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From: Weiping Zhang <zwp10758@gmail.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: Bart Van Assche <bvanassche@acm.org>,
	tom.leiming@gmail.com, linux-block@vger.kernel.org
Subject: Re: [PATCH] block: reset mapping if failed to update hardware queue count
Date: Wed, 13 May 2020 11:14:08 +0800	[thread overview]
Message-ID: <CAA70yB6SLv4g+Vihnf5M24J_ibTsEh5VLZzwoXJb0GZMhp+jZg@mail.gmail.com> (raw)
In-Reply-To: <585b0389-aa83-59b8-a155-f23621155bcd@kernel.dk>

On Wed, May 13, 2020 at 10:22 AM Jens Axboe <axboe@kernel.dk> wrote:
>
> On 5/12/20 6:44 PM, Weiping Zhang wrote:
> > When we increase hardware queue count, blk_mq_update_queue_map will
> > reset the mapping between cpu and hardware queue base on the hardware
> > queue count(set->nr_hw_queues). The mapping cannot be reset if it
> > encounters error in blk_mq_realloc_hw_ctxs, but the fallback flow will
> > continue using it, then blk_mq_map_swqueue will touch a invalid memory,
> > because the mapping points to a wrong hctx.
> >
> > blktest block/030:
> >
> > null_blk: module loaded
> > Increasing nr_hw_queues to 8 fails, fallback to 1
> > ==================================================================
> > BUG: KASAN: null-ptr-deref in blk_mq_map_swqueue+0x2f2/0x830
> > Read of size 8 at addr 0000000000000128 by task nproc/8541
> >
> > CPU: 5 PID: 8541 Comm: nproc Not tainted 5.7.0-rc4-dbg+ #3
> > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> > rel-1.13.0-0-gf21b5a4-rebuilt.opensuse.org 04/01/2014
> > Call Trace:
> > dump_stack+0xa5/0xe6
> > __kasan_report.cold+0x65/0xbb
> > kasan_report+0x45/0x60
> > check_memory_region+0x15e/0x1c0
> > __kasan_check_read+0x15/0x20
> > blk_mq_map_swqueue+0x2f2/0x830
> > __blk_mq_update_nr_hw_queues+0x3df/0x690
> > blk_mq_update_nr_hw_queues+0x32/0x50
> > nullb_device_submit_queues_store+0xde/0x160 [null_blk]
> > configfs_write_file+0x1c4/0x250 [configfs]
> > __vfs_write+0x4c/0x90
> > vfs_write+0x14b/0x2d0
> > ksys_write+0xdd/0x180
> > __x64_sys_write+0x47/0x50
> > do_syscall_64+0x6f/0x310
> > entry_SYSCALL_64_after_hwframe+0x49/0xb3
>
> Applied, thanks. Please do run blktests on your series in the future.
>
No problem, thanks a lot.
> --
> Jens Axboe
>

      reply	other threads:[~2020-05-13  3:14 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-13  0:44 [PATCH] block: reset mapping if failed to update hardware queue count Weiping Zhang
2020-05-13  2:20 ` Jens Axboe
2020-05-13  3:14   ` Weiping Zhang [this message]

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