* general protection fault in khugepaged
@ 2020-07-09 6:43 syzbot
2020-07-17 22:40 ` syzbot
[not found] ` <20200718085409.1448-1-hdanton@sina.com>
0 siblings, 2 replies; 6+ messages in thread
From: syzbot @ 2020-07-09 6:43 UTC (permalink / raw)
To: akpm, linux-kernel, linux-mm, netdev, syzkaller-bugs
Hello,
syzbot found the following crash on:
HEAD commit: e44f65fd xen-netfront: remove redundant assignment to vari..
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=15de54a7100000
kernel config: https://syzkaller.appspot.com/x/.config?x=829871134ca5e230
dashboard link: https://syzkaller.appspot.com/bug?extid=ed318e8b790ca72c5ad0
compiler: gcc (GCC) 10.1.0-syz 20200507
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=113406a7100000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=175597d3100000
IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+ed318e8b790ca72c5ad0@syzkaller.appspotmail.com
general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 1 PID: 1155 Comm: khugepaged Not tainted 5.8.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:anon_vma_lock_write include/linux/rmap.h:120 [inline]
RIP: 0010:collapse_huge_page mm/khugepaged.c:1110 [inline]
RIP: 0010:khugepaged_scan_pmd mm/khugepaged.c:1349 [inline]
RIP: 0010:khugepaged_scan_mm_slot mm/khugepaged.c:2110 [inline]
RIP: 0010:khugepaged_do_scan mm/khugepaged.c:2193 [inline]
RIP: 0010:khugepaged+0x3bba/0x5a10 mm/khugepaged.c:2238
Code: 01 00 00 48 8d bb 88 00 00 00 48 89 f8 48 c1 e8 03 42 80 3c 30 00 0f 85 fa 0f 00 00 48 8b 9b 88 00 00 00 48 89 d8 48 c1 e8 03 <42> 80 3c 30 00 0f 85 d4 0f 00 00 48 8b 3b 48 83 c7 08 e8 9f ff 30
RSP: 0018:ffffc90004be7c80 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff81a72d8b
RDX: ffff8880a69d8100 RSI: ffffffff81b7606b RDI: ffff88809f0577c0
RBP: 0000000000000000 R08: 0000000000000000 R09: ffff8881ff213a7f
R10: 0000000000000080 R11: 0000000000000000 R12: ffffffff8aae6110
R13: ffffc90004be7de0 R14: dffffc0000000000 R15: 0000000020000000
FS: 0000000000000000(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000001fe0cf000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
kthread+0x3b5/0x4a0 kernel/kthread.c:291
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293
Modules linked in:
---[ end trace f1f03dbd2ea0777e ]---
RIP: 0010:anon_vma_lock_write include/linux/rmap.h:120 [inline]
RIP: 0010:collapse_huge_page mm/khugepaged.c:1110 [inline]
RIP: 0010:khugepaged_scan_pmd mm/khugepaged.c:1349 [inline]
RIP: 0010:khugepaged_scan_mm_slot mm/khugepaged.c:2110 [inline]
RIP: 0010:khugepaged_do_scan mm/khugepaged.c:2193 [inline]
RIP: 0010:khugepaged+0x3bba/0x5a10 mm/khugepaged.c:2238
Code: 01 00 00 48 8d bb 88 00 00 00 48 89 f8 48 c1 e8 03 42 80 3c 30 00 0f 85 fa 0f 00 00 48 8b 9b 88 00 00 00 48 89 d8 48 c1 e8 03 <42> 80 3c 30 00 0f 85 d4 0f 00 00 48 8b 3b 48 83 c7 08 e8 9f ff 30
RSP: 0018:ffffc90004be7c80 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff81a72d8b
RDX: ffff8880a69d8100 RSI: ffffffff81b7606b RDI: ffff88809f0577c0
RBP: 0000000000000000 R08: 0000000000000000 R09: ffff8881ff213a7f
R10: 0000000000000080 R11: 0000000000000000 R12: ffffffff8aae6110
R13: ffffc90004be7de0 R14: dffffc0000000000 R15: 0000000020000000
FS: 0000000000000000(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000004c00c8 CR3: 00000001f7ac5000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.
syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: general protection fault in khugepaged
2020-07-09 6:43 general protection fault in khugepaged syzbot
@ 2020-07-17 22:40 ` syzbot
2020-07-17 23:10 ` Kirill A. Shutemov
[not found] ` <20200718085409.1448-1-hdanton@sina.com>
1 sibling, 1 reply; 6+ messages in thread
From: syzbot @ 2020-07-17 22:40 UTC (permalink / raw)
To: akpm, kirill.shutemov, linux-kernel, linux-mm, netdev,
syzkaller-bugs, torvalds, william.kucharski, yang.shi, ziy
syzbot has bisected this issue to:
commit ffe945e633b527d5a4577b42cbadec3c7cbcf096
Author: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Date: Wed Jun 3 23:00:09 2020 +0000
khugepaged: do not stop collapse if less than half PTEs are referenced
bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=17356c2f100000
start commit: e44f65fd xen-netfront: remove redundant assignment to vari..
git tree: net-next
final oops: https://syzkaller.appspot.com/x/report.txt?x=14b56c2f100000
console output: https://syzkaller.appspot.com/x/log.txt?x=10b56c2f100000
kernel config: https://syzkaller.appspot.com/x/.config?x=829871134ca5e230
dashboard link: https://syzkaller.appspot.com/bug?extid=ed318e8b790ca72c5ad0
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=113406a7100000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=175597d3100000
Reported-by: syzbot+ed318e8b790ca72c5ad0@syzkaller.appspotmail.com
Fixes: ffe945e633b5 ("khugepaged: do not stop collapse if less than half PTEs are referenced")
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: general protection fault in khugepaged
2020-07-17 22:40 ` syzbot
@ 2020-07-17 23:10 ` Kirill A. Shutemov
0 siblings, 0 replies; 6+ messages in thread
From: Kirill A. Shutemov @ 2020-07-17 23:10 UTC (permalink / raw)
To: syzbot
Cc: akpm, kirill.shutemov, linux-kernel, linux-mm, netdev,
syzkaller-bugs, torvalds, william.kucharski, yang.shi, ziy
On Fri, Jul 17, 2020 at 03:40:04PM -0700, syzbot wrote:
> syzbot has bisected this issue to:
>
> commit ffe945e633b527d5a4577b42cbadec3c7cbcf096
> Author: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Date: Wed Jun 3 23:00:09 2020 +0000
>
> khugepaged: do not stop collapse if less than half PTEs are referenced
>
> bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=17356c2f100000
> start commit: e44f65fd xen-netfront: remove redundant assignment to vari..
> git tree: net-next
> final oops: https://syzkaller.appspot.com/x/report.txt?x=14b56c2f100000
> console output: https://syzkaller.appspot.com/x/log.txt?x=10b56c2f100000
> kernel config: https://syzkaller.appspot.com/x/.config?x=829871134ca5e230
> dashboard link: https://syzkaller.appspot.com/bug?extid=ed318e8b790ca72c5ad0
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=113406a7100000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=175597d3100000
>
> Reported-by: syzbot+ed318e8b790ca72c5ad0@syzkaller.appspotmail.com
> Fixes: ffe945e633b5 ("khugepaged: do not stop collapse if less than half PTEs are referenced")
>
> For information about bisection process see: https://goo.gl/tpsmEJ#bisection
>
My guess is that anonymous VMA got replaced by file VMA under us.
Could you reproduce the issue with the patch below? I have hard time
triggering it myself.
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index b043c40a21d4..f8ec58a1e72b 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1107,6 +1107,8 @@ static void collapse_huge_page(struct mm_struct *mm,
if (mm_find_pmd(mm, address) != pmd)
goto out;
+ if (!vma->anon_vma)
+ dump_vma(vma);
anon_vma_lock_write(vma->anon_vma);
mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, NULL, mm,
--
Kirill A. Shutemov
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: general protection fault in khugepaged
[not found] ` <20200718085409.1448-1-hdanton@sina.com>
@ 2020-07-20 9:08 ` Kirill A. Shutemov
2020-07-22 23:53 ` Song Liu
0 siblings, 1 reply; 6+ messages in thread
From: Kirill A. Shutemov @ 2020-07-20 9:08 UTC (permalink / raw)
To: Hillf Danton
Cc: syzbot, linux-kernel, linux-mm, Song Liu, Kirill A . Shutemov,
syzkaller-bugs, Markus Elfring
On Sat, Jul 18, 2020 at 04:54:09PM +0800, Hillf Danton wrote:
>
> Wed, 08 Jul 2020 23:43:19 -0700
> > syzbot found the following crash on:
> >
> > HEAD commit: e44f65fd xen-netfront: remove redundant assignment to vari..
