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Commit 85d9fc89 authored by KAMEZAWA Hiroyuki's avatar KAMEZAWA Hiroyuki Committed by Linus Torvalds
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memcg: fix refcnt handling at swapoff 



Now, at swapoff, even while try_charge() fails, commit is executed.  This
is a bug which turns the refcnt of cgroup_subsys_state negative.

Reported-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
Tested-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
Tested-by: default avatarDaisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: default avatarDaisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7460db56

mm/swapfile.c

+4 −1
Original line number Original line Diff line number Diff line
@@ -698,8 +698,10 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, 
	pte_t *pte;

	pte_t *pte;

	int ret = 1;

	int ret = 1;





	if (mem_cgroup_try_charge_swapin(vma->vm_mm, page, GFP_KERNEL, &ptr))

	if (mem_cgroup_try_charge_swapin(vma->vm_mm, page, GFP_KERNEL, &ptr)) {

		ret = -ENOMEM;

		ret = -ENOMEM;

		goto out_nolock;

	}





	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);

	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);

	if (unlikely(!pte_same(*pte, swp_entry_to_pte(entry)))) {

	if (unlikely(!pte_same(*pte, swp_entry_to_pte(entry)))) {
@@ -723,6 +725,7 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, 
	activate_page(page);

	activate_page(page);

out:

out:

	pte_unmap_unlock(pte, ptl);

	pte_unmap_unlock(pte, ptl);

out_nolock:

	return ret;

	return ret;

}

}