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authorMichal Hocko <mhocko@suse.com>2016-05-23 16:25:45 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-05-23 17:04:14 -0700
commit4e80153a6044bcd9a7d65c1ec4b1d1c44ba0ed6c (patch)
tree003fcb1ecafae6143e8e159517b6905f3442d5ee /fs
parent2d6c928241add2848e4eebfce407e95164229976 (diff)
downloadlwn-4e80153a6044bcd9a7d65c1ec4b1d1c44ba0ed6c.tar.gz
lwn-4e80153a6044bcd9a7d65c1ec4b1d1c44ba0ed6c.zip
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>
Diffstat (limited to 'fs')
-rw-r--r--fs/proc/task_mmu.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 541583510cfb..4648c7f63ae2 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1027,11 +1027,15 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
};
if (type == CLEAR_REFS_MM_HIWATER_RSS) {
+ if (down_write_killable(&mm->mmap_sem)) {
+ count = -EINTR;
+ goto out_mm;
+ }
+
/*
* Writing 5 to /proc/pid/clear_refs resets the peak
* resident set size to this mm's current rss value.
*/
- down_write(&mm->mmap_sem);
reset_mm_hiwater_rss(mm);
up_write(&mm->mmap_sem);
goto out_mm;
@@ -1043,7 +1047,10 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
if (!(vma->vm_flags & VM_SOFTDIRTY))
continue;
up_read(&mm->mmap_sem);
- down_write(&mm->mmap_sem);
+ if (down_write_killable(&mm->mmap_sem)) {
+ count = -EINTR;
+ goto out_mm;
+ }
for (vma = mm->mmap; vma; vma = vma->vm_next) {
vma->vm_flags &= ~VM_SOFTDIRTY;
vma_set_page_prot(vma);