From: Konstantin Khlebnikov khlebnikov@yandex-team.ru
[ Upstream commit a26a97815548574213fd37f29b4b78ccc6d9ed20 ]
Do not remain stuck forever if something goes wrong. Using a killable lock permits cleanup of stuck tasks and simplifies investigation.
Link: http://lkml.kernel.org/r/156007493429.3335.14666825072272692455.stgit@buzz Signed-off-by: Konstantin Khlebnikov khlebnikov@yandex-team.ru Reviewed-by: Roman Gushchin guro@fb.com Reviewed-by: Cyrill Gorcunov gorcunov@gmail.com Reviewed-by: Kirill Tkhai ktkhai@virtuozzo.com Acked-by: Michal Hocko mhocko@suse.com Cc: Alexey Dobriyan adobriyan@gmail.com Cc: Al Viro viro@zeniv.linux.org.uk Cc: Matthew Wilcox willy@infradead.org Cc: Michal Koutný mkoutny@suse.com Cc: Oleg Nesterov oleg@redhat.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/proc/task_mmu.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index c5819baee35c..b2010055180e 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -826,7 +826,10 @@ static int show_smaps_rollup(struct seq_file *m, void *v)
memset(&mss, 0, sizeof(mss));
- down_read(&mm->mmap_sem); + ret = down_read_killable(&mm->mmap_sem); + if (ret) + goto out_put_mm; + hold_task_mempolicy(priv);
for (vma = priv->mm->mmap; vma; vma = vma->vm_next) { @@ -843,8 +846,9 @@ static int show_smaps_rollup(struct seq_file *m, void *v)
release_task_mempolicy(priv); up_read(&mm->mmap_sem); - mmput(mm);
+out_put_mm: + mmput(mm); out_put_task: put_task_struct(priv->task); priv->task = NULL;