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![Jiexun Wang](/assets/img/avatar_default.png)
I conducted real-time testing and observed that madvise_cold_or_pageout_pte_range() causes significant latency under memory pressure, which can be effectively reduced by adding cond_resched() within the loop. I tested on the LicheePi 4A board using Cylictest for latency testing and Ftrace for latency tracing. The board uses TH1520 processor and has a memory size of 8GB. The kernel version is 6.5.0 with the PREEMPT_RT patch applied. The script I tested is as follows: echo wakeup_rt > /sys/kernel/tracing/current_tracer echo 1 > /sys/kernel/tracing/tracing_on echo 0 > /sys/kernel/tracing/tracing_max_latency stress-ng --vm 8 --vm-bytes 2G & cyclictest --mlockall --smp --priority=99 --distance=0 --duration=30m echo 0 > /sys/kernel/tracing/tracing_on cat /sys/kernel/tracing/trace The tracing results before modification are as follows: # tracer: wakeup_rt # # wakeup_rt latency trace v1.1.5 on 6.5.0-rt6-r1208-00003-g999d221864bf # -------------------------------------------------------------------- # latency: 2552 us, #6/6, CPU#3 | (M:preempt_rt VP:0, KP:0, SP:0 HP:0 #P:4) # ----------------- # | task: cyclictest-196 (uid:0 nice:0 policy:1 rt_prio:99) # ----------------- # # _--------=> CPU# # / _-------=> irqs-off/BH-disabled # | / _------=> need-resched # || / _-----=> need-resched-lazy # ||| / _----=> hardirq/softirq # |||| / _---=> preempt-depth # ||||| / _--=> preempt-lazy-depth # |||||| / _-=> migrate-disable # ||||||| / delay # cmd pid |||||||| time | caller # \ / |||||||| \ | / stress-n-206 3dn.h512 2us : 206:120:R + [003] 196: 0:R cyclictest stress-n-206 3dn.h512 7us : <stack trace> => __ftrace_trace_stack => __trace_stack => probe_wakeup => ttwu_do_activate => try_to_wake_up => wake_up_process => hrtimer_wakeup => __hrtimer_run_queues => hrtimer_interrupt => riscv_timer_interrupt => handle_percpu_devid_irq => generic_handle_domain_irq => riscv_intc_irq => handle_riscv_irq => do_irq stress-n-206 3dn.h512 9us#: 0 stress-n-206 3d...3.. 2544us : __schedule stress-n-206 3d...3.. 2545us : 206:120:R ==> [003] 196: 0:R cyclictest stress-n-206 3d...3.. 2551us : <stack trace> => __ftrace_trace_stack => __trace_stack => probe_wakeup_sched_switch => __schedule => preempt_schedule => migrate_enable => rt_spin_unlock => madvise_cold_or_pageout_pte_range => walk_pgd_range => __walk_page_range => walk_page_range => madvise_pageout => madvise_vma_behavior => do_madvise => sys_madvise => do_trap_ecall_u => ret_from_exception The tracing results after modification are as follows: # tracer: wakeup_rt # # wakeup_rt latency trace v1.1.5 on 6.5.0-rt6-r1208-00004-gca3876fc69a6-dirty # -------------------------------------------------------------------- # latency: 1689 us, #6/6, CPU#0 | (M:preempt_rt VP:0, KP:0, SP:0 HP:0 #P:4) # ----------------- # | task: cyclictest-217 (uid:0 nice:0 policy:1 rt_prio:99) # ----------------- # # _--------=> CPU# # / _-------=> irqs-off/BH-disabled # | / _------=> need-resched # || / _-----=> need-resched-lazy # ||| / _----=> hardirq/softirq # |||| / _---=> preempt-depth # ||||| / _--=> preempt-lazy-depth # |||||| / _-=> migrate-disable # ||||||| / delay # cmd pid |||||||| time | caller # \ / |||||||| \ | / stress-n-232 0dn.h413 1us+: 232:120:R + [000] 217: 0:R cyclictest stress-n-232 0dn.h413 12us : <stack trace> => __ftrace_trace_stack => __trace_stack => probe_wakeup => ttwu_do_activate => try_to_wake_up => wake_up_process => hrtimer_wakeup => __hrtimer_run_queues => hrtimer_interrupt => riscv_timer_interrupt => handle_percpu_devid_irq => generic_handle_domain_irq => riscv_intc_irq => handle_riscv_irq => do_irq stress-n-232 0dn.h413 19us#: 0 stress-n-232 0d...3.. 1671us : __schedule stress-n-232 0d...3.. 1676us+: 232:120:R ==> [000] 217: 0:R cyclictest stress-n-232 0d...3.. 1687us : <stack trace> => __ftrace_trace_stack => __trace_stack => probe_wakeup_sched_switch => __schedule => preempt_schedule => migrate_enable => free_unref_page_list => release_pages => free_pages_and_swap_cache => tlb_batch_pages_flush => tlb_flush_mmu => unmap_page_range => unmap_vmas => unmap_region => do_vmi_align_munmap.constprop.0 => do_vmi_munmap => __vm_munmap => sys_munmap => do_trap_ecall_u => ret_from_exception After the modification, the cause of maximum latency is no longer madvise_cold_or_pageout_pte_range(), so this modification can reduce the latency caused by madvise_cold_or_pageout_pte_range(). Currently the madvise_cold_or_pageout_pte_range() function exhibits significant latency under memory pressure, which can be effectively reduced by adding cond_resched() within the loop. When the batch_count reaches SWAP_CLUSTER_MAX, we reschedule the task to ensure fairness and avoid long lock holding times. Link: https://lkml.kernel.org/r/85363861af65fac66c7a98c251906afc0d9c8098.1695291046.git.wangjiexun@tinylab.org Signed-off-by: Jiexun Wang <wangjiexun@tinylab.org> Cc: Zhangjin Wu <falcon@tinylab.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
1524 lines
39 KiB
C
1524 lines
39 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* linux/mm/madvise.c
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*
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* Copyright (C) 1999 Linus Torvalds
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* Copyright (C) 2002 Christoph Hellwig
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*/
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#include <linux/mman.h>
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#include <linux/pagemap.h>
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#include <linux/syscalls.h>
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#include <linux/mempolicy.h>
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#include <linux/page-isolation.h>
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#include <linux/page_idle.h>
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#include <linux/userfaultfd_k.h>
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#include <linux/hugetlb.h>
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#include <linux/falloc.h>
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#include <linux/fadvise.h>
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#include <linux/sched.h>
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#include <linux/sched/mm.h>
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#include <linux/mm_inline.h>
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#include <linux/string.h>
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#include <linux/uio.h>
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#include <linux/ksm.h>
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#include <linux/fs.h>
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#include <linux/file.h>
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#include <linux/blkdev.h>
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#include <linux/backing-dev.h>
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#include <linux/pagewalk.h>
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#include <linux/swap.h>
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#include <linux/swapops.h>
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#include <linux/shmem_fs.h>
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#include <linux/mmu_notifier.h>
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#include <asm/tlb.h>
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#include "internal.h"
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#include "swap.h"
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struct madvise_walk_private {
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struct mmu_gather *tlb;
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bool pageout;
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};
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/*
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* Any behaviour which results in changes to the vma->vm_flags needs to
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* take mmap_lock for writing. Others, which simply traverse vmas, need
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* to only take it for reading.
