[ 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 <khlebni...@yandex-team.ru> Reviewed-by: Roman Gushchin <g...@fb.com> Reviewed-by: Cyrill Gorcunov <gorcu...@gmail.com> Reviewed-by: Kirill Tkhai <ktk...@virtuozzo.com> Acked-by: Michal Hocko <mho...@suse.com> Cc: Alexey Dobriyan <adobri...@gmail.com> Cc: Al Viro <v...@zeniv.linux.org.uk> Cc: Matthew Wilcox <wi...@infradead.org> Cc: Michal Koutný <mkou...@suse.com> Cc: Oleg Nesterov <o...@redhat.com> Signed-off-by: Andrew Morton <a...@linux-foundation.org> Signed-off-by: Linus Torvalds <torva...@linux-foundation.org> Signed-off-by: Sasha Levin <sas...@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 01d4eb0e6bd1..4d9a8e72d91f 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -828,7 +828,10 @@ 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) { @@ -845,8 +848,9 @@ 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; -- 2.20.1
