* [PATCH] mm: migration: deposit page table when copying a PMD migration entry.
@ 2017-10-30 14:46 Zi Yan
2017-10-30 16:09 ` Kirill A. Shutemov
0 siblings, 1 reply; 2+ messages in thread
From: Zi Yan @ 2017-10-30 14:46 UTC (permalink / raw)
To: Andrew Morton, linux-mm, linux-kernel
Cc: Kirill A . Shutemov, Zi Yan, Fengguang Wu
From: Zi Yan <zi.yan@cs.rutgers.edu>
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
Fixes: 84c3fc4e9c563 ("mm: thp: check pmd migration entry in common path")
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Zi Yan <zi.yan@cs.rutgers.edu>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
mm/huge_memory.c | 3 +++
1 file changed, 3 insertions(+)
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;
--
2.14.2
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] mm: migration: deposit page table when copying a PMD migration entry.
2017-10-30 14:46 [PATCH] mm: migration: deposit page table when copying a PMD migration entry Zi Yan
@ 2017-10-30 16:09 ` Kirill A. Shutemov
0 siblings, 0 replies; 2+ messages in thread
From: Kirill A. Shutemov @ 2017-10-30 16:09 UTC (permalink / raw)
To: Zi Yan
Cc: Andrew Morton, linux-mm, linux-kernel, Kirill A . Shutemov,
Zi Yan, Fengguang Wu
On Mon, Oct 30, 2017 at 10:46:36AM -0400, Zi Yan wrote:
> From: Zi Yan <zi.yan@cs.rutgers.edu>
>
> 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
>
> Fixes: 84c3fc4e9c563 ("mm: thp: check pmd migration entry in common path")
> Reported-by: Fengguang Wu <fengguang.wu@intel.com>
> Signed-off-by: Zi Yan <zi.yan@cs.rutgers.edu>
> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
--
Kirill A. Shutemov
^ permalink raw reply [flat|nested] 2+ messages in thread
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