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*/
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static int madvise_need_mmap_write(int behavior)
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{
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switch (behavior) {
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case MADV_REMOVE:
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case MADV_WILLNEED:
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case MADV_DONTNEED:
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case MADV_DONTNEED_LOCKED:
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case MADV_COLD:
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case MADV_PAGEOUT:
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case MADV_FREE:
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case MADV_POPULATE_READ:
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case MADV_POPULATE_WRITE:
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case MADV_COLLAPSE:
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return 0;
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default:
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/* be safe, default to 1. list exceptions explicitly */
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return 1;
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}
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}
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#ifdef CONFIG_ANON_VMA_NAME
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struct anon_vma_name *anon_vma_name_alloc(const char *name)
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{
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struct anon_vma_name *anon_name;
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size_t count;
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/* Add 1 for NUL terminator at the end of the anon_name->name */
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count = strlen(name) + 1;
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anon_name = kmalloc(struct_size(anon_name, name, count), GFP_KERNEL);
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if (anon_name) {
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kref_init(&anon_name->kref);
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memcpy(anon_name->name, name, count);
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}
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return anon_name;
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}
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void anon_vma_name_free(struct kref *kref)
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{
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struct anon_vma_name *anon_name =
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container_of(kref, struct anon_vma_name, kref);
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kfree(anon_name);
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}
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struct anon_vma_name *anon_vma_name(struct vm_area_struct *vma)
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{
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mmap_assert_locked(vma->vm_mm);
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return vma->anon_name;
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}
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/* mmap_lock should be write-locked */
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static int replace_anon_vma_name(struct vm_area_struct *vma,
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struct anon_vma_name *anon_name)
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{
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struct anon_vma_name *orig_name = anon_vma_name(vma);
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if (!anon_name) {
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vma->anon_name = NULL;
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anon_vma_name_put(orig_name);
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return 0;
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}
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if (anon_vma_name_eq(orig_name, anon_name))
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return 0;
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vma->anon_name = anon_vma_name_reuse(anon_name);
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anon_vma_name_put(orig_name);
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return 0;
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}
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#else /* CONFIG_ANON_VMA_NAME */
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static int replace_anon_vma_name(struct vm_area_struct *vma,
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struct anon_vma_name *anon_name)
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{
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if (anon_name)
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return -EINVAL;
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return 0;
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}
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#endif /* CONFIG_ANON_VMA_NAME */
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/*
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* Update the vm_flags on region of a vma, splitting it or merging it as
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* necessary. Must be called with mmap_lock held for writing;
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* Caller should ensure anon_name stability by raising its refcount even when
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* anon_name belongs to a valid vma because this function might free that vma.
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*/
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static int madvise_update_vma(struct vm_area_struct *vma,
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struct vm_area_struct **prev, unsigned long start,
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unsigned long end, unsigned long new_flags,
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struct anon_vma_name *anon_name)
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{
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struct mm_struct *mm = vma->vm_mm;
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int error;
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VMA_ITERATOR(vmi, mm, start);
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if (new_flags == vma->vm_flags && anon_vma_name_eq(anon_vma_name(vma), anon_name)) {
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*prev = vma;
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return 0;
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}
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vma = vma_modify_flags_name(&vmi, *prev, vma, start, end, new_flags,
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anon_name);
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if (IS_ERR(vma))
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return PTR_ERR(vma);
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*prev = vma;
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/* vm_flags is protected by the mmap_lock held in write mode. */
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vma_start_write(vma);
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vm_flags_reset(vma, new_flags);
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if (!vma->vm_file || vma_is_anon_shmem(vma)) {
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error = replace_anon_vma_name(vma, anon_name);
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if (error)
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return error;
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}
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return 0;
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}
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#ifdef CONFIG_SWAP
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static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start,
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unsigned long end, struct mm_walk *walk)
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{
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struct vm_area_struct *vma = walk->private;
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struct swap_iocb *splug = NULL;
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pte_t *ptep = NULL;
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spinlock_t *ptl;
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unsigned long addr;
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for (addr = start; addr < end; addr += PAGE_SIZE) {
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pte_t pte;
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swp_entry_t entry;
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struct page *page;
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if (!ptep++) {
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ptep = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
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if (!ptep)
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break;
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}
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pte = ptep_get(ptep);
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if (!is_swap_pte(pte))
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continue;
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entry = pte_to_swp_entry(pte);
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if (unlikely(non_swap_entry(entry)))
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continue;
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pte_unmap_unlock(ptep, ptl);
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ptep = NULL;
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page = read_swap_cache_async(entry, GFP_HIGHUSER_MOVABLE,
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vma, addr, &splug);
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if (page)
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put_page(page);
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}
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if (ptep)
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pte_unmap_unlock(ptep, ptl);
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swap_read_unplug(splug);
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cond_resched();
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return 0;
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}
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static const struct mm_walk_ops swapin_walk_ops = {
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.pmd_entry = swapin_walk_pmd_entry,
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.walk_lock = PGWALK_RDLOCK,
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};
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static void shmem_swapin_range(struct vm_area_struct *vma,
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unsigned long start, unsigned long end,
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struct address_space *mapping)
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{
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XA_STATE(xas, &mapping->i_pages, linear_page_index(vma, start));
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pgoff_t end_index = linear_page_index(vma, end) - 1;
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struct page *page;
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struct swap_iocb *splug = NULL;
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rcu_read_lock();
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xas_for_each(&xas, page, end_index) {
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unsigned long addr;
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swp_entry_t entry;
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if (!xa_is_value(page))
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continue;
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entry = radix_to_swp_entry(page);
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/* There might be swapin error entries in shmem mapping. */
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if (non_swap_entry(entry))
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continue;
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addr = vma->vm_start +
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((xas.xa_index - vma->vm_pgoff) << PAGE_SHIFT);
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xas_pause(&xas);
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rcu_read_unlock();
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page = read_swap_cache_async(entry, mapping_gfp_mask(mapping),
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vma, addr, &splug);
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if (page)
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put_page(page);
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rcu_read_lock();
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}
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rcu_read_unlock();
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swap_read_unplug(splug);
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}
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#endif /* CONFIG_SWAP */
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/*
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* Schedule all required I/O operations. Do not wait for completion.
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*/
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static long madvise_willneed(struct vm_area_struct *vma,
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struct vm_area_struct **prev,
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unsigned long start, unsigned long end)
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{
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struct mm_struct *mm = vma->vm_mm;
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struct file *file = vma->vm_file;
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loff_t offset;
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*prev = vma;
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#ifdef CONFIG_SWAP
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if (!file) {
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walk_page_range(vma->vm_mm, start, end, &swapin_walk_ops, vma);
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lru_add_drain(); /* Push any new pages onto the LRU now */
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return 0;
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}
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if (shmem_mapping(file->f_mapping)) {
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shmem_swapin_range(vma, start, end, file->f_mapping);
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lru_add_drain(); /* Push any new pages onto the LRU now */
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return 0;
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}
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#else
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if (!file)
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return -EBADF;
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#endif
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if (IS_DAX(file_inode(file))) {
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/* no bad return value, but ignore advice */
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return 0;
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}
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/*
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* Filesystem's fadvise may need to take various locks. We need to
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* explicitly grab a reference because the vma (and hence the
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* vma's reference to the file) can go away as soon as we drop
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* mmap_lock.
