syzbot


invalid opcode in srcu_delay_timer

Status: moderation: reported on 2025/03/29 04:53
Subsystems: bcachefs
[Documentation on labels]
Reported-by: syzbot+f06cd1a16727b05214a8@syzkaller.appspotmail.com
First crash: 8d18h, last: 8d18h

Sample crash report:
Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 1 UID: 0 PID: 6135 Comm: syz.0.31 Not tainted 6.14.0-syzkaller-00624-g2f2d52945852 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:srcu_delay_timer+0x2/0x90 kernel/rcu/srcutree.c:821
Code: 49 ff ff ff 48 89 df e8 dc 83 7f 00 e9 3c ff ff ff e8 52 65 5a 0a 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f <1e> fa 55 41 57 41 56 53 48 89 fb 4c 8d b7 b8 00 00 00 4c 89 f0 48
RSP: 0018:ffffc90000a28b98 EFLAGS: 00010246
RAX: ffffffff81aee0b1 RBX: 0000000000000001 RCX: ffff88802e949e00
RDX: 0000000000000100 RSI: ffffffff8c801800 RDI: ffffe8ffffc54010
RBP: ffffc90000a28c90 R08: ffffffff81aee09e R09: 1ffffffff207770e
R10: dffffc0000000000 R11: ffffffff81a738a2 R12: 1ffff92000145178
R13: ffffe8ffffc54010 R14: 0000000000000001 R15: 0000000080000100
FS:  00007f5f1dbdf6c0(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000014000 CR3: 0000000025fbe000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 call_timer_fn+0x187/0x650 kernel/time/timer.c:1789
 expire_timers kernel/time/timer.c:1840 [inline]
 __run_timers kernel/time/timer.c:2414 [inline]
 __run_timer_base+0x66a/0x8e0 kernel/time/timer.c:2426
 run_timer_base kernel/time/timer.c:2435 [inline]
 run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2445
 handle_softirqs+0x2d4/0x9b0 kernel/softirq.c:561
 __do_softirq kernel/softirq.c:595 [inline]
 invoke_softirq kernel/softirq.c:435 [inline]
 __irq_exit_rcu+0xf7/0x220 kernel/softirq.c:662
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:678
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline]
 sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1049
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:printbuf_reset_keep_tabstops fs/bcachefs/printbuf.h:260 [inline]
RIP: 0010:printbuf_reset fs/bcachefs/printbuf.h:269 [inline]
RIP: 0010:bch2_write_super+0x109f/0x3cd0 fs/bcachefs/super-io.c:1039
Code: 04 18 84 c0 0f 85 8b 01 00 00 c7 84 24 34 01 00 00 00 00 00 00 48 8b 44 24 50 48 c1 e8 03 0f b6 04 18 84 c0 0f 85 8d 01 00 00 <c7> 84 24 38 01 00 00 00 00 00 00 48 8b 44 24 28 48 c1 e8 03 0f b6
RSP: 0018:ffffc900034070e0 EFLAGS: 00000246
RAX: 0000000000000000 RBX: dffffc0000000000 RCX: ffffc9000340720c
RDX: ffffc90004ed2000 RSI: 000000000005d733 RDI: 000000000005d734
RBP: ffffc900034073e8 R08: 0000000e00000016 R09: 0000000000200409
R10: 0000000e00000016 R11: 0000000000200409 R12: ffff888145b3e248
R13: 1ffff92000680e41 R14: 1ffff92000680e42 R15: ffff888145b3e240
 bch2_fs_freespace_init+0x13f/0x320 fs/bcachefs/alloc_background.c:2339
 bch2_fs_initialize+0xbd7/0x1610 fs/bcachefs/recovery.c:1154
 bch2_fs_start+0x36d/0x610 fs/bcachefs/super.c:1042
 bch2_fs_get_tree+0xdb7/0x17a0 fs/bcachefs/fs.c:2203
 vfs_get_tree+0x90/0x2b0 fs/super.c:1759
 do_new_mount+0x2be/0xb40 fs/namespace.c:3878
 do_mount fs/namespace.c:4218 [inline]
 __do_sys_mount fs/namespace.c:4429 [inline]
 __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:4406
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5f1cd8e90a
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 1a 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5f1dbdee68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f5f1dbdeef0 RCX: 00007f5f1cd8e90a
RDX: 0000200000000040 RSI: 0000200000000180 RDI: 00007f5f1dbdeeb0
RBP: 0000200000000040 R08: 00007f5f1dbdeef0 R09: 0000000000000010
R10: 0000000000000010 R11: 0000000000000246 R12: 0000200000000180
R13: 00007f5f1dbdeeb0 R14: 0000000000005a38 R15: 0000200000000400
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:srcu_delay_timer+0x2/0x90 kernel/rcu/srcutree.c:821
Code: 49 ff ff ff 48 89 df e8 dc 83 7f 00 e9 3c ff ff ff e8 52 65 5a 0a 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f <1e> fa 55 41 57 41 56 53 48 89 fb 4c 8d b7 b8 00 00 00 4c 89 f0 48
RSP: 0018:ffffc90000a28b98 EFLAGS: 00010246
RAX: ffffffff81aee0b1 RBX: 0000000000000001 RCX: ffff88802e949e00
RDX: 0000000000000100 RSI: ffffffff8c801800 RDI: ffffe8ffffc54010
RBP: ffffc90000a28c90 R08: ffffffff81aee09e R09: 1ffffffff207770e
R10: dffffc0000000000 R11: ffffffff81a738a2 R12: 1ffff92000145178
R13: ffffe8ffffc54010 R14: 0000000000000001 R15: 0000000080000100
FS:  00007f5f1dbdf6c0(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000014000 CR3: 0000000025fbe000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	04 18                	add    $0x18,%al
   2:	84 c0                	test   %al,%al
   4:	0f 85 8b 01 00 00    	jne    0x195
   a:	c7 84 24 34 01 00 00 	movl   $0x0,0x134(%rsp)
  11:	00 00 00 00
  15:	48 8b 44 24 50       	mov    0x50(%rsp),%rax
  1a:	48 c1 e8 03          	shr    $0x3,%rax
  1e:	0f b6 04 18          	movzbl (%rax,%rbx,1),%eax
  22:	84 c0                	test   %al,%al
  24:	0f 85 8d 01 00 00    	jne    0x1b7
* 2a:	c7 84 24 38 01 00 00 	movl   $0x0,0x138(%rsp) <-- trapping instruction
  31:	00 00 00 00
  35:	48 8b 44 24 28       	mov    0x28(%rsp),%rax
  3a:	48 c1 e8 03          	shr    $0x3,%rax
  3e:	0f                   	.byte 0xf
  3f:	b6                   	.byte 0xb6

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/03/25 04:48 upstream 2f2d52945852 875573af .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs invalid opcode in srcu_delay_timer
* Struck through repros no longer work on HEAD.