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From: syzbot <syzbot+ff9ab4a23afa7553@syzkaller.appspotmail.com>
To: Bart Van Assche <bvanassche@acm.org>
Cc: 00moses.alexander00@gmail.com, axboe@kernel.dk,
	bvanassche@acm.org, hare@suse.com, hch@lst.de,
	joseph.qi@linux.alibaba.com, jthumshirn@suse.de,
	linux-block@vger.kernel.org, ming.lei@redhat.com, tj@kernel.org
Subject: Re: [PATCH 2/2] block: Fix a race condition in submit_bio()
Date: Tue, 30 Jul 2019 11:18:08 -0700	[thread overview]
Message-ID: <000000000000d6f79d058eea075f@google.com> (raw)
In-Reply-To: <20190730181757.248832-3-bvanassche@acm.org>

> generic_make_request_checks() needs to be protected by a
> blk_queue_enter() / blk_queue_exit() pair because it calls
> blkcg_bio_issue_check() and because that last function calls
> blkg_lookup().

> This patch fixes  
> https://syzkaller.appspot.com/bug?id=ff9ab4a23afa7553fb79f745a92be87ba4144508.

> This patch also fixes the following kernel warning, triggered by
> blktests:

> WARNING: CPU: 5 PID: 10706 at block/blk-core.c:903  
> generic_make_request_checks+0x9c6/0xe60
> RIP: 0010:generic_make_request_checks+0x9c6/0xe60
> Call Trace:
>   generic_make_request+0x7a/0x5c0
>   submit_bio+0x92/0x280
>   mpage_readpages+0x2b1/0x300
>   blkdev_readpages+0x1d/0x20
>   read_pages+0xd9/0x2c0
>   __do_page_cache_readahead+0x2e0/0x310
>   force_page_cache_readahead+0xfb/0x170
>   page_cache_sync_readahead+0x28d/0x2a0
>   generic_file_read_iter+0xc13/0x1530
>   blkdev_read_iter+0x7d/0x90
>   new_sync_read+0x2c5/0x3d0
>   __vfs_read+0x7b/0x90
>   vfs_read+0xc6/0x1f0
>   ksys_read+0xc3/0x160
>   __x64_sys_read+0x43/0x50
>   do_syscall_64+0x71/0x270
>   entry_SYSCALL_64_after_hwframe+0x49/0xbe

> Cc: Tejun Heo <tj@kernel.org>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Ming Lei <ming.lei@redhat.com>
> Cc: Hannes Reinecke <hare@suse.com>
> Cc: Johannes Thumshirn <jthumshirn@suse.de>
> Cc: Alexandru Moise <00moses.alexander00@gmail.com>
> Cc: Joseph Qi <joseph.qi@linux.alibaba.com>
> Reported-by: syzbot+ff9ab4a23afa7553@syzkaller.appspotmail.com
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> ---
>   block/blk-core.c | 13 ++++++++++++-
>   1 file changed, 12 insertions(+), 1 deletion(-)

> diff --git a/block/blk-core.c b/block/blk-core.c
> index ff27c3080348..cd844c54e9f1 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -1150,6 +1150,9 @@ EXPORT_SYMBOL_GPL(direct_make_request);
>    */
>   blk_qc_t submit_bio(struct bio *bio)
>   {
> +	struct request_queue *q = bio->bi_disk->queue;
> +	blk_qc_t ret;
> +
>   	if (blkcg_punt_bio_submit(bio))
>   		return BLK_QC_T_NONE;

> @@ -1182,7 +1185,15 @@ blk_qc_t submit_bio(struct bio *bio)
>   		}
>   	}

> -	return generic_make_request(bio);
> +	if (unlikely(blk_queue_enter(q, 0) < 0)) {
> +		bio->bi_status = BLK_STS_IOERR;
> +		bio->bi_end_io(bio);
> +		return BLK_QC_T_NONE;
> +	}
> +	ret = generic_make_request(bio);
> +	blk_queue_exit(q);
> +
> +	return ret;
>   }
>   EXPORT_SYMBOL(submit_bio);

> --
> 2.22.0.709.g102302147b-goog


I see the command but can't find the corresponding bug.
The email is sent to  syzbot+HASH@syzkaller.appspotmail.com address
but the HASH does not correspond to any known bug.
Please double check the address.


  reply	other threads:[~2019-07-30 18:18 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-30 18:17 [PATCH 0/2] Fix a race condition triggered by submit_bio() Bart Van Assche
2019-07-30 18:17 ` [PATCH 1/2] block: Verify whether blk_queue_enter() is used when necessary Bart Van Assche
2019-07-31  1:46   ` Ming Lei
2019-07-31 18:26     ` Bart Van Assche
2019-07-30 18:17 ` [PATCH 2/2] block: Fix a race condition in submit_bio() Bart Van Assche
2019-07-30 18:18   ` syzbot [this message]
2019-07-31  1:53   ` Ming Lei
2019-07-31  1:53     ` syzbot

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