Commit 073e587e authored Oct 18, 2008 by KAMEZAWA Hiroyuki Committed by Linus Torvalds Oct 20, 2008

memcg: move charge swapin under lock



While page-cache's charge/uncharge is done under page_lock(), swap-cache
isn't.  (anonymous page is charged when it's newly allocated.)

This patch moves do_swap_page()'s charge() call under lock.  I don't see
any bad problem *now* but this fix will be good for future for avoiding
unnecessary racy state.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 47c59803

mm/memory.c

+6 −5

Original line number	Original line	Diff line number	Diff line
	@@ -2326,16 +2326,17 @@ static int do_swap_page(struct mm_struct mm, struct vm_area_struct vma,
	count_vm_event(PGMAJFAULT);		count_vm_event(PGMAJFAULT);
	}		}

	if (mem_cgroup_charge(page, mm, GFP_KERNEL)) {		mark_page_accessed(page);

			lock_page(page);
	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);		delayacct_clear_flag(DELAYACCT_PF_SWAPIN);

			if (mem_cgroup_charge(page, mm, GFP_KERNEL)) {
	ret = VM_FAULT_OOM;		ret = VM_FAULT_OOM;
			unlock_page(page);
	goto out;		goto out;
	}		}

	mark_page_accessed(page);
	lock_page(page);
	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);

	/*		/*
	* Back out if somebody else already faulted in this pte.		* Back out if somebody else already faulted in this pte.
	*/		*/