[moderation] [bcachefs?] general protection fault in poll_state_synchronize_srcu

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 0450d2083be6 Merge tag '6.10-rc-smb-fix' of git://git.samb..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14f71844980000
kernel config: https://syzkaller.appspot.com/x/.config?x=11eee78d9c5171fd
dashboard link: https://syzkaller.appspot.com/bug?extid=6416c5500c60d1df0f93
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: i386
CC: [bfo...@redhat.com kent.ov...@linux.dev linux-b...@vger.kernel.org linux-...@vger.kernel.org]

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-0450d208.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/93488b2dd484/vmlinux-0450d208.xz
kernel image: https://storage.googleapis.com/syzbot-assets/86e4c49ad04d/bzImage-0450d208.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6416c5...@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000030: 0000 [#1] PREEMPT SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000180-0x0000000000000187]
CPU: 1 PID: 13172 Comm: syz-executor.0 Not tainted 6.9.0-syzkaller-08995-g0450d2083be6 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:rcu_seq_done kernel/rcu/rcu.h:156 [inline]
RIP: 0010:poll_state_synchronize_srcu+0x43/0x90 kernel/rcu/srcutree.c:1543
Code: 48 83 ec 08 48 c1 ea 03 80 3c 02 00 75 45 48 b8 00 00 00 00 00 fc ff df 48 8b 5b 38 48 8d bb 80 01 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 75 32 48 8b 93 80 01 00 00 31 c0 48 39 f2 78 0b f0 83
RSP: 0018:ffffc900036cf4e0 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc90027ec9000
RDX: 0000000000000030 RSI: 0000000000000004 RDI: 0000000000000180
RBP: dffffc0000000000 R08: 0000000000000000 R09: fffffbfff283de73
R10: ffffffff941ef39f R11: 00000000000001db R12: ffff8880551e4790
R13: ffff8880551e4810 R14: ffff888059780000 R15: ffff888059780000
FS: 0000000000000000(0000) GS:ffff88802c100000(0063) knlGS:00000000f5e98b40
CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000f740d0c4 CR3: 0000000028fde000 CR4: 0000000000350ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
bch2_btree_key_cache_scan+0x376/0x1740 fs/bcachefs/btree_key_cache.c:846
do_shrink_slab+0x44f/0x11c0 mm/shrinker.c:435
shrink_slab+0x18a/0x1310 mm/shrinker.c:662
drop_slab_node mm/vmscan.c:393 [inline]
drop_slab+0x14c/0x2c0 mm/vmscan.c:411
drop_caches_sysctl_handler+0x171/0x190 fs/drop_caches.c:68
proc_sys_call_handler+0x4cc/0x6f0 fs/proc/proc_sysctl.c:592
call_write_iter include/linux/fs.h:2120 [inline]
iter_file_splice_write+0x906/0x10b0 fs/splice.c:743
do_splice_from fs/splice.c:941 [inline]
direct_splice_actor+0x19b/0x6d0 fs/splice.c:1164
splice_direct_to_actor+0x346/0xa40 fs/splice.c:1108
do_splice_direct_actor fs/splice.c:1207 [inline]
do_splice_direct+0x17e/0x250 fs/splice.c:1233
do_sendfile+0xaa8/0xdb0 fs/read_write.c:1295
__do_compat_sys_sendfile fs/read_write.c:1377 [inline]
__se_compat_sys_sendfile fs/read_write.c:1366 [inline]
__ia32_compat_sys_sendfile+0x163/0x230 fs/read_write.c:1366
do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
__do_fast_syscall_32+0x75/0x120 arch/x86/entry/common.c:386
do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf72c7579
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000f5e985ac EFLAGS: 00000292 ORIG_RAX: 00000000000000bb
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000000003
RDX: 0000000020002080 RSI: 000000000000023b RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:rcu_seq_done kernel/rcu/rcu.h:156 [inline]
RIP: 0010:poll_state_synchronize_srcu+0x43/0x90 kernel/rcu/srcutree.c:1543
Code: 48 83 ec 08 48 c1 ea 03 80 3c 02 00 75 45 48 b8 00 00 00 00 00 fc ff df 48 8b 5b 38 48 8d bb 80 01 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 75 32 48 8b 93 80 01 00 00 31 c0 48 39 f2 78 0b f0 83
RSP: 0018:ffffc900036cf4e0 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc90027ec9000
RDX: 0000000000000030 RSI: 0000000000000004 RDI: 0000000000000180
RBP: dffffc0000000000 R08: 0000000000000000 R09: fffffbfff283de73
R10: ffffffff941ef39f R11: 00000000000001db R12: ffff8880551e4790
R13: ffff8880551e4810 R14: ffff888059780000 R15: ffff888059780000
FS: 0000000000000000(0000) GS:ffff88802c000000(0063) knlGS:00000000f5e98b40
CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 000000002062e000 CR3: 0000000028fde000 CR4: 0000000000350ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 48 83 ec 08 sub $0x8,%rsp
4: 48 c1 ea 03 shr $0x3,%rdx
8: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1)
c: 75 45 jne 0x53
e: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
15: fc ff df
18: 48 8b 5b 38 mov 0x38(%rbx),%rbx
1c: 48 8d bb 80 01 00 00 lea 0x180(%rbx),%rdi
23: 48 89 fa mov %rdi,%rdx
26: 48 c1 ea 03 shr $0x3,%rdx
* 2a: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction
2e: 75 32 jne 0x62
30: 48 8b 93 80 01 00 00 mov 0x180(%rbx),%rdx
37: 31 c0 xor %eax,%eax
39: 48 39 f2 cmp %rsi,%rdx
3c: 78 0b js 0x49
3e: f0 lock
3f: 83 .byte 0x83


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