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i915: Limit the length of an sg list to the requested length

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The folio conversion changed the behaviour of shmem_sg_alloc_table() to
put the entire length of the last folio into the sg list, even if the sg
list should have been shorter.  gen8_ggtt_insert_entries() relied on the
list being the right length and would overrun the end of the page tables.
Other functions may also have been affected.

Clamp the length of the last entry in the sg list to be the expected
length.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Fixes: 0b62af28f2 ("i915: convert shmem_sg_free_table() to use a folio_batch")
Cc: stable@vger.kernel.org # 6.5.x
Link: https://gitlab.freedesktop.org/drm/intel/-/issues/9256
Link: https://lore.kernel.org/lkml/6287208.lOV4Wx5bFT@natalenko.name/
Reported-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230919194855.347582-1-willy@infradead.org
(cherry picked from commit 26a8e32e6d)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
This commit is contained in:
Matthew Wilcox (Oracle) 2023-09-19 20:48:55 +01:00 committed by Rodrigo Vivi
parent 6465e260f4
commit 863a8eb3f2
1 changed files with 7 additions and 4 deletions
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11
drivers/gpu/drm/i915/gem/i915_gem_shmem.c
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@ -100,6 +100,7 @@ int shmem_sg_alloc_table(struct drm_i915_private *i915, struct sg_table *st,
st->nents = 0;
for (i = 0; i < page_count; i++) {
struct folio *folio;
unsigned long nr_pages;
const unsigned int shrink[] = {
I915_SHRINK_BOUND | I915_SHRINK_UNBOUND,
0,
@ -150,6 +151,8 @@ int shmem_sg_alloc_table(struct drm_i915_private *i915, struct sg_table *st,
}
} while (1);
nr_pages = min_t(unsigned long,
folio_nr_pages(folio), page_count - i);
if (!i ||
sg->length >= max_segment ||
folio_pfn(folio) != next_pfn) {
@ -157,13 +160,13 @@ int shmem_sg_alloc_table(struct drm_i915_private *i915, struct sg_table *st,
sg = sg_next(sg);
st->nents++;
sg_set_folio(sg, folio, folio_size(folio), 0);
sg_set_folio(sg, folio, nr_pages * PAGE_SIZE, 0);
} else {
/* XXX: could overflow? */
sg->length += folio_size(folio);
sg->length += nr_pages * PAGE_SIZE;
}
next_pfn = folio_pfn(folio) + folio_nr_pages(folio);
i += folio_nr_pages(folio) - 1;
next_pfn = folio_pfn(folio) + nr_pages;
i += nr_pages - 1;
/* Check that the i965g/gm workaround works. */
GEM_BUG_ON(gfp & __GFP_DMA32 && next_pfn >= 0x00100000UL);