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authorZi Yan <zi.yan@cs.rutgers.edu>2017-11-03 01:59:47 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2017-11-03 17:39:19 +0300
commitdd8a67f9a37c74b61e5e050924ceec9ffb4f8c3c (patch)
tree047993d332418b884aa60f0acf08932842d47701 /mm
parente08b1877452a0055c65f6394163ce5a0fbd720a3 (diff)
downloadlinux-dd8a67f9a37c74b61e5e050924ceec9ffb4f8c3c.tar.xz
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@sent.com Fixes: 84c3fc4e9c563 ("mm: thp: check pmd migration entry in common path") Signed-off-by: Zi Yan <zi.yan@cs.rutgers.edu> Reported-by: Fengguang Wu <fengguang.wu@intel.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/huge_memory.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 269b5df58543..1981ed697dab 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -941,6 +941,9 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
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;