Message-ID: <Zva9oi6jfBSoGwn0@google.com>
Date: Fri, 27 Sep 2024 07:13:54 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: syzbot <syzbot+314c2cfd4071ad738810@...kaller.appspotmail.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, pbonzini@...hat.com, 
	syzkaller-bugs@...glegroups.com, Kent Overstreet <kent.overstreet@...ux.dev>
Subject: Re: [syzbot] [kvm?] WARNING in srcu_check_nmi_safety (2)

+Kent

On Wed, Sep 25, 2024, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    abf2050f51fd Merge tag 'media/v6.12-1' of git://git.kernel..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=114cc99f980000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=bc30a30374b0753
> dashboard link: https://syzkaller.appspot.com/bug?extid=314c2cfd4071ad738810
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> 
> Unfortunately, I don't have any reproducer for this issue yet.
> 
> Downloadable assets:
> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-abf2050f.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/2179ebeade58/vmlinux-abf2050f.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/f05289b5cf7c/bzImage-abf2050f.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+314c2cfd4071ad738810@...kaller.appspotmail.com
> 
> ------------[ cut here ]------------
> CPU 0 old state 2 new state 1
> WARNING: CPU: 0 PID: 73 at kernel/rcu/srcutree.c:708 srcu_check_nmi_safety+0xca/0x150 kernel/rcu/srcutree.c:708
> Modules linked in:
> CPU: 0 UID: 0 PID: 73 Comm: kswapd0 Not tainted 6.11.0-syzkaller-09959-gabf2050f51fd #0
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
> RIP: 0010:srcu_check_nmi_safety+0xca/0x150 kernel/rcu/srcutree.c:708
> Code: 81 c3 c8 01 00 00 48 89 d8 48 c1 e8 03 42 0f b6 04 20 84 c0 75 77 8b 33 48 c7 c7 20 0c 0c 8c 89 ea 44 89 f9 e8 b7 8c db ff 90 <0f> 0b 90 90 eb 0c 42 0f b6 04 23 84 c0 75 3d 45 89 3e 48 83 c4 08
> RSP: 0018:ffffc90000e464e0 EFLAGS: 00010246
> RAX: 41404736cdfea900 RBX: ffffe8ffffc414c8 RCX: ffff88801efb0000
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: 0000000000000002 R08: ffffffff8155aaa2 R09: 1ffff11003f8519a
> R10: dffffc0000000000 R11: ffffed1003f8519b R12: dffffc0000000000
> R13: 0000607fe0041300 R14: ffffe8ffffc41320 R15: 0000000000000001
> FS:  0000000000000000(0000) GS:ffff88801fc00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000564aa6d10940 CR3: 0000000011c68000 CR4: 0000000000352ef0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  <TASK>
>  srcu_read_lock include/linux/srcu.h:248 [inline]
>  __kvm_handle_hva_range virt/kvm/kvm_main.c:612 [inline]
>  kvm_handle_hva_range virt/kvm/kvm_main.c:684 [inline]
>  kvm_mmu_notifier_clear_flush_young+0xe6/0x820 virt/kvm/kvm_main.c:867
>  __mmu_notifier_clear_flush_young+0x11d/0x1d0 mm/mmu_notifier.c:379
>  mmu_notifier_clear_flush_young include/linux/mmu_notifier.h:410 [inline]
>  folio_referenced_one+0xb9d/0x2160 mm/rmap.c:895
>  rmap_walk_anon+0x4cd/0x8a0 mm/rmap.c:2638
>  rmap_walk mm/rmap.c:2716 [inline]
>  folio_referenced+0x394/0x7a0 mm/rmap.c:1008
>  folio_check_references mm/vmscan.c:863 [inline]
>  shrink_folio_list+0xe96/0x8cc0 mm/vmscan.c:1198
>  evict_folios+0x549b/0x7b50 mm/vmscan.c:4583
>  try_to_shrink_lruvec+0x9ab/0xbb0 mm/vmscan.c:4778
>  shrink_one+0x3b9/0x850 mm/vmscan.c:4816
>  shrink_many mm/vmscan.c:4879 [inline]
>  lru_gen_shrink_node mm/vmscan.c:4957 [inline]
>  shrink_node+0x3799/0x3de0 mm/vmscan.c:5937
>  kswapd_shrink_node mm/vmscan.c:6765 [inline]
>  balance_pgdat mm/vmscan.c:6957 [inline]
>  kswapd+0x1ca3/0x3700 mm/vmscan.c:7226
>  kthread+0x2f0/0x390 kernel/kthread.c:389
>  ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
>  </TASK>

#syz set subsystems: bcachefs

Looks like another bcachefs shutdown problem.  The failure happened on a kernel
with d293ece10810 ("bcachefs: Fix shutdown ordering"), so it's not the exact same
thing as reported in https://lore.kernel.org/all/Zr-bCqSWRS3yob7V@google.com.

[   82.068524][ T5112] bcachefs (loop0): going read-write
[   82.076688][ T4530] Bluetooth: hci0: command tx timeout
[   82.092465][ T5112] bcachefs (loop0): journal_replay... done
[   82.150223][ T5112] bcachefs (loop0): resume_logged_ops... done
[   82.152607][ T5112] bcachefs (loop0): delete_dead_inodes... done
[   82.164815][ T5112] bcachefs (loop0): Fixed errors, running fsck a second time to verify fs is clean
[   82.176357][ T5112] bcachefs (loop0): resume_logged_ops... done
[   82.178950][ T5112] bcachefs (loop0): delete_dead_inodes... done
[   82.188910][ T5112] bcachefs (loop0): done starting filesystem
[   82.302896][ T5112] bcachefs (loop0): shutting down
[   82.305956][ T5112] bcachefs (loop0): going read-only
[   82.317925][ T5112] bcachefs (loop0): finished waiting for writes to stop
[   82.328724][ T5112] bcachefs (loop0): flushing journal and stopping allocators, journal seq 17
[   82.354271][ T5113] netlink: 16 bytes leftover after parsing attributes in process `syz.0.0'.
[   82.366356][ T5112] bcachefs (loop0): flushing journal and stopping allocators complete, journal seq 18
[   82.386917][ T5112] bcachefs (loop0): shutdown complete, journal seq 19
[   82.390927][ T5112] bcachefs (loop0): marking filesystem clean
[   82.472328][ T5112] bcachefs (loop0): shutdown complete
[   82.504701][   T73] ------------[ cut here ]------------
[   82.507314][   T73] CPU 0 old state 2 new state 1
[   82.509635][   T73] WARNING: CPU: 0 PID: 73 at kernel/rcu/srcutree.c:708 srcu_check_nmi_safety+0xca/0x150
[   82.513331][   T73] Modules linked in:

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