linux-kernel - Re: [sporadic crash] blk: request botched

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Message-ID: <4D91C4BA.9030502@fusionio.com>
Date:	Tue, 29 Mar 2011 13:38:34 +0200
From:	Jens Axboe <jaxboe@...ionio.com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Linus Torvalds <torvalds@...ux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>, Tejun Heo <tj@...nel.org>
Subject: Re: [sporadic crash] blk: request botched

On 2011-03-29 13:17, Ingo Molnar wrote:
> 
> FYI, i'm seeing a new block IO related boot failure. It starts by the kernel spewing:
> 
>  [   84.434778] blk: request botched
>  [   84.437546] blk: request botched
>  [   84.441532] blk: request botched
> 
> And after more dying noises, a colorful kernel crash in an apparently rarely
> excercised error handler:

I don't think it's the error handler being broken, it simply looks like
a request that is in a bad bad state thus causing the normal rq -> bio
-> bvec run through to bomb out.

So the 'request botched' is the real BUG here.

Is that part reproducible? If so, can you please try with this patch?

diff --git a/block/blk-core.c b/block/blk-core.c
index e0a0623..3045d0e 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2163,7 +2163,8 @@ bool blk_update_request(struct request *req, int error, unsigned int nr_bytes)
 	 * size, something has gone terribly wrong.
 	 */
 	if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) {
-		printk(KERN_ERR "blk: request botched\n");
+		blk_dump_rq_flags(req, "request botched");
+		WARN_ON(1);
 		req->__data_len = blk_rq_cur_bytes(req);
 	}
 

-- 
Jens Axboe

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