mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-25 05:34:00 +08:00
23955622ff
For fast flash disk, async IO could introduce overhead because of context switch. block-mq now supports IO poll, which improves performance and latency a lot. swapin is a good place to use this technique, because the task is waiting for the swapin page to continue execution. In my virtual machine, directly read 4k data from a NVMe with iopoll is about 60% better than that without poll. With iopoll support in swapin patch, my microbenchmark (a task does random memory write) is about 10%~25% faster. CPU utilization increases a lot though, 2x and even 3x CPU utilization. This will depend on disk speed. While iopoll in swapin isn't intended for all usage cases, it's a win for latency sensistive workloads with high speed swap disk. block layer has knob to control poll in runtime. If poll isn't enabled in block layer, there should be no noticeable change in swapin. I got a chance to run the same test in a NVMe with DRAM as the media. In simple fio IO test, blkpoll boosts 50% performance in single thread test and ~20% in 8 threads test. So this is the base line. In above swap test, blkpoll boosts ~27% performance in single thread test. blkpoll uses 2x CPU time though. If we enable hybid polling, the performance gain has very slight drop but CPU time is only 50% worse than that without blkpoll. Also we can adjust parameter of hybid poll, with it, the CPU time penality is reduced further. In 8 threads test, blkpoll doesn't help though. The performance is similar to that without blkpoll, but cpu utilization is similar too. There is lock contention in swap path. The cpu time spending on blkpoll isn't high. So overall, blkpoll swapin isn't worse than that without it. The swapin readahead might read several pages in in the same time and form a big IO request. Since the IO will take longer time, it doesn't make sense to do poll, so the patch only does iopoll for single page swapin. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/070c3c3e40b711e7b1390002c991e86a-b5408f0@7511894063d3764ff01ea8111f5a004d7dd700ed078797c204a24e620ddb965c Signed-off-by: Shaohua Li <shli@fb.com> Cc: Tim Chen <tim.c.chen@intel.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Jens Axboe <axboe@fb.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
852 lines
22 KiB
C
852 lines
22 KiB
C
/*
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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/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/sched.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/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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/*
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* Any behaviour which results in changes to the vma->vm_flags needs to
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* take mmap_sem 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_FREE:
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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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/*
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* We can potentially split a vm area into separate
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* areas, each area with its own behavior.
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*/
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static long madvise_behavior(struct vm_area_struct *vma,
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struct vm_area_struct **prev,
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unsigned long start, unsigned long end, int behavior)
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{
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struct mm_struct *mm = vma->vm_mm;
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int error = 0;
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pgoff_t pgoff;
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unsigned long new_flags = vma->vm_flags;
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switch (behavior) {
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case MADV_NORMAL:
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new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ;
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break;
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case MADV_SEQUENTIAL:
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new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ;
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break;
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case MADV_RANDOM:
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new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ;
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break;
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case MADV_DONTFORK:
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new_flags |= VM_DONTCOPY;
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break;
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case MADV_DOFORK:
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if (vma->vm_flags & VM_IO) {
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error = -EINVAL;
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goto out;
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}
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new_flags &= ~VM_DONTCOPY;
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break;
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case MADV_DONTDUMP:
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new_flags |= VM_DONTDUMP;
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break;
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case MADV_DODUMP:
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if (new_flags & VM_SPECIAL) {
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error = -EINVAL;
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goto out;
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}
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new_flags &= ~VM_DONTDUMP;
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break;
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case MADV_MERGEABLE:
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case MADV_UNMERGEABLE:
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error = ksm_madvise(vma, start, end, behavior, &new_flags);
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if (error) {
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/*
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* madvise() returns EAGAIN if kernel resources, such as
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* slab, are temporarily unavailable.
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*/
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if (error == -ENOMEM)
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error = -EAGAIN;
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goto out;
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}
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break;
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case MADV_HUGEPAGE:
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case MADV_NOHUGEPAGE:
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error = hugepage_madvise(vma, &new_flags, behavior);
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if (error) {
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/*
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* madvise() returns EAGAIN if kernel resources, such as
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* slab, are temporarily unavailable.
