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![Kirill A. Shutemov](/assets/img/avatar_default.png)
In struct page we have enough space to fit long-size page->ptl there, but we use dynamically-allocated page->ptl if size(spinlock_t) is larger than sizeof(int). It hurts 64-bit architectures with CONFIG_GENERIC_LOCKBREAK, where sizeof(spinlock_t) == 8, but it easily fits into struct page. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Hugh Dickins <hughd@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
512 lines
15 KiB
C
512 lines
15 KiB
C
#ifndef _LINUX_MM_TYPES_H
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#define _LINUX_MM_TYPES_H
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#include <linux/auxvec.h>
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#include <linux/types.h>
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#include <linux/threads.h>
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#include <linux/list.h>
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#include <linux/spinlock.h>
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#include <linux/rbtree.h>
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#include <linux/rwsem.h>
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#include <linux/completion.h>
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#include <linux/cpumask.h>
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#include <linux/page-debug-flags.h>
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#include <linux/uprobes.h>
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#include <linux/page-flags-layout.h>
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#include <asm/page.h>
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#include <asm/mmu.h>
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#ifndef AT_VECTOR_SIZE_ARCH
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#define AT_VECTOR_SIZE_ARCH 0
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#endif
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#define AT_VECTOR_SIZE (2*(AT_VECTOR_SIZE_ARCH + AT_VECTOR_SIZE_BASE + 1))
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struct address_space;
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#define USE_SPLIT_PTE_PTLOCKS (NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS)
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#define USE_SPLIT_PMD_PTLOCKS (USE_SPLIT_PTE_PTLOCKS && \
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IS_ENABLED(CONFIG_ARCH_ENABLE_SPLIT_PMD_PTLOCK))
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#define ALLOC_SPLIT_PTLOCKS (SPINLOCK_SIZE > BITS_PER_LONG/8)
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/*
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* Each physical page in the system has a struct page associated with
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* it to keep track of whatever it is we are using the page for at the
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* moment. Note that we have no way to track which tasks are using
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* a page, though if it is a pagecache page, rmap structures can tell us
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* who is mapping it.
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*
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* The objects in struct page are organized in double word blocks in
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* order to allows us to use atomic double word operations on portions
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* of struct page. That is currently only used by slub but the arrangement
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* allows the use of atomic double word operations on the flags/mapping
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* and lru list pointers also.
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*/
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struct page {
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/* First double word block */
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unsigned long flags; /* Atomic flags, some possibly
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* updated asynchronously */
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union {
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struct address_space *mapping; /* If low bit clear, points to
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* inode address_space, or NULL.
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* If page mapped as anonymous
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* memory, low bit is set, and
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* it points to anon_vma object:
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* see PAGE_MAPPING_ANON below.
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*/
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void *s_mem; /* slab first object */
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};
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/* Second double word */
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struct {
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union {
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pgoff_t index; /* Our offset within mapping. */
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void *freelist; /* sl[aou]b first free object */
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bool pfmemalloc; /* If set by the page allocator,
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* ALLOC_NO_WATERMARKS was set
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* and the low watermark was not
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* met implying that the system
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* is under some pressure. The
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* caller should try ensure
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* this page is only used to
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* free other pages.
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*/
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};
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union {
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#if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \
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defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
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/* Used for cmpxchg_double in slub */
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unsigned long counters;
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#else
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/*
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* Keep _count separate from slub cmpxchg_double data.
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* As the rest of the double word is protected by
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* slab_lock but _count is not.
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*/
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unsigned counters;
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#endif
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struct {
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union {
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/*
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* Count of ptes mapped in
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* mms, to show when page is
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* mapped & limit reverse map
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* searches.
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*
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* Used also for tail pages
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* refcounting instead of
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* _count. Tail pages cannot
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* be mapped and keeping the
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* tail page _count zero at
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* all times guarantees
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* get_page_unless_zero() will
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* never succeed on tail
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* pages.
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*/
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atomic_t _mapcount;
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struct { /* SLUB */
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unsigned inuse:16;
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unsigned objects:15;
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unsigned frozen:1;
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};
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int units; /* SLOB */
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};
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atomic_t _count; /* Usage count, see below. */
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};
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unsigned int active; /* SLAB */
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};
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};
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/* Third double word block */
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union {
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struct list_head lru; /* Pageout list, eg. active_list
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* protected by zone->lru_lock !
