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| author | Will Deacon <will@kernel.org> | 2021-01-27 23:53:42 +0000 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2021-01-29 20:02:28 +0100 |
| commit | 912efa17e5121693dfbadae29768f4144a3f9e62 (patch) | |
| tree | 8f2befff7da747e3c0c8cb135ae4129670e9c625 /fs/proc | |
| parent | 6ee1d745b7c9fd573fba142a2efdad76a9f1cb04 (diff) | |
| download | linux-912efa17e5121693dfbadae29768f4144a3f9e62.tar.gz linux-912efa17e5121693dfbadae29768f4144a3f9e62.tar.bz2 linux-912efa17e5121693dfbadae29768f4144a3f9e62.zip | |
mm: proc: Invalidate TLB after clearing soft-dirty page state
Since commit 0758cd830494 ("asm-generic/tlb: avoid potential double
flush"), TLB invalidation is elided in tlb_finish_mmu() if no entries
were batched via the tlb_remove_*() functions. Consequently, the
page-table modifications performed by clear_refs_write() in response to
a write to /proc/<pid>/clear_refs do not perform TLB invalidation.
Although this is fine when simply aging the ptes, in the case of
clearing the "soft-dirty" state we can end up with entries where
pte_write() is false, yet a writable mapping remains in the TLB.
Fix this by avoiding the mmu_gather API altogether: managing both the
'tlb_flush_pending' flag on the 'mm_struct' and explicit TLB
invalidation for the sort-dirty path, much like mprotect() does already.
Fixes: 0758cd830494 ("asm-generic/tlb: avoid potential double flushâ)
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Yu Zhao <yuzhao@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lkml.kernel.org/r/20210127235347.1402-2-will@kernel.org
Diffstat (limited to 'fs/proc')
| -rw-r--r-- | fs/proc/task_mmu.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 602e3a52884d..3cec6fbef725 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1210,7 +1210,6 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf, struct mm_struct *mm; struct vm_area_struct *vma; enum clear_refs_types type; - struct mmu_gather tlb; int itype; int rv; @@ -1249,7 +1248,6 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf, goto out_unlock; } - tlb_gather_mmu(&tlb, mm, 0, -1); if (type == CLEAR_REFS_SOFT_DIRTY) { for (vma = mm->mmap; vma; vma = vma->vm_next) { if (!(vma->vm_flags & VM_SOFTDIRTY)) @@ -1258,15 +1256,18 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf, vma_set_page_prot(vma); } + inc_tlb_flush_pending(mm); mmu_notifier_range_init(&range, MMU_NOTIFY_SOFT_DIRTY, 0, NULL, mm, 0, -1UL); mmu_notifier_invalidate_range_start(&range); } walk_page_range(mm, 0, mm->highest_vm_end, &clear_refs_walk_ops, &cp); - if (type == CLEAR_REFS_SOFT_DIRTY) + if (type == CLEAR_REFS_SOFT_DIRTY) { mmu_notifier_invalidate_range_end(&range); - tlb_finish_mmu(&tlb, 0, -1); + flush_tlb_mm(mm); + dec_tlb_flush_pending(mm); + } out_unlock: mmap_write_unlock(mm); out_mm: |