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Date: Wed, 18 Jan 2012 10:26:38 +0800 From: Shaohua Li <shaohua.li@...el.com> To: Tejun Heo <tj@...nel.org> Cc: Vivek Goyal <vgoyal@...hat.com>, linux kernel mailing list <linux-kernel@...r.kernel.org>, Jens Axboe <axboe@...nel.dk> Subject: Re: Kernel crash in icq_free_icq_rcu 2012/1/18 Shaohua Li <shaohua.li@...el.com>: > On Tue, 2012-01-17 at 17:11 -0800, Tejun Heo wrote: >> On Wed, Jan 18, 2012 at 09:05:26AM +0800, Shaohua Li wrote: >> > > Vivek is seeing the problem while switching elevators. Are you too? >> > > Or is it during normal operation? >> > same here. I had some problems when I debug my ioscheduler, but >> > eventually found even switching cfq and noop can trigger oops. >> >> Hmmm... maybe quiescing isn't working as expected and kmem cache is >> being destroyed with live icq's. I'll try to reproduce it. > this debug patch seems to fix for me. > > diff --git a/block/blk-core.c b/block/blk-core.c > index e6c05a9..c6a8ef5 100644 > --- a/block/blk-core.c > +++ b/block/blk-core.c > @@ -872,11 +872,11 @@ retry: > spin_unlock_irq(q->queue_lock); > > /* create icq if missing */ > - if (unlikely(et->icq_cache && !icq)) > + if (unlikely(et->icq_cache && !icq && (rw_flags & REQ_ELVPRIV))) > icq = ioc_create_icq(q, gfp_mask); > > /* rqs are guaranteed to have icq on elv_set_request() if requested */ > - if (likely(!et->icq_cache || icq)) > + if (likely(!et->icq_cache || icq || !(rw_flags & REQ_ELVPRIV))) > rq = blk_alloc_request(q, icq, rw_flags, gfp_mask); > > if (unlikely(!rq)) { this passed my test, but I didn't get reason why it can help ... blk_alloc_request doesn't use icq if REQ_ELVPRIV isn't set, so the code has problem for sure. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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