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mm: fix pageref leak in do_swap_page()

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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>
This commit is contained in:
Johannes Weiner 2009-04-30 15:08:08 -07:00 committed by Linus Torvalds
parent 53951bd57d
commit bc43f75cd9
1 changed files with 2 additions and 2 deletions
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4
mm/memory.c
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@ -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)) { if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
ret = VM_FAULT_OOM; ret = VM_FAULT_OOM;
unlock_page(page); goto out_page;
goto out;
} }
/* /*
@ -2521,6 +2520,7 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
out_nomap: out_nomap:
mem_cgroup_cancel_charge_swapin(ptr); mem_cgroup_cancel_charge_swapin(ptr);
pte_unmap_unlock(page_table, ptl); pte_unmap_unlock(page_table, ptl);
out_page:
unlock_page(page); unlock_page(page);
page_cache_release(page); page_cache_release(page);
return ret; return ret;