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Code Issues Releases Wiki Activity

fs: use nth_page() in place of direct struct page manipulation 

When dealing with hugetlb pages, struct page is not guaranteed to be
contiguous on SPARSEMEM without VMEMMAP.  Use nth_page() to handle it
properly.

Without the fix, a wrong subpage might be checked for HWPoison, causing wrong
number of bytes of a page copied to user space. No bug is reported. The fix
comes from code inspection.

Link: https://lkml.kernel.org/r/20230913201248.452081-5-zi.yan@sent.com
Fixes: 38c1ddbde6 ("hugetlbfs: improve read HWPOISON hugepage")
Signed-off-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Zi Yan 2023-09-13 16:12:47 -04:00 committed by Andrew Morton
parent 1640a0ef80
commit 8db0ec791f
1 changed files with 2 additions and 2 deletions
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4
fs/hugetlbfs/inode.c
View File

@ -295,7 +295,7 @@ static size_t adjust_range_hwpoison(struct page *page, size_t offset, size_t byt
size_t res = 0;
/* First subpage to start the loop. */
page += offset / PAGE_SIZE;
page = nth_page(page, offset / PAGE_SIZE);
offset %= PAGE_SIZE;
while (1) {
if (is_raw_hwpoison_page_in_hugepage(page))
@ -309,7 +309,7 @@ static size_t adjust_range_hwpoison(struct page *page, size_t offset, size_t byt
break;
offset += n;
if (offset == PAGE_SIZE) {
page++;
page = nth_page(page, 1);
offset = 0;
}
}