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* mm: kernel BUG at mm/swap.c:609!
@ 2014-03-11 20:07 Sasha Levin
  2014-03-12  1:25 ` Bob Liu
  0 siblings, 1 reply; 4+ messages in thread
From: Sasha Levin @ 2014-03-11 20:07 UTC (permalink / raw)
  To: linux-mm@kvack.org; +Cc: Andrew Morton, Mel Gorman, LKML, Rik van Riel

Hi all,

While fuzzing with trinity inside a KVM tools guest running latest -next kernel
I've stumbled on the following spew:

[  477.301955] kernel BUG at mm/swap.c:609!
[  477.302564] invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
[  477.303590] Dumping ftrace buffer:
[  477.305022]    (ftrace buffer empty)
[  477.305899] Modules linked in:
[  477.306397] CPU: 35 PID: 10092 Comm: trinity-c374 Tainted: G        W    3.14.0-rc5-next-20140307-sasha-00010-g1f812cb #142
[  477.307644] task: ffff8800a7f80000 ti: ffff8800a7f6a000 task.ti: ffff8800a7f6a000
[  477.309124] RIP: 0010:[<ffffffff8127f311>]  [<ffffffff8127f311>] lru_cache_add+0x21/0x60
[  477.310301] RSP: 0000:ffff8800a7f6bbc8  EFLAGS: 00010292
[  477.311110] RAX: 000000000000003f RBX: ffffea0013d68000 RCX: 0000000000000006
[  477.311110] RDX: 0000000000000006 RSI: ffff8800a7f80d60 RDI: 0000000000000282
[  477.311110] RBP: ffff8800a7f6bbc8 R08: 0000000000000001 R09: 0000000000000001
[  477.311110] R10: 0000000000000001 R11: 0000000000000001 R12: ffff8800ab9b0c00
[  477.311110] R13: 0000000002400000 R14: ffff8800ab9b0c00 R15: 0000000000000001
[  477.311110] FS:  00007ff2c047c700(0000) GS:ffff88042bc00000(0000) knlGS:0000000000000000
[  477.311110] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[  477.311110] CR2: 0000000003788a68 CR3: 00000000a7f68000 CR4: 00000000000006a0
[  477.311110] DR0: 000000000069b000 DR1: 0000000000000000 DR2: 0000000000000000
[  477.311110] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
[  477.311110] Stack:
[  477.311110]  ffff8800a7f6bbf8 ffffffff812adaec ffffea0013d68000 ffffea002bdb8000
[  477.311110]  ffffea0013d68000 ffff8800a7f7c090 ffff8800a7f6bca8 ffffffff812db8ec
[  477.311110]  0000000000000001 ffffffff812e1321 ffff8800a7f6bc48 ffffffff811ad632
[  477.311110] Call Trace:
[  477.311110]  [<ffffffff812adaec>] page_add_new_anon_rmap+0x1ec/0x210
[  477.311110]  [<ffffffff812db8ec>] migrate_misplaced_transhuge_page+0x55c/0x830
[  477.311110]  [<ffffffff812e1321>] ? do_huge_pmd_numa_page+0x311/0x460
[  477.311110]  [<ffffffff811ad632>] ? __lock_release+0x1e2/0x200
[  477.311110]  [<ffffffff812e133f>] do_huge_pmd_numa_page+0x32f/0x460
[  477.311110]  [<ffffffff81af6aca>] ? delay_tsc+0xfa/0x120
[  477.311110]  [<ffffffff812a31f4>] __handle_mm_fault+0x244/0x3a0
[  477.311110]  [<ffffffff812e37ed>] ? rcu_read_unlock+0x5d/0x60
[  477.311110]  [<ffffffff812a3463>] handle_mm_fault+0x113/0x1c0
[  477.311110]  [<ffffffff844abd42>] ? __do_page_fault+0x302/0x5d0
[  477.311110]  [<ffffffff844abfd1>] __do_page_fault+0x591/0x5d0
[  477.311110]  [<ffffffff8118ab46>] ? vtime_account_user+0x96/0xb0
[  477.311110]  [<ffffffff844ac492>] ? preempt_count_sub+0xe2/0x120
[  477.311110]  [<ffffffff81269567>] ? context_tracking_user_exit+0x187/0x1d0
[  477.311110]  [<ffffffff844ac0d5>] do_page_fault+0x45/0x70
[  477.311110]  [<ffffffff844ab386>] do_async_page_fault+0x36/0x100
[  477.311110]  [<ffffffff844a7f18>] async_page_fault+0x28/0x30
[  477.311110] Code: 65 f0 4c 8b 6d f8 c9 c3 66 90 55 48 89 e5 66 66 66 66 90 48 8b 07 a8 40 74 18 48 8b 07 a9 00 00 10 00 74 0e 31 f6 e8 2f 20 ff ff <0f> 0b eb fe 0f 1f 00 48 8b 07 a8 20 74 19 31 f6 e8 1a 20 ff ff
[  477.311110] RIP  [<ffffffff8127f311>] lru_cache_add+0x21/0x60
[  477.311110]  RSP <ffff8800a7f6bbc8>

