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Message-ID: <YrQ2gXtX2FOkyNgu@kroah.com>
Date: Thu, 23 Jun 2022 11:46:41 +0200
From: Greg KH <gregkh@...uxfoundation.org>
To: Duoming Zhou <duoming@....edu.cn>
Cc: linux-staging@...ts.linux.dev, davem@...emloft.net,
alexander.deucher@....com, kuba@...nel.org, broonie@...nel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] staging: rtl8192u: Fix sleep in atomic context bug in
dm_fsync_timer_callback
On Thu, Jun 23, 2022 at 01:59:12PM +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 or GFP_NOIO parameters 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
> usb_control_msg
> kmalloc(.., GFP_NOIO); //may sleep
> write_nic_dword
> kzalloc(sizeof(data), GFP_KERNEL); //may sleep
> usb_control_msg
> kmalloc(.., GFP_NOIO); //may sleep
>
> This patch uses delayed work to replace timer and moves the operations
> that may sleep into the delayed work in order to mitigate bugs.
>
> Fixes: 8fc8598e61f6 ("Staging: Added Realtek rtl8192u driver to staging")
> Signed-off-by: Duoming Zhou <duoming@....edu.cn>
> ---
> Changes in v2:
> - Use delayed work to replace timer.
Did you test this with real hardware to verify it still works?
thanks,
greg k-h
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