diff options
| author | David Hildenbrand <david@redhat.com> | 2025-09-01 17:03:45 +0200 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2025-09-21 14:22:06 -0700 |
| commit | 80e7bb74d4ff24725f0ddb1c72d8de45a3d975f6 (patch) | |
| tree | 33bc0d3e966f6a54c909be8221d2f95ac87db75d /include/linux | |
| parent | a16c46c2402026162111ed9fd1fc28d25223443e (diff) | |
scatterlist: disallow non-contigous page ranges in a single SG entry
The expectation is that there is currently no user that would pass in
non-contigous page ranges: no allocator, not even VMA, will hand these
out.
The only problematic part would be if someone would provide a range
obtained directly from memblock, or manually merge problematic ranges. If
we find such cases, we should fix them to create separate SG entries.
Let's check in sg_set_page() that this is really the case. No need to
check in sg_set_folio(), as pages in a folio are guaranteed to be
contiguous. As sg_set_page() gets inlined into modules, we have to export
the page_range_contiguous() helper -- use EXPORT_SYMBOL, there is nothing
special about this helper such that we would want to enforce GPL-only
modules.
We can now drop the nth_page() usage in sg_page_iter_page().
Link: https://lkml.kernel.org/r/20250901150359.867252-25-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/scatterlist.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h index 6f8a4965f9b9..29f6ceb98d74 100644 --- a/include/linux/scatterlist.h +++ b/include/linux/scatterlist.h @@ -158,6 +158,7 @@ static inline void sg_assign_page(struct scatterlist *sg, struct page *page) static inline void sg_set_page(struct scatterlist *sg, struct page *page, unsigned int len, unsigned int offset) { + VM_WARN_ON_ONCE(!page_range_contiguous(page, ALIGN(len + offset, PAGE_SIZE) / PAGE_SIZE)); sg_assign_page(sg, page); sg->offset = offset; sg->length = len; @@ -600,7 +601,7 @@ void __sg_page_iter_start(struct sg_page_iter *piter, */ static inline struct page *sg_page_iter_page(struct sg_page_iter *piter) { - return nth_page(sg_page(piter->sg), piter->sg_pgoffset); + return sg_page(piter->sg) + piter->sg_pgoffset; } /** |