Thanks,
Sasha

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^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: mm: kernel BUG at mm/swap.c:609!
  2014-03-11 20:07 mm: kernel BUG at mm/swap.c:609! Sasha Levin
@ 2014-03-12  1:25 ` Bob Liu
  2014-03-20  9:21   ` Bob Liu
  0 siblings, 1 reply; 4+ messages in thread
From: Bob Liu @ 2014-03-12  1:25 UTC (permalink / raw)
  To: Sasha Levin
  Cc: linux-mm@kvack.org, Andrew Morton, Mel Gorman, LKML, Rik van Riel


On 03/12/2014 04:07 AM, Sasha Levin wrote:
> Hi all,
> 
> While fuzzing with trinity inside a KVM tools guest running latest -next
> kernel
> I've stumbled on the following spew:
> 
> [  477.301955] kernel BUG at mm/swap.c:609!
> [  477.302564] invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
> [  477.303590] Dumping ftrace buffer:
> [  477.305022]    (ftrace buffer empty)
> [  477.305899] Modules linked in:
> [  477.306397] CPU: 35 PID: 10092 Comm: trinity-c374 Tainted: G       
> W    3.14.0-rc5-next-20140307-sasha-00010-g1f812cb #142
> [  477.307644] task: ffff8800a7f80000 ti: ffff8800a7f6a000 task.ti:
> ffff8800a7f6a000
> [  477.309124] RIP: 0010:[<ffffffff8127f311>]  [<ffffffff8127f311>]
> lru_cache_add+0x21/0x60
> [  477.310301] RSP: 0000:ffff8800a7f6bbc8  EFLAGS: 00010292
> [  477.311110] RAX: 000000000000003f RBX: ffffea0013d68000 RCX:
> 0000000000000006
> [  477.311110] RDX: 0000000000000006 RSI: ffff8800a7f80d60 RDI:
> 0000000000000282
> [  477.311110] RBP: ffff8800a7f6bbc8 R08: 0000000000000001 R09:
> 0000000000000001
> [  477.311110] R10: 0000000000000001 R11: 0000000000000001 R12:
> ffff8800ab9b0c00
> [  477.311110] R13: 0000000002400000 R14: ffff8800ab9b0c00 R15:
> 0000000000000001
> [  477.311110] FS:  00007ff2c047c700(0000) GS:ffff88042bc00000(0000)
> knlGS:0000000000000000
> [  477.311110] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> [  477.311110] CR2: 0000000003788a68 CR3: 00000000a7f68000 CR4:
> 00000000000006a0
> [  477.311110] DR0: 000000000069b000 DR1: 0000000000000000 DR2:
> 0000000000000000
> [  477.311110] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7:
> 0000000000000600
> [  477.311110] Stack:
> [  477.311110]  ffff8800a7f6bbf8 ffffffff812adaec ffffea0013d68000
> ffffea002bdb8000
> [  477.311110]  ffffea0013d68000 ffff8800a7f7c090 ffff8800a7f6bca8
> ffffffff812db8ec
> [  477.311110]  0000000000000001 ffffffff812e1321 ffff8800a7f6bc48
> ffffffff811ad632
> [  477.311110] Call Trace:
> [  477.311110]  [<ffffffff812adaec>] page_add_new_anon_rmap+0x1ec/0x210
> [  477.311110]  [<ffffffff812db8ec>]
> migrate_misplaced_transhuge_page+0x55c/0x830
> [  477.311110]  [<ffffffff812e1321>] ? do_huge_pmd_numa_page+0x311/0x460
> [  477.311110]  [<ffffffff811ad632>] ? __lock_release+0x1e2/0x200
> [  477.311110]  [<ffffffff812e133f>] do_huge_pmd_numa_page+0x32f/0x460
> [  477.311110]  [<ffffffff81af6aca>] ? delay_tsc+0xfa/0x120
> [  477.311110]  [<ffffffff812a31f4>] __handle_mm_fault+0x244/0x3a0
> [  477.311110]  [<ffffffff812e37ed>] ? rcu_read_unlock+0x5d/0x60
> [  477.311110]  [<ffffffff812a3463>] handle_mm_fault+0x113/0x1c0
> [  477.311110]  [<ffffffff844abd42>] ? __do_page_fault+0x302/0x5d0
> [  477.311110]  [<ffffffff844abfd1>] __do_page_fault+0x591/0x5d0
> [  477.311110]  [<ffffffff8118ab46>] ? vtime_account_user+0x96/0xb0
> [  477.311110]  [<ffffffff844ac492>] ? preempt_count_sub+0xe2/0x120
> [  477.311110]  [<ffffffff81269567>] ?
> context_tracking_user_exit+0x187/0x1d0
> [  477.311110]  [<ffffffff844ac0d5>] do_page_fault+0x45/0x70
> [  477.311110]  [<ffffffff844ab386>] do_async_page_fault+0x36/0x100
> [  477.311110]  [<ffffffff844a7f18>] async_page_fault+0x28/0x30
> [  477.311110] Code: 65 f0 4c 8b 6d f8 c9 c3 66 90 55 48 89 e5 66 66 66
> 66 90 48 8b 07 a8 40 74 18 48 8b 07 a9 00 00 10 00 74 0e 31 f6 e8 2f 20
> ff ff <0f> 0b eb fe 0f 1f 00 48 8b 07 a8 20 74 19 31 f6 e8 1a 20 ff ff
> [  477.311110] RIP  [<ffffffff8127f311>] lru_cache_add+0x21/0x60
> [  477.311110]  RSP <ffff8800a7f6bbc8>
> 


If PageUnevictable(old_page) is true, new page will also be set before
page_add_new_anon_rmap().

migrate_misplaced_transhuge_page()
    > migrate_page_copy()
        > SetPageUnevictable(newpage)
    > page_add_new_anon_rmap()

But in page_add_new_anon_rmap(), there is only mlocked_vma_newpage()
called to check whether a page should be added to unevictable list. I
think that is incorrect in some cases and may trigger this BUG().

We can see from vmscan:
int page_evictable(struct page *page)
{
    return !mapping_unevictable(page_mapping(page)) && !PageMlocked(page);
}

Besides mlock, we may also set a page to unevictable when that page's
mapping marked unevictable.

mlocked_vma_newpage(new_page) can't detect this situation if the old
page is set to unevictable by this reason. So I think we should add an
extra !PageUnevictable(page) checking in page_add_new_anon_rmap().
Fix me if I misunderstood something.

diff --git a/mm/rmap.c b/mm/rmap.c
index 9056a1f..8d13318 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1024,7 +1024,7 @@ void page_add_new_anon_rmap(struct page *page,
        __mod_zone_page_state(page_zone(page), NR_ANON_PAGES,
                        hpage_nr_pages(page));
        __page_set_anon_rmap(page, vma, address, 1);
-       if (!mlocked_vma_newpage(vma, page)) {
+       if (!mlocked_vma_newpage(vma, page) && !PageUnevictable(page)) {
                SetPageActive(page);
                lru_cache_add(page);
        } else