> > git tree: net-next
> > console output: https://syzkaller.appspot.com/x/log.txt?x=15de54a7100000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=829871134ca5e230
> > dashboard link: https://syzkaller.appspot.com/bug?extid=ed318e8b790ca72c5ad0
> > compiler: gcc (GCC) 10.1.0-syz 20200507
> > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=113406a7100000
> > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=175597d3100000
> >
> > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > Reported-by: syzbot+ed318e8b790ca72c5ad0@syzkaller.appspotmail.com
> >
> > general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
> > KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
> > CPU: 1 PID: 1155 Comm: khugepaged Not tainted 5.8.0-rc2-syzkaller #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> > RIP: 0010:anon_vma_lock_write include/linux/rmap.h:120 [inline]
> > RIP: 0010:collapse_huge_page mm/khugepaged.c:1110 [inline]
> > RIP: 0010:khugepaged_scan_pmd mm/khugepaged.c:1349 [inline]
> > RIP: 0010:khugepaged_scan_mm_slot mm/khugepaged.c:2110 [inline]
> > RIP: 0010:khugepaged_do_scan mm/khugepaged.c:2193 [inline]
> > RIP: 0010:khugepaged+0x3bba/0x5a10 mm/khugepaged.c:2238
> > Code: 01 00 00 48 8d bb 88 00 00 00 48 89 f8 48 c1 e8 03 42 80 3c 30 00 0f 85 fa 0f 00 00 48 8b 9b 88 00 00 00 48 89 d8 48 c1 e8 03 <42> 80 3c 30 00 0f 85 d4 0f 00 00 48 8b 3b 48 83 c7 08 e8 9f ff 30
> > RSP: 0018:ffffc90004be7c80 EFLAGS: 00010246
> > RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff81a72d8b
> > RDX: ffff8880a69d8100 RSI: ffffffff81b7606b RDI: ffff88809f0577c0
> > RBP: 0000000000000000 R08: 0000000000000000 R09: ffff8881ff213a7f
> > R10: 0000000000000080 R11: 0000000000000000 R12: ffffffff8aae6110
> > R13: ffffc90004be7de0 R14: dffffc0000000000 R15: 0000000020000000
> > FS: 0000000000000000(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
> > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 0000000000000000 CR3: 00000001fe0cf000 CR4: 00000000001406e0
> > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > Call Trace:
> > kthread+0x3b5/0x4a0 kernel/kthread.c:291
> > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293
>
> Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS")
It looks sane, but I think it's easier to check in
hugepage_vma_revalidate(). Something like this (untested):
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index b043c40a21d4..700f5160f3e4 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -958,6 +958,9 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
return SCAN_ADDRESS_RANGE;
if (!hugepage_vma_check(vma, vma->vm_flags))
return SCAN_VMA_CHECK;
+ /* Anon VMA expected */
+ if (!vma->anon_vma || vma->vm_ops)
+ return SCAN_VMA_CHECK;
return 0;
}
--
Kirill A. Shutemov
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: general protection fault in khugepaged
2020-07-20 9:08 ` Kirill A. Shutemov
@ 2020-07-22 23:53 ` Song Liu
2020-07-24 11:06 ` Kirill A. Shutemov
0 siblings, 1 reply; 6+ messages in thread
From: Song Liu @ 2020-07-22 23:53 UTC (permalink / raw)
To: Kirill A. Shutemov
Cc: Hillf Danton, syzbot, open list, Linux MM, Kirill A . Shutemov,
syzkaller-bugs, Markus Elfring
> On Jul 20, 2020, at 2:08 AM, Kirill A. Shutemov <kirill@shutemov.name> wrote:
>
> On Sat, Jul 18, 2020 at 04:54:09PM +0800, Hillf Danton wrote:
>>
>> Wed, 08 Jul 2020 23:43:19 -0700
>>> syzbot found the following crash on:
>>>
>>> HEAD commit: e44f65fd xen-netfront: remove redundant assignment to vari..