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*/
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struct { /* slub per cpu partial pages */
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struct page *next; /* Next partial slab */
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#ifdef CONFIG_64BIT
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int pages; /* Nr of partial slabs left */
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int pobjects; /* Approximate # of objects */
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#else
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short int pages;
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short int pobjects;
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#endif
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};
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struct list_head list; /* slobs list of pages */
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struct slab *slab_page; /* slab fields */
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struct rcu_head rcu_head; /* Used by SLAB
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* when destroying via RCU
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*/
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#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && USE_SPLIT_PMD_PTLOCKS
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pgtable_t pmd_huge_pte; /* protected by page->ptl */
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#endif
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};
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/* Remainder is not double word aligned */
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union {
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unsigned long private; /* Mapping-private opaque data:
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* usually used for buffer_heads
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* if PagePrivate set; used for
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* swp_entry_t if PageSwapCache;
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* indicates order in the buddy
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* system if PG_buddy is set.
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*/
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#if USE_SPLIT_PTE_PTLOCKS
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#if ALLOC_SPLIT_PTLOCKS
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spinlock_t *ptl;
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#else
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spinlock_t ptl;
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#endif
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#endif
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struct kmem_cache *slab_cache; /* SL[AU]B: Pointer to slab */
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struct page *first_page; /* Compound tail pages */
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};
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/*
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* On machines where all RAM is mapped into kernel address space,
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* we can simply calculate the virtual address. On machines with
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* highmem some memory is mapped into kernel virtual memory
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* dynamically, so we need a place to store that address.
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* Note that this field could be 16 bits on x86 ... ;)
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*
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* Architectures with slow multiplication can define
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* WANT_PAGE_VIRTUAL in asm/page.h
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*/
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#if defined(WANT_PAGE_VIRTUAL)
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void *virtual; /* Kernel virtual address (NULL if
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not kmapped, ie. highmem) */
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#endif /* WANT_PAGE_VIRTUAL */
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#ifdef CONFIG_WANT_PAGE_DEBUG_FLAGS
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unsigned long debug_flags; /* Use atomic bitops on this */
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#endif
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#ifdef CONFIG_KMEMCHECK
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/*
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* kmemcheck wants to track the status of each byte in a page; this
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* is a pointer to such a status block. NULL if not tracked.
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*/
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void *shadow;
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#endif
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#ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
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int _last_cpupid;
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#endif
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}
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/*
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* The struct page can be forced to be double word aligned so that atomic ops
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* on double words work. The SLUB allocator can make use of such a feature.
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*/
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#ifdef CONFIG_HAVE_ALIGNED_STRUCT_PAGE
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__aligned(2 * sizeof(unsigned long))
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#endif
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;
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struct page_frag {
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struct page *page;
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#if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536)
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__u32 offset;
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__u32 size;
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#else
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__u16 offset;
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__u16 size;
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#endif
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};
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typedef unsigned long __nocast vm_flags_t;
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/*
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* A region containing a mapping of a non-memory backed file under NOMMU
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* conditions. These are held in a global tree and are pinned by the VMAs that
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* map parts of them.
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*/
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struct vm_region {
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struct rb_node vm_rb; /* link in global region tree */
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vm_flags_t vm_flags; /* VMA vm_flags */
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unsigned long vm_start; /* start address of region */
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unsigned long vm_end; /* region initialised to here */
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unsigned long vm_top; /* region allocated to here */
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unsigned long vm_pgoff; /* the offset in vm_file corresponding to vm_start */
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struct file *vm_file; /* the backing file or NULL */
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int vm_usage; /* region usage count (access under nommu_region_sem) */
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bool vm_icache_flushed : 1; /* true if the icache has been flushed for
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* this region */
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};
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/*
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* This struct defines a memory VMM memory area. There is one of these
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* per VM-area/task. A VM area is any part of the process virtual memory
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* space that has a special rule for the page-fault handlers (ie a shared
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* library, the executable area etc).
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*/
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struct vm_area_struct {
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/* The first cache line has the info for VMA tree walking. */
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unsigned long vm_start; /* Our start address within vm_mm. */
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unsigned long vm_end; /* The first byte after our end address
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within vm_mm. */
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/* linked list of VM areas per task, sorted by address */
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struct vm_area_struct *vm_next, *vm_prev;
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struct rb_node vm_rb;
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/*
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* Largest free memory gap in bytes to the left of this VMA.
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* Either between this VMA and vma->vm_prev, or between one of the
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* VMAs below us in the VMA rbtree and its ->vm_prev. This helps
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* get_unmapped_area find a free area of the right size.
