linux-kernel - [PATCH V2] mm: mempolicy: skip non-migratable VMAs when setting MPOL_MF

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <1452138758-30031-1-git-send-email-liangchen.linux@gmail.com>
Date:	Thu,  7 Jan 2016 11:52:38 +0800
From:	Liang Chen <liangchen.linux@...il.com>
To:	riel@...hat.com
Cc:	mgorman@...e.de, akpm@...ux-foundation.org, linux-mm@...ck.org,
	n-horiguchi@...jp.nec.com, linux-kernel@...r.kernel.org,
	Liang Chen <liangchen.linux@...il.com>,
	Gavin Guo <gavin.guo@...onical.com>
Subject: [PATCH V2] mm: mempolicy: skip non-migratable VMAs when setting MPOL_MF_LAZY

MPOL_MF_LAZY is not visible from userspace since 'commit a720094ded8c
("mm: mempolicy: Hide MPOL_NOOP and MPOL_MF_LAZY from userspace for now")'
, but it should still skip non-migratable VMAs such as VM_IO, VM_PFNMAP,
and VM_HUGETLB VMAs, and avoid useless overhead of minor faults.

Signed-off-by: Liang Chen <liangchen.linux@...il.com>
Signed-off-by: Gavin Guo <gavin.guo@...onical.com>
---
Changes since v2:
- Add more description into the changelog

We have been evaluating the enablement of MPOL_MF_LAZY again, and found
this issue. And we decided to push this patch upstream no matter if we
finally determine to propose re-enablement of MPOL_MF_LAZY or not. Since
it can be a potential problem even if MPOL_MF_LAZY is not enabled this
time.
---
 mm/mempolicy.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 87a1779..436ff411 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -610,7 +610,8 @@ static int queue_pages_test_walk(unsigned long start, unsigned long end,
 
 	if (flags & MPOL_MF_LAZY) {
 		/* Similar to task_numa_work, skip inaccessible VMAs */
-		if (vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))
+		if (vma_migratable(vma) &&
+			vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))
 			change_prot_numa(vma, start, endvma);
 		return 1;
 	}
-- 
1.9.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/