general protection fault, probably for non-canonical address 0xdffffc00000000bb: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x00000000000005d8-0x00000000000005df] CPU: 0 PID: 4646 Comm: kworker/u4:7 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 Workqueue: writeback wb_workfn (flush-7:3) RIP: 0010:bio_associate_blkg_from_css+0x128/0x9c0 block/blk-cgroup.c:1882 Code: df 41 80 3c 04 00 74 08 48 89 df e8 12 0b ec fd 41 be d8 05 00 00 4c 03 33 4c 89 f0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 f7 e8 ea 0a ec fd 41 bf 90 00 00 00 4d 03 RSP: 0000:ffffc900035d7260 EFLAGS: 00010206 RAX: 00000000000000bb RBX: ffff888061a4a008 RCX: dffffc0000000000 RDX: 0000000000000000 RSI: ffffffff96486e20 RDI: ffff888061a4a000 RBP: 1ffff1100c349409 R08: dffffc0000000000 R09: 1ffffffff203b018 R10: dffffc0000000000 R11: fffffbfff203b019 R12: 1ffff1100c349401 R13: ffff888061a4a048 R14: 00000000000005d8 R15: ffff888021911dec FS: 0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f5442d14eac CR3: 00000000638b0000 CR4: 00000000003506f0 DR0: ffffffffffffffff DR1: 00000000000001f8 DR2: 0000000000000002 DR3: ffffffffefffff15 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: bio_associate_blkg+0x23a/0x340 block/blk-cgroup.c:1908 lbmStartIO+0x204/0x4c0 fs/jfs/jfs_logmgr.c:2130 lbmWrite+0x361/0x480 fs/jfs/jfs_logmgr.c:2079 lmGCwrite fs/jfs/jfs_logmgr.c:-1 [inline] jfs_flush_journal+0x537/0xec0 fs/jfs/jfs_logmgr.c:1556 jfs_write_inode+0x12b/0x220 fs/jfs/inode.c:134 write_inode fs/fs-writeback.c:1505 [inline] __writeback_single_inode+0x6c3/0xda0 fs/fs-writeback.c:1715 writeback_sb_inodes+0xa4e/0x1680 fs/fs-writeback.c:1940 wb_writeback+0x45d/0xbe0 fs/fs-writeback.c:2114 wb_do_writeback fs/fs-writeback.c:2257 [inline] wb_workfn+0x43a/0xf20 fs/fs-writeback.c:2298 process_one_work+0x85f/0x1010 kernel/workqueue.c:2310 worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457 kthread+0x436/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 Modules linked in: ---[ end trace 453c9c61150901f5 ]--- RIP: 0010:bio_associate_blkg_from_css+0x128/0x9c0 block/blk-cgroup.c:1882 Code: df 41 80 3c 04 00 74 08 48 89 df e8 12 0b ec fd 41 be d8 05 00 00 4c 03 33 4c 89 f0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 f7 e8 ea 0a ec fd 41 bf 90 00 00 00 4d 03 RSP: 0000:ffffc900035d7260 EFLAGS: 00010206 RAX: 00000000000000bb RBX: ffff888061a4a008 RCX: dffffc0000000000 RDX: 0000000000000000 RSI: ffffffff96486e20 RDI: ffff888061a4a000 RBP: 1ffff1100c349409 R08: dffffc0000000000 R09: 1ffffffff203b018 R10: dffffc0000000000 R11: fffffbfff203b019 R12: 1ffff1100c349401 R13: ffff888061a4a048 R14: 00000000000005d8 R15: ffff888021911dec FS: 0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffee4c83228 CR3: 000000001ea39000 CR4: 00000000003506f0 DR0: ffffffffffffffff DR1: 00000000000001f8 DR2: 0000000000000002 DR3: ffffffffefffff15 DR6: 00000000fffe0ff0 DR7: 0000000000000400 ---------------- Code disassembly (best guess): 0: df 41 80 filds -0x80(%rcx) 3: 3c 04 cmp $0x4,%al 5: 00 74 08 48 add %dh,0x48(%rax,%rcx,1) 9: 89 df mov %ebx,%edi b: e8 12 0b ec fd call 0xfdec0b22 10: 41 be d8 05 00 00 mov $0x5d8,%r14d 16: 4c 03 33 add (%rbx),%r14 19: 4c 89 f0 mov %r14,%rax 1c: 48 c1 e8 03 shr $0x3,%rax 20: 48 b9 00 00 00 00 00 movabs $0xdffffc0000000000,%rcx 27: fc ff df * 2a: 80 3c 08 00 cmpb $0x0,(%rax,%rcx,1) <-- trapping instruction 2e: 74 08 je 0x38 30: 4c 89 f7 mov %r14,%rdi 33: e8 ea 0a ec fd call 0xfdec0b22 38: 41 bf 90 00 00 00 mov $0x90,%r15d 3e: 4d rex.WRB 3f: 03 .byte 0x3