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Message-ID: <539F5E4B.3090302@oracle.com>
Date: Mon, 16 Jun 2014 17:14:51 -0400
From: Sasha Levin <sasha.levin@...cle.com>
To: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
CC: linux-mm@...ck.org, Dave Hansen <dave.hansen@...el.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Hugh Dickins <hughd@...gle.com>,
"Kirill A. Shutemov" <kirill@...temov.name>,
linux-kernel@...r.kernel.org, Dave Jones <davej@...hat.com>
Subject: Re: [PATCH 7/7] mincore: apply page table walker on do_mincore()
On 06/16/2014 12:44 PM, Naoya Horiguchi wrote:
> Hi Sasha,
>
> Thanks for bug reporting.
>
> On Mon, Jun 16, 2014 at 11:24:16AM -0400, Sasha Levin wrote:
>> On 06/06/2014 06:58 PM, Naoya Horiguchi wrote:
>>> This patch makes do_mincore() use walk_page_vma(), which reduces many lines
>>> of code by using common page table walk code.
>>>
>>> Signed-off-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
>>
>> Hi Naoya,
>>
>> This patch is causing a few issues on -next:
>>
>> [ 367.679282] BUG: sleeping function called from invalid context at mm/mincore.c:37
>
> cond_resched() in mincore_hugetlb() triggered this. This is done in common
> pagewalk code, so I should have removed it.
>
> ...
>> And:
>>
>> [ 391.118663] BUG: unable to handle kernel paging request at ffff880142aca000
>> [ 391.118663] IP: mincore_hole (mm/mincore.c:99 (discriminator 2))
>
> walk->pte_hole cannot assume walk->vma != NULL, so I should've checked it
> in mincore_hole() before using walk->vma.
>
> Could you try the following fixes?
That solved those two, but I'm seeing new ones:
[ 650.352956] BUG: unable to handle kernel paging request at ffff8802fdf03000
[ 650.352956] IP: mincore_hole (mm/mincore.c:101 (discriminator 2))
[ 650.352956] PGD 23bcd067 PUD 704b48067 PMD 704958067 PTE 80000002fdf03060
[ 650.352956] Oops: 0002 [#1] PREEMPT SMP DEBUG_PAGEALLOC
[ 650.352956] Dumping ftrace buffer:
[ 650.352956] (ftrace buffer empty)
[ 650.352956] Modules linked in:
[ 650.352956] CPU: 12 PID: 15403 Comm: trinity-c363 Tainted: G W 3.15.0-next-20140616-sasha-00025-g0fd1f7d-dirty #657
[ 650.352956] task: ffff88027caf3000 ti: ffff880279d5c000 task.ti: ffff880279d5c000
[ 650.352956] RIP: mincore_hole (mm/mincore.c:101 (discriminator 2))
[ 650.352956] RSP: 0018:ffff880279d5fd48 EFLAGS: 00010202
[ 650.352956] RAX: 0000000000000001 RBX: 00007f2445400000 RCX: 0000000000000000
[ 650.352956] RDX: 0000000000000000 RSI: 00007f2445400000 RDI: 00007f2445200000
[ 650.352956] RBP: ffff880279d5fd88 R08: 0000000000000001 R09: ffff880000000100
[ 650.352956] R10: 0000000000000001 R11: 00007f2444126000 R12: 00007f2480000000
[ 650.352956] R13: ffff8802fdf03000 R14: 0000000000000200 R15: ffff8804e32f2000
[ 650.352956] FS: 00007f24899ec700(0000) GS:ffff8802ff000000(0000) knlGS:0000000000000000
[ 650.352956] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 650.352956] CR2: ffff8802fdf03000 CR3: 000000027c39b000 CR4: 00000000000006a0
[ 650.352956] DR0: 00000000006df000 DR1: 0000000000000000 DR2: 0000000000000000
[ 650.352956] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
[ 650.352956] Stack:
[ 650.352956] ffff880279d5fef0 0000000000000000 0000000000000000 00007f2445400000
[ 650.352956] 00007f2480000000 ffff880279d5fef0 00007f2445200000 ffff8804e30fd148
[ 650.352956] ffff880279d5fe38 ffffffff9c2d1c4d ffff880200000000 ffffffff9c1a0038
[ 650.352956] Call Trace:
[ 650.352956] walk_pgd_range (mm/pagewalk.c:73 mm/pagewalk.c:141 mm/pagewalk.c:170)
[ 650.352956] ? preempt_count_sub (kernel/sched/core.c:2602)
[ 650.352956] __walk_page_range (mm/pagewalk.c:264)
[ 650.352956] ? SyS_mincore (mm/mincore.c:160 mm/mincore.c:244 mm/mincore.c:212)
[ 650.352956] walk_page_vma (mm/pagewalk.c:376)
[ 650.352956] SyS_mincore (mm/mincore.c:177 mm/mincore.c:244 mm/mincore.c:212)
[ 650.352956] ? mincore_hugetlb (mm/mincore.c:143)
[ 650.352956] ? mincore_hole (mm/mincore.c:109)
[ 650.352956] ? mincore_page (mm/mincore.c:87)
[ 650.352956] ? copy_page_range (mm/mincore.c:24)
[ 650.352956] tracesys (arch/x86/kernel/entry_64.S:542)
[ 650.352956] Code: 87 a0 00 00 00 48 83 c3 01 48 8b b8 f8 01 00 00 e8 ab fe ff ff 48 8b 55 c8 88 02 49 63 c4 49 39 c6 77 cd eb 14 0f 1f 00 83 c0 01 <41> c6 44 15 00 00 48 63 d0 49 39 d6 77 ef 48 8b 55 c0 4c 8b 6a
All code
========
0: 87 a0 00 00 00 48 xchg %esp,0x48000000(%rax)
6: 83 c3 01 add $0x1,%ebx
9: 48 8b b8 f8 01 00 00 mov 0x1f8(%rax),%rdi
10: e8 ab fe ff ff callq 0xfffffffffffffec0
15: 48 8b 55 c8 mov -0x38(%rbp),%rdx
19: 88 02 mov %al,(%rdx)
1b: 49 63 c4 movslq %r12d,%rax
1e: 49 39 c6 cmp %rax,%r14
21: 77 cd ja 0xfffffffffffffff0
23: eb 14 jmp 0x39
25: 0f 1f 00 nopl (%rax)
28: 83 c0 01 add $0x1,%eax
2b:* 41 c6 44 15 00 00 movb $0x0,0x0(%r13,%rdx,1) <-- trapping instruction
31: 48 63 d0 movslq %eax,%rdx
34: 49 39 d6 cmp %rdx,%r14
37: 77 ef ja 0x28
39: 48 8b 55 c0 mov -0x40(%rbp),%rdx
3d: 4c 8b 6a 00 mov 0x0(%rdx),%r13
Code starting with the faulting instruction
===========================================
0: 41 c6 44 15 00 00 movb $0x0,0x0(%r13,%rdx,1)
6: 48 63 d0 movslq %eax,%rdx
9: 49 39 d6 cmp %rdx,%r14
c: 77 ef ja 0xfffffffffffffffd
e: 48 8b 55 c0 mov -0x40(%rbp),%rdx
12: 4c 8b 6a 00 mov 0x0(%rdx),%r13
[ 650.352956] RIP mincore_hole (mm/mincore.c:101 (discriminator 2))
[ 650.352956] RSP <ffff880279d5fd48>
[ 650.352956] CR2: ffff8802fdf03000
Thanks,
Sasha
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