linux-kernel - RE: [PATCH v3] drm/i915: Fix page cleanup on DMA remap failure

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Message-ID: <PH7PR11MB82521EC01BA03D0C44631F5989EF2@PH7PR11MB8252.namprd11.prod.outlook.com>
Date: Tue, 28 Jan 2025 03:42:36 +0000
From: "Srinivas, Vidya" <vidya.srinivas@...el.com>
To: "Cavitt, Jonathan" <jonathan.cavitt@...el.com>, Brian Geffon
	<bgeffon@...gle.com>, "intel-gfx@...ts.freedesktop.org"
	<intel-gfx@...ts.freedesktop.org>
CC: "Wilson, Chris P" <chris.p.wilson@...el.com>, "Saarinen, Jani"
	<jani.saarinen@...el.com>, "Mistat, Tomasz" <tomasz.mistat@...el.com>,
	"ville.syrjala@...ux.intel.com" <ville.syrjala@...ux.intel.com>,
	"jani.nikula@...ux.intel.com" <jani.nikula@...ux.intel.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>, "Joonas
 Lahtinen" <joonas.lahtinen@...ux.intel.com>, "stable@...r.kernel.org"
	<stable@...r.kernel.org>, Tomasz Figa <tfiga@...gle.com>
Subject: RE: [PATCH v3] drm/i915: Fix page cleanup on DMA remap failure



> -----Original Message-----
> From: Cavitt, Jonathan <jonathan.cavitt@...el.com>
> Sent: 28 January 2025 02:45
> To: Brian Geffon <bgeffon@...gle.com>; intel-gfx@...ts.freedesktop.org
> Cc: Wilson, Chris P <chris.p.wilson@...el.com>; Saarinen, Jani
> <jani.saarinen@...el.com>; Mistat, Tomasz <tomasz.mistat@...el.com>;
> Srinivas, Vidya <vidya.srinivas@...el.com>; ville.syrjala@...ux.intel.com;
> jani.nikula@...ux.intel.com; linux-kernel@...r.kernel.org; dri-
> devel@...ts.freedesktop.org; Joonas Lahtinen
> <joonas.lahtinen@...ux.intel.com>; stable@...r.kernel.org; Tomasz Figa
> <tfiga@...gle.com>; Cavitt, Jonathan <jonathan.cavitt@...el.com>
> Subject: RE: [PATCH v3] drm/i915: Fix page cleanup on DMA remap failure
> 
> -----Original Message-----
> From: Intel-gfx <intel-gfx-bounces@...ts.freedesktop.org> On Behalf Of Brian
> Geffon
> Sent: Monday, January 27, 2025 12:44 PM
> To: intel-gfx@...ts.freedesktop.org
> Cc: Wilson, Chris P <chris.p.wilson@...el.com>; Saarinen, Jani
> <jani.saarinen@...el.com>; Mistat, Tomasz <tomasz.mistat@...el.com>;
> Srinivas, Vidya <vidya.srinivas@...el.com>; ville.syrjala@...ux.intel.com;
> jani.nikula@...ux.intel.com; linux-kernel@...r.kernel.org; dri-
> devel@...ts.freedesktop.org; Joonas Lahtinen
> <joonas.lahtinen@...ux.intel.com>; Brian Geffon <bgeffon@...gle.com>;
> stable@...r.kernel.org; Tomasz Figa <tfiga@...gle.com>
> Subject: [PATCH v3] drm/i915: Fix page cleanup on DMA remap failure
> >
> > When converting to folios the cleanup path of shmem_get_pages() was
> > missed. When a DMA remap fails and the max segment size is greater
> > than PAGE_SIZE it will attempt to retry the remap with a PAGE_SIZEd
> > segment size. The cleanup code isn't properly using the folio apis and
> > as a result isn't handling compound pages correctly.
> >
> > v2 -> v3:
> > (Ville) Just use shmem_sg_free_table() as-is in the failure path of
> > shmem_get_pages(). shmem_sg_free_table() will clear mapping
> > unevictable but it will be reset when it retries in shmem_sg_alloc_table().
> >
> > v1 -> v2:
> > (Ville) Fixed locations where we were not clearing mapping unevictable.
> >
> > Cc: stable@...r.kernel.org
> > Cc: Ville Syrjala <ville.syrjala@...ux.intel.com>
> > Cc: Vidya Srinivas <vidya.srinivas@...el.com>
> > Link: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/13487
> > Link:
> > https://lore.kernel.org/lkml/20250116135636.410164-1-bgeffon@google.co
> > m/
> > Fixes: 0b62af28f249 ("i915: convert shmem_sg_free_table() to use a
> > folio_batch")
> > Signed-off-by: Brian Geffon <bgeffon@...gle.com>
> > Suggested-by: Tomasz Figa <tfiga@...gle.com>
> 
> Seems good to me.
> Reviewed-by: Jonathan Cavitt <jonathan.cavitt@...el.com> -Jonathan Cavitt
> 

Thank you so much to all.
Tested-by: Vidya Srinivas <vidya.srinivas@...el.com>

> > ---
> >  drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 6 +-----
> >  1 file changed, 1 insertion(+), 5 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
> > b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
> > index fe69f2c8527d..ae3343c81a64 100644
> > --- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
> > +++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
> > @@ -209,8 +209,6 @@ static int shmem_get_pages(struct
> drm_i915_gem_object *obj)
> >  	struct address_space *mapping = obj->base.filp->f_mapping;
> >  	unsigned int max_segment = i915_sg_segment_size(i915->drm.dev);
> >  	struct sg_table *st;
> > -	struct sgt_iter sgt_iter;
> > -	struct page *page;
> >  	int ret;
> >
> >  	/*
> > @@ -239,9 +237,7 @@ static int shmem_get_pages(struct
> drm_i915_gem_object *obj)
> >  		 * for PAGE_SIZE chunks instead may be helpful.
> >  		 */
> >  		if (max_segment > PAGE_SIZE) {
> > -			for_each_sgt_page(page, sgt_iter, st)
> > -				put_page(page);
> > -			sg_free_table(st);
> > +			shmem_sg_free_table(st, mapping, false, false);
> >  			kfree(st);
> >
> >  			max_segment = PAGE_SIZE;
> > --
> > 2.48.1.262.g85cc9f2d1e-goog
> >
> >