>>> git tree: net-next
>>> console output: https://urldefense.proofpoint.com/v2/url?u=https-3A__syzkaller.appspot.com_x_log.txt-3Fx-3D15de54a7100000&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=dR8692q0_uaizy0jkrBJQM5k2hfm4CiFxYT8KaysFrg&m=MQfhDjE9yj2_juw34scN2XTASkKaxHCfKtrY5UlwTx4&s=6MfBZJE4yUynBic_FV4udh1WdM1wXz8vdcsOfuR23y0&e=
>>> kernel config: https://urldefense.proofpoint.com/v2/url?u=https-3A__syzkaller.appspot.com_x_.config-3Fx-3D829871134ca5e230&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=dR8692q0_uaizy0jkrBJQM5k2hfm4CiFxYT8KaysFrg&m=MQfhDjE9yj2_juw34scN2XTASkKaxHCfKtrY5UlwTx4&s=KvhWD3PT9mC8iTIUtQGrMj2UJpBMlsmJOv_wx1kxkQQ&e=
>>> dashboard link: https://urldefense.proofpoint.com/v2/url?u=https-3A__syzkaller.appspot.com_bug-3Fextid-3Ded318e8b790ca72c5ad0&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=dR8692q0_uaizy0jkrBJQM5k2hfm4CiFxYT8KaysFrg&m=MQfhDjE9yj2_juw34scN2XTASkKaxHCfKtrY5UlwTx4&s=sLoGzpV5UcRyP33XaPaGp_NoxP6VSXh4jttnxne6n6I&e=
>>> compiler: gcc (GCC) 10.1.0-syz 20200507
>>> syz repro: https://urldefense.proofpoint.com/v2/url?u=https-3A__syzkaller.appspot.com_x_repro.syz-3Fx-3D113406a7100000&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=dR8692q0_uaizy0jkrBJQM5k2hfm4CiFxYT8KaysFrg&m=MQfhDjE9yj2_juw34scN2XTASkKaxHCfKtrY5UlwTx4&s=HXYlOJ8r_Xv84UDkW6MSoEiG122ATfKJdhQlv3J7mao&e=
>>> C reproducer: https://urldefense.proofpoint.com/v2/url?u=https-3A__syzkaller.appspot.com_x_repro.c-3Fx-3D175597d3100000&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=dR8692q0_uaizy0jkrBJQM5k2hfm4CiFxYT8KaysFrg&m=MQfhDjE9yj2_juw34scN2XTASkKaxHCfKtrY5UlwTx4&s=c5Vlm43NNztzFCNb0S6s8IKJuVUtEtm0yWwfV55CeAo&e=
>>>
>>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>>> Reported-by: syzbot+ed318e8b790ca72c5ad0@syzkaller.appspotmail.com
>>>
>>> general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
>>> KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
>>> CPU: 1 PID: 1155 Comm: khugepaged Not tainted 5.8.0-rc2-syzkaller #0
>>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
>>> RIP: 0010:anon_vma_lock_write include/linux/rmap.h:120 [inline]
>>> RIP: 0010:collapse_huge_page mm/khugepaged.c:1110 [inline]
>>> RIP: 0010:khugepaged_scan_pmd mm/khugepaged.c:1349 [inline]
>>> RIP: 0010:khugepaged_scan_mm_slot mm/khugepaged.c:2110 [inline]
>>> RIP: 0010:khugepaged_do_scan mm/khugepaged.c:2193 [inline]
>>> RIP: 0010:khugepaged+0x3bba/0x5a10 mm/khugepaged.c:2238
>>> Code: 01 00 00 48 8d bb 88 00 00 00 48 89 f8 48 c1 e8 03 42 80 3c 30 00 0f 85 fa 0f 00 00 48 8b 9b 88 00 00 00 48 89 d8 48 c1 e8 03 <42> 80 3c 30 00 0f 85 d4 0f 00 00 48 8b 3b 48 83 c7 08 e8 9f ff 30
>>> RSP: 0018:ffffc90004be7c80 EFLAGS: 00010246
>>> RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff81a72d8b
>>> RDX: ffff8880a69d8100 RSI: ffffffff81b7606b RDI: ffff88809f0577c0
>>> RBP: 0000000000000000 R08: 0000000000000000 R09: ffff8881ff213a7f
>>> R10: 0000000000000080 R11: 0000000000000000 R12: ffffffff8aae6110
>>> R13: ffffc90004be7de0 R14: dffffc0000000000 R15: 0000000020000000
>>> FS: 0000000000000000(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
>>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>> CR2: 0000000000000000 CR3: 00000001fe0cf000 CR4: 00000000001406e0
>>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>>> Call Trace:
>>> kthread+0x3b5/0x4a0 kernel/kthread.c:291
>>> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293
>>
>> Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS")
>
> It looks sane, but I think it's easier to check in
> hugepage_vma_revalidate(). Something like this (untested):
>
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index b043c40a21d4..700f5160f3e4 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -958,6 +958,9 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
> return SCAN_ADDRESS_RANGE;
> if (!hugepage_vma_check(vma, vma->vm_flags))
> return SCAN_VMA_CHECK;
> + /* Anon VMA expected */
> + if (!vma->anon_vma || vma->vm_ops)
> + return SCAN_VMA_CHECK;
> return 0;
> }
Maybe move the new check to earlier in the function, say right after
we get the vma?