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*/
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*prev = NULL; /* tell sys_madvise we drop mmap_lock */
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get_file(file);
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offset = (loff_t)(start - vma->vm_start)
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+ ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
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mmap_read_unlock(mm);
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vfs_fadvise(file, offset, end - start, POSIX_FADV_WILLNEED);
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fput(file);
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mmap_read_lock(mm);
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return 0;
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}
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static inline bool can_do_file_pageout(struct vm_area_struct *vma)
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{
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if (!vma->vm_file)
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return false;
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/*
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* paging out pagecache only for non-anonymous mappings that correspond
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* to the files the calling process could (if tried) open for writing;
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* otherwise we'd be including shared non-exclusive mappings, which
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* opens a side channel.
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*/
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return inode_owner_or_capable(&nop_mnt_idmap,
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file_inode(vma->vm_file)) ||
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file_permission(vma->vm_file, MAY_WRITE) == 0;
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}
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static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
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unsigned long addr, unsigned long end,
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struct mm_walk *walk)
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{
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struct madvise_walk_private *private = walk->private;
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struct mmu_gather *tlb = private->tlb;
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bool pageout = private->pageout;
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struct mm_struct *mm = tlb->mm;
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struct vm_area_struct *vma = walk->vma;
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pte_t *start_pte, *pte, ptent;
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spinlock_t *ptl;
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struct folio *folio = NULL;
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LIST_HEAD(folio_list);
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bool pageout_anon_only_filter;
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unsigned int batch_count = 0;
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if (fatal_signal_pending(current))
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return -EINTR;
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pageout_anon_only_filter = pageout && !vma_is_anonymous(vma) &&
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!can_do_file_pageout(vma);
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#ifdef CONFIG_TRANSPARENT_HUGEPAGE
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if (pmd_trans_huge(*pmd)) {
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pmd_t orig_pmd;
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unsigned long next = pmd_addr_end(addr, end);
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tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
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ptl = pmd_trans_huge_lock(pmd, vma);
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if (!ptl)
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return 0;
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orig_pmd = *pmd;
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if (is_huge_zero_pmd(orig_pmd))
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goto huge_unlock;
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if (unlikely(!pmd_present(orig_pmd))) {
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VM_BUG_ON(thp_migration_supported() &&
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!is_pmd_migration_entry(orig_pmd));
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goto huge_unlock;
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}
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folio = pfn_folio(pmd_pfn(orig_pmd));
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/* Do not interfere with other mappings of this folio */
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if (folio_estimated_sharers(folio) != 1)
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goto huge_unlock;
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if (pageout_anon_only_filter && !folio_test_anon(folio))
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goto huge_unlock;
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if (next - addr != HPAGE_PMD_SIZE) {
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int err;
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folio_get(folio);
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spin_unlock(ptl);
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folio_lock(folio);
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err = split_folio(folio);
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folio_unlock(folio);
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folio_put(folio);
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if (!err)
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goto regular_folio;
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return 0;
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}
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if (pmd_young(orig_pmd)) {
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pmdp_invalidate(vma, addr, pmd);
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orig_pmd = pmd_mkold(orig_pmd);
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set_pmd_at(mm, addr, pmd, orig_pmd);
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tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
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}
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folio_clear_referenced(folio);
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folio_test_clear_young(folio);
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if (folio_test_active(folio))
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folio_set_workingset(folio);
|
|
if (pageout) {
|
|
if (folio_isolate_lru(folio)) {
|
|
if (folio_test_unevictable(folio))
|
|
folio_putback_lru(folio);
|
|
else
|
|
list_add(&folio->lru, &folio_list);
|
|
}
|
|
} else
|
|
folio_deactivate(folio);
|
|
huge_unlock:
|
|
spin_unlock(ptl);
|
|
if (pageout)
|
|
reclaim_pages(&folio_list);
|
|
return 0;
|
|
}
|
|
|
|
regular_folio:
|
|
#endif
|
|
tlb_change_page_size(tlb, PAGE_SIZE);
|
|
restart:
|
|
start_pte = pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
|
|
if (!start_pte)
|
|
return 0;
|
|
flush_tlb_batched_pending(mm);
|
|
arch_enter_lazy_mmu_mode();
|
|
for (; addr < end; pte++, addr += PAGE_SIZE) {
|
|
ptent = ptep_get(pte);
|
|
|
|
if (++batch_count == SWAP_CLUSTER_MAX) {
|
|
batch_count = 0;
|
|
if (need_resched()) {
|
|
pte_unmap_unlock(start_pte, ptl);
|
|
cond_resched();
|
|
goto restart;
|
|
}
|
|
}
|
|
|
|
if (pte_none(ptent))
|
|
continue;
|
|
|
|
if (!pte_present(ptent))
|
|
continue;
|
|
|
|
folio = vm_normal_folio(vma, addr, ptent);
|
|
if (!folio || folio_is_zone_device(folio))
|
|
continue;
|
|
|
|
/*
|
|
* Creating a THP page is expensive so split it only if we
|
|
* are sure it's worth. Split it if we are only owner.
|
|
*/
|
|
if (folio_test_large(folio)) {
|
|
int err;
|
|
|
|
if (folio_estimated_sharers(folio) != 1)
|
|
break;
|
|
if (pageout_anon_only_filter && !folio_test_anon(folio))
|
|
break;
|
|
if (!folio_trylock(folio))
|
|
break;
|
|
folio_get(folio);
|
|
arch_leave_lazy_mmu_mode();
|
|
pte_unmap_unlock(start_pte, ptl);
|
|
start_pte = NULL;
|
|
err = split_folio(folio);
|
|
folio_unlock(folio);
|
|
folio_put(folio);
|
|
if (err)
|
|
break;
|
|
start_pte = pte =
|
|
pte_offset_map_lock(mm, pmd, addr, &ptl);
|
|
if (!start_pte)
|
|
break;
|
|
arch_enter_lazy_mmu_mode();
|
|
pte--;
|
|
addr -= PAGE_SIZE;
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* Do not interfere with other mappings of this folio and
|
|
* non-LRU folio.
|
|
*/
|
|
if (!folio_test_lru(folio) || folio_mapcount(folio) != 1)
|
|
continue;
|
|
|
|
if (pageout_anon_only_filter && !folio_test_anon(folio))
|
|
continue;
|
|
|
|
VM_BUG_ON_FOLIO(folio_test_large(folio), folio);
|
|
|
|
if (pte_young(ptent)) {
|
|
ptent = ptep_get_and_clear_full(mm, addr, pte,
|
|
tlb->fullmm);
|
|
ptent = pte_mkold(ptent);
|
|
set_pte_at(mm, addr, pte, ptent);
|
|
tlb_remove_tlb_entry(tlb, pte, addr);
|
|
}
|
|
|
|
/*
|
|
* We are deactivating a folio for accelerating reclaiming.
|
|
* VM couldn't reclaim the folio unless we clear PG_young.
|
|
* As a side effect, it makes confuse idle-page tracking
|
|
* because they will miss recent referenced history.
