
|
|
* rmap_walk_anon - do something to anonymous page using the object-based
|
|
* rmap method
|
|
* @page: the page to be handled
|
|
* @rwc: control variable according to each walk type
|
|
*
|
|
* Find all the mappings of a page using the mapping pointer and the vma chains
|
|
* contained in the anon_vma struct it points to.
|
|
*
|
|
* When called from page_mlock(), the mmap_lock of the mm containing the vma
|
|
* where the page was found will be held for write. So, we won't recheck
|
|
* vm_flags for that VMA. That should be OK, because that vma shouldn't be
|
|
* LOCKED.
|
|
*/
|
|
static void rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc,
|
|
bool locked)
|
|
{
|
|
struct anon_vma *anon_vma;
|
|
pgoff_t pgoff_start, pgoff_end;
|
|
struct anon_vma_chain *avc;
|
|
|
|
if (locked) {
|
|
anon_vma = page_anon_vma(page);
|
|
/* anon_vma disappear under us? */
|
|
VM_BUG_ON_PAGE(!anon_vma, page);
|
|
} else {
|
|
anon_vma = rmap_walk_anon_lock(page, rwc);
|
|
}
|
|
if (!anon_vma)
|
|
return;
|
|
|
|
pgoff_start = page_to_pgoff(page);
|
|
pgoff_end = pgoff_start + thp_nr_pages(page) - 1;
|
|
anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root,
|
|
pgoff_start, pgoff_end) {
|
|
struct vm_area_struct *vma = avc->vma;
|
|
unsigned long address = vma_address(page, vma);
|
|
|
|
VM_BUG_ON_VMA(address == -EFAULT, vma);
|
|
cond_resched();
|
|
|
|
if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
|
|
continue;
|
|
|
|
if (!rwc->rmap_one(page, vma, address, rwc->arg))
|
|
break;
|
|
if (rwc->done && rwc->done(page))
|
|
break;
|
|
}
|
|
|
|
if (!locked)
|
|
anon_vma_unlock_read(anon_vma);
|
|
}
|
|
|
|
/*
|
|
* rmap_walk_file - do something to file page using the object-based rmap method
|
|
* @page: the page to be handled
|
|
* @rwc: control variable according to each walk type
|
|
*
|
|
* Find all the mappings of a page using the mapping pointer and the vma chains
|
|
* contained in the address_space struct it points to.
|
|
*
|
|
* When called from page_mlock(), the mmap_lock of the mm containing the vma
|
|
* where the page was found will be held for write. So, we won't recheck
|
|
* vm_flags for that VMA. That should be OK, because that vma shouldn't be
|
|
* LOCKED.
|
|
*/
|
|
static void rmap_walk_file(struct page *page, struct rmap_walk_control *rwc,
|
|
bool locked)
|
|
{
|
|
struct address_space *mapping = page_mapping(page);
|
|
pgoff_t pgoff_start, pgoff_end;
|
|
struct vm_area_struct *vma;
|
|
|
|
/*
|
|
* The page lock not only makes sure that page->mapping cannot
|
|
* suddenly be NULLified by truncation, it makes sure that the
|
|
* structure at mapping cannot be freed and reused yet,
|
|
* so we can safely take mapping->i_mmap_rwsem.
|
|
*/
|
|
VM_BUG_ON_PAGE(!PageLocked(page), page);
|
|
|
|
if (!mapping)
|
|
return;
|
|
|
|
pgoff_start = page_to_pgoff(page);
|
|
pgoff_end = pgoff_start + thp_nr_pages(page) - 1;
|
|
if (!locked)
|
|
i_mmap_lock_read(mapping);
|
|
vma_interval_tree_foreach(vma, &mapping->i_mmap,
|
|
pgoff_start, pgoff_end) {
|
|
unsigned long address = vma_address(page, vma);
|
|
|
|
VM_BUG_ON_VMA(address == -EFAULT, vma);
|
|
cond_resched();
|
|
|
|
if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
|
|
continue;
|
|
|
|
if (!rwc->rmap_one(page, vma, address, rwc->arg))
|
|
goto done;
|
|
if (rwc->done && rwc->done(page))
|
|
goto done;
|
|
}
|
|
|
|
done:
|
|
if (!locked)
|
|
i_mmap_unlock_read(mapping);
|
|
}
|
|
|
|
void rmap_walk(struct page *page, struct rmap_walk_control *rwc)
|
|
{
|
|
if (unlikely(PageKsm(page)))
|
|
rmap_walk_ksm(page, rwc);
|
|
else if (PageAnon(page))
|
|
rmap_walk_anon(page, rwc, false);
|
|
else
|
|
rmap_walk_file(page, rwc, false);
|
|
}
|
|
|
|
/* Like rmap_walk, but caller holds relevant rmap lock */
|
|
void rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc)
|
|
{
|
|
/* no ksm support for now */
|
|
VM_BUG_ON_PAGE(PageKsm(page), page);
|
|
if (PageAnon(page))
|
|
rmap_walk_anon(page, rwc, true);
|
|
else
|
|
rmap_walk_file(page, rwc, true);
|
|
}
|
|
|
|
#ifdef CONFIG_HUGETLB_PAGE
|
|
/*
|
|
* The following two functions are for anonymous (private mapped) hugepages.
|
|
* Unlike common anonymous pages, anonymous hugepages have no accounting code
|
|
* and no lru code, because we handle hugepages differently from common pages.
|
|
*/
|
|
void hugepage_add_anon_rmap(struct page *page,
|
|
struct vm_area_struct *vma, unsigned long address)
|
|
{
|
|
struct anon_vma *anon_vma = vma->anon_vma;
|
|
int first;
|
|
|
|
BUG_ON(!PageLocked(page));
|
|
BUG_ON(!anon_vma);
|
|
/* address might be in next vma when migration races vma_adjust */
|
|
first = atomic_inc_and_test(compound_mapcount_ptr(page));
|
|
if (first)
|
|
__page_set_anon_rmap(page, vma, address, 0);
|
|
}
|
|
|
|
void hugepage_add_new_anon_rmap(struct page *page,
|
|
struct vm_area_struct *vma, unsigned long address)
|
|
{
|
|
BUG_ON(address < vma->vm_start || address >= vma->vm_end);
|
|
atomic_set(compound_mapcount_ptr(page), 0);
|
|
if (hpage_pincount_available(page))
|
|
atomic_set(compound_pincount_ptr(page), 0);
|
|
|
|
__page_set_anon_rmap(page, vma, address, 1);
|
|
}
|
|
#endif /* CONFIG_HUGETLB_PAGE */
|