lkml.org 
[lkml]   [2019]   [Nov]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
Subject[PATCH v2] mm: replace is_zero_pfn with is_huge_zero_pmd for thp
From
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.

Signed-off-by: Yu Zhao <yuzhao@google.com>
---
mm/memory.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/memory.c b/mm/memory.c
index b1ca51a079f2..cf209f84ce4a 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -654,7 +654,7 @@ struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,

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;
--
2.24.0.rc1.363.gb1bccd3e3d-goog
\
 
 \ /
  Last update: 2019-11-08 20:27    [W:0.070 / U:6.128 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site