[PATCH 4.11 077/197] pid_ns: Sleep in TASK_INTERRUPTIBLE in zap_pid_ns_processes

From	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Newsgroups	linux.kernel
Subject	[PATCH 4.11 077/197] pid_ns: Sleep in TASK_INTERRUPTIBLE in zap_pid_ns_processes
Date	2017-05-23 22:20 +0200
Message-ID	<tKorD-8dL-1@gated-at.bofh.it> (permalink)
References	<tKorD-8dL-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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

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

From: Eric W. Biederman <ebiederm@xmission.com>

commit b9a985db98961ae1ba0be169f19df1c567e4ffe0 upstream.

The code can potentially sleep for an indefinite amount of time in
zap_pid_ns_processes triggering the hung task timeout, and increasing
the system average.  This is undesirable.  Sleep with a task state of
TASK_INTERRUPTIBLE instead of TASK_UNINTERRUPTIBLE to remove these
undesirable side effects.

Apparently under heavy load this has been allowing Chrome to trigger
the hung time task timeout error and cause ChromeOS to reboot.

Reported-by: Vovo Yang <vovoy@google.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Fixes: 6347e9009104 ("pidns: guarantee that the pidns init will be the last pidns process reaped")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -277,7 +277,7 @@ void zap_pid_ns_processes(struct pid_nam
 	 * if reparented.
 	 */
 	for (;;) {
-		set_current_state(TASK_UNINTERRUPTIBLE);
+		set_current_state(TASK_INTERRUPTIBLE);
 		if (pid_ns->nr_hashed == init_pids)
 			break;
 		schedule();

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[PATCH 4.11 077/197] pid_ns: Sleep in TASK_INTERRUPTIBLE in zap_pid_ns_processes Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-23 22:20 +0200

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