[dm-devel] [PATCH v2 02/13] dm-mpath: Avoid that path removal can trigger an infinite loop

[Hannes Reinecke]

On 04/27/2017 07:11 PM, Bart Van Assche wrote:
> If blk_get_request() fails check whether the failure is due to
> a path being removed. If that is the case fail the path by
> triggering a call to fail_path(). This patch avoids that the
> following scenario can be encountered while removing paths:
> * CPU usage of a kworker thread jumps to 100%.
> * Removing the dm device becomes impossible.
> 
> Delay requeueing if blk_get_request() returns -EBUSY or
> -EWOULDBLOCK because in these cases immediate requeuing is
> inappropriate.
> 
> Signed-off-by: Bart Van Assche <bart.vanassche at sandisk.com>
> Cc: Hannes Reinecke <hare at suse.com>
> Cc: Christoph Hellwig <hch at lst.de>
> Cc: <stable at vger.kernel.org>
> ---
>  drivers/md/dm-mpath.c | 17 ++++++++++++-----
>  1 file changed, 12 insertions(+), 5 deletions(-)
> 
Reviewed-by: Hannes Reinecke <hare at suse.com>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
hare at suse.de			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)