[PATCH] drm/etnaviv: switch devcoredump allocations to GFP_NOWAIT

[Daniel Vetter]

On Fri, May 17, 2024 at 10:18:50AM +0200, Philipp Zabel wrote:
> On Do, 2024-05-16 at 19:20 +0200, Lucas Stach wrote:
> > Am Freitag, dem 26.01.2024 um 17:46 +0100 schrieb Lucas Stach:
> > > The etnaviv devcoredump is created in the GPU reset path, which
> > > must make forward progress to avoid stalling memory reclaim on
> > > unsignalled dma fences. The currently used __GFP_NORETRY does not
> > > prohibit sleeping on direct reclaim, breaking the forward progress
> > > guarantee. Switch to GFP_NOWAIT, which allows background reclaim
> > > to be triggered, but avoids any stalls waiting for direct reclaim.
> > > 
> > Any takers for reviewing this one?
> > 
> > Regards,
> > Lucas
> > 
> > > Signed-off-by: Lucas Stach <l.stach at pengutronix.de>
> > > ---
> > >  drivers/gpu/drm/etnaviv/etnaviv_dump.c | 6 +++---
> > >  1 file changed, 3 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/etnaviv/etnaviv_dump.c b/drivers/gpu/drm/etnaviv/etnaviv_dump.c
> > > index 898f84a0fc30c..42c5028872d54 100644
> > > --- a/drivers/gpu/drm/etnaviv/etnaviv_dump.c
> > > +++ b/drivers/gpu/drm/etnaviv/etnaviv_dump.c
> > > @@ -159,8 +159,7 @@ void etnaviv_core_dump(struct etnaviv_gem_submit *submit)
> > >  	file_size += sizeof(*iter.hdr) * n_obj;
> > >  
> > >  	/* Allocate the file in vmalloc memory, it's likely to be big */
> > > -	iter.start = __vmalloc(file_size, GFP_KERNEL | __GFP_NOWARN |
> > > -			__GFP_NORETRY);
> > > +	iter.start = __vmalloc(file_size, GFP_NOWAIT | __GFP_NOWARN);
> > >  	if (!iter.start) {
> > >  		mutex_unlock(&submit->mmu_context->lock);
> > >  		dev_warn(gpu->dev, "failed to allocate devcoredump file\n");
> > > @@ -230,5 +229,6 @@ void etnaviv_core_dump(struct etnaviv_gem_submit *submit)
> > >  
> > >  	etnaviv_core_dump_header(&iter, ETDUMP_BUF_END, iter.data);
> > >  
> > > -	dev_coredumpv(gpu->dev, iter.start, iter.data - iter.start, GFP_KERNEL);
> > > +	dev_coredumpv(gpu->dev, iter.start, iter.data - iter.start,
> > > +		      GFP_NOWAIT | __GFP_NOWARN);
> 
> Should this be __GFP_NOWARN? There is no fallback on failure, and if
> this fails and the __vmalloc() above didn't, there is no error message
> at all.

GFP_NOWAIT already has __GFP_NOWARN, so redundant. And there's really
nothing you can do as a fallback (aside from dmesg output, which this code
already does - ok mabye dev_coredump could also do warnings, but that's a
separate patch).

With the __GFP_NOWARN dropped:

Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>

Cheers, Sima
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch