[PATCH] mm/mempolicy: fix !vma in new_vma_page()
From: Wanpeng Li
Date: Tue Dec 17 2013 - 01:44:44 EST
BUG_ON(!vma) assumption is introduced by commit 0bf598d8 (mbind: add BUG_ON(!vma)
in new_vma_page()), however, even if address = __vma_address(page, vma); and
vma->start < address < vma->end; page_address_in_vma() may still return -EFAULT
because of many other conditions in it. As a result the while loop in new_vma_page()
may end with vma=NULL. This patch revert the commit and also fix the potential
dereference NULL pointer by Dan. http://marc.info/?l=linux-mm&m=137689530323257&w=2
kernel BUG at mm/mempolicy.c:1204!
invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
CPU: 3 PID: 7056 Comm: trinity-child3 Not tainted 3.13.0-rc3+ #2
task: ffff8801ca5295d0 ti: ffff88005ab20000 task.ti: ffff88005ab20000
RIP: 0010:[<ffffffff8119f200>] [<ffffffff8119f200>] new_vma_page+0x70/0x90
RSP: 0000:ffff88005ab21db0 EFLAGS: 00010246
RAX: fffffffffffffff2 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000008040075 RSI: ffff8801c3d74600 RDI: ffffea00079a8b80
RBP: ffff88005ab21dc8 R08: 0000000000000004 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: fffffffffffffff2
R13: ffffea00079a8b80 R14: 0000000000400000 R15: 0000000000400000
FS: 00007ff49c6f4740(0000) GS:ffff880244e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff49c68f994 CR3: 000000005a205000 CR4: 00000000001407e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
ffffea00079a8b80 ffffea00079a8bc0 ffffea00079a8ba0 ffff88005ab21e50
ffffffff811adc7a 0000000000000000 ffff8801ca5295d0 0000000464e224f8
0000000000000000 0000000000000002 0000000000000000 ffff88020ce75c00
Call Trace:
[<ffffffff811adc7a>] migrate_pages+0x12a/0x850
[<ffffffff8119f190>] ? alloc_pages_vma+0x1b0/0x1b0
[<ffffffff8119fa13>] SYSC_mbind+0x513/0x6a0
[<ffffffff810aa7de>] ? lock_release_holdtime.part.29+0xee/0x170
[<ffffffff8119fbae>] SyS_mbind+0xe/0x10
[<ffffffff817626a9>] ia32_do_call+0x13/0x13
Code: 85 c0 75 2f 4c 89 e1 48 89 da 31 f6 bf da 00 02 00 65 44 8b 04 25 08 f7 1c 00 e8 ec fd ff ff 5b 41 5c 41 5d 5d c3 0f 1f 44 00 00 <0f> 0b 66 0f 1f 44 00
+00 4c 89 e6 48 89 df ba 01 00 00 00 e8 48
RIP [<ffffffff8119f200>] new_vma_page+0x70/0x90
RSP <ffff88005ab21db0>
Reported-by: Dave Jones <davej@xxxxxxxxxx>
Reported-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
Signed-off-by: Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx>
---
mm/mempolicy.c | 14 ++++++++------
1 files changed, 8 insertions(+), 6 deletions(-)
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index eca4a31..7247c38 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1197,14 +1197,16 @@ static struct page *new_vma_page(struct page *page, unsigned long private, int *
break;
vma = vma->vm_next;
}
+
+ if (PageHuge(page)) {
+ if (vma)
+ return alloc_huge_page_noerr(vma, address, 1);
+ else
+ return NULL;
+ }
/*
- * queue_pages_range() confirms that @page belongs to some vma,
- * so vma shouldn't be NULL.
+ * if !vma, alloc_page_vma() will use task or system default policy
*/
- BUG_ON(!vma);
-
- if (PageHuge(page))
- return alloc_huge_page_noerr(vma, address, 1);
return alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
}
#else
--
1.7.5.4
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