Thanks,
Song
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: general protection fault in khugepaged
2020-07-22 23:53 ` Song Liu
@ 2020-07-24 11:06 ` Kirill A. Shutemov
0 siblings, 0 replies; 6+ messages in thread
From: Kirill A. Shutemov @ 2020-07-24 11:06 UTC (permalink / raw)
To: Song Liu
Cc: Hillf Danton, syzbot, open list, Linux MM, Kirill A . Shutemov,
syzkaller-bugs, Markus Elfring
On Wed, Jul 22, 2020 at 11:53:11PM +0000, Song Liu wrote:
>
>
> > On Jul 20, 2020, at 2:08 AM, Kirill A. Shutemov <kirill@shutemov.name> wrote:
> >
> > On Sat, Jul 18, 2020 at 04:54:09PM +0800, Hillf Danton wrote:
> >>
> >> Wed, 08 Jul 2020 23:43:19 -0700
> >>> syzbot found the following crash on:
> >>>
> >>> HEAD commit: e44f65fd xen-netfront: remove redundant assignment to vari..
> >>> git tree: net-next
> >>> console output: https://urldefense.proofpoint.com/v2/url?u=https-3A__syzkaller.appspot.com_x_log.txt-3Fx-3D15de54a7100000&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=dR8692q0_uaizy0jkrBJQM5k2hfm4CiFxYT8KaysFrg&m=MQfhDjE9yj2_juw34scN2XTASkKaxHCfKtrY5UlwTx4&s=6MfBZJE4yUynBic_FV4udh1WdM1wXz8vdcsOfuR23y0&e=
> >>> kernel config: https://urldefense.proofpoint.com/v2/url?u=https-3A__syzkaller.appspot.com_x_.config-3Fx-3D829871134ca5e230&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=dR8692q0_uaizy0jkrBJQM5k2hfm4CiFxYT8KaysFrg&m=MQfhDjE9yj2_juw34scN2XTASkKaxHCfKtrY5UlwTx4&s=KvhWD3PT9mC8iTIUtQGrMj2UJpBMlsmJOv_wx1kxkQQ&e=
> >>> dashboard link: https://urldefense.proofpoint.com/v2/url?u=https-3A__syzkaller.appspot.com_bug-3Fextid-3Ded318e8b790ca72c5ad0&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=dR8692q0_uaizy0jkrBJQM5k2hfm4CiFxYT8KaysFrg&m=MQfhDjE9yj2_juw34scN2XTASkKaxHCfKtrY5UlwTx4&s=sLoGzpV5UcRyP33XaPaGp_NoxP6VSXh4jttnxne6n6I&e=
> >>> compiler: gcc (GCC) 10.1.0-syz 20200507
> >>> syz repro: https://urldefense.proofpoint.com/v2/url?u=https-3A__syzkaller.appspot.com_x_repro.syz-3Fx-3D113406a7100000&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=dR8692q0_uaizy0jkrBJQM5k2hfm4CiFxYT8KaysFrg&m=MQfhDjE9yj2_juw34scN2XTASkKaxHCfKtrY5UlwTx4&s=HXYlOJ8r_Xv84UDkW6MSoEiG122ATfKJdhQlv3J7mao&e=
> >>> C reproducer: https://urldefense.proofpoint.com/v2/url?u=https-3A__syzkaller.appspot.com_x_repro.c-3Fx-3D175597d3100000&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=dR8692q0_uaizy0jkrBJQM5k2hfm4CiFxYT8KaysFrg&m=MQfhDjE9yj2_juw34scN2XTASkKaxHCfKtrY5UlwTx4&s=c5Vlm43NNztzFCNb0S6s8IKJuVUtEtm0yWwfV55CeAo&e=
> >>>
> >>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> >>> Reported-by: syzbot+ed318e8b790ca72c5ad0@syzkaller.appspotmail.com
> >>>
> >>> general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
> >>> KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
> >>> CPU: 1 PID: 1155 Comm: khugepaged Not tainted 5.8.0-rc2-syzkaller #0
