Re: [PATCH] drm/amd/display: avoid sleeping in atomic context while creating new context or state

From: Harry Wentland <harry.wentland-5C7GfCeVMHo@public.gmane.org>
To: Shirish S <shirish.s-5C7GfCeVMHo@public.gmane.org>,
	amd-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org
Subject: Re: [PATCH] drm/amd/display: avoid sleeping in atomic context while creating new context or state
Date: Wed, 30 May 2018 12:03:10 -0400	[thread overview]
Message-ID: <1b831a0f-3d54-2b07-12f8-b1ddda9007f6@amd.com> (raw)
In-Reply-To: <1527675436-24022-1-git-send-email-shirish.s-5C7GfCeVMHo@public.gmane.org>

On 2018-05-30 06:17 AM, Shirish S wrote:
> This patch fixes the warning messages that are caused due to calling
> sleep in atomic context as below:
> 
> BUG: sleeping function called from invalid context at mm/slab.h:419
> in_atomic(): 1, irqs_disabled(): 1, pid: 5, name: kworker/u4:0
> CPU: 1 PID: 5 Comm: kworker/u4:0 Tainted: G        W       4.14.35 #941
> Workqueue: events_unbound commit_work
> Call Trace:
>  dump_stack+0x4d/0x63
>  ___might_sleep+0x11f/0x12e
>  kmem_cache_alloc_trace+0x41/0xea
>  dc_create_state+0x1f/0x30
>  dc_commit_updates_for_stream+0x73/0x4cf
>  ? amdgpu_get_crtc_scanoutpos+0x82/0x16b
>  amdgpu_dm_do_flip+0x239/0x298
>  amdgpu_dm_commit_planes.isra.23+0x379/0x54b
>  ? dc_commit_state+0x3da/0x404
>  amdgpu_dm_atomic_commit_tail+0x4fc/0x5d2
>  ? wait_for_common+0x5b/0x69
>  commit_tail+0x42/0x64
>  process_one_work+0x1b0/0x314
>  worker_thread+0x1cb/0x2c1
>  ? create_worker+0x1da/0x1da
>  kthread+0x156/0x15e
>  ? kthread_flush_work+0xea/0xea
>  ret_from_fork+0x22/0x40
> 
> Signed-off-by: Shirish S <shirish.s@amd.com>
> ---
>  drivers/gpu/drm/amd/display/dc/core/dc.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/dc/core/dc.c b/drivers/gpu/drm/amd/display/dc/core/dc.c
> index 33149ed..d62206f 100644
> --- a/drivers/gpu/drm/amd/display/dc/core/dc.c
> +++ b/drivers/gpu/drm/amd/display/dc/core/dc.c
> @@ -588,7 +588,7 @@ static void disable_dangling_plane(struct dc *dc, struct dc_state *context)
>  
>  struct dc *dc_create(const struct dc_init_data *init_params)
>   {
> -	struct dc *dc = kzalloc(sizeof(*dc), GFP_KERNEL);
> +	struct dc *dc = kzalloc(sizeof(*dc), GFP_ATOMIC);

Are you sure this one can be called in atomic_context?

If so then everything in consstruct() would also need GFP_ATOMIC.

Harry

>  	unsigned int full_pipe_count;
>  
>  	if (NULL == dc)
> @@ -937,7 +937,7 @@ bool dc_post_update_surfaces_to_stream(struct dc *dc)
>  struct dc_state *dc_create_state(void)
>  {
>  	struct dc_state *context = kzalloc(sizeof(struct dc_state),
> -					   GFP_KERNEL);
> +					   GFP_ATOMIC);
>  
>  	if (!context)
>  		return NULL;
> 
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