From: Jens Axboe <axboe@kernel.dk>
To: syzbot <syzbot+4f8bfd804b4a1f95b8f6@syzkaller.appspotmail.com>,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] KCSAN: data-race in sbitmap_queue_clear / sbitmap_queue_clear (3)
Date: Mon, 25 Oct 2021 07:35:59 -0600 [thread overview]
Message-ID: <f37aa186-8820-451f-6fa2-eee45799a428@kernel.dk> (raw)
In-Reply-To: <00000000000089871905cf2b7d09@google.com>
On 10/25/21 5:16 AM, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 2f111a6fd5b5 Merge tag 'ceph-for-5.15-rc7' of git://github..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=10dae330b00000
> kernel config: https://syzkaller.appspot.com/x/.config?x=b2868748300e5cf6
> dashboard link: https://syzkaller.appspot.com/bug?extid=4f8bfd804b4a1f95b8f6
> compiler: Debian clang version 11.0.1-2, GNU ld (GNU Binutils for Debian) 2.35.2
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+4f8bfd804b4a1f95b8f6@syzkaller.appspotmail.com
>
> ==================================================================
> BUG: KCSAN: data-race in sbitmap_queue_clear / sbitmap_queue_clear
>
> write to 0xffffe8ffffd145b8 of 4 bytes by interrupt on cpu 1:
> sbitmap_queue_clear+0xca/0xf0 lib/sbitmap.c:606
> blk_mq_put_tag+0x82/0x90
> __blk_mq_free_request+0x114/0x180 block/blk-mq.c:507
> blk_mq_free_request+0x2c8/0x340 block/blk-mq.c:541
> __blk_mq_end_request+0x214/0x230 block/blk-mq.c:565
> blk_mq_end_request+0x37/0x50 block/blk-mq.c:574
> lo_complete_rq+0xca/0x170 drivers/block/loop.c:541
> blk_complete_reqs block/blk-mq.c:584 [inline]
> blk_done_softirq+0x69/0x90 block/blk-mq.c:589
> __do_softirq+0x12c/0x26e kernel/softirq.c:558
> run_ksoftirqd+0x13/0x20 kernel/softirq.c:920
> smpboot_thread_fn+0x22f/0x330 kernel/smpboot.c:164
> kthread+0x262/0x280 kernel/kthread.c:319
> ret_from_fork+0x1f/0x30
>
> write to 0xffffe8ffffd145b8 of 4 bytes by interrupt on cpu 0:
> sbitmap_queue_clear+0xca/0xf0 lib/sbitmap.c:606
> blk_mq_put_tag+0x82/0x90
> __blk_mq_free_request+0x114/0x180 block/blk-mq.c:507
> blk_mq_free_request+0x2c8/0x340 block/blk-mq.c:541
> __blk_mq_end_request+0x214/0x230 block/blk-mq.c:565
> blk_mq_end_request+0x37/0x50 block/blk-mq.c:574
> lo_complete_rq+0xca/0x170 drivers/block/loop.c:541
> blk_complete_reqs block/blk-mq.c:584 [inline]
> blk_done_softirq+0x69/0x90 block/blk-mq.c:589
> __do_softirq+0x12c/0x26e kernel/softirq.c:558
> run_ksoftirqd+0x13/0x20 kernel/softirq.c:920
> smpboot_thread_fn+0x22f/0x330 kernel/smpboot.c:164
> kthread+0x262/0x280 kernel/kthread.c:319
> ret_from_fork+0x1f/0x30
This is just a per-cpu alloc hint, it's racy by nature. What's the
preferred way to silence these?
--
Jens Axboe
next prev parent reply other threads:[~2021-10-25 13:36 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-25 11:16 [syzbot] KCSAN: data-race in sbitmap_queue_clear / sbitmap_queue_clear (3) syzbot
2021-10-25 13:35 ` Jens Axboe [this message]
2021-10-25 14:29 ` Marco Elver
2021-10-25 15:40 ` Jens Axboe
2021-10-25 16:03 ` Marco Elver
2021-10-25 16:47 ` Jens Axboe
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