[syzbot] [mm?] [io-uring?] WARNING in hpage_collapse_scan_pmd (2)

[syzbot] [mm?] [io-uring?] WARNING in hpage_collapse_scan_pmd (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    e67572cd2204 Linux 6.9-rc6
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1067d2f8980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3310e643b6ef5d69
dashboard link: https://syzkaller.appspot.com/bug?extid=5ea2845f44caa77f5543
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10874a40980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d3c4905a7f32/disk-e67572cd.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9e4d1fc8f9c1/vmlinux-e67572cd.xz
kernel image: https://storage.googleapis.com/syzbot-assets/4616b77edaee/bzImage-e67572cd.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5ea2845f44caa77f5543@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 1 PID: 5288 at arch/x86/include/asm/pgtable.h:403 pte_uffd_wp arch/x86/include/asm/pgtable.h:403 [inline]
WARNING: CPU: 1 PID: 5288 at arch/x86/include/asm/pgtable.h:403 hpage_collapse_scan_pmd+0xd32/0x14c0 mm/khugepaged.c:1316
Modules linked in:
CPU: 1 PID: 5288 Comm: syz-executor.4 Not tainted 6.9.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
RIP: 0010:pte_uffd_wp arch/x86/include/asm/pgtable.h:403 [inline]
RIP: 0010:hpage_collapse_scan_pmd+0xd32/0x14c0 mm/khugepaged.c:1316
Code: 90 90 e9 4b f6 ff ff 4c 8b 64 24 48 e8 f7 ee 9e ff 31 ff 4c 89 ee e8 fd e9 9e ff 4d 85 ed 0f 84 b5 01 00 00 e8 df ee 9e ff 90 <0f> 0b 90 41 be 09 00 00 00 0f b6 6c 24 47 48 8b 5c 24 10 e9 fb fa
RSP: 0018:ffffc90003abf9b0 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff88807a402000 RCX: ffffffff81eed643
RDX: ffff888021ddbc00 RSI: ffffffff81eed651 RDI: 0000000000000007
RBP: 000000006897fc67 R08: 0000000000000007 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000002 R12: 0000000020800000
R13: 0000000000000002 R14: 0000000000000400 R15: ffff88801e4dcc00
FS:  00007fd661dde6c0(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7e57ed9ba1 CR3: 0000000025328000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 madvise_collapse+0x738/0xb10 mm/khugepaged.c:2761
 madvise_vma_behavior+0x202/0x1b20 mm/madvise.c:1074
 madvise_walk_vmas+0x1cf/0x2c0 mm/madvise.c:1248
 do_madvise+0x309/0x640 mm/madvise.c:1428
 __do_sys_madvise mm/madvise.c:1441 [inline]
 __se_sys_madvise mm/madvise.c:1439 [inline]
 __x64_sys_madvise+0xa9/0x110 mm/madvise.c:1439
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcf/0x260 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd66227dea9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fd661dde0c8 EFLAGS: 00000246 ORIG_RAX: 000000000000001c
RAX: ffffffffffffffda RBX: 00007fd6623ac050 RCX: 00007fd66227dea9
RDX: 0000000000000019 RSI: 00000000dfc3efff RDI: 00000000203c1000
RBP: 00007fd6622ca4a4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007fd6623ac050 R15: 00007ffd98c8dfa8
 </TASK>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
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If the report is already addressed, let syzbot know by replying with:
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Re: [syzbot] [mm?] [io-uring?] WARNING in hpage_collapse_scan_pmd (2)

[David Hildenbrand]

On 03.05.24 15:41, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    e67572cd2204 Linux 6.9-rc6
> git tree:       upstream
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=1067d2f8980000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=3310e643b6ef5d69
> dashboard link: https://syzkaller.appspot.com/bug?extid=5ea2845f44caa77f5543
> compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10874a40980000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/d3c4905a7f32/disk-e67572cd.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/9e4d1fc8f9c1/vmlinux-e67572cd.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/4616b77edaee/bzImage-e67572cd.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+5ea2845f44caa77f5543@syzkaller.appspotmail.com
> 
> ------------[ cut here ]------------
> WARNING: CPU: 1 PID: 5288 at arch/x86/include/asm/pgtable.h:403 pte_uffd_wp arch/x86/include/asm/pgtable.h:403 [inline]
> WARNING: CPU: 1 PID: 5288 at arch/x86/include/asm/pgtable.h:403 hpage_collapse_scan_pmd+0xd32/0x14c0 mm/khugepaged.c:1316

That's the

WARN_ON_ONCE(wp && pte_write(pte));

check during pte_uffd_wp() in hpage_collapse_scan_pmd().

