diff mbox series

[v2,2/6] proc: use down_read_killable mmap_sem for /proc/pid/smaps_rollup

Message ID 156007493429.3335.14666825072272692455.stgit@buzz (mailing list archive)
State New, archived
Headers show
Series mm: use down_read_killable for locking mmap_sem in proc | expand

Commit Message

Konstantin Khlebnikov June 9, 2019, 10:08 a.m. UTC 
Do not stuck forever if something wrong.
Killable lock allows to cleanup stuck tasks and simplifies investigation.

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>
---
 fs/proc/task_mmu.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)
diff mbox series

Patch

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;