-- 
Regards,
--Bob

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
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^ permalink raw reply related	[flat|nested] 4+ messages in thread

* Re: mm: kernel BUG at mm/swap.c:609!
  2014-03-12  1:25 ` Bob Liu
@ 2014-03-20  9:21   ` Bob Liu
  2014-03-30  0:47     ` Sasha Levin
  0 siblings, 1 reply; 4+ messages in thread
From: Bob Liu @ 2014-03-20  9:21 UTC (permalink / raw)
  To: Sasha Levin
  Cc: linux-mm@kvack.org, Andrew Morton, Mel Gorman, LKML, Rik van Riel


On 03/12/2014 09:25 AM, Bob Liu wrote:
> 
> On 03/12/2014 04:07 AM, Sasha Levin wrote:
>> Hi all,
>>
>> While fuzzing with trinity inside a KVM tools guest running latest -next
>> kernel
>> I've stumbled on the following spew:
>>
>> [  477.301955] kernel BUG at mm/swap.c:609!
>> [  477.302564] invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
>> [  477.303590] Dumping ftrace buffer:
>> [  477.305022]    (ftrace buffer empty)
>> [  477.305899] Modules linked in:
>> [  477.306397] CPU: 35 PID: 10092 Comm: trinity-c374 Tainted: G       
>> W    3.14.0-rc5-next-20140307-sasha-00010-g1f812cb #142
>> [  477.307644] task: ffff8800a7f80000 ti: ffff8800a7f6a000 task.ti:
>> ffff8800a7f6a000
>> [  477.309124] RIP: 0010:[<ffffffff8127f311>]  [<ffffffff8127f311>]
>> lru_cache_add+0x21/0x60
>> [  477.310301] RSP: 0000:ffff8800a7f6bbc8  EFLAGS: 00010292
>> [  477.311110] RAX: 000000000000003f RBX: ffffea0013d68000 RCX:
>> 0000000000000006
>> [  477.311110] RDX: 0000000000000006 RSI: ffff8800a7f80d60 RDI:
>> 0000000000000282
>> [  477.311110] RBP: ffff8800a7f6bbc8 R08: 0000000000000001 R09:
>> 0000000000000001
>> [  477.311110] R10: 0000000000000001 R11: 0000000000000001 R12:
>> ffff8800ab9b0c00
>> [  477.311110] R13: 0000000002400000 R14: ffff8800ab9b0c00 R15:
>> 0000000000000001
>> [  477.311110] FS:  00007ff2c047c700(0000) GS:ffff88042bc00000(0000)
>> knlGS:0000000000000000
>> [  477.311110] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
>> [  477.311110] CR2: 0000000003788a68 CR3: 00000000a7f68000 CR4:
>> 00000000000006a0
>> [  477.311110] DR0: 000000000069b000 DR1: 0000000000000000 DR2:
>> 0000000000000000
>> [  477.311110] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7:
>> 0000000000000600
>> [  477.311110] Stack:
>> [  477.311110]  ffff8800a7f6bbf8 ffffffff812adaec ffffea0013d68000
>> ffffea002bdb8000
>> [  477.311110]  ffffea0013d68000 ffff8800a7f7c090 ffff8800a7f6bca8
>> ffffffff812db8ec
>> [  477.311110]  0000000000000001 ffffffff812e1321 ffff8800a7f6bc48
>> ffffffff811ad632
>> [  477.311110] Call Trace:
>> [  477.311110]  [<ffffffff812adaec>] page_add_new_anon_rmap+0x1ec/0x210
>> [  477.311110]  [<ffffffff812db8ec>]
>> migrate_misplaced_transhuge_page+0x55c/0x830
>> [  477.311110]  [<ffffffff812e1321>] ? do_huge_pmd_numa_page+0x311/0x460
>> [  477.311110]  [<ffffffff811ad632>] ? __lock_release+0x1e2/0x200
