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SubjectRe: [REVIEW][PATCH] pid_ns: Sleep in TASK_INTERRUPTIBLE in zap_pid_ns_processes
On Fri, May 12, 2017 at 12:55:22PM -0500, Eric W. Biederman wrote:
> Date: Thu, 11 May 2017 18:21:01 -0500
>
> 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")
> Cc: stable@vger.kernel.org
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
> ---
>
> This is what I have queued up posting so it is public knowledge and so
> that if anyone can see a flaw it can get fixed.
>
> kernel/pid_namespace.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
> index de461aa0bf9a..6e51b8820495 100644
> --- a/kernel/pid_namespace.c
> +++ b/kernel/pid_namespace.c
> @@ -277,7 +277,7 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns)
> * if reparented.
> */
> for (;;) {
> - set_current_state(TASK_UNINTERRUPTIBLE);
> + set_current_state(TASK_INTERRUPTIBLE);
> if (pid_ns->nr_hashed == init_pids)
> break;
> schedule();
> --
> 2.10.1
>

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