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*/
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if (error == -ENOMEM)
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error = -EAGAIN;
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goto out;
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}
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break;
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}
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if (new_flags == vma->vm_flags) {
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*prev = vma;
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goto out;
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}
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pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
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*prev = vma_merge(mm, *prev, start, end, new_flags, vma->anon_vma,
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vma->vm_file, pgoff, vma_policy(vma),
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vma->vm_userfaultfd_ctx);
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if (*prev) {
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vma = *prev;
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goto success;
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}
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*prev = vma;
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if (start != vma->vm_start) {
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if (unlikely(mm->map_count >= sysctl_max_map_count)) {
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error = -ENOMEM;
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goto out;
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}
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error = __split_vma(mm, vma, start, 1);
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if (error) {
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/*
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* madvise() returns EAGAIN if kernel resources, such as
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* slab, are temporarily unavailable.
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*/
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if (error == -ENOMEM)
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error = -EAGAIN;
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goto out;
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}
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}
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if (end != vma->vm_end) {
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if (unlikely(mm->map_count >= sysctl_max_map_count)) {
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error = -ENOMEM;
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goto out;
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}
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error = __split_vma(mm, vma, end, 0);
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if (error) {
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/*
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* madvise() returns EAGAIN if kernel resources, such as
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* slab, are temporarily unavailable.
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*/
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if (error == -ENOMEM)
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error = -EAGAIN;
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goto out;
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}
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}
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success:
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/*
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* vm_flags is protected by the mmap_sem held in write mode.
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*/
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vma->vm_flags = new_flags;
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out:
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return error;
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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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pte_t *orig_pte;
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struct vm_area_struct *vma = walk->private;
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unsigned long index;
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if (pmd_none_or_trans_huge_or_clear_bad(pmd))
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return 0;
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for (index = start; index != end; index += 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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spinlock_t *ptl;
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orig_pte = pte_offset_map_lock(vma->vm_mm, pmd, start, &ptl);
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pte = *(orig_pte + ((index - start) / PAGE_SIZE));
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pte_unmap_unlock(orig_pte, ptl);
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if (pte_present(pte) || pte_none(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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page = read_swap_cache_async(entry, GFP_HIGHUSER_MOVABLE,
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vma, index, false);
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if (page)
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put_page(page);
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}
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return 0;
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}
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static void force_swapin_readahead(struct vm_area_struct *vma,
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unsigned long start, unsigned long end)
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{
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struct mm_walk walk = {
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.mm = vma->vm_mm,
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.pmd_entry = swapin_walk_pmd_entry,
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.private = vma,
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};
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walk_page_range(start, end, &walk);
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lru_add_drain(); /* Push any new pages onto the LRU now */
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}
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static void force_shm_swapin_readahead(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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pgoff_t index;
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struct page *page;
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swp_entry_t swap;
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for (; start < end; start += PAGE_SIZE) {
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index = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
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page = find_get_entry(mapping, index);
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if (!radix_tree_exceptional_entry(page)) {
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if (page)
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put_page(page);
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continue;
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}
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swap = radix_to_swp_entry(page);
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page = read_swap_cache_async(swap, GFP_HIGHUSER_MOVABLE,
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NULL, 0, false);
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if (page)
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put_page(page);
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}
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lru_add_drain(); /* Push any new pages onto the LRU now */
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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 file *file = vma->vm_file;
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#ifdef CONFIG_SWAP
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if (!file) {
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*prev = vma;
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force_swapin_readahead(vma, start, end);
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return 0;
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}
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if (shmem_mapping(file->f_mapping)) {
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*prev = vma;
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force_shm_swapin_readahead(vma, start, end,
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file->f_mapping);
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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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*prev = vma;
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start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
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if (end > vma->vm_end)
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end = vma->vm_end;
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end = ((end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
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force_page_cache_readahead(file->f_mapping, file, start, end - start);
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return 0;
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}
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static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
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unsigned long end, struct mm_walk *walk)
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{
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struct mmu_gather *tlb = walk->private;
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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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spinlock_t *ptl;
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pte_t *orig_pte, *pte, ptent;
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struct page *page;
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int nr_swap = 0;
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unsigned long next;
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next = pmd_addr_end(addr, end);
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if (pmd_trans_huge(*pmd))
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if (madvise_free_huge_pmd(tlb, vma, pmd, addr, next))
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goto next;
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if (pmd_trans_unstable(pmd))
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return 0;
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tlb_remove_check_page_size_change(tlb, PAGE_SIZE);
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orig_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
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arch_enter_lazy_mmu_mode();
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for (; addr != end; pte++, addr += PAGE_SIZE) {
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ptent = *pte;
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if (pte_none(ptent))
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continue;
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/*
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* If the pte has swp_entry, just clear page table to
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* prevent swap-in which is more expensive rather than
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* (page allocation + zeroing).
