linux-kernel - Re: block: BUG: using smp_processor_id() in preemptible [00000000] code

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Message-ID: <4E2E4FF1.1010103@fusionio.com>
Date:	Tue, 26 Jul 2011 07:26:09 +0200
From:	Jens Axboe <jaxboe@...ionio.com>
To:	Ming Lei <tom.leiming@...il.com>
CC:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: block: BUG: using smp_processor_id() in preemptible [00000000]
 code

On 2011-07-26 06:49, Ming Lei wrote:
> Hi,
> 
> The bug is observed in -next-20110725, follows the stack trace[1], and
> seems the attachment patch can fix the bug.

Does this work, too? We don't necessarily need the CPU stable, but
spewing debug output isn't very nice.

diff --git a/block/blk-core.c b/block/blk-core.c
index f8cb099..f925581 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1283,7 +1283,7 @@ get_rq:
 
 	if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags) ||
 	    bio_flagged(bio, BIO_CPU_AFFINE))
-		req->cpu = smp_processor_id();
+		req->cpu = raw_smp_processor_id();
 
 	plug = current->plug;
 	if (plug) {

-- 
Jens Axboe

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