mm, thp: drop page_table_lock to uncharge memcg pages

mm->page_table_lock is hotly contested for page fault tests and isn't
necessary to do mem_cgroup_uncharge_page() in do_huge_pmd_wp_page().

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Rientjes 2012-05-29 15:06:26 -07:00 committed by Linus Torvalds
parent 096a7cf447
commit 6f60b69d8c
1 changed files with 2 additions and 0 deletions

View File

@ -973,8 +973,10 @@ int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
spin_lock(&mm->page_table_lock);
put_page(page);
if (unlikely(!pmd_same(*pmd, orig_pmd))) {
spin_unlock(&mm->page_table_lock);
mem_cgroup_uncharge_page(new_page);
put_page(new_page);
goto out;
} else {
pmd_t entry;
VM_BUG_ON(!PageHead(page));