On Wed, Oct 01, 2014 at 11:32:29AM +0200, Philipp Reisner wrote:
> From: Lars Ellenberg <lars.ellenberg@xxxxxxxxxx>
>
> Stable info:
> This patch landed in upstream with v3.16 as commit
> bbc1c5e8ad6dfebf9d13b8a4ccdf66c92913eac9
> it should go into v3.14+
>
> Since linux kernel 3.13, kthread_run() internally uses
> wait_for_completion_killable(). We sometimes may use kthread_run()
> while we still have a signal pending, which we used to kick our threads
> out of potentially blocking network functions, causing kthread_run() to
> mistake that as a new fatal signal and fail.
>
> Fix: flush_signals() before kthread_run().
>
> Signed-off-by: Philipp Reisner <philipp.reisner@xxxxxxxxxx>
> Signed-off-by: Lars Ellenberg <lars.ellenberg@xxxxxxxxxx>
> Signed-off-by: Jens Axboe <axboe@xxxxxx>
> ---
> drivers/block/drbd/drbd_nl.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
> index 1b35c45..3f2e167 100644
> --- a/drivers/block/drbd/drbd_nl.c
> +++ b/drivers/block/drbd/drbd_nl.c
> @@ -544,6 +544,12 @@ void conn_try_outdate_peer_async(struct drbd_connection *connection)
> struct task_struct *opa;
>
> kref_get(&connection->kref);
> + /* We may just have force_sig()'ed this thread
> + * to get it out of some blocking network function.
> + * Clear signals; otherwise kthread_run(), which internally uses
> + * wait_on_completion_killable(), will mistake our pending signal
> + * for a new fatal signal and fail. */
> + flush_signals(current);
> opa = kthread_run(_try_outdate_peer_async, connection, "drbd_async_h");
> if (IS_ERR(opa)) {
> drbd_err(connection, "out of mem, failed to invoke fence-peer helper\n");
This doesn't apply to 3.16-stable or 3.14-stable, can you please provide
a working backport?
thanks,
greg k-h
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