From: Konstantin Khlebnikov <[email protected]> [ 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 <[email protected]> Reviewed-by: Roman Gushchin <[email protected]> Reviewed-by: Cyrill Gorcunov <[email protected]> Reviewed-by: Kirill Tkhai <[email protected]> Acked-by: Michal Hocko <[email protected]> Cc: Alexey Dobriyan <[email protected]> Cc: Al Viro <[email protected]> Cc: Matthew Wilcox <[email protected]> Cc: Michal Koutný <[email protected]> Cc: Oleg Nesterov <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Sasha Levin <[email protected]> --- 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
