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 <[email protected]> Cc: Balbir Singh <[email protected]> Reviewed-by: Minchan Kim <[email protected]> Acked-by: KAMEZAWA Hiroyuki <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
mna · May 2, 2009 · bc43f75 · bc43f75
1 parent 53951bd
commit bc43f75
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/mm/memory.c b/mm/memory.c
@@ -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;