mm, proc: make clear_refs killable
CLEAR_REFS_MM_HIWATER_RSS and CLEAR_REFS_SOFT_DIRTY are relying on mmap_sem for write. If the waiting task gets killed by the oom killer and it would operate on the current's mm it would block oom_reaper from asynchronous address space reclaim and reduce the chances of timely OOM resolving. Wait for the lock in the killable mode and return with EINTR if the task got killed while waiting. This will also expedite the return to the userspace and do_exit even if the mm is remote. Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Petr Cermak <petrcermak@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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2d6c928241
Коммит
4e80153a60
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@ -1027,11 +1027,15 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
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};
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if (type == CLEAR_REFS_MM_HIWATER_RSS) {
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if (down_write_killable(&mm->mmap_sem)) {
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count = -EINTR;
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goto out_mm;
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}
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/*
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* Writing 5 to /proc/pid/clear_refs resets the peak
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* resident set size to this mm's current rss value.
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*/
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down_write(&mm->mmap_sem);
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reset_mm_hiwater_rss(mm);
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up_write(&mm->mmap_sem);
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goto out_mm;
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@ -1043,7 +1047,10 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
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if (!(vma->vm_flags & VM_SOFTDIRTY))
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continue;
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up_read(&mm->mmap_sem);
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down_write(&mm->mmap_sem);
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if (down_write_killable(&mm->mmap_sem)) {
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count = -EINTR;
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goto out_mm;
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}
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for (vma = mm->mmap; vma; vma = vma->vm_next) {
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vma->vm_flags &= ~VM_SOFTDIRTY;
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vma_set_page_prot(vma);
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