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*/
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if (!pte_present(ptent)) {
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swp_entry_t entry;
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entry = pte_to_swp_entry(ptent);
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if (non_swap_entry(entry))
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continue;
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nr_swap--;
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free_swap_and_cache(entry);
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pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
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continue;
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}
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page = vm_normal_page(vma, addr, ptent);
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if (!page)
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continue;
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/*
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* If pmd isn't transhuge but the page is THP and
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* is owned by only this process, split it and
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* deactivate all pages.
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*/
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if (PageTransCompound(page)) {
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if (page_mapcount(page) != 1)
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goto out;
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get_page(page);
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if (!trylock_page(page)) {
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put_page(page);
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goto out;
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}
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pte_unmap_unlock(orig_pte, ptl);
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if (split_huge_page(page)) {
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unlock_page(page);
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put_page(page);
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pte_offset_map_lock(mm, pmd, addr, &ptl);
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goto out;
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}
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put_page(page);
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unlock_page(page);
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pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
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pte--;
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addr -= PAGE_SIZE;
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continue;
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}
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VM_BUG_ON_PAGE(PageTransCompound(page), page);
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if (PageSwapCache(page) || PageDirty(page)) {
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if (!trylock_page(page))
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continue;
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/*
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* If page is shared with others, we couldn't clear
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* PG_dirty of the page.
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*/
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if (page_mapcount(page) != 1) {
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unlock_page(page);
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continue;
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}
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if (PageSwapCache(page) && !try_to_free_swap(page)) {
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unlock_page(page);
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continue;
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}
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ClearPageDirty(page);
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unlock_page(page);
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}
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if (pte_young(ptent) || pte_dirty(ptent)) {
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/*
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* Some of architecture(ex, PPC) don't update TLB
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* with set_pte_at and tlb_remove_tlb_entry so for
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* the portability, remap the pte with old|clean
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* after pte clearing.
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*/
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ptent = ptep_get_and_clear_full(mm, addr, pte,
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tlb->fullmm);
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ptent = pte_mkold(ptent);
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ptent = pte_mkclean(ptent);
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set_pte_at(mm, addr, pte, ptent);
