linux-kernel - [PATCH 3.4 003/134] audit: wait_for_auditd() should use TASK

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Message-Id: <20140410032300.079283146@linuxfoundation.org>
Date:	Wed,  9 Apr 2014 20:21:59 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Oleg Nesterov <oleg@...hat.com>,
	Guy Streeter <streeter@...hat.com>,
	Eric Paris <eparis@...hat.com>,
	Al Viro <viro@...iv.linux.org.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ben Hutchings <ben@...adent.org.uk>,
	Qiang Huang <h.huangqiang@...wei.com>,
	Li Zefan <lizefan@...wei.com>,
	Jianguo Wu <wujianguo@...wei.com>
Subject: [PATCH 3.4 003/134] audit: wait_for_auditd() should use TASK_UNINTERRUPTIBLE

3.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Oleg Nesterov <oleg@...hat.com>

commit f000cfdde5de4fc15dead5ccf524359c07eadf2b upstream.

audit_log_start() does wait_for_auditd() in a loop until
audit_backlog_wait_time passes or audit_skb_queue has a room.

If signal_pending() is true this becomes a busy-wait loop, schedule() in
TASK_INTERRUPTIBLE won't block.

Thanks to Guy for fully investigating and explaining the problem.

(akpm: that'll cause the system to lock up on a non-preemptible
uniprocessor kernel)

(Guy: "Our customer was in fact running a uniprocessor machine, and they
reported a system hang.")

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
Reported-by: Guy Streeter <streeter@...hat.com>
Cc: Eric Paris <eparis@...hat.com>
Cc: Al Viro <viro@...iv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
[bwh: Backported to 3.2: adjust context, indentation]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
Cc: Qiang Huang <h.huangqiang@...wei.com>
Cc: Li Zefan <lizefan@...wei.com>
Cc: Jianguo Wu <wujianguo@...wei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 kernel/audit.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -1168,7 +1168,7 @@ struct audit_buffer *audit_log_start(str
 
 			/* Wait for auditd to drain the queue a little */
 			DECLARE_WAITQUEUE(wait, current);
-			set_current_state(TASK_INTERRUPTIBLE);
+			set_current_state(TASK_UNINTERRUPTIBLE);
 			add_wait_queue(&audit_backlog_wait, &wait);
 
 			if (audit_backlog_limit &&


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