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Message-Id: <20190729190716.968891980@linuxfoundation.org>
Date: Mon, 29 Jul 2019 21:22:57 +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 4.19 090/113] proc: use down_read_killable mmap_sem for /proc/pid/pagemap
[ Upstream commit ad80b932c57d85fd6377f97f359b025baf179a87 ]
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/156007493638.3335.4872164955523928492.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 | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index b2010055180e..74965e17ffd5 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1535,7 +1535,9 @@ 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;
--
2.20.1
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