Re: [blk_mq_register_hctx] 29dee3c03a WARNING: CPU: 0 PID: 5 at lib/refcount.c:114 refcount_inc

On Tue, Feb 28, 2017 at 12:11:17PM +0800, Fengguang Wu wrote:

Hello,

FYI, an old blk_mq bug triggers new warnings on this commit. It's very
reproducible and you may try the attached reproduce-* script.

https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master

commit 29dee3c03abce04cd527878ef5f9e5f91b7b83f4
Author:     Peter Zijlstra [off-list ref]
AuthorDate: Fri Feb 10 16:27:52 2017 +0100
Commit:     Ingo Molnar [off-list ref]
CommitDate: Fri Feb 24 09:02:10 2017 +0100

     locking/refcounts: Out-of-line everything
     
     Linus asked to please make this real C code.
     
     And since size then isn't an issue what so ever anymore, remove the
     debug knob and make all WARN()s unconditional.

       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

I suspect that if you revert, but enable CONFIG_DEBUG_REFCOUNT you'd
have gotten the same splats..


I'll go have a look though, something looks buggered.