linux-kernel - Re: [PATCH] workqueue: Remove duplicate worqueue attributes allocation

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Message-ID: <20c53c92-5f70-4471-bd4d-0cf001f1bf16@tessares.net>
Date:   Tue, 12 Sep 2023 14:51:13 +0200
From:   Matthieu Baerts <matthieu.baerts@...sares.net>
To:     Catalin Marinas <catalin.marinas@....com>, tj@...nel.org
Cc:     linux-kernel@...r.kernel.org, dhavale@...gle.com
Subject: Re: [PATCH] workqueue: Remove duplicate worqueue attributes
 allocation

Hi Catalin,

On 06/09/2023 19:39, Catalin Marinas wrote:
> Commit 84193c07105c ("workqueue: Generalize unbound CPU pods")
> inadvertently introduced another call to alloc_workqueue_attrs()
> overriding the pointer returned by a previous alloc_workqueue_attrs() a
> few lines up in workqueue_init_early(). This leads to a kmemleak report:
> 
> unreferenced object 0xffff000040015000 (size 96):
>   comm "swapper/0", pid 0, jiffies 4294892296 (age 163.956s)
>   hex dump (first 32 bytes):
>     00 00 00 00 00 00 00 00 03 00 00 00 00 00 00 00  ................
>     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>   backtrace:
>     [<000000004cec0d50>] __kmem_cache_alloc_node+0x1c4/0x288
>     [<0000000083361c2a>] kmalloc_trace+0x20/0x2c
>     [<000000005ca61f11>] workqueue_init_early+0xe4/0x538
>     [<000000004e6ea358>] start_kernel+0x23c/0x5ec
>     [<00000000aea9761e>] __primary_switched+0xbc/0xc4
> 
> Remove the first allocation.

Thank you for having shared this patch!

We had the same issue when validating MPTCP tree and your patch fixes
the problem on our side:

Tested-by: Matthieu Baerts <matthieu.baerts@...sares.net>

Cheers,
Matt
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