The patch titled
Subject: mm/huge_memory.c: deposit page table when copying a PMD migration entry
has been added to the -mm tree. Its filename is
mm-migration-deposit-page-table-when-copying-a-pmd-migration-entry.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-migration-deposit-page-table-when-copying-a-pmd-migration-entry.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-migration-deposit-page-table-when-copying-a-pmd-migration-entry.patch
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------------------------------------------------------
From: Zi Yan <zi.yan@xxxxxxxxxxxxxx>
Subject: mm/huge_memory.c: deposit page table when copying a PMD migration entry
We need to deposit pre-allocated PTE page table when a PMD migration entry
is copied in copy_huge_pmd(). Otherwise, we will leak the pre-allocated
page and cause a NULL pointer dereference later in zap_huge_pmd().
The missing counters during PMD migration entry copy process are added as
well.
The bug report is here: https://lkml.org/lkml/2017/10/29/214
Link: http://lkml.kernel.org/r/20171030144636.4836-1-zi.yan@xxxxxxxx
Fixes: 84c3fc4e9c563 ("mm: thp: check pmd migration entry in common path")
Signed-off-by: Zi Yan <zi.yan@xxxxxxxxxxxxxx>
Reported-by: Fengguang Wu <fengguang.wu@xxxxxxxxx>
Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/huge_memory.c | 3 +++
1 file changed, 3 insertions(+)
diff -puN mm/huge_memory.c~mm-migration-deposit-page-table-when-copying-a-pmd-migration-entry mm/huge_memory.c
--- a/mm/huge_memory.c~mm-migration-deposit-page-table-when-copying-a-pmd-migration-entry
+++ a/mm/huge_memory.c
@@ -941,6 +941,9 @@ int copy_huge_pmd(struct mm_struct *dst_
pmd = pmd_swp_mksoft_dirty(pmd);
set_pmd_at(src_mm, addr, src_pmd, pmd);
}
+ add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
+ atomic_long_inc(&dst_mm->nr_ptes);
+ pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
set_pmd_at(dst_mm, addr, dst_pmd, pmd);
ret = 0;
goto out_unlock;
_
Patches currently in -mm which might be from zi.yan@xxxxxxxxxxxxxx are
mm-migration-deposit-page-table-when-copying-a-pmd-migration-entry.patch
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