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*/
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unsigned long rb_subtree_gap;
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/* Second cache line starts here. */
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struct mm_struct *vm_mm; /* The address space we belong to. */
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pgprot_t vm_page_prot; /* Access permissions of this VMA. */
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unsigned long vm_flags; /* Flags, see mm.h. */
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/*
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* For areas with an address space and backing store,
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* linkage into the address_space->i_mmap interval tree, or
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* linkage of vma in the address_space->i_mmap_nonlinear list.
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*/
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union {
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struct {
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struct rb_node rb;
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unsigned long rb_subtree_last;
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} linear;
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struct list_head nonlinear;
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} shared;
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/*
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* A file's MAP_PRIVATE vma can be in both i_mmap tree and anon_vma
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* list, after a COW of one of the file pages. A MAP_SHARED vma
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* can only be in the i_mmap tree. An anonymous MAP_PRIVATE, stack
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* or brk vma (with NULL file) can only be in an anon_vma list.
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*/
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struct list_head anon_vma_chain; /* Serialized by mmap_sem &
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* page_table_lock */
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struct anon_vma *anon_vma; /* Serialized by page_table_lock */
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/* Function pointers to deal with this struct. */
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const struct vm_operations_struct *vm_ops;
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/* Information about our backing store: */
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unsigned long vm_pgoff; /* Offset (within vm_file) in PAGE_SIZE
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units, *not* PAGE_CACHE_SIZE */
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struct file * vm_file; /* File we map to (can be NULL). */
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void * vm_private_data; /* was vm_pte (shared mem) */
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#ifndef CONFIG_MMU
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struct vm_region *vm_region; /* NOMMU mapping region */
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#endif
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#ifdef CONFIG_NUMA
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struct mempolicy *vm_policy; /* NUMA policy for the VMA */
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#endif
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};
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struct core_thread {
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struct task_struct *task;
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struct core_thread *next;
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};
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struct core_state {
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atomic_t nr_threads;
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struct core_thread dumper;
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struct completion startup;
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};
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enum {
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MM_FILEPAGES,
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MM_ANONPAGES,
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MM_SWAPENTS,
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NR_MM_COUNTERS
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};
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#if USE_SPLIT_PTE_PTLOCKS && defined(CONFIG_MMU)
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#define SPLIT_RSS_COUNTING
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/* per-thread cached information, */
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struct task_rss_stat {
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int events; /* for synchronization threshold */
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int count[NR_MM_COUNTERS];
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};
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#endif /* USE_SPLIT_PTE_PTLOCKS */
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struct mm_rss_stat {
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atomic_long_t count[NR_MM_COUNTERS];
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};
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struct kioctx_table;
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struct mm_struct {
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struct vm_area_struct * mmap; /* list of VMAs */
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struct rb_root mm_rb;
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struct vm_area_struct * mmap_cache; /* last find_vma result */
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#ifdef CONFIG_MMU
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unsigned long (*get_unmapped_area) (struct file *filp,
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unsigned long addr, unsigned long len,
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unsigned long pgoff, unsigned long flags);
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#endif
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unsigned long mmap_base; /* base of mmap area */
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unsigned long mmap_legacy_base; /* base of mmap area in bottom-up allocations */
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unsigned long task_size; /* size of task vm space */
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unsigned long highest_vm_end; /* highest vma end address */
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pgd_t * pgd;
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atomic_t mm_users; /* How many users with user space? */
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atomic_t mm_count; /* How many references to "struct mm_struct" (users count as 1) */
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atomic_long_t nr_ptes; /* Page table pages */
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int map_count; /* number of VMAs */
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spinlock_t page_table_lock; /* Protects page tables and some counters */
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struct rw_semaphore mmap_sem;
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struct list_head mmlist; /* List of maybe swapped mm's. These are globally strung
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* together off init_mm.mmlist, and are protected
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* by mmlist_lock
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*/
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unsigned long hiwater_rss; /* High-watermark of RSS usage */
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unsigned long hiwater_vm; /* High-water virtual memory usage */
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unsigned long total_vm; /* Total pages mapped */
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unsigned long locked_vm; /* Pages that have PG_mlocked set */
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unsigned long pinned_vm; /* Refcount permanently increased */
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unsigned long shared_vm; /* Shared pages (files) */
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unsigned long exec_vm; /* VM_EXEC & ~VM_WRITE */
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unsigned long stack_vm; /* VM_GROWSUP/DOWN */
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unsigned long def_flags;
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unsigned long start_code, end_code, start_data, end_data;
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unsigned long start_brk, brk, start_stack;
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unsigned long arg_start, arg_end, env_start, env_end;
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unsigned long saved_auxv[AT_VECTOR_SIZE]; /* for /proc/PID/auxv */
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/*
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* Special counters, in some configurations protected by the
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* page_table_lock, in other configurations by being atomic.
