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Message-ID: <476ef488-5f3c-420d-97ea-bb281f2891f2@arm.com>
Date: Thu, 4 Apr 2024 12:23:43 +0100
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Subject: Re: [syzbot] [mm?] WARNING: bad unlock balance in
 madvise_cold_or_pageout_pte_range
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To: syzbot <syzbot+c641706ad4e9688cccdf@syzkaller.appspotmail.com>,
 akpm@linux-foundation.org, david@redhat.com, linux-kernel@vger.kernel.org,
 linux-mm@kvack.org, syzkaller-bugs@googlegroups.com
References: <000000000000b92a9d0615433065@google.com>
From: Ryan Roberts <ryan.roberts@arm.com>
In-Reply-To: <000000000000b92a9d0615433065@google.com>
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#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm mm-unstable

mm-unstable now has the fix; let's check it actually fixes the problem.


On 04/04/2024 11:56, syzbot wrote:
> syzbot has found a reproducer for the following issue on:
> 
> HEAD commit:    727900b675b7 Add linux-next specific files for 20240403
> git tree:       linux-next
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=11f66223180000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=afcaf46d374cec8c
> dashboard link: https://syzkaller.appspot.com/bug?extid=c641706ad4e9688cccdf
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12a62423180000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13764a3d180000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/f8fb4daa7a83/disk-727900b6.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/d2a6994aee53/vmlinux-727900b6.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/6759e5411c39/bzImage-727900b6.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+c641706ad4e9688cccdf@syzkaller.appspotmail.com
> 
> =====================================
> WARNING: bad unlock balance detected!
> 6.9.0-rc2-next-20240403-syzkaller #0 Not tainted
> -------------------------------------
> syz-executor799/5099 is trying to release lock (ptlock_ptr(ptdesc)) at:
> [<ffffffff81f01f3f>] spin_unlock include/linux/spinlock.h:391 [inline]
> [<ffffffff81f01f3f>] madvise_cold_or_pageout_pte_range+0x170f/0x3990 mm/madvise.c:480
> but there are no more locks to release!
> 
> other info that might help us debug this:
> 1 lock held by syz-executor799/5099:
>  #0: ffff888015073a98 (&mm->mmap_lock){++++}-{3:3}
> , at: mmap_read_lock include/linux/mmap_lock.h:144 [inline]
> , at: do_madvise+0x481/0x44a0 mm/madvise.c:1429
> 
> stack backtrace:
> CPU: 1 PID: 5099 Comm: syz-executor799 Not tainted 6.9.0-rc2-next-20240403-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
> Call Trace:
>  <TASK>
>  __dump_stack lib/dump_stack.c:88 [inline]
>  dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
>  print_unlock_imbalance_bug+0x256/0x2c0 kernel/locking/lockdep.c:5194
>  __lock_release kernel/locking/lockdep.c:5431 [inline]
>  lock_release+0x599/0x9f0 kernel/locking/lockdep.c:5774
>  __raw_spin_unlock include/linux/spinlock_api_smp.h:141 [inline]
>  _raw_spin_unlock+0x16/0x50 kernel/locking/spinlock.c:186
>  spin_unlock include/linux/spinlock.h:391 [inline]
>  madvise_cold_or_pageout_pte_range+0x170f/0x3990 mm/madvise.c:480
>  walk_pmd_range mm/pagewalk.c:143 [inline]
>  walk_pud_range mm/pagewalk.c:221 [inline]
>  walk_p4d_range mm/pagewalk.c:256 [inline]
>  walk_pgd_range+0xba1/0x1810 mm/pagewalk.c:293
>  __walk_page_range+0x132/0x720 mm/pagewalk.c:395
>  walk_page_range+0x58f/0x7c0 mm/pagewalk.c:521
>  madvise_cold_page_range mm/madvise.c:562 [inline]
>  madvise_cold mm/madvise.c:584 [inline]
>  madvise_vma_behavior mm/madvise.c:1028 [inline]
>  madvise_walk_vmas mm/madvise.c:1256 [inline]
>  do_madvise+0x1e7b/0x44a0 mm/madvise.c:1442
>  __do_sys_madvise mm/madvise.c:1457 [inline]
>  __se_sys_madvise mm/madvise.c:1455 [inline]
>  __x64_sys_madvise+0xa6/0xc0 mm/madvise.c:1455
>  do_syscall_64+0xfb/0x240
>  entry_SYSCALL_64_after_hwframe+0x72/0x7a
> RIP: 0033:0x7f3928ac2419
> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 18 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:00007f3928a5c218 EFLAGS: 00000246 ORIG_RAX: 000000000000001c
> RAX: ffffffffffffffda RBX: 00007f3928b4c318 RCX: 00007f3928ac2419
> RDX: 0000000000000014 RSI: 00000000dfc3efff RDI: 00000000203c1000
> RBP: 00007f3928b4c310 R08: 00007ffd7796b097 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 00007f3928b19064
> R13: 000000080000000e R14: 000000200000007f R15: 00000000dfc3efff
>  </TASK>
> ------------[ cut here ]------------
> pvqspinlock: lock 0xffff88802ec45b40 has corrupted value 0x0!
