Messages in this thread Patch in this message | | | From | Peter Xu <> | Subject | [PATCH] mm: thp: fix soft dirty for migration when split | Date | Thu, 6 Dec 2018 16:46:04 +0800 |
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When splitting a huge migrating PMD, we'll transfer the soft dirty bit from the huge page to the small pages. However we're possibly using a wrong data since when fetching the bit we're using pmd_soft_dirty() upon a migration entry. Fix it up.
CC: Andrea Arcangeli <aarcange@redhat.com> CC: Andrew Morton <akpm@linux-foundation.org> CC: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> CC: Matthew Wilcox <willy@infradead.org> CC: Michal Hocko <mhocko@suse.com> CC: Dave Jiang <dave.jiang@intel.com> CC: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> CC: Souptick Joarder <jrdr.linux@gmail.com> CC: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> CC: linux-mm@kvack.org CC: linux-kernel@vger.kernel.org Signed-off-by: Peter Xu <peterx@redhat.com> ---
I noticed this during code reading. Only compile tested. I'm sending a patch directly for review comments since it's relatively straightforward and not easy to test. Please have a look, thanks. --- mm/huge_memory.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index f2d19e4fe854..fb0787c3dd3b 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2161,7 +2161,10 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, SetPageDirty(page); write = pmd_write(old_pmd); young = pmd_young(old_pmd); - soft_dirty = pmd_soft_dirty(old_pmd); + if (unlikely(pmd_migration)) + soft_dirty = pmd_swp_soft_dirty(old_pmd); + else + soft_dirty = pmd_soft_dirty(old_pmd); /* * Withdraw the table only after we mark the pmd entry invalid. -- 2.17.1
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