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Groups > linux.kernel > #1424619
| From | Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH v1 2/2] mm: rmap: call page_check_address() with sync enabled to avoid racy check |
| Date | 2016-06-17 04:40 +0200 |
| Message-ID | <rKRRo-uH-9@gated-at.bofh.it> (permalink) |
| References | <rKRRo-uH-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
The previous patch addresses the race between split_huge_pmd_address() and someone changing the pmd. The fix is only for splitting of normal thp (i.e. pmd-mapped thp,) and for splitting of pte-mapped thp there still is the similar race. For splitting pte-mapped thp, the pte's conversion is done by try_to_unmap_one(TTU_MIGRATION). This function checks page_check_address() to get the target pte, but it can return NULL under some race, leading to VM_BUG_ON() in freeze_page(). Fortunately, page_check_address() already has an argument to decide whether we do a quick/racy check or not, so let's flip it when called from freeze_page(). Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> --- mm/rmap.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git v4.6/mm/rmap.c v4.6_patched/mm/rmap.c index 4282b56..c357fb36 100644 --- v4.6/mm/rmap.c +++ v4.6_patched/mm/rmap.c @@ -1424,7 +1424,8 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, goto out; } - pte = page_check_address(page, mm, address, &ptl, 0); + pte = page_check_address(page, mm, address, &ptl, + PageTransCompound(page)); if (!pte) goto out; -- 2.7.0
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[PATCH v1 1/2] mm: thp: move pmd check inside ptl for freeze_page() Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> - 2016-06-17 04:40 +0200
[PATCH v1 2/2] mm: rmap: call page_check_address() with sync enabled to avoid racy check Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> - 2016-06-17 04:40 +0200
Re: [PATCH v1 1/2] mm: thp: move pmd check inside ptl for freeze_page() "Kirill A. Shutemov" <kirill@shutemov.name> - 2016-06-17 10:50 +0200
Re: [PATCH v1 1/2] mm: thp: move pmd check inside ptl for freeze_page() Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> - 2016-06-20 11:00 +0200
Re: [PATCH v1 1/2] mm: thp: move pmd check inside ptl for freeze_page() "Kirill A. Shutemov" <kirill@shutemov.name> - 2016-06-20 11:40 +0200
Re: [PATCH v1 1/2] mm: thp: move pmd check inside ptl for freeze_page() "Kirill A. Shutemov" <kirill@shutemov.name> - 2016-06-21 17:10 +0200
Re: [PATCH v1 1/2] mm: thp: move pmd check inside ptl for freeze_page() Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> - 2016-06-22 03:40 +0200
Re: [PATCH v1 1/2] mm: thp: move pmd check inside ptl for freeze_page() Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> - 2016-06-22 04:50 +0200
Re: [PATCH v1 1/2] mm: thp: move pmd check inside ptl for freeze_page() "Kirill A. Shutemov" <kirill@shutemov.name> - 2016-06-22 14:10 +0200
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