|
|
*/
|
|
folio_clear_referenced(folio);
|
|
folio_test_clear_young(folio);
|
|
if (folio_test_active(folio))
|
|
folio_set_workingset(folio);
|
|
if (pageout) {
|
|
if (folio_isolate_lru(folio)) {
|
|
if (folio_test_unevictable(folio))
|
|
folio_putback_lru(folio);
|
|
else
|
|
list_add(&folio->lru, &folio_list);
|
|
}
|
|
} else
|
|
folio_deactivate(folio);
|
|
}
|
|
|
|
if (start_pte) {
|
|
arch_leave_lazy_mmu_mode();
|
|
pte_unmap_unlock(start_pte, ptl);
|
|
}
|
|
if (pageout)
|
|
reclaim_pages(&folio_list);
|
|
cond_resched();
|
|
|
|
return 0;
|
|
}
|
|
|
|
static const struct mm_walk_ops cold_walk_ops = {
|
|
.pmd_entry = madvise_cold_or_pageout_pte_range,
|
|
.walk_lock = PGWALK_RDLOCK,
|
|
};
|
|
|
|
static void madvise_cold_page_range(struct mmu_gather *tlb,
|
|
struct vm_area_struct *vma,
|
|
unsigned long addr, unsigned long end)
|
|
{
|
|
struct madvise_walk_private walk_private = {
|
|
.pageout = false,
|
|
.tlb = tlb,
|
|
};
|
|
|
|
tlb_start_vma(tlb, vma);
|
|
walk_page_range(vma->vm_mm, addr, end, &cold_walk_ops, &walk_private);
|
|
tlb_end_vma(tlb, vma);
|
|
}
|
|
|
|
static inline bool can_madv_lru_vma(struct vm_area_struct *vma)
|
|
{
|
|
return !(vma->vm_flags & (VM_LOCKED|VM_PFNMAP|VM_HUGETLB));
|
|
}
|
|
|
|
static long madvise_cold(struct vm_area_struct *vma,
|
|
struct vm_area_struct **prev,
|
|
unsigned long start_addr, unsigned long end_addr)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
struct mmu_gather tlb;
|
|
|
|
*prev = vma;
|
|
if (!can_madv_lru_vma(vma))
|
|
return -EINVAL;
|
|
|
|
lru_add_drain();
|
|
tlb_gather_mmu(&tlb, mm);
|
|
madvise_cold_page_range(&tlb, vma, start_addr, end_addr);
|
|
tlb_finish_mmu(&tlb);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void madvise_pageout_page_range(struct mmu_gather *tlb,
|
|
struct vm_area_struct *vma,
|
|
unsigned long addr, unsigned long end)
|
|
{
|
|
struct madvise_walk_private walk_private = {
|
|
.pageout = true,
|
|
.tlb = tlb,
|
|
};
|
|
|
|
tlb_start_vma(tlb, vma);
|
|
walk_page_range(vma->vm_mm, addr, end, &cold_walk_ops, &walk_private);
|
|
tlb_end_vma(tlb, vma);
|
|
}
|
|
|
|
static long madvise_pageout(struct vm_area_struct *vma,
|
|
struct vm_area_struct **prev,
|
|
unsigned long start_addr, unsigned long end_addr)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
struct mmu_gather tlb;
|
|
|
|
*prev = vma;
|
|
if (!can_madv_lru_vma(vma))
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* If the VMA belongs to a private file mapping, there can be private
|
|
* dirty pages which can be paged out if even this process is neither
|
|
* owner nor write capable of the file. We allow private file mappings
|
|
* further to pageout dirty anon pages.
|
|
*/
|
|
if (!vma_is_anonymous(vma) && (!can_do_file_pageout(vma) &&
|
|
(vma->vm_flags & VM_MAYSHARE)))
|
|
return 0;
|
|
|
|
lru_add_drain();
|
|
tlb_gather_mmu(&tlb, mm);
|
|
madvise_pageout_page_range(&tlb, vma, start_addr, end_addr);
|
|
tlb_finish_mmu(&tlb);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
|
|
unsigned long end, struct mm_walk *walk)
|
|
|
|
{
|
|
struct mmu_gather *tlb = walk->private;
|
|
struct mm_struct *mm = tlb->mm;
|
|
struct vm_area_struct *vma = walk->vma;
|
|
spinlock_t *ptl;
|
|
pte_t *start_pte, *pte, ptent;
|
|
struct folio *folio;
|
|
int nr_swap = 0;
|
|
unsigned long next;
|
|
|
|
next = pmd_addr_end(addr, end);
|
|
if (pmd_trans_huge(*pmd))
|
|
if (madvise_free_huge_pmd(tlb, vma, pmd, addr, next))
|
|
return 0;
|
|
|
|
tlb_change_page_size(tlb, PAGE_SIZE);
|
|
start_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
|
|
if (!start_pte)
|
|
return 0;
|
|
flush_tlb_batched_pending(mm);
|
|
arch_enter_lazy_mmu_mode();
|
|
for (; addr != end; pte++, addr += PAGE_SIZE) {
|
|
ptent = ptep_get(pte);
|
|
|
|
if (pte_none(ptent))
|
|
continue;
|
|
/*
|
|
* If the pte has swp_entry, just clear page table to
|
|
* prevent swap-in which is more expensive rather than
|
|
* (page allocation + zeroing).
|
|
*/
|
|
if (!pte_present(ptent)) {
|
|
swp_entry_t entry;
|
|
|
|
entry = pte_to_swp_entry(ptent);
|
|
if (!non_swap_entry(entry)) {
|
|
nr_swap--;
|
|
free_swap_and_cache(entry);
|
|
pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
|
|
} else if (is_hwpoison_entry(entry) ||
|
|
is_poisoned_swp_entry(entry)) {
|
|
pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
|
|
}
|
|
continue;
|
|
}
|
|
|
|
folio = vm_normal_folio(vma, addr, ptent);
|
|
if (!folio || folio_is_zone_device(folio))
|
|
continue;
|
|
|
|
/*
|
|
* If pmd isn't transhuge but the folio is large and
|
|
* is owned by only this process, split it and
|
|
* deactivate all pages.
|
|
*/
|
|
if (folio_test_large(folio)) {
|
|
int err;
|
|
|
|
if (folio_estimated_sharers(folio) != 1)
|
|
break;
|
|
if (!folio_trylock(folio))
|
|
break;
|
|
folio_get(folio);
|
|
arch_leave_lazy_mmu_mode();
|
|
pte_unmap_unlock(start_pte, ptl);
|
|
start_pte = NULL;
|
|
err = split_folio(folio);
|
|
folio_unlock(folio);
|
|
folio_put(folio);
|
|
if (err)
|
|
break;
|
|
start_pte = pte =
|
|
pte_offset_map_lock(mm, pmd, addr, &ptl);
|
|
if (!start_pte)
|
|
break;
|
|
arch_enter_lazy_mmu_mode();
|
|
pte--;
|
|
addr -= PAGE_SIZE;
|
|
continue;
|
|
}
|
|
|
|
if (folio_test_swapcache(folio) || folio_test_dirty(folio)) {
|
|
if (!folio_trylock(folio))
|
|
continue;
|
|
/*
|
|
* If folio is shared with others, we mustn't clear
|
|
* the folio's dirty flag.
|
|
*/
|
|
if (folio_mapcount(folio) != 1) {
|
|
folio_unlock(folio);
|
|
continue;
|
|
}
|
|
|
|
if (folio_test_swapcache(folio) &&
|
|
!folio_free_swap(folio)) {
|
|
folio_unlock(folio);
|
|
continue;
|
|
}
|
|
|
|
folio_clear_dirty(folio);
|
|
folio_unlock(folio);
|
|
}
|
|
|
|
if (pte_young(ptent) || pte_dirty(ptent)) {
|
|
/*
|
|
* Some of architecture(ex, PPC) don't update TLB
|
|
* with set_pte_at and tlb_remove_tlb_entry so for
|
|
* the portability, remap the pte with old|clean
|
|
* after pte clearing.