> >>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> >>> RIP: 0010:anon_vma_lock_write include/linux/rmap.h:120 [inline]
> >>> RIP: 0010:collapse_huge_page mm/khugepaged.c:1110 [inline]
> >>> RIP: 0010:khugepaged_scan_pmd mm/khugepaged.c:1349 [inline]
> >>> RIP: 0010:khugepaged_scan_mm_slot mm/khugepaged.c:2110 [inline]
> >>> RIP: 0010:khugepaged_do_scan mm/khugepaged.c:2193 [inline]
> >>> RIP: 0010:khugepaged+0x3bba/0x5a10 mm/khugepaged.c:2238
> >>> Code: 01 00 00 48 8d bb 88 00 00 00 48 89 f8 48 c1 e8 03 42 80 3c 30 00 0f 85 fa 0f 00 00 48 8b 9b 88 00 00 00 48 89 d8 48 c1 e8 03 <42> 80 3c 30 00 0f 85 d4 0f 00 00 48 8b 3b 48 83 c7 08 e8 9f ff 30
> >>> RSP: 0018:ffffc90004be7c80 EFLAGS: 00010246
> >>> RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff81a72d8b
> >>> RDX: ffff8880a69d8100 RSI: ffffffff81b7606b RDI: ffff88809f0577c0
> >>> RBP: 0000000000000000 R08: 0000000000000000 R09: ffff8881ff213a7f
> >>> R10: 0000000000000080 R11: 0000000000000000 R12: ffffffff8aae6110
> >>> R13: ffffc90004be7de0 R14: dffffc0000000000 R15: 0000000020000000
> >>> FS: 0000000000000000(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
> >>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> >>> CR2: 0000000000000000 CR3: 00000001fe0cf000 CR4: 00000000001406e0
> >>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> >>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> >>> Call Trace:
> >>> kthread+0x3b5/0x4a0 kernel/kthread.c:291
> >>> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293
> >>
> >> Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS")
> >
> > It looks sane, but I think it's easier to check in
> > hugepage_vma_revalidate(). Something like this (untested):
> >
> > diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> > index b043c40a21d4..700f5160f3e4 100644
> > --- a/mm/khugepaged.c
> > +++ b/mm/khugepaged.c
> > @@ -958,6 +958,9 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
> > return SCAN_ADDRESS_RANGE;
> > if (!hugepage_vma_check(vma, vma->vm_flags))
> > return SCAN_VMA_CHECK;
> > + /* Anon VMA expected */
> > + if (!vma->anon_vma || vma->vm_ops)
> > + return SCAN_VMA_CHECK;
> > return 0;
> > }
>
> Maybe move the new check to earlier in the function, say right after
> we get the vma?
Maybe. But we only protect against the race and it's not going to make a
difference for performance.
--
Kirill A. Shutemov
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2020-07-24 11:06 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-07-09 6:43 general protection fault in khugepaged syzbot
2020-07-17 22:40 ` syzbot
2020-07-17 23:10 ` Kirill A. Shutemov
[not found] ` <20200718085409.1448-1-hdanton@sina.com>
2020-07-20 9:08 ` Kirill A. Shutemov
2020-07-22 23:53 ` Song Liu
2020-07-24 11:06 ` Kirill A. Shutemov
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