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tlb_remove_tlb_entry(tlb, pte, addr);
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}
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mark_page_lazyfree(page);
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}
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out:
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if (nr_swap) {
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if (current->mm == mm)
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sync_mm_rss(mm);
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add_mm_counter(mm, MM_SWAPENTS, nr_swap);
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}
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arch_leave_lazy_mmu_mode();
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pte_unmap_unlock(orig_pte, ptl);
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cond_resched();
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next:
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return 0;
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}
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static void madvise_free_page_range(struct mmu_gather *tlb,
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struct vm_area_struct *vma,
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unsigned long addr, unsigned long end)
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{
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struct mm_walk free_walk = {
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.pmd_entry = madvise_free_pte_range,
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.mm = vma->vm_mm,
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.private = tlb,
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};
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tlb_start_vma(tlb, vma);
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walk_page_range(addr, end, &free_walk);
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tlb_end_vma(tlb, vma);
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}
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static int madvise_free_single_vma(struct vm_area_struct *vma,
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unsigned long start_addr, unsigned long end_addr)
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{
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unsigned long start, end;
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struct mm_struct *mm = vma->vm_mm;
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struct mmu_gather tlb;
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if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP))
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return -EINVAL;
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/* MADV_FREE works for only anon vma at the moment */
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if (!vma_is_anonymous(vma))
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return -EINVAL;
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start = max(vma->vm_start, start_addr);
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if (start >= vma->vm_end)
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return -EINVAL;
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end = min(vma->vm_end, end_addr);
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if (end <= vma->vm_start)
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return -EINVAL;
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lru_add_drain();
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tlb_gather_mmu(&tlb, mm, start, end);
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update_hiwater_rss(mm);
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mmu_notifier_invalidate_range_start(mm, start, end);
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madvise_free_page_range(&tlb, vma, start, end);
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mmu_notifier_invalidate_range_end(mm, start, end);
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tlb_finish_mmu(&tlb, start, end);
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return 0;
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}
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static long madvise_free(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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*prev = vma;
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return madvise_free_single_vma(vma, start, end);
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|
}
|
|
|
|
/*
|
|
* 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 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(struct vm_area_struct *vma,
|
|
struct vm_area_struct **prev,
|
|
unsigned long start, unsigned long end)
|
|
{
|
|
*prev = vma;
|
|
if (!can_madv_dontneed_vma(vma))
|
|
return -EINVAL;
|
|
|
|
if (!userfaultfd_remove(vma, start, end)) {
|
|
*prev = NULL; /* mmap_sem has been dropped, prev is stale */
|
|
|
|
down_read(¤t->mm->mmap_sem);
|
|
vma = find_vma(current->mm, start);
|
|
if (!vma)
|
|
return -ENOMEM;
|
|
if (start < vma->vm_start) {
|
|
/*
|
|
* This "vma" under revalidation is the one
|
|
* with the lowest vma->vm_start where start
|
|
* is also < vma->vm_end. If start <
|
|
