lkml.org 
[lkml]   [2013]   [Dec]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 07/15] mm: numa: Do not clear PMD during PTE update scan
Date
If the PMD is flushed then a parallel fault in handle_mm_fault() will
enter the pmd_none and do_huge_pmd_anonymous_page() path where it'll
attempt to insert a huge zero page. This is wasteful so the patch
avoids clearing the PMD when setting pmd_numa.

Signed-off-by: Mel Gorman <mgorman@suse.de>
---
mm/huge_memory.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 203b5bc..d6c3bf4 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1474,20 +1474,24 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,

if (__pmd_trans_huge_lock(pmd, vma) == 1) {
pmd_t entry;
- entry = pmdp_get_and_clear(mm, addr, pmd);
+
if (!prot_numa) {
+ entry = pmdp_get_and_clear(mm, addr, pmd);
entry = pmd_modify(entry, newprot);
BUG_ON(pmd_write(entry));
+ set_pmd_at(mm, addr, pmd, entry);
} else {
struct page *page = pmd_page(*pmd);
+ entry = *pmd;

/* only check non-shared pages */
if (page_mapcount(page) == 1 &&
!pmd_numa(*pmd)) {
entry = pmd_mknuma(entry);
+ set_pmd_at(mm, addr, pmd, entry);
}
}
- set_pmd_at(mm, addr, pmd, entry);
+
spin_unlock(&vma->vm_mm->page_table_lock);
ret = 1;
}
--
1.8.4


\
 
 \ /
  Last update: 2013-12-03 10:21    [W:0.169 / U:0.080 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site