|
|
*/
|
|
ptent = ptep_get_and_clear_full(mm, addr, pte,
|
|
tlb->fullmm);
|
|
|
|
ptent = pte_mkold(ptent);
|
|
ptent = pte_mkclean(ptent);
|
|
set_pte_at(mm, addr, pte, ptent);
|
|
tlb_remove_tlb_entry(tlb, pte, addr);
|
|
}
|
|
folio_mark_lazyfree(folio);
|
|
}
|
|
|
|
if (nr_swap)
|
|
add_mm_counter(mm, MM_SWAPENTS, nr_swap);
|
|
if (start_pte) {
|
|
arch_leave_lazy_mmu_mode();
|
|
pte_unmap_unlock(start_pte, ptl);
|
|
}
|
|
cond_resched();
|
|
|
|
return 0;
|
|
}
|
|
|
|
static const struct mm_walk_ops madvise_free_walk_ops = {
|
|
.pmd_entry = madvise_free_pte_range,
|
|
.walk_lock = PGWALK_RDLOCK,
|
|
};
|
|
|
|
static int madvise_free_single_vma(struct vm_area_struct *vma,
|
|
unsigned long start_addr, unsigned long end_addr)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
struct mmu_notifier_range range;
|
|
struct mmu_gather tlb;
|
|
|
|
/* MADV_FREE works for only anon vma at the moment */
|
|
if (!vma_is_anonymous(vma))
|
|
return -EINVAL;
|
|
|
|
range.start = max(vma->vm_start, start_addr);
|
|
if (range.start >= vma->vm_end)
|
|
return -EINVAL;
|
|
range.end = min(vma->vm_end, end_addr);
|
|
if (range.end <= vma->vm_start)
|
|
return -EINVAL;
|
|
mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm,
|
|
range.start, range.end);
|
|
|
|
lru_add_drain();
|
|
tlb_gather_mmu(&tlb, mm);
|
|
update_hiwater_rss(mm);
|
|
|
|
mmu_notifier_invalidate_range_start(&range);
|
|
tlb_start_vma(&tlb, vma);
|
|
walk_page_range(vma->vm_mm, range.start, range.end,
|
|
&madvise_free_walk_ops, &tlb);
|
|
tlb_end_vma(&tlb, vma);
|
|
mmu_notifier_invalidate_range_end(&range);
|
|
tlb_finish_mmu(&tlb);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Application no longer needs these pages. If the pages are dirty,
|
|
* it's OK to just throw them away. The app will be more careful about
|
|
* data it wants to keep. Be sure to free swap resources too. The
|
|
* zap_page_range_single call sets things up for shrink_active_list to actually
|
|
* free these pages later if no one else has touched them in the meantime,
|
|
* although we could add these pages to a global reuse list for
|
|
* shrink_active_list to pick up before reclaiming other pages.
|
|
*
|
|
* NB: This interface discards data rather than pushes it out to swap,
|
|
* as some implementations do. This has performance implications for
|
|
* applications like large transactional databases which want to discard
|
|
* pages in anonymous maps after committing to backing store the data
|
|
* that was kept in them. There is no reason to write this data out to
|
|
* the swap area if the application is discarding it.
|
|
*
|
|
* An interface that causes the system to free clean pages and flush
|
|
* dirty pages is already available as msync(MS_INVALIDATE).
|
|
*/
|
|
static long madvise_dontneed_single_vma(struct vm_area_struct *vma,
|
|
unsigned long start, unsigned long end)
|
|
{
|
|
zap_page_range_single(vma, start, end - start, NULL);
|
|
return 0;
|
|
}
|
|
|
|
static bool madvise_dontneed_free_valid_vma(struct vm_area_struct *vma,
|
|
unsigned long start,
|
|
unsigned long *end,
|
|
int behavior)
|
|
{
|
|
if (!is_vm_hugetlb_page(vma)) {
|
|
unsigned int forbidden = VM_PFNMAP;
|
|
|
|
if (behavior != MADV_DONTNEED_LOCKED)
|
|
forbidden |= VM_LOCKED;
|
|
|
|
return !(vma->vm_flags & forbidden);
|
|
}
|
|
|
|
if (behavior != MADV_DONTNEED && behavior != MADV_DONTNEED_LOCKED)
|
|
return false;
|
|
if (start & ~huge_page_mask(hstate_vma(vma)))
|
|
return false;
|
|
|
|
/*
|
|
* Madvise callers expect the length to be rounded up to PAGE_SIZE
|
|
* boundaries, and may be unaware that this VMA uses huge pages.
|
|
* Avoid unexpected data loss by rounding down the number of
|
|
* huge pages freed.
|
|
*/
|
|
*end = ALIGN_DOWN(*end, huge_page_size(hstate_vma(vma)));
|
|
|
|
return true;
|
|
}
|
|
|
|
static long madvise_dontneed_free(struct vm_area_struct *vma,
|
|
struct vm_area_struct **prev,
|
|
unsigned long start, unsigned long end,
|
|
int behavior)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
|
|
*prev = vma;
|
|
if (!madvise_dontneed_free_valid_vma(vma, start, &end, behavior))
|
|
return -EINVAL;
|
|
|
|
if (start == end)
|
|
return 0;
|
|
|
|
if (!userfaultfd_remove(vma, start, end)) {
|
|
*prev = NULL; /* mmap_lock has been dropped, prev is stale */
|
|
|
|
mmap_read_lock(mm);
|
|
vma = vma_lookup(mm, start);
|
|
if (!vma)
|
|
return -ENOMEM;
|
|
/*
|
|
* Potential end adjustment for hugetlb vma is OK as
|
|
* the check below keeps end within vma.
|
|
*/
|
|
if (!madvise_dontneed_free_valid_vma(vma, start, &end,
|
|
behavior))
|
|
return -EINVAL;
|
|
if (end > vma->vm_end) {
|
|
/*
|
|
* Don't fail if end > vma->vm_end. If the old
|
|
* vma was split while the mmap_lock was
|
|
* released the effect of the concurrent
|
|
* operation may not cause madvise() to
|
|
* have an undefined result. There may be an
|
|
* adjacent next vma that we'll walk
|
|
* next. userfaultfd_remove() will generate an
|
|
* UFFD_EVENT_REMOVE repetition on the
|
|
* end-vma->vm_end range, but the manager can
|
|
* handle a repetition fine.
|
|
*/
|
|
end = vma->vm_end;
|
|
}
|
|
VM_WARN_ON(start >= end);
|
|
}
|
|
|
|
if (behavior == MADV_DONTNEED || behavior == MADV_DONTNEED_LOCKED)
|
|
return madvise_dontneed_single_vma(vma, start, end);
|
|
else if (behavior == MADV_FREE)
|
|
return madvise_free_single_vma(vma, start, end);
|
|
else
|
|
return -EINVAL;
|
|
}
|
|
|
|
static long madvise_populate(struct vm_area_struct *vma,
|
|
struct vm_area_struct **prev,
|
|
unsigned long start, unsigned long end,
|
|
int behavior)
|
|
{
|
|
const bool write = behavior == MADV_POPULATE_WRITE;
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
unsigned long tmp_end;
|
|
int locked = 1;
|
|
long pages;
|
|
|
|
*prev = vma;
|
|
|
|
while (start < end) {
|
|
/*
|
|
* We might have temporarily dropped the lock. For example,
|
|
* our VMA might have been split.