* vma->vm_start it means an hole materialized
|
|
* in the user address space within the
|
|
* virtual range passed to MADV_DONTNEED.
|
|
*/
|
|
return -ENOMEM;
|
|
}
|
|
if (!can_madv_dontneed_vma(vma))
|
|
return -EINVAL;
|
|
if (end > vma->vm_end) {
|
|
/*
|
|
* Don't fail if end > vma->vm_end. If the old
|
|
* vma was splitted while the mmap_sem was
|
|
* released the effect of the concurrent
|
|
* operation may not cause MADV_DONTNEED 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);
|
|
}
|
|
zap_page_range(vma, start, end - start);
|
|
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;
|
|
|
|
*prev = NULL; /* tell sys_madvise we drop mmap_sem */
|
|
|
|
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->vm_flags & (VM_SHARED|VM_WRITE)) != (VM_SHARED|VM_WRITE))
|
|
return -EACCES;
|
|
|
|
offset = (loff_t)(start - vma->vm_start)
|
|
+ ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
|
|
|
|
/*
|
|
* Filesystem's fallocate may need to take i_mutex. 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_sem.
|
|
*/
|
|
get_file(f);
|
|
if (userfaultfd_remove(vma, start, end)) {
|
|
/* mmap_sem was not released by userfaultfd_remove() */
|
|
up_read(¤t->mm->mmap_sem);
|
|
}
|
|
error = vfs_fallocate(f,
|
|
FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
|
|
offset, end - start);
|
|
fput(f);
|
|
down_read(¤t->mm->mmap_sem);
|
|
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)
|
|
{
|
|
struct page *page;
|
|
|
|
if (!capable(CAP_SYS_ADMIN))
|
|
return -EPERM;
|
|
|
|
for (; start < end; start += PAGE_SIZE <<
|
|
compound_order(compound_head(page))) {
|
|
int ret;
|
|
|
|
ret = get_user_pages_fast(start, 1, 0, &page);
|
|
if (ret != 1)
|
|
return ret;
|
|
|
|
if (PageHWPoison(page)) {
|
|
put_page(page);
|
|
continue;
|
|
}
|
|
|
|
if (behavior == MADV_SOFT_OFFLINE) {
|
|
pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n",
|
|
page_to_pfn(page), start);
|
|
|
|
ret = soft_offline_page(page, MF_COUNT_INCREASED);
|
|
if (ret)
|
|
return ret;
|
|
continue;
|
|
}
|
|
pr_info("Injecting memory failure for pfn %#lx at process virtual address %#lx\n",
|
|
page_to_pfn(page), start);
|
|
|
|
ret = memory_failure(page_to_pfn(page), 0, MF_COUNT_INCREASED);
|
|
if (ret)
|
|
return ret;
|
|
}
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
static long
|
|
madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
|
|
unsigned long start, unsigned long end, int behavior)
|
|
{
|
|
switch (behavior) {
|
|
case MADV_REMOVE:
|
|
return madvise_remove(vma, prev, start, end);
|
|
case MADV_WILLNEED:
|
|
return madvise_willneed(vma, prev, start, end);
|
|
case MADV_FREE:
|
|
return madvise_free(vma, prev, start, end);
|
|
case MADV_DONTNEED:
|
|
return madvise_dontneed(vma, prev, start, end);
|
|
default:
|
|
return madvise_behavior(vma, prev, start, end, behavior);
|
|
}
|
|
}
|
|
|
|
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_FREE:
|
|
#ifdef CONFIG_KSM
|
|
case MADV_MERGEABLE:
|
|
case MADV_UNMERGEABLE:
|
|
#endif
|
|
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
|
|
case MADV_HUGEPAGE:
|
|
case MADV_NOHUGEPAGE:
|
|
#endif
|
|
case MADV_DONTDUMP:
|
|
case MADV_DODUMP:
|
|
#ifdef CONFIG_MEMORY_FAILURE
|
|
case MADV_SOFT_OFFLINE:
|
|
case MADV_HWPOISON:
|
|
#endif
|
|
return true;
|
|
|
|
default:
|
|
return false;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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_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_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.
|
|
*
|
|
* 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.
|
|
* -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.
|
|
*/
|
|
SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
|
|
{
|
|
unsigned long end, tmp;
|
|
struct vm_area_struct *vma, *prev;
|
|
int unmapped_error = 0;
|
|
int error = -EINVAL;
|
|
int write;
|
|
size_t len;
|
|
struct blk_plug plug;
|
|
|
|
if (!madvise_behavior_valid(behavior))
|
|
return error;
|
|
|
|
if (start & ~PAGE_MASK)
|
|
return error;
|
|
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 error;
|
|
|
|
end = start + len;
|
|
if (end < start)
|
|
return error;
|
|
|
|
error = 0;
|
|
if (end == start)
|
|
return error;
|
|
|
|
#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 (down_write_killable(¤t->mm->mmap_sem))
|
|
return -EINTR;
|
|
} else {
|
|
down_read(¤t->mm->mmap_sem);
|
|
}
|
|
|
|
/*
|
|
* 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(current->mm, start, &prev);
|
|
if (vma && start > vma->vm_start)
|
|
prev = vma;
|
|
|
|
blk_start_plug(&plug);
|
|
for (;;) {
|
|
/* Still start < end. */
|
|
error = -ENOMEM;
|
|
if (!vma)
|
|
goto out;
|
|
|
|
/* Here start < (end|vma->vm_end). */
|
|
if (start < vma->vm_start) {
|
|
unmapped_error = -ENOMEM;
|
|
start = vma->vm_start;
|
|
if (start >= end)
|
|
goto out;
|
|
}
|
|
|
|
/* 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 = madvise_vma(vma, &prev, start, tmp, behavior);
|
|
if (error)
|
|
goto out;
|
|
start = tmp;
|
|
if (prev && start < prev->vm_end)
|
|
start = prev->vm_end;
|
|
error = unmapped_error;
|
|
if (start >= end)
|
|
goto out;
|
|
if (prev)
|
|
vma = prev->vm_next;
|
|
else /* madvise_remove dropped mmap_sem */
|
|
vma = find_vma(current->mm, start);
|
|
}
|
|
out:
|
|
blk_finish_plug(&plug);
|
|
if (write)
|
|
up_write(¤t->mm->mmap_sem);
|
|
else
|
|
up_read(¤t->mm->mmap_sem);
|
|
|
|
return error;
|
|
}
|