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authorDave Hansen <dave.hansen@linux.intel.com>2013-11-21 14:31:58 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2013-11-21 16:42:27 -0800
commit30b0a105d9f7141e4cbf72ae5511832457d89788 (patch)
treebbd52a86e93e43e7e5a2bfd234bffef9b796e055 /include
parentc11230f44b3c3e055e4e7cd572fc1c4a22c6f4a9 (diff)
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mm: thp: give transparent hugepage code a separate copy_page
Right now, the migration code in migrate_page_copy() uses copy_huge_page() for hugetlbfs and thp pages: if (PageHuge(page) || PageTransHuge(page)) copy_huge_page(newpage, page); So, yay for code reuse. But: void copy_huge_page(struct page *dst, struct page *src) { struct hstate *h = page_hstate(src); and a non-hugetlbfs page has no page_hstate(). This works 99% of the time because page_hstate() determines the hstate from the page order alone. Since the page order of a THP page matches the default hugetlbfs page order, it works. But, if you change the default huge page size on the boot command-line (say default_hugepagesz=1G), then we might not even *have* a 2MB hstate so page_hstate() returns null and copy_huge_page() oopses pretty fast since copy_huge_page() dereferences the hstate: void copy_huge_page(struct page *dst, struct page *src) { struct hstate *h = page_hstate(src); if (unlikely(pages_per_huge_page(h) > MAX_ORDER_NR_PAGES)) { ... Mel noticed that the migration code is really the only user of these functions. This moves all the copy code over to migrate.c and makes copy_huge_page() work for THP by checking for it explicitly. I believe the bug was introduced in commit b32967ff101a ("mm: numa: Add THP migration for the NUMA working set scanning fault case") [akpm@linux-foundation.org: fix coding-style and comment text, per Naoya Horiguchi] Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Acked-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Tested-by: Dave Jiang <dave.jiang@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/hugetlb.h4
1 files changed, 0 insertions, 4 deletions
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index acd2010328f3..85e0c58bdfdf 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -69,7 +69,6 @@ int dequeue_hwpoisoned_huge_page(struct page *page);
bool isolate_huge_page(struct page *page, struct list_head *list);
void putback_active_hugepage(struct page *page);
bool is_hugepage_active(struct page *page);
-void copy_huge_page(struct page *dst, struct page *src);
#ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE
pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud);
@@ -140,9 +139,6 @@ static inline int dequeue_hwpoisoned_huge_page(struct page *page)
#define isolate_huge_page(p, l) false
#define putback_active_hugepage(p) do {} while (0)
#define is_hugepage_active(x) false
-static inline void copy_huge_page(struct page *dst, struct page *src)
-{
-}
static inline unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
unsigned long address, unsigned long end, pgprot_t newprot)