|
|
*/
|
|
if (!vma || start >= vma->vm_end) {
|
|
vma = vma_lookup(mm, start);
|
|
if (!vma)
|
|
return -ENOMEM;
|
|
}
|
|
|
|
tmp_end = min_t(unsigned long, end, vma->vm_end);
|
|
/* Populate (prefault) page tables readable/writable. */
|
|
pages = faultin_vma_page_range(vma, start, tmp_end, write,
|
|
&locked);
|
|
if (!locked) {
|
|
mmap_read_lock(mm);
|
|
locked = 1;
|
|
*prev = NULL;
|
|
vma = NULL;
|
|
}
|
|
if (pages < 0) {
|
|
switch (pages) {
|
|
case -EINTR:
|
|
return -EINTR;
|
|
case -EINVAL: /* Incompatible mappings / permissions. */
|
|
return -EINVAL;
|
|
case -EHWPOISON:
|
|
return -EHWPOISON;
|
|
case -EFAULT: /* VM_FAULT_SIGBUS or VM_FAULT_SIGSEGV */
|
|
return -EFAULT;
|
|
default:
|
|
pr_warn_once("%s: unhandled return value: %ld\n",
|
|
__func__, pages);
|
|
fallthrough;
|
|
case -ENOMEM:
|
|
return -ENOMEM;
|
|
}
|
|
}
|
|
start += pages * PAGE_SIZE;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Application wants to free up the pages and associated backing store.
|
|
* This is effectively punching a hole into the middle of a file.
|
|
*/
|
|
static long madvise_remove(struct vm_area_struct *vma,
|
|
struct vm_area_struct **prev,
|
|
unsigned long start, unsigned long end)
|
|
{
|
|
loff_t offset;
|
|
int error;
|
|
struct file *f;
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
|
|
*prev = NULL; /* tell sys_madvise we drop mmap_lock */
|
|
|
|
if (vma->vm_flags & VM_LOCKED)
|
|
return -EINVAL;
|
|
|
|
f = vma->vm_file;
|
|
|
|
if (!f || !f->f_mapping || !f->f_mapping->host) {
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (!vma_is_shared_maywrite(vma))
|
|
return -EACCES;
|
|
|
|
offset = (loff_t)(start - vma->vm_start)
|
|
+ ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
|
|
|
|
/*
|
|
* Filesystem's fallocate may need to take i_rwsem. We need to
|
|
* explicitly grab a reference because the vma (and hence the
|
|
* vma's reference to the file) can go away as soon as we drop
|
|
* mmap_lock.
|
|
*/
|
|
get_file(f);
|
|
if (userfaultfd_remove(vma, start, end)) {
|
|
/* mmap_lock was not released by userfaultfd_remove() */
|
|
mmap_read_unlock(mm);
|
|
}
|
|
error = vfs_fallocate(f,
|
|
FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
|
|
offset, end - start);
|
|
fput(f);
|
|
mmap_read_lock(mm);
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* Apply an madvise behavior to a region of a vma. madvise_update_vma
|
|
* will handle splitting a vm area into separate areas, each area with its own
|
|
* behavior.
|
|
*/
|
|
static int madvise_vma_behavior(struct vm_area_struct *vma,
|
|
struct vm_area_struct **prev,
|
|
unsigned long start, unsigned long end,
|
|
unsigned long behavior)
|
|
{
|
|
int error;
|
|
struct anon_vma_name *anon_name;
|
|
unsigned long new_flags = vma->vm_flags;
|
|
|
|
switch (behavior) {
|
|
case MADV_REMOVE:
|
|
return madvise_remove(vma, prev, start, end);
|
|
case MADV_WILLNEED:
|
|
return madvise_willneed(vma, prev, start, end);
|
|
case MADV_COLD:
|
|
return madvise_cold(vma, prev, start, end);
|
|
case MADV_PAGEOUT:
|
|
return madvise_pageout(vma, prev, start, end);
|
|
case MADV_FREE:
|
|
case MADV_DONTNEED:
|
|
case MADV_DONTNEED_LOCKED:
|
|
return madvise_dontneed_free(vma, prev, start, end, behavior);
|
|
case MADV_POPULATE_READ:
|
|
case MADV_POPULATE_WRITE:
|
|
return madvise_populate(vma, prev, start, end, behavior);
|
|
case MADV_NORMAL:
|
|
new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ;
|
|
break;
|
|
case MADV_SEQUENTIAL:
|
|
new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ;
|
|
break;
|
|
case MADV_RANDOM:
|
|
new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ;
|
|
break;
|
|
case MADV_DONTFORK:
|
|
new_flags |= VM_DONTCOPY;
|
|
break;
|
|
case MADV_DOFORK:
|
|
if (vma->vm_flags & VM_IO)
|
|
return -EINVAL;
|
|
new_flags &= ~VM_DONTCOPY;
|
|
break;
|
|
case MADV_WIPEONFORK:
|
|
/* MADV_WIPEONFORK is only supported on anonymous memory. */
|
|
if (vma->vm_file || vma->vm_flags & VM_SHARED)
|
|
return -EINVAL;
|
|
new_flags |= VM_WIPEONFORK;
|
|
break;
|
|
case MADV_KEEPONFORK:
|
|
new_flags &= ~VM_WIPEONFORK;
|
|
break;
|
|
case MADV_DONTDUMP:
|
|
new_flags |= VM_DONTDUMP;
|
|
break;
|
|
case MADV_DODUMP:
|
|
if (!is_vm_hugetlb_page(vma) && new_flags & VM_SPECIAL)
|
|
return -EINVAL;
|
|
new_flags &= ~VM_DONTDUMP;
|
|
break;
|
|
case MADV_MERGEABLE:
|
|
case MADV_UNMERGEABLE:
|
|
error = ksm_madvise(vma, start, end, behavior, &new_flags);
|
|
if (error)
|
|
goto out;
|
|
break;
|
|
case MADV_HUGEPAGE:
|
|
case MADV_NOHUGEPAGE:
|
|
error = hugepage_madvise(vma, &new_flags, behavior);
|
|
if (error)
|
|
goto out;
|
|
break;
|
|
case MADV_COLLAPSE:
|
|
return madvise_collapse(vma, prev, start, end);
|
|
}
|
|
|
|
anon_name = anon_vma_name(vma);
|
|
anon_vma_name_get(anon_name);
|
|
error = madvise_update_vma(vma, prev, start, end, new_flags,
|
|
anon_name);
|
|
anon_vma_name_put(anon_name);
|
|
|
|
out:
|
|
/*
|
|
* madvise() returns EAGAIN if kernel resources, such as
|
|
* slab, are temporarily unavailable.
|
|
*/
|
|
if (error == -ENOMEM)
|
|
error = -EAGAIN;
|
|
return error;
|
|
}
|
|
|
|
#ifdef CONFIG_MEMORY_FAILURE
|
|
/*
|
|
* Error injection support for memory error handling.
|
|
*/
|
|
static int madvise_inject_error(int behavior,
|
|
unsigned long start, unsigned long end)
|
|
{
|
|
unsigned long size;
|
|
|
|
if (!capable(CAP_SYS_ADMIN))
|
|
return -EPERM;
|
|
|
|
|
|
for (; start < end; start += size) {
|
|
unsigned long pfn;
|
|
struct page *page;
|
|
int ret;
|
|
|
|
ret = get_user_pages_fast(start, 1, 0, &page);
|
|
if (ret != 1)
|
|
return ret;
|
|
pfn = page_to_pfn(page);
|
|
|
|
/*
|
|
* When soft offlining hugepages, after migrating the page
|
|
* we dissolve it, therefore in the second loop "page" will
|
|
* no longer be a compound page.
