linux-kernel - Re: [PATCH] staging: rtl8192u: Fix sleep in atomic context bug in dm_fsync_timer

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Message-ID: <Yp2T7xSM8YX7lX0/@kroah.com>
Date:   Mon, 6 Jun 2022 07:43:11 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Duoming Zhou <duoming@....edu.cn>
Cc:     linux-staging@...ts.linux.dev, davem@...emloft.net,
        kuba@...nel.org, alexander.deucher@....com, broonie@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: rtl8192u: Fix sleep in atomic context bug in
 dm_fsync_timer_callback

On Fri, May 20, 2022 at 02:15:41PM +0800, Duoming Zhou wrote:
> There are sleep in atomic context bugs when dm_fsync_timer_callback is
> executing. The root cause is that the memory allocation functions with
> GFP_KERNEL parameter are called in dm_fsync_timer_callback which is a
> timer handler. The call paths that could trigger bugs are shown below:
> 
>     (interrupt context)
> dm_fsync_timer_callback
>   write_nic_byte
>     kzalloc(sizeof(data), GFP_KERNEL); //may sleep
>   write_nic_dword
>     kzalloc(sizeof(data), GFP_KERNEL); //may sleep
> 
> This patch changes allocation mode from GFP_KERNEL to GFP_ATOMIC
> in order to prevent atomic context sleeping. The GFP_ATOMIC flag
> makes memory allocation operation could be used in atomic context.
> 
> Signed-off-by: Duoming Zhou <duoming@....edu.cn>

What commit id does this fix?

And how did you find this issue?  Did you run the code to verify it
still works properly?

thanks,

greg k-h