[PATCH] drm/amd/display: use GFP_ATOMIC for bounding box

[Alex Deucher]

On Tue, Jun 4, 2024 at 10:32 AM Christian König
<ckoenig.leichtzumerken at gmail.com> wrote:
>
> Am 04.06.24 um 15:50 schrieb Alex Deucher:
> > This can be called in atomic context.  Should fix:
> >
> > BUG: sleeping function called from invalid context at include/linux/sched/mm.h:306
> > in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 449, name: kworker/u64:8
> > preempt_count: 2, expected: 0
> > RCU nest depth: 0, expected: 0
> > Preemption disabled at:
> > ffffffffc0ce1580>] dc_fpu_begin+0x30/0xd0 [amdgpu]
> > CPU: 5 PID: 449 Comm: kworker/u64:8 Tainted: G        W          6.8.0+ #35
> > Hardware name: System manufacturer System Product Name/ROG STRIX X570-E GAMING WIFI II, BIOS 4204 02/24/2022
> > Workqueue: events_unbound async_run_entry_fn
>
> That most likely only papers over the real problem and is not a valid fix.
>
> The question is why is that an atomic context?  If the function is used
> under a spinlock then this might indeed be the right fix.
>
> If it's because of floating point operation then that here won't work
> either.
>
> In that case the only real fix is to avoid the allocation altogether.

Reverting the patch will bring back the stack size warning.  I guess
the display folks will need to look more closely at this.

Alex

>
> Regards,
> Christian.
>
> >
> > Fixes: 88c61827cedc ("drm/amd/display: dynamically allocate dml2_configuration_options structures")
> > Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
> > Cc: George Zhang <george.zhang at amd.com>
> > Cc: Arnd Bergmann <arnd at arndb.de>
> > Cc: harry.wentland at amd.com
> > Cc: sunpeng.li at amd.com
> > Cc: Rodrigo.Siqueira at amd.com
> > ---
> >   drivers/gpu/drm/amd/display/dc/resource/dcn32/dcn32_resource.c  | 2 +-
> >   .../gpu/drm/amd/display/dc/resource/dcn321/dcn321_resource.c    | 2 +-
> >   2 files changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/display/dc/resource/dcn32/dcn32_resource.c b/drivers/gpu/drm/amd/display/dc/resource/dcn32/dcn32_resource.c
> > index 0f11d7c8791c..3fe0d5334145 100644
> > --- a/drivers/gpu/drm/amd/display/dc/resource/dcn32/dcn32_resource.c
> > +++ b/drivers/gpu/drm/amd/display/dc/resource/dcn32/dcn32_resource.c
> > @@ -2009,7 +2009,7 @@ static void dcn32_update_bw_bounding_box(struct dc *dc, struct clk_bw_params *bw
> >   {
> >       struct dml2_configuration_options *dml2_opt;
> >
> > -     dml2_opt = kmemdup(&dc->dml2_options, sizeof(dc->dml2_options), GFP_KERNEL);
> > +     dml2_opt = kmemdup(&dc->dml2_options, sizeof(dc->dml2_options), GFP_ATOMIC);
> >       if (!dml2_opt)
> >               return;
> >
> > diff --git a/drivers/gpu/drm/amd/display/dc/resource/dcn321/dcn321_resource.c b/drivers/gpu/drm/amd/display/dc/resource/dcn321/dcn321_resource.c
> > index 07ca6f58447d..a61cf5741275 100644
> > --- a/drivers/gpu/drm/amd/display/dc/resource/dcn321/dcn321_resource.c
> > +++ b/drivers/gpu/drm/amd/display/dc/resource/dcn321/dcn321_resource.c
> > @@ -1583,7 +1583,7 @@ static void dcn321_update_bw_bounding_box(struct dc *dc, struct clk_bw_params *b
> >   {
> >       struct dml2_configuration_options *dml2_opt;
> >
> > -     dml2_opt = kmemdup(&dc->dml2_options, sizeof(dc->dml2_options), GFP_KERNEL);
> > +     dml2_opt = kmemdup(&dc->dml2_options, sizeof(dc->dml2_options), GFP_ATOMIC);
> >       if (!dml2_opt)
> >               return;
> >
>