linux-kernel - Re: [PATCH AUTOSEL 6.0 38/44] drm/amdgpu: Unlock bo_list

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Message-ID: <e08c0d60-45d1-85a6-9c55-38c8e87b56c3@mailbox.org>
Date:   Mon, 21 Nov 2022 10:57:51 +0100
From:   Michel Dänzer <michel.daenzer@...lbox.org>
To:     Sasha Levin <sashal@...nel.org>, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Cc:     Philip Yang <Philip.Yang@....com>, Xinhui.Pan@....com,
        amd-gfx@...ts.freedesktop.org, luben.tuikov@....com,
        dri-devel@...ts.freedesktop.org, daniel@...ll.ch,
        Alex Deucher <alexander.deucher@....com>, airlied@...il.com,
        Christian König <christian.koenig@....com>
Subject: Re: [PATCH AUTOSEL 6.0 38/44] drm/amdgpu: Unlock bo_list_mutex after
 error handling

On 11/19/22 03:11, Sasha Levin wrote:
> From: Philip Yang <Philip.Yang@....com>
> 
> [ Upstream commit 64f65135c41a75f933d3bca236417ad8e9eb75de ]
> 
> Get below kernel WARNING backtrace when pressing ctrl-C to kill kfdtest
> application.
> 
> If amdgpu_cs_parser_bos returns error after taking bo_list_mutex, as
> caller amdgpu_cs_ioctl will not unlock bo_list_mutex, this generates the
> kernel WARNING.
> 
> Add unlock bo_list_mutex after amdgpu_cs_parser_bos error handling to
> cleanup bo_list userptr bo.
> 
>  WARNING: kfdtest/2930 still has locks held!
>  1 lock held by kfdtest/2930:
>   (&list->bo_list_mutex){+.+.}-{3:3}, at: amdgpu_cs_ioctl+0xce5/0x1f10 [amdgpu]
>   stack backtrace:
>    dump_stack_lvl+0x44/0x57
>    get_signal+0x79f/0xd00
>    arch_do_signal_or_restart+0x36/0x7b0
>    exit_to_user_mode_prepare+0xfd/0x1b0
>    syscall_exit_to_user_mode+0x19/0x40
>    do_syscall_64+0x40/0x80
> 
> Signed-off-by: Philip Yang <Philip.Yang@....com>
> Reviewed-by: Christian König <christian.koenig@....com>
> Signed-off-by: Alex Deucher <alexander.deucher@....com>
> Signed-off-by: Sasha Levin <sashal@...nel.org>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> index b7bae833c804..9d59f83c8faa 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> @@ -655,6 +655,7 @@ static int amdgpu_cs_parser_bos(struct amdgpu_cs_parser *p,
>  		}
>  		mutex_unlock(&p->bo_list->bo_list_mutex);
>  	}
> +	mutex_unlock(&p->bo_list->bo_list_mutex);
>  	return r;
>  }
>  

Looks doubtful that this is a correct backport — there's an identical mutex_unlock call just above.


-- 
Earthling Michel Dänzer            |                  https://redhat.com
Libre software enthusiast          |         Mesa and Xwayland developer