From: Jens Axboe <axboe@kernel.dk>
To: 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: Tue, 12 May 2020 20:20:58 -0600 [thread overview]
Message-ID: <585b0389-aa83-59b8-a155-f23621155bcd@kernel.dk> (raw)
In-Reply-To: <20200513004345.GA28465@192.168.3.9>
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.
--
Jens Axboe
next prev parent reply other threads:[~2020-05-13 2:21 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 [this message]
2020-05-13 3:14 ` Weiping Zhang
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