|
|
*/
|
|
size = page_size(compound_head(page));
|
|
|
|
if (behavior == MADV_SOFT_OFFLINE) {
|
|
pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n",
|
|
pfn, start);
|
|
ret = soft_offline_page(pfn, MF_COUNT_INCREASED);
|
|
} else {
|
|
pr_info("Injecting memory failure for pfn %#lx at process virtual address %#lx\n",
|
|
pfn, start);
|
|
ret = memory_failure(pfn, MF_COUNT_INCREASED | MF_SW_SIMULATED);
|
|
if (ret == -EOPNOTSUPP)
|
|
ret = 0;
|
|
}
|
|
|
|
if (ret)
|
|
return ret;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
static bool
|
|
madvise_behavior_valid(int behavior)
|
|
{
|
|
switch (behavior) {
|
|
case MADV_DOFORK:
|
|
case MADV_DONTFORK:
|
|
case MADV_NORMAL:
|
|
case MADV_SEQUENTIAL:
|
|
case MADV_RANDOM:
|
|
case MADV_REMOVE:
|
|
case MADV_WILLNEED:
|
|
case MADV_DONTNEED:
|
|
case MADV_DONTNEED_LOCKED:
|
|
case MADV_FREE:
|
|
case MADV_COLD:
|
|
case MADV_PAGEOUT:
|
|
case MADV_POPULATE_READ:
|
|
case MADV_POPULATE_WRITE:
|
|
#ifdef CONFIG_KSM
|
|
case MADV_MERGEABLE:
|
|
case MADV_UNMERGEABLE:
|
|
#endif
|
|
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
|
|
case MADV_HUGEPAGE:
|
|
case MADV_NOHUGEPAGE:
|
|
case MADV_COLLAPSE:
|
|
#endif
|
|
case MADV_DONTDUMP:
|
|
case MADV_DODUMP:
|
|
case MADV_WIPEONFORK:
|
|
case MADV_KEEPONFORK:
|
|
#ifdef CONFIG_MEMORY_FAILURE
|
|
case MADV_SOFT_OFFLINE:
|
|
case MADV_HWPOISON:
|
|
#endif
|
|
return true;
|
|
|
|
default:
|
|
return false;
|
|
}
|
|
}
|
|
|
|
static bool process_madvise_behavior_valid(int behavior)
|
|
{
|
|
switch (behavior) {
|
|
case MADV_COLD:
|
|
case MADV_PAGEOUT:
|
|
case MADV_WILLNEED:
|
|
case MADV_COLLAPSE:
|
|
return true;
|
|
default:
|
|
return false;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Walk the vmas in range [start,end), and call the visit function on each one.
|
|
* The visit function will get start and end parameters that cover the overlap
|
|
* between the current vma and the original range. Any unmapped regions in the
|
|
* original range will result in this function returning -ENOMEM while still
|
|
* calling the visit function on all of the existing vmas in the range.
|
|
* Must be called with the mmap_lock held for reading or writing.
|
|
*/
|
|
static
|
|
int madvise_walk_vmas(struct mm_struct *mm, unsigned long start,
|
|
unsigned long end, unsigned long arg,
|
|
int (*visit)(struct vm_area_struct *vma,
|
|
struct vm_area_struct **prev, unsigned long start,
|
|
unsigned long end, unsigned long arg))
|
|
{
|
|
struct vm_area_struct *vma;
|
|
struct vm_area_struct *prev;
|
|
unsigned long tmp;
|
|
int unmapped_error = 0;
|
|
|
|
/*
|
|
* If the interval [start,end) covers some unmapped address
|
|
* ranges, just ignore them, but return -ENOMEM at the end.
|
|
* - different from the way of handling in mlock etc.
|
|
*/
|
|
vma = find_vma_prev(mm, start, &prev);
|
|
if (vma && start > vma->vm_start)
|
|
prev = vma;
|
|
|
|
for (;;) {
|
|
int error;
|
|
|
|
/* Still start < end. */
|
|
if (!vma)
|
|
return -ENOMEM;
|
|
|
|
/* Here start < (end|vma->vm_end). */
|
|
if (start < vma->vm_start) {
|
|
unmapped_error = -ENOMEM;
|
|
start = vma->vm_start;
|
|
if (start >= end)
|
|
break;
|
|
}
|
|
|
|
/* Here vma->vm_start <= start < (end|vma->vm_end) */
|
|
tmp = vma->vm_end;
|
|
if (end < tmp)
|
|
tmp = end;
|
|
|
|
/* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
|
|
error = visit(vma, &prev, start, tmp, arg);
|
|
if (error)
|
|
return error;
|
|
start = tmp;
|
|
if (prev && start < prev->vm_end)
|
|
start = prev->vm_end;
|
|
if (start >= end)
|
|
break;
|
|
if (prev)
|
|
vma = find_vma(mm, prev->vm_end);
|
|
else /* madvise_remove dropped mmap_lock */
|
|
vma = find_vma(mm, start);
|
|
}
|
|
|
|
return unmapped_error;
|
|
}
|
|
|
|
#ifdef CONFIG_ANON_VMA_NAME
|
|
static int madvise_vma_anon_name(struct vm_area_struct *vma,
|
|
struct vm_area_struct **prev,
|
|
unsigned long start, unsigned long end,
|
|
unsigned long anon_name)
|
|
{
|
|
int error;
|
|
|
|
/* Only anonymous mappings can be named */
|
|
if (vma->vm_file && !vma_is_anon_shmem(vma))
|
|
return -EBADF;
|
|
|
|
error = madvise_update_vma(vma, prev, start, end, vma->vm_flags,
|
|
(struct anon_vma_name *)anon_name);
|
|
|
|
/*
|
|
* madvise() returns EAGAIN if kernel resources, such as
|
|
* slab, are temporarily unavailable.
|
|
*/
|
|
if (error == -ENOMEM)
|
|
error = -EAGAIN;
|
|
return error;
|
|
}
|
|
|
|
int madvise_set_anon_name(struct mm_struct *mm, unsigned long start,
|
|
unsigned long len_in, struct anon_vma_name *anon_name)
|
|
{
|
|
unsigned long end;
|
|
unsigned long len;
|
|
|
|
if (start & ~PAGE_MASK)
|
|
return -EINVAL;
|
|
len = (len_in + ~PAGE_MASK) & PAGE_MASK;
|
|
|
|
/* Check to see whether len was rounded up from small -ve to zero */
|
|
if (len_in && !len)
|
|
return -EINVAL;
|
|
|
|
end = start + len;
|
|
if (end < start)
|
|
return -EINVAL;
|
|
|
|
if (end == start)
|
|
return 0;
|
|
|
|
return madvise_walk_vmas(mm, start, end, (unsigned long)anon_name,
|
|
madvise_vma_anon_name);
|
|
}
|
|
#endif /* CONFIG_ANON_VMA_NAME */
|
|
/*
|
|
* The madvise(2) system call.
|
|
*
|
|
* Applications can use madvise() to advise the kernel how it should
|
|
* handle paging I/O in this VM area. The idea is to help the kernel
|
|
* use appropriate read-ahead and caching techniques. The information
|
|
* provided is advisory only, and can be safely disregarded by the
|
|
* kernel without affecting the correct operation of the application.
|
|
*
|
|
* behavior values:
|
|
* MADV_NORMAL - the default behavior is to read clusters. This
|
|
* results in some read-ahead and read-behind.
|
|
* MADV_RANDOM - the system should read the minimum amount of data
|
|
* on any access, since it is unlikely that the appli-
|
|
* cation will need more than what it asks for.
|
|
* MADV_SEQUENTIAL - pages in the given range will probably be accessed
|
|
* once, so they can be aggressively read ahead, and
|
|
* can be freed soon after they are accessed.
