On Mon, Oct 21, 2024 at 02:07:21PM +0200, Niklas Cassel wrote: > Hello Yi Lai, > > On Mon, Oct 21, 2024 at 06:58:59PM +0800, Lai, Yi wrote: > > Hi Niklas Cassel, > > > > Greetings! > > > > I used Syzkaller and found that there is INFO: task hung in blk_mq_get_tag in v6.12-rc3 > > > > After bisection and the first bad commit is: > > " > > e5dd410acb34 ata: libata: Clear DID_TIME_OUT for ATA PT commands with sense data > > " > > It might be that your bisection results are accurate. > > However, after looking at the stacktraces, I find it way more likely that > bisection has landed on the wrong commit. > > See this series that was just queued (for 6.13) a few days ago that solves a > similar starvation: > https://lore.kernel.org/linux-block/20241014092934.53630-1-songmuchun@xxxxxxxxxxxxx/ > https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git/log/?h=for-6.13/block > > You could perhaps run with v6.14-rc4 (which should be able to trigger the bug) > and then try v6.14-rc4 + that series applied, to see if you can still trigger > the bug? Another patch that might be relevant: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e972b08b91ef48488bae9789f03cfedb148667fb Which fixes a use after delete in rq_qos_wake_function(). (We can see that the stack trace has rq_qos_wake_function() before getting stuck forever in rq_qos_wait()) Who knows what could go wrong when accessing a deleted entry, in the report there was a crash, but I could image other surprises :) The fix was first included in v6.12-rc4. Kind regards, Niklas
