hugetlb: make unmap_ref_private multi-size-aware (7526674d) · Commits · 戴 / test

Oops. Part of the hugetlb private reservation code was not fully converted to use hstates. When a huge page must be unmapped from VMAs due to a failed COW, HPAGE_SIZE is used in the call to unmap_hugepage_range() regardless of the page size being used. This works if the VMA is using the default huge page size. Otherwise we might unmap too much, too little, or trigger a BUG_ON. Rare but serious -- fix it. Signed-off-by:

Adam Litke <agl@us.ibm.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

mm/hugetlb.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -1796,6 +1796,7 @@ void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
		static int unmap_ref_private(struct mm_struct mm, struct vm_area_struct vma,
		struct page *page, unsigned long address)
		{
		struct hstate *h = hstate_vma(vma);
		struct vm_area_struct *iter_vma;
		struct address_space *mapping;
		struct prio_tree_iter iter;
		@@ -1805,7 +1806,7 @@ static int unmap_ref_private(struct mm_struct mm, struct vm_area_struct vma,
		* vm_pgoff is in PAGE_SIZE units, hence the different calculation
		* from page cache lookup which is in HPAGE_SIZE units.
		*/
		address = address & huge_page_mask(hstate_vma(vma));
		address = address & huge_page_mask(h);
		pgoff = ((address - vma->vm_start) >> PAGE_SHIFT)
		+ (vma->vm_pgoff >> PAGE_SHIFT);
		mapping = (struct address_space *)page_private(page);
		@@ -1824,7 +1825,7 @@ static int unmap_ref_private(struct mm_struct mm, struct vm_area_struct vma,
		*/
		if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER))
		unmap_hugepage_range(iter_vma,
		address, address + HPAGE_SIZE,
		address, address + huge_page_size(h),
		page);
		}

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