diff mbox series

[v2,3/6] proc: use down_read_killable mmap_sem for /proc/pid/pagemap

Message ID 156007493638.3335.4872164955523928492.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 |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 781879a91e3b..78bed6adc62d 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1547,7 +1547,9 @@  static ssize_t pagemap_read(struct file *file, char __user *buf,
 		/* overflow ? */
 		if (end < start_vaddr || end > end_vaddr)
 			end = end_vaddr;
-		down_read(&mm->mmap_sem);
+		ret = down_read_killable(&mm->mmap_sem);
+		if (ret)
+			goto out_free;
 		ret = walk_page_range(start_vaddr, end, &pagemap_walk);
 		up_read(&mm->mmap_sem);
 		start_vaddr = end;