The patch titled
Subject: mm/memory.c: replace is_zero_pfn with is_huge_zero_pmd for thp
has been added to the -mm tree. Its filename is
mm-replace-is_zero_pfn-with-is_huge_zero_pmd-for-thp.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-replace-is_zero_pfn-with-is_huge_zero_pmd-for-thp.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-replace-is_zero_pfn-with-is_huge_zero_pmd-for-thp.patch
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------------------------------------------------------
From: Yu Zhao <yuzhao@xxxxxxxxxx>
Subject: mm/memory.c: replace is_zero_pfn with is_huge_zero_pmd for thp
For hugely mapped thp, we use is_huge_zero_pmd() to check if it's zero
page or not.
We do fill ptes with my_zero_pfn() when we split zero thp pmd, but this is
not what we have in vm_normal_page_pmd() -- pmd_trans_huge_lock() makes
sure of it.
This is a trivial fix for /proc/pid/numa_maps, and AFAIK nobody complains
about it.
Gerald Schaefer asked:
: Maybe the description could also mention the symptom of this bug?
: I would assume that it affects anon/dirty accounting in gather_pte_stats(),
: for huge mappings, if zero page mappings are not correctly recognized.
I came across this while I was looking at the code, so I'm not aware of
any symptom.
Link: http://lkml.kernel.org/r/20191108192629.201556-1-yuzhao@xxxxxxxxxx
Signed-off-by: Yu Zhao <yuzhao@xxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Ralph Campbell <rcampbell@xxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@xxxxxxxxxxxxx>
Cc: Dave Airlie <airlied@xxxxxxxxxx>
Cc: Thomas Hellstrom <thellstrom@xxxxxxxxxx>
Cc: Souptick Joarder <jrdr.linux@xxxxxxxxx>
Cc: Gerald Schaefer <gerald.schaefer@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/memory.c~mm-replace-is_zero_pfn-with-is_huge_zero_pmd-for-thp
+++ a/mm/memory.c
@@ -660,7 +660,7 @@ struct page *vm_normal_page_pmd(struct v
if (pmd_devmap(pmd))
return NULL;
- if (is_zero_pfn(pfn))
+ if (is_huge_zero_pmd(pmd))
return NULL;
if (unlikely(pfn > highest_memmap_pfn))
return NULL;
_
Patches currently in -mm which might be from yuzhao@xxxxxxxxxx are
mm-update-comments-in-slubc.patch
mm-clean-up-validate_slab.patch
mm-avoid-slub-allocation-while-holding-list_lock.patch
mm-replace-is_zero_pfn-with-is_huge_zero_pmd-for-thp.patch