Maybe fixed by

commit fffa0c5024e8c90dced69b7fcde1d738384a1069
Author: Peter Xu <peterx@redhat.com>
Date:   Mon Apr 22 09:33:11 2024 -0400

     mm/userfaultfd: reset ptes when close() for wr-protected ones


That resides in mm-hotfixes-unstable

(in which case we might want to tag it as stable)


> Modules linked in:
> CPU: 1 PID: 5288 Comm: syz-executor.4 Not tainted 6.9.0-rc6-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
> RIP: 0010:pte_uffd_wp arch/x86/include/asm/pgtable.h:403 [inline]
> RIP: 0010:hpage_collapse_scan_pmd+0xd32/0x14c0 mm/khugepaged.c:1316
> Code: 90 90 e9 4b f6 ff ff 4c 8b 64 24 48 e8 f7 ee 9e ff 31 ff 4c 89 ee e8 fd e9 9e ff 4d 85 ed 0f 84 b5 01 00 00 e8 df ee 9e ff 90 <0f> 0b 90 41 be 09 00 00 00 0f b6 6c 24 47 48 8b 5c 24 10 e9 fb fa
> RSP: 0018:ffffc90003abf9b0 EFLAGS: 00010293
> RAX: 0000000000000000 RBX: ffff88807a402000 RCX: ffffffff81eed643
> RDX: ffff888021ddbc00 RSI: ffffffff81eed651 RDI: 0000000000000007
> RBP: 000000006897fc67 R08: 0000000000000007 R09: 0000000000000000
> R10: 0000000000000002 R11: 0000000000000002 R12: 0000000020800000
> R13: 0000000000000002 R14: 0000000000000400 R15: ffff88801e4dcc00
> FS:  00007fd661dde6c0(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f7e57ed9ba1 CR3: 0000000025328000 CR4: 00000000003506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>   <TASK>
>   madvise_collapse+0x738/0xb10 mm/khugepaged.c:2761
>   madvise_vma_behavior+0x202/0x1b20 mm/madvise.c:1074
>   madvise_walk_vmas+0x1cf/0x2c0 mm/madvise.c:1248
>   do_madvise+0x309/0x640 mm/madvise.c:1428
>   __do_sys_madvise mm/madvise.c:1441 [inline]
>   __se_sys_madvise mm/madvise.c:1439 [inline]
>   __x64_sys_madvise+0xa9/0x110 mm/madvise.c:1439
>   do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>   do_syscall_64+0xcf/0x260 arch/x86/entry/common.c:83
>   entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7fd66227dea9
> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007fd661dde0c8 EFLAGS: 00000246 ORIG_RAX: 000000000000001c
> RAX: ffffffffffffffda RBX: 00007fd6623ac050 RCX: 00007fd66227dea9
> RDX: 0000000000000019 RSI: 00000000dfc3efff RDI: 00000000203c1000
> RBP: 00007fd6622ca4a4 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 000000000000006e R14: 00007fd6623ac050 R15: 00007ffd98c8dfa8
>   </TASK>
> 
> 
> ---
> This report 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 issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> 
> If the report is already addressed, let syzbot know by replying with:
> #syz fix: exact-commit-title
> 
> If you want syzbot to run the reproducer, reply with:
> #syz test: git://repo/address.git branch-or-commit-hash
> If you attach or paste a git patch, syzbot will apply it before testing.

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-hotfixes-unstable

-- 
Cheers,

David / dhildenb

Re: [syzbot] [mm?] [io-uring?] WARNING in hpage_collapse_scan_pmd (2)

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+5ea2845f44caa77f5543@syzkaller.appspotmail.com

Tested on:

commit:         5f8be0ef mailmap: add entry for John Garry
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-hotfixes-unstable
console output: https://syzkaller.appspot.com/x/log.txt?x=1511f1c0980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=85dbe39cf8e4f599
dashboard link: https://syzkaller.appspot.com/bug?extid=5ea2845f44caa77f5543
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

Note: no patches were applied.
Note: testing is done by a robot and is best-effort only.

Re: [syzbot] [mm?] WARNING in hpage_collapse_scan_pmd (2)

[syzbot]

syzbot has bisected this issue to:

commit ef5b6a542b1dbb718226a5f8208be09ef405983d
Author: Paolo Bonzini <pbonzini@redhat.com>
Date:   Wed Nov 8 09:40:35 2023 +0000

    selftests: kvm/s390x: use vm_create_barebones()

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=14071cd3980000
start commit:   e67572cd2204 Linux 6.9-rc6
git tree:       upstream
final oops:     https://syzkaller.appspot.com/x/report.txt?x=16071cd3980000
console output: https://syzkaller.appspot.com/x/log.txt?x=12071cd3980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3310e643b6ef5d69
dashboard link: https://syzkaller.appspot.com/bug?extid=5ea2845f44caa77f5543
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10874a40980000

Reported-by: syzbot+5ea2845f44caa77f5543@syzkaller.appspotmail.com
Fixes: ef5b6a542b1d ("selftests: kvm/s390x: use vm_create_barebones()")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

Re: [syzbot] [mm?] WARNING in hpage_collapse_scan_pmd (2)

[syzbot]

syzbot suspects this issue was fixed by commit:

commit c88033efe9a391e72ba6b5df4b01d6e628f4e734
Author: Peter Xu <peterx@redhat.com>
Date:   Mon Apr 22 13:33:11 2024 +0000

    mm/userfaultfd: reset ptes when close() for wr-protected ones

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=12f2396b980000
start commit:   e67572cd2204 Linux 6.9-rc6
git tree:       upstream
kernel config:  https://syzkaller.appspot.com/x/.config?x=3310e643b6ef5d69
dashboard link: https://syzkaller.appspot.com/bug?extid=5ea2845f44caa77f5543
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10874a40980000

If the result looks correct, please mark the issue as fixed by replying with:

#syz fix: mm/userfaultfd: reset ptes when close() for wr-protected ones

For information about bisection process see: https://goo.gl/tpsmEJ#bisection