diff options
| author | Mel Gorman <mgorman@suse.de> | 2014-01-07 14:00:39 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-01-09 12:25:13 -0800 |
| commit | c18e3316d198f4ffcf2129fb8f03940a1f9616bc (patch) | |
| tree | 5c00932d1fd3bc7e4c7f875b75e0d7088d848c46 /mm | |
| parent | 00c987e8443bd1c317a97b49ddadae4f9f828054 (diff) | |
mm: numa: do not clear PMD during PTE update scan
commit 5a6dac3ec5f583cc8ee7bc53b5500a207c4ca433 upstream.
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>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Alex Thorlton <athorlton@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/huge_memory.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 90cd2c35f46..5003349637f 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1474,20 +1474,22 @@ 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; } |