> WARNING: CPU: 1 PID: 5099 at kernel/locking/qspinlock_paravirt.h:510 __pv_queued_spin_unlock_slowpath+0x241/0x2f0 kernel/locking/qspinlock_paravirt.h:508
> Modules linked in:
> 
> CPU: 1 PID: 5099 Comm: syz-executor799 Not tainted 6.9.0-rc2-next-20240403-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
> RIP: 0010:__pv_queued_spin_unlock_slowpath+0x241/0x2f0 kernel/locking/qspinlock_paravirt.h:508
> Code: 85 0a 6e f6 4c 89 f0 48 c1 e8 03 0f b6 04 18 84 c0 0f 85 9f 00 00 00 41 8b 16 48 c7 c7 c0 26 cb 8b 4c 89 f6 e8 40 b3 cb f5 90 <0f> 0b 90 90 eb 8d 44 89 f1 80 e1 07 38 c1 0f 8c 26 ff ff ff 4c 89
> RSP: 0018:ffffc9000364f238 EFLAGS: 00010246
> 
> RAX: 9a7270b7f8439200 RBX: dffffc0000000000 RCX: ffff888023139e00
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: dffffc0000000000 R08: ffffffff81580152 R09: 1ffffffff1f526cd
> R10: dffffc0000000000 R11: fffffbfff1f526ce R12: 1ffff11005d88b6a
> R13: ffff88802ec45b50 R14: ffff88802ec45b40 R15: ffff88802ec45b40
> FS:  00007f3928a5c6c0(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000561c1eec8018 CR3: 00000000213dc000 CR4: 00000000003506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  <TASK>
>  __raw_callee_save___pv_queued_spin_unlock_slowpath+0x15/0x30
>  .slowpath+0x9/0x16
>  pv_queued_spin_unlock arch/x86/include/asm/paravirt.h:589 [inline]
>  queued_spin_unlock arch/x86/include/asm/qspinlock.h:57 [inline]
>  do_raw_spin_unlock+0x13c/0x8b0 kernel/locking/spinlock_debug.c:142
>  __raw_spin_unlock include/linux/spinlock_api_smp.h:142 [inline]
>  _raw_spin_unlock+0x1e/0x50 kernel/locking/spinlock.c:186
>  spin_unlock include/linux/spinlock.h:391 [inline]
>  madvise_cold_or_pageout_pte_range+0x170f/0x3990 mm/madvise.c:480
>  walk_pmd_range mm/pagewalk.c:143 [inline]
>  walk_pud_range mm/pagewalk.c:221 [inline]
>  walk_p4d_range mm/pagewalk.c:256 [inline]
>  walk_pgd_range+0xba1/0x1810 mm/pagewalk.c:293
>  __walk_page_range+0x132/0x720 mm/pagewalk.c:395
>  walk_page_range+0x58f/0x7c0 mm/pagewalk.c:521
>  madvise_cold_page_range mm/madvise.c:562 [inline]
>  madvise_cold mm/madvise.c:584 [inline]
>  madvise_vma_behavior mm/madvise.c:1028 [inline]
>  madvise_walk_vmas mm/madvise.c:1256 [inline]
>  do_madvise+0x1e7b/0x44a0 mm/madvise.c:1442
> 
> 
> ---
> 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.