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*/
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struct mm_rss_stat rss_stat;
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struct linux_binfmt *binfmt;
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cpumask_var_t cpu_vm_mask_var;
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/* Architecture-specific MM context */
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mm_context_t context;
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unsigned long flags; /* Must use atomic bitops to access the bits */
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struct core_state *core_state; /* coredumping support */
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#ifdef CONFIG_AIO
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spinlock_t ioctx_lock;
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struct kioctx_table __rcu *ioctx_table;
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#endif
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#ifdef CONFIG_MM_OWNER
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/*
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* "owner" points to a task that is regarded as the canonical
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* user/owner of this mm. All of the following must be true in
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* order for it to be changed:
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*
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* current == mm->owner
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* current->mm != mm
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* new_owner->mm == mm
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* new_owner->alloc_lock is held
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*/
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struct task_struct __rcu *owner;
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#endif
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/* store ref to file /proc/<pid>/exe symlink points to */
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struct file *exe_file;
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#ifdef CONFIG_MMU_NOTIFIER
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struct mmu_notifier_mm *mmu_notifier_mm;
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#endif
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#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
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pgtable_t pmd_huge_pte; /* protected by page_table_lock */
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#endif
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#ifdef CONFIG_CPUMASK_OFFSTACK
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struct cpumask cpumask_allocation;
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#endif
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#ifdef CONFIG_NUMA_BALANCING
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/*
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* numa_next_scan is the next time that the PTEs will be marked
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* pte_numa. NUMA hinting faults will gather statistics and migrate
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* pages to new nodes if necessary.
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*/
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unsigned long numa_next_scan;
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/* Restart point for scanning and setting pte_numa */
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unsigned long numa_scan_offset;
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/* numa_scan_seq prevents two threads setting pte_numa */
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int numa_scan_seq;
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#endif
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#if defined(CONFIG_NUMA_BALANCING) || defined(CONFIG_COMPACTION)
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/*
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* An operation with batched TLB flushing is going on. Anything that
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* can move process memory needs to flush the TLB when moving a
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* PROT_NONE or PROT_NUMA mapped page.
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*/
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bool tlb_flush_pending;
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#endif
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struct uprobes_state uprobes_state;
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};
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static inline void mm_init_cpumask(struct mm_struct *mm)
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{
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#ifdef CONFIG_CPUMASK_OFFSTACK
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mm->cpu_vm_mask_var = &mm->cpumask_allocation;
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#endif
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}
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/* Future-safe accessor for struct mm_struct's cpu_vm_mask. */
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static inline cpumask_t *mm_cpumask(struct mm_struct *mm)
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{
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return mm->cpu_vm_mask_var;
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}
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#if defined(CONFIG_NUMA_BALANCING) || defined(CONFIG_COMPACTION)
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/*
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* Memory barriers to keep this state in sync are graciously provided by
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* the page table locks, outside of which no page table modifications happen.
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* The barriers below prevent the compiler from re-ordering the instructions
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* around the memory barriers that are already present in the code.
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*/
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static inline bool mm_tlb_flush_pending(struct mm_struct *mm)
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{
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barrier();
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return mm->tlb_flush_pending;
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}
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static inline void set_tlb_flush_pending(struct mm_struct *mm)
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{
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mm->tlb_flush_pending = true;
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/*
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* Guarantee that the tlb_flush_pending store does not leak into the
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* critical section updating the page tables
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*/
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smp_mb__before_spinlock();
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}
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/* Clearing is done after a TLB flush, which also provides a barrier. */
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static inline void clear_tlb_flush_pending(struct mm_struct *mm)
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{
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barrier();
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mm->tlb_flush_pending = false;
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}
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#else
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static inline bool mm_tlb_flush_pending(struct mm_struct *mm)
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|
{
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|
return false;
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|
}
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static inline void set_tlb_flush_pending(struct mm_struct *mm)
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|
{
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|
}
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|
static inline void clear_tlb_flush_pending(struct mm_struct *mm)
|
|
{
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|
}
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|
#endif
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|
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#endif /* _LINUX_MM_TYPES_H */
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