>> [  477.311110]  [<ffffffff812e133f>] do_huge_pmd_numa_page+0x32f/0x460
>> [  477.311110]  [<ffffffff81af6aca>] ? delay_tsc+0xfa/0x120
>> [  477.311110]  [<ffffffff812a31f4>] __handle_mm_fault+0x244/0x3a0
>> [  477.311110]  [<ffffffff812e37ed>] ? rcu_read_unlock+0x5d/0x60
>> [  477.311110]  [<ffffffff812a3463>] handle_mm_fault+0x113/0x1c0
>> [  477.311110]  [<ffffffff844abd42>] ? __do_page_fault+0x302/0x5d0
>> [  477.311110]  [<ffffffff844abfd1>] __do_page_fault+0x591/0x5d0
>> [  477.311110]  [<ffffffff8118ab46>] ? vtime_account_user+0x96/0xb0
>> [  477.311110]  [<ffffffff844ac492>] ? preempt_count_sub+0xe2/0x120
>> [  477.311110]  [<ffffffff81269567>] ?
>> context_tracking_user_exit+0x187/0x1d0
>> [  477.311110]  [<ffffffff844ac0d5>] do_page_fault+0x45/0x70
>> [  477.311110]  [<ffffffff844ab386>] do_async_page_fault+0x36/0x100
>> [  477.311110]  [<ffffffff844a7f18>] async_page_fault+0x28/0x30
>> [  477.311110] Code: 65 f0 4c 8b 6d f8 c9 c3 66 90 55 48 89 e5 66 66 66
>> 66 90 48 8b 07 a8 40 74 18 48 8b 07 a9 00 00 10 00 74 0e 31 f6 e8 2f 20
>> ff ff <0f> 0b eb fe 0f 1f 00 48 8b 07 a8 20 74 19 31 f6 e8 1a 20 ff ff
>> [  477.311110] RIP  [<ffffffff8127f311>] lru_cache_add+0x21/0x60
>> [  477.311110]  RSP <ffff8800a7f6bbc8>
>>
> 
> 
> If PageUnevictable(old_page) is true, new page will also be set before
> page_add_new_anon_rmap().
> 
> migrate_misplaced_transhuge_page()
>     > migrate_page_copy()
>         > SetPageUnevictable(newpage)
>     > page_add_new_anon_rmap()
> 
> But in page_add_new_anon_rmap(), there is only mlocked_vma_newpage()
> called to check whether a page should be added to unevictable list. I
> think that is incorrect in some cases and may trigger this BUG().
> 
> We can see from vmscan:
> int page_evictable(struct page *page)
> {
>     return !mapping_unevictable(page_mapping(page)) && !PageMlocked(page);
> }
> 
> Besides mlock, we may also set a page to unevictable when that page's
> mapping marked unevictable.
> 
> mlocked_vma_newpage(new_page) can't detect this situation if the old
> page is set to unevictable by this reason. So I think we should add an
> extra !PageUnevictable(page) checking in page_add_new_anon_rmap().
> Fix me if I misunderstood something.
> 
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 9056a1f..8d13318 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -1024,7 +1024,7 @@ void page_add_new_anon_rmap(struct page *page,
>         __mod_zone_page_state(page_zone(page), NR_ANON_PAGES,
>                         hpage_nr_pages(page));
>         __page_set_anon_rmap(page, vma, address, 1);
> -       if (!mlocked_vma_newpage(vma, page)) {
> +       if (!mlocked_vma_newpage(vma, page) && !PageUnevictable(page)) {
>                 SetPageActive(page);
>                 lru_cache_add(page);
>         } else
> 
> 

Sasha, any lucky with above changes? If it can fix this issue, I'll
resend out a patch.

