The patch titled Subject: i915: limit the length of an sg list to the requested length has been added to the -mm mm-hotfixes-unstable branch. Its filename is i915-limit-the-length-of-an-sg-list-to-the-requested-length.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: "Matthew Wilcox (Oracle)" willy@infradead.org Subject: i915: limit the length of an sg list to the requested length Date: Tue, 19 Sep 2023 20:48:55 +0100

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 langth 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.

Link: https://lkml.kernel.org/r/20230919194855.347582-1-willy@infradead.org Link: https://gitlab.freedesktop.org/drm/intel/-/issues/9256 Fixes: 0b62af28f249 ("i915: convert shmem_sg_free_table() to use a folio_batch") Signed-off-by: Matthew Wilcox (Oracle) willy@infradead.org Reported-by: Oleksandr Natalenko oleksandr@natalenko.name Closes: https://lore.kernel.org/lkml/6287208.lOV4Wx5bFT@natalenko.name/ Tested-by: Oleksandr Natalenko oleksandr@natalenko.name Cc: Jani Nikula jani.nikula@linux.intel.com Cc: Joonas Lahtinen joonas.lahtinen@linux.intel.com Cc: Rodrigo Vivi rodrigo.vivi@intel.com Cc: Tvrtko Ursulin tvrtko.ursulin@linux.intel.com Cc: stable@vger.kernel.org [6.5.x] Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)

--- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c~i915-limit-the-length-of-an-sg-list-to-the-requested-length +++ a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c @@ -100,6 +100,7 @@ int shmem_sg_alloc_table(struct drm_i915 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 } } 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 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); _

Patches currently in -mm which might be from willy@infradead.org are

i915-limit-the-length-of-an-sg-list-to-the-requested-length.patch mm-convert-dax-lock-unlock-page-to-lock-unlock-folio.patch buffer-pass-gfp-flags-to-folio_alloc_buffers.patch buffer-hoist-gfp-flags-from-grow_dev_page-to-__getblk_gfp.patch ext4-use-bdev_getblk-to-avoid-memory-reclaim-in-readahead-path.patch buffer-use-bdev_getblk-to-avoid-memory-reclaim-in-readahead-path.patch buffer-convert-getblk_unmovable-and-__getblk-to-use-bdev_getblk.patch buffer-convert-sb_getblk-to-call-__getblk.patch ext4-call-bdev_getblk-from-sb_getblk_gfp.patch buffer-remove-__getblk_gfp.patch hugetlb-use-a-folio-in-free_hpage_workfn.patch hugetlb-remove-a-few-calls-to-page_folio.patch hugetlb-convert-remove_pool_huge_page-to-remove_pool_hugetlb_folio.patch