Commit 61469f1d authored Mar 04, 2008 by Hugh Dickins Committed by Linus Torvalds Mar 04, 2008

memcg: when do_swap's do_wp_page fails



Don't uncharge when do_swap_page's call to do_wp_page fails: the page which
was charged for is there in the pagetable, and will be correctly uncharged
when that area is unmapped - it was only its COWing which failed.

And while we're here, remove earlier XXX comment: yes, OR in do_wp_page's
return value (maybe VM_FAULT_WRITE) with do_swap_page's there; but if it
fails, mask out success bits, which might confuse some arches e.g.  sparc.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: David Rientjes <rientjes@google.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hirokazu Takahashi <taka@valinux.co.jp>
Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Cc: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 6dbf6d3b

mm/memory.c

+3 −6

Original line number	Original line	Diff line number	Diff line
	@@ -2093,12 +2093,9 @@ static int do_swap_page(struct mm_struct mm, struct vm_area_struct vma,
	unlock_page(page);		unlock_page(page);

	if (write_access) {		if (write_access) {
	/* XXX: We could OR the do_wp_page code with this one? */		ret \|= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
	if (do_wp_page(mm, vma, address,		if (ret & VM_FAULT_ERROR)
	page_table, pmd, ptl, pte) & VM_FAULT_OOM) {		ret &= VM_FAULT_ERROR;
	mem_cgroup_uncharge_page(page);
	ret = VM_FAULT_OOM;
	}
	goto out;		goto out;
	}		}