Commit bc43f75c authored Apr 30, 2009 by Johannes Weiner Committed by Linus Torvalds May 02, 2009

mm: fix pageref leak in do_swap_page()



By the time the memory cgroup code is notified about a swapin we
already hold a reference on the fault page.

If the cgroup callback fails make sure to unlock AND release the page
reference which was taken by lookup_swap_cach(), or we leak the reference.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 53951bd5

mm/memory.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -2458,8 +2458,7 @@ static int do_swap_page(struct mm_struct mm, struct vm_area_struct vma,

		if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
		ret = VM_FAULT_OOM;
		unlock_page(page);
		goto out;
		goto out_page;
		}

		/*
		@@ -2521,6 +2520,7 @@ static int do_swap_page(struct mm_struct mm, struct vm_area_struct vma,
		out_nomap:
		mem_cgroup_cancel_charge_swapin(ptr);
		pte_unmap_unlock(page_table, ptl);
		out_page:
		unlock_page(page);
		page_cache_release(page);
		return ret;