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Message-ID: <156007493826.3335.5424884725467456239.stgit@buzz>
Date: Sun, 09 Jun 2019 13:08:58 +0300
From: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
To: linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
linux-kernel@...r.kernel.org
Cc: Oleg Nesterov <oleg@...hat.com>,
Matthew Wilcox <willy@...radead.org>,
Michal Hocko <mhocko@...nel.org>,
Cyrill Gorcunov <gorcunov@...il.com>,
Kirill Tkhai <ktkhai@...tuozzo.com>,
Michal Koutný <mkoutny@...e.com>,
Al Viro <viro@...iv.linux.org.uk>, Roman Gushchin <guro@...com>
Subject: [PATCH v2 4/6] proc: use down_read_killable mmap_sem for
/proc/pid/clear_refs
Do not stuck forever if something wrong.
Killable lock allows to cleanup stuck tasks and simplifies investigation.
Replace the only unkillable mmap_sem lock in clear_refs_write.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
Reviewed-by: Roman Gushchin <guro@...com>
Reviewed-by: Cyrill Gorcunov <gorcunov@...il.com>
Reviewed-by: Kirill Tkhai <ktkhai@...tuozzo.com>
Acked-by: Michal Hocko <mhocko@...e.com>
---
fs/proc/task_mmu.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 78bed6adc62d..7f84d1477b5b 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1140,7 +1140,10 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
goto out_mm;
}
- down_read(&mm->mmap_sem);
+ if (down_read_killable(&mm->mmap_sem)) {
+ count = -EINTR;
+ goto out_mm;
+ }
tlb_gather_mmu(&tlb, mm, 0, -1);
if (type == CLEAR_REFS_SOFT_DIRTY) {
for (vma = mm->mmap; vma; vma = vma->vm_next) {
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