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Message-Id: <20190729190717.991622786@linuxfoundation.org>
Date: Mon, 29 Jul 2019 21:23:01 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org,
Konstantin Khlebnikov <khlebnikov@...dex-team.ru>,
Roman Gushchin <guro@...com>,
Cyrill Gorcunov <gorcunov@...il.com>,
Kirill Tkhai <ktkhai@...tuozzo.com>,
Michal Hocko <mhocko@...e.com>,
Alexey Dobriyan <adobriyan@...il.com>,
Al Viro <viro@...iv.linux.org.uk>,
Matthew Wilcox <willy@...radead.org>,
Michal Koutný <mkoutny@...e.com>,
Oleg Nesterov <oleg@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 094/113] proc: use down_read_killable mmap_sem for /proc/pid/maps
[ Upstream commit 8a713e7df3352b8d9392476e9cf29e4e185dac32 ]
Do not remain stuck forever if something goes wrong. Using a killable
lock permits cleanup of stuck tasks and simplifies investigation.
This function is also used for /proc/pid/smaps.
Link: http://lkml.kernel.org/r/156007493160.3335.14447544314127417266.stgit@buzz
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>
Cc: Alexey Dobriyan <adobriyan@...il.com>
Cc: Al Viro <viro@...iv.linux.org.uk>
Cc: Matthew Wilcox <willy@...radead.org>
Cc: Michal Koutný <mkoutny@...e.com>
Cc: Oleg Nesterov <oleg@...hat.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
fs/proc/task_mmu.c | 6 +++++-
fs/proc/task_nommu.c | 6 +++++-
2 files changed, 10 insertions(+), 2 deletions(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 195fbbaf77d4..71aba44c4fa6 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -166,7 +166,11 @@ static void *m_start(struct seq_file *m, loff_t *ppos)
if (!mm || !mmget_not_zero(mm))
return NULL;
- down_read(&mm->mmap_sem);
+ if (down_read_killable(&mm->mmap_sem)) {
+ mmput(mm);
+ return ERR_PTR(-EINTR);
+ }
+
hold_task_mempolicy(priv);
priv->tail_vma = get_gate_vma(mm);
diff --git a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c
index 0b63d68dedb2..5161894a6d62 100644
--- a/fs/proc/task_nommu.c
+++ b/fs/proc/task_nommu.c
@@ -211,7 +211,11 @@ static void *m_start(struct seq_file *m, loff_t *pos)
if (!mm || !mmget_not_zero(mm))
return NULL;
- down_read(&mm->mmap_sem);
+ if (down_read_killable(&mm->mmap_sem)) {
+ mmput(mm);
+ return ERR_PTR(-EINTR);
+ }
+
/* start from the Nth VMA */
for (p = rb_first(&mm->mm_rb); p; p = rb_next(p))
if (n-- == 0)
--
2.20.1
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