Re: [PATCH] scsi: Fix a bdi reregistration race

[Bart Van Assche <bvanassche@acm.org>]

On 09/20/15 02:57, Sagi Grimberg wrote:
> On 9/19/2015 3:23 AM, Bart Van Assche wrote:
>> Unregister and reregister BDI devices in the proper order. This patch
>> avoids that the following kernel warning can get triggered:
>
> Can you share the scenario that reproduced this? I think I might
> have seen this before.

Hello Sagi,

The details of the setup on which I can reproduce the reported behavior 
easily are as follows:
* Several kernel debugging options were enabled on the initiator system
   (PROVE_LOCKING, SLUB_DEBUG, KMEMLEAK, ...).
* srp_daemon and multipathd were running on the initiator system.
* Four IB ports were present the initiator system.
* Eight IB ports were present the target system.
* 100 LUNs were defined on the target system.
* As a result, 3200 /dev/sd* device nodes were created on the
   initiator system by the SRP initiator driver.
* The following command was run on the initiator system:
   for p in /sys/class/srp_remote_ports/*; do echo 1 >$p/delete & done;
   wait; dmsetup remove_all

Bart.