-- 
Regards,
-Bob

--
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^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: mm: kernel BUG at mm/swap.c:609!
  2014-03-20  9:21   ` Bob Liu
@ 2014-03-30  0:47     ` Sasha Levin
  0 siblings, 0 replies; 4+ messages in thread
From: Sasha Levin @ 2014-03-30  0:47 UTC (permalink / raw)
  To: Bob Liu; +Cc: linux-mm@kvack.org, Andrew Morton, Mel Gorman, LKML, Rik van Riel

On 03/20/2014 05:21 AM, Bob Liu wrote:
>
> On 03/12/2014 09:25 AM, Bob Liu wrote:
>>
>> On 03/12/2014 04:07 AM, Sasha Levin wrote:
>>> Hi all,
>>>
>>> While fuzzing with trinity inside a KVM tools guest running latest -next
>>> kernel
>>> I've stumbled on the following spew:
>>>
>>> [  477.301955] kernel BUG at mm/swap.c:609!
>>> [  477.302564] invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
>>> [  477.303590] Dumping ftrace buffer:
>>> [  477.305022]    (ftrace buffer empty)
>>> [  477.305899] Modules linked in:
>>> [  477.306397] CPU: 35 PID: 10092 Comm: trinity-c374 Tainted: G
>>> W    3.14.0-rc5-next-20140307-sasha-00010-g1f812cb #142
>>> [  477.307644] task: ffff8800a7f80000 ti: ffff8800a7f6a000 task.ti:
>>> ffff8800a7f6a000
>>> [  477.309124] RIP: 0010:[<ffffffff8127f311>]  [<ffffffff8127f311>]
>>> lru_cache_add+0x21/0x60
>>> [  477.310301] RSP: 0000:ffff8800a7f6bbc8  EFLAGS: 00010292
>>> [  477.311110] RAX: 000000000000003f RBX: ffffea0013d68000 RCX:
>>> 0000000000000006
>>> [  477.311110] RDX: 0000000000000006 RSI: ffff8800a7f80d60 RDI:
>>> 0000000000000282
>>> [  477.311110] RBP: ffff8800a7f6bbc8 R08: 0000000000000001 R09:
>>> 0000000000000001
>>> [  477.311110] R10: 0000000000000001 R11: 0000000000000001 R12:
>>> ffff8800ab9b0c00
>>> [  477.311110] R13: 0000000002400000 R14: ffff8800ab9b0c00 R15:
>>> 0000000000000001
>>> [  477.311110] FS:  00007ff2c047c700(0000) GS:ffff88042bc00000(0000)
>>> knlGS:0000000000000000
>>> [  477.311110] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
>>> [  477.311110] CR2: 0000000003788a68 CR3: 00000000a7f68000 CR4:
>>> 00000000000006a0
>>> [  477.311110] DR0: 000000000069b000 DR1: 0000000000000000 DR2:
>>> 0000000000000000
>>> [  477.311110] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7:
>>> 0000000000000600
>>> [  477.311110] Stack:
>>> [  477.311110]  ffff8800a7f6bbf8 ffffffff812adaec ffffea0013d68000
>>> ffffea002bdb8000
>>> [  477.311110]  ffffea0013d68000 ffff8800a7f7c090 ffff8800a7f6bca8
>>> ffffffff812db8ec
>>> [  477.311110]  0000000000000001 ffffffff812e1321 ffff8800a7f6bc48
>>> ffffffff811ad632
>>> [  477.311110] Call Trace:
>>> [  477.311110]  [<ffffffff812adaec>] page_add_new_anon_rmap+0x1ec/0x210
>>> [  477.311110]  [<ffffffff812db8ec>]
>>> migrate_misplaced_transhuge_page+0x55c/0x830
>>> [  477.311110]  [<ffffffff812e1321>] ? do_huge_pmd_numa_page+0x311/0x460
>>> [  477.311110]  [<ffffffff811ad632>] ? __lock_release+0x1e2/0x200
>>> [  477.311110]  [<ffffffff812e133f>] do_huge_pmd_numa_page+0x32f/0x460
>>> [  477.311110]  [<ffffffff81af6aca>] ? delay_tsc+0xfa/0x120
>>> [  477.311110]  [<ffffffff812a31f4>] __handle_mm_fault+0x244/0x3a0
>>> [  477.311110]  [<ffffffff812e37ed>] ? rcu_read_unlock+0x5d/0x60