|
|
* MADV_WILLNEED - the application is notifying the system to read
|
|
* some pages ahead.
|
|
* MADV_DONTNEED - the application is finished with the given range,
|
|
* so the kernel can free resources associated with it.
|
|
* MADV_FREE - the application marks pages in the given range as lazy free,
|
|
* where actual purges are postponed until memory pressure happens.
|
|
* MADV_REMOVE - the application wants to free up the given range of
|
|
* pages and associated backing store.
|
|
* MADV_DONTFORK - omit this area from child's address space when forking:
|
|
* typically, to avoid COWing pages pinned by get_user_pages().
|
|
* MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking.
|
|
* MADV_WIPEONFORK - present the child process with zero-filled memory in this
|
|
* range after a fork.
|
|
* MADV_KEEPONFORK - undo the effect of MADV_WIPEONFORK
|
|
* MADV_HWPOISON - trigger memory error handler as if the given memory range
|
|
* were corrupted by unrecoverable hardware memory failure.
|
|
* MADV_SOFT_OFFLINE - try to soft-offline the given range of memory.
|
|
* MADV_MERGEABLE - the application recommends that KSM try to merge pages in
|
|
* this area with pages of identical content from other such areas.
|
|
* MADV_UNMERGEABLE- cancel MADV_MERGEABLE: no longer merge pages with others.
|
|
* MADV_HUGEPAGE - the application wants to back the given range by transparent
|
|
* huge pages in the future. Existing pages might be coalesced and
|
|
* new pages might be allocated as THP.
|
|
* MADV_NOHUGEPAGE - mark the given range as not worth being backed by
|
|
* transparent huge pages so the existing pages will not be
|
|
* coalesced into THP and new pages will not be allocated as THP.
|
|
* MADV_COLLAPSE - synchronously coalesce pages into new THP.
|
|
* MADV_DONTDUMP - the application wants to prevent pages in the given range
|
|
* from being included in its core dump.
|
|
* MADV_DODUMP - cancel MADV_DONTDUMP: no longer exclude from core dump.
|
|
* MADV_COLD - the application is not expected to use this memory soon,
|
|
* deactivate pages in this range so that they can be reclaimed
|
|
* easily if memory pressure happens.
|
|
* MADV_PAGEOUT - the application is not expected to use this memory soon,
|
|
* page out the pages in this range immediately.
|
|
* MADV_POPULATE_READ - populate (prefault) page tables readable by
|
|
* triggering read faults if required
|
|
* MADV_POPULATE_WRITE - populate (prefault) page tables writable by
|
|
* triggering write faults if required
|
|
*
|
|
* return values:
|
|
* zero - success
|
|
* -EINVAL - start + len < 0, start is not page-aligned,
|
|
* "behavior" is not a valid value, or application
|
|
* is attempting to release locked or shared pages,
|
|
* or the specified address range includes file, Huge TLB,
|
|
* MAP_SHARED or VMPFNMAP range.
|
|
* -ENOMEM - addresses in the specified range are not currently
|
|
* mapped, or are outside the AS of the process.
|
|
* -EIO - an I/O error occurred while paging in data.
|
|
* -EBADF - map exists, but area maps something that isn't a file.
|
|
* -EAGAIN - a kernel resource was temporarily unavailable.
|
|
*/
|
|
int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int behavior)
|
|
{
|
|
unsigned long end;
|
|
int error;
|
|
int write;
|
|
size_t len;
|
|
struct blk_plug plug;
|
|
|
|
if (!madvise_behavior_valid(behavior))
|
|
return -EINVAL;
|
|
|
|
if (!PAGE_ALIGNED(start))
|
|
return -EINVAL;
|
|
len = PAGE_ALIGN(len_in);
|
|
|
|
/* Check to see whether len was rounded up from small -ve to zero */
|
|
if (len_in && !len)
|
|
return -EINVAL;
|
|
|
|
end = start + len;
|
|
if (end < start)
|
|
return -EINVAL;
|
|
|
|
if (end == start)
|
|
return 0;
|
|
|
|
#ifdef CONFIG_MEMORY_FAILURE
|
|
if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
|
|
return madvise_inject_error(behavior, start, start + len_in);
|
|
#endif
|
|
|
|
write = madvise_need_mmap_write(behavior);
|
|
if (write) {
|
|
if (mmap_write_lock_killable(mm))
|
|
return -EINTR;
|
|
} else {
|
|
mmap_read_lock(mm);
|
|
}
|
|
|
|
start = untagged_addr_remote(mm, start);
|
|
end = start + len;
|
|
|
|
blk_start_plug(&plug);
|
|
error = madvise_walk_vmas(mm, start, end, behavior,
|
|
madvise_vma_behavior);
|
|
blk_finish_plug(&plug);
|
|
if (write)
|
|
mmap_write_unlock(mm);
|
|
else
|
|
mmap_read_unlock(mm);
|
|
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
|
|
{
|
|
return do_madvise(current->mm, start, len_in, behavior);
|
|
}
|
|
|
|
SYSCALL_DEFINE5(process_madvise, int, pidfd, const struct iovec __user *, vec,
|
|
size_t, vlen, int, behavior, unsigned int, flags)
|
|
{
|
|
ssize_t ret;
|
|
struct iovec iovstack[UIO_FASTIOV];
|
|
struct iovec *iov = iovstack;
|
|
struct iov_iter iter;
|
|
struct task_struct *task;
|
|
struct mm_struct *mm;
|
|
size_t total_len;
|
|
unsigned int f_flags;
|
|
|
|
if (flags != 0) {
|
|
ret = -EINVAL;
|
|
goto out;
|
|
}
|
|
|
|
ret = import_iovec(ITER_DEST, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
|
|
if (ret < 0)
|
|
goto out;
|
|
|
|
task = pidfd_get_task(pidfd, &f_flags);
|
|
if (IS_ERR(task)) {
|
|
ret = PTR_ERR(task);
|
|
goto free_iov;
|
|
}
|
|
|
|
if (!process_madvise_behavior_valid(behavior)) {
|
|
ret = -EINVAL;
|
|
goto release_task;
|
|
}
|
|
|
|
/* Require PTRACE_MODE_READ to avoid leaking ASLR metadata. */
|
|
mm = mm_access(task, PTRACE_MODE_READ_FSCREDS);
|
|
if (IS_ERR_OR_NULL(mm)) {
|
|
ret = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH;
|
|
goto release_task;
|
|
}
|
|
|
|
/*
|
|
* Require CAP_SYS_NICE for influencing process performance. Note that
|
|
* only non-destructive hints are currently supported.
|
|
*/
|
|
if (!capable(CAP_SYS_NICE)) {
|
|
ret = -EPERM;
|
|
goto release_mm;
|
|
}
|
|
|
|
total_len = iov_iter_count(&iter);
|
|
|
|
while (iov_iter_count(&iter)) {
|
|
ret = do_madvise(mm, (unsigned long)iter_iov_addr(&iter),
|
|
iter_iov_len(&iter), behavior);
|
|
if (ret < 0)
|
|
break;
|
|
iov_iter_advance(&iter, iter_iov_len(&iter));
|
|
}
|
|
|
|
ret = (total_len - iov_iter_count(&iter)) ? : ret;
|
|
|
|
release_mm:
|
|
mmput(mm);
|
|
release_task:
|
|
put_task_struct(task);
|
|
free_iov:
|
|
kfree(iov);
|
|
out:
|
|
return ret;
|
|
}
|