linux-kernel - Re: [BUG] KCSAN: data-race in process_one_work / process_one

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Message-ID: <ZN6YVG114AZv9Yp8@slm.duckdns.org>
Date:   Thu, 17 Aug 2023 11:59:48 -1000
From:   Tejun Heo <tj@...nel.org>
To:     Mirsad Todorovac <mirsad.todorovac@....unizg.hr>
Cc:     linux-kernel@...r.kernel.org,
        Lai Jiangshan <jiangshanlai@...il.com>
Subject: Re: [BUG] KCSAN: data-race in process_one_work / process_one_work

On Thu, Aug 17, 2023 at 09:24:28PM +0200, Mirsad Todorovac wrote:
> Hi,
> 
> This is your friendly bug reporter.
> 
> The environment is vanilla torvalds tree kernel on Ubuntu 22.04 LTS and on a Ryzen 7950X
> assembled box.
> 
> The kernel reports G taint "properietary module loaded", but I know of no module since
> the boot state when the status was "Not tainted".
> 
> Please find the complete dmesg output (or what's left in the ring buffer) and lshw output
> attached.
> 
> Here is the dmesg output excerpt:
> 
> [ 6849.221584] ==================================================================
> [ 6849.221607] BUG: KCSAN: data-race in process_one_work / process_one_work
> 
> [ 6849.221635] write to 0xffff9b7440151398 of 8 bytes by task 6364 on cpu 7:
> [ 6849.221647]  process_one_work+0x504/0x930
> [ 6849.221660]  worker_thread+0x311/0x7e0
> [ 6849.221673]  kthread+0x18b/0x1d0
> [ 6849.221683]  ret_from_fork+0x43/0x70
> [ 6849.221695]  ret_from_fork_asm+0x1b/0x30
> 
> [ 6849.221712] read to 0xffff9b7440151398 of 8 bytes by task 5586 on cpu 28:
> [ 6849.221724]  process_one_work+0x4e8/0x930
> [ 6849.221737]  worker_thread+0x519/0x7e0
> [ 6849.221749]  kthread+0x18b/0x1d0
> [ 6849.221759]  ret_from_fork+0x43/0x70
> [ 6849.221770]  ret_from_fork_asm+0x1b/0x30
> 
> [ 6849.221786] value changed: 0x00000000000154d0 -> 0x00000000000154d1
> 
> [ 6849.221802] Reported by Kernel Concurrency Sanitizer on:
> [ 6849.221811] CPU: 28 PID: 5586 Comm: kworker/u64:0 Tainted: G             L     6.5.0-rc6-net-cfg-kcsan-00038-g16931859a650 #35
> [ 6849.221825] Hardware name: ASRock X670E PG Lightning/X670E PG Lightning, BIOS 1.21 04/26/2023
> [ 6849.221833] Workqueue: events_unbound wq_barrier_func
> [ 6849.221846] ==================================================================

That looks like the PENDING bit. The setting is atomic. Maybe there's a raw
read? Can you map the addresses to lines?

Thanks.

-- 
tejun