>>> [  477.311110]  [<ffffffff812a3463>] handle_mm_fault+0x113/0x1c0
>>> [  477.311110]  [<ffffffff844abd42>] ? __do_page_fault+0x302/0x5d0
>>> [  477.311110]  [<ffffffff844abfd1>] __do_page_fault+0x591/0x5d0
>>> [  477.311110]  [<ffffffff8118ab46>] ? vtime_account_user+0x96/0xb0
>>> [  477.311110]  [<ffffffff844ac492>] ? preempt_count_sub+0xe2/0x120
>>> [  477.311110]  [<ffffffff81269567>] ?
>>> context_tracking_user_exit+0x187/0x1d0
>>> [  477.311110]  [<ffffffff844ac0d5>] do_page_fault+0x45/0x70
>>> [  477.311110]  [<ffffffff844ab386>] do_async_page_fault+0x36/0x100
>>> [  477.311110]  [<ffffffff844a7f18>] async_page_fault+0x28/0x30
>>> [  477.311110] Code: 65 f0 4c 8b 6d f8 c9 c3 66 90 55 48 89 e5 66 66 66
>>> 66 90 48 8b 07 a8 40 74 18 48 8b 07 a9 00 00 10 00 74 0e 31 f6 e8 2f 20
>>> ff ff <0f> 0b eb fe 0f 1f 00 48 8b 07 a8 20 74 19 31 f6 e8 1a 20 ff ff
>>> [  477.311110] RIP  [<ffffffff8127f311>] lru_cache_add+0x21/0x60
>>> [  477.311110]  RSP <ffff8800a7f6bbc8>
>>>
>>
>>
>> If PageUnevictable(old_page) is true, new page will also be set before
>> page_add_new_anon_rmap().
>>
>> migrate_misplaced_transhuge_page()
>>      > migrate_page_copy()
>>          > SetPageUnevictable(newpage)
>>      > page_add_new_anon_rmap()
>>
>> But in page_add_new_anon_rmap(), there is only mlocked_vma_newpage()
>> called to check whether a page should be added to unevictable list. I
>> think that is incorrect in some cases and may trigger this BUG().
>>
>> We can see from vmscan:
>> int page_evictable(struct page *page)
>> {
>>      return !mapping_unevictable(page_mapping(page)) && !PageMlocked(page);
>> }
>>
>> Besides mlock, we may also set a page to unevictable when that page's
>> mapping marked unevictable.
>>
>> mlocked_vma_newpage(new_page) can't detect this situation if the old
>> page is set to unevictable by this reason. So I think we should add an
>> extra !PageUnevictable(page) checking in page_add_new_anon_rmap().
>> Fix me if I misunderstood something.
>>
>> diff --git a/mm/rmap.c b/mm/rmap.c
>> index 9056a1f..8d13318 100644
>> --- a/mm/rmap.c
>> +++ b/mm/rmap.c
>> @@ -1024,7 +1024,7 @@ void page_add_new_anon_rmap(struct page *page,
>>          __mod_zone_page_state(page_zone(page), NR_ANON_PAGES,
>>                          hpage_nr_pages(page));
>>          __page_set_anon_rmap(page, vma, address, 1);
>> -       if (!mlocked_vma_newpage(vma, page)) {
>> +       if (!mlocked_vma_newpage(vma, page) && !PageUnevictable(page)) {
>>                  SetPageActive(page);
>>                  lru_cache_add(page);
>>          } else
>>
>>
>
> Sasha, any lucky with above changes? If it can fix this issue, I'll
> resend out a patch.

I've been running with it for a while and haven't seen the issue reproduce,
looks good to me.


Thanks,
Sasha

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^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2014-03-30  0:47 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2014-03-11 20:07 mm: kernel BUG at mm/swap.c:609! Sasha Levin
2014-03-12  1:25 ` Bob Liu
2014-03-20  9:21   ` Bob Liu
2014-03-30  0:47     ` Sasha Levin

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