From a26a97815548574213fd37f29b4b78ccc6d9ed20 Mon Sep 17 00:00:00 2001 From: Konstantin Khlebnikov Date: Thu, 11 Jul 2019 20:59:53 -0700 Subject: proc: use down_read_killable mmap_sem for /proc/pid/smaps_rollup MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: Roman Gushchin Reviewed-by: Cyrill Gorcunov Reviewed-by: Kirill Tkhai Acked-by: Michal Hocko Cc: Alexey Dobriyan Cc: Al Viro Cc: Matthew Wilcox Cc: Michal Koutný Cc: Oleg Nesterov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/task_mmu.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'fs') diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 2bf210229daf..781879a91e3b 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -832,7 +832,10 @@ 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) { @@ -849,8 +852,9 @@ 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; -- cgit v1.2.3-59-g8ed1b