Hello, syzbot found the following issue on: HEAD commit: ed9a4ad6e5bd Add linux-next specific files for 20241126 git tree: linux-next console+strace: https://syzkaller.appspot.com/x/log.txt?x=17615530580000 kernel config: https://syzkaller.appspot.com/x/.config?x=e348a4873516af92 dashboard link: https://syzkaller.appspot.com/bug?extid=8965fea6a159ab9aa32d 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=175c8dc0580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1103a1e8580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/3b9ba5fbd895/disk-ed9a4ad6.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/e30aed8d0305/vmlinux-ed9a4ad6.xz kernel image: https://storage.googleapis.com/syzbot-assets/1092546e50cf/bzImage-ed9a4ad6.xz The issue was bisected to: commit 1bd9011ee163e11f186b72705978fd6b21bdc07b Author: David Howells <dhowells@xxxxxxxxxx> Date: Fri Nov 8 17:32:29 2024 +0000 netfs: Change the read result collector to only use one work item bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=174cc3c0580000 final oops: https://syzkaller.appspot.com/x/report.txt?x=14ccc3c0580000 console output: https://syzkaller.appspot.com/x/log.txt?x=10ccc3c0580000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+8965fea6a159ab9aa32d@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: 1bd9011ee163 ("netfs: Change the read result collector to only use one work item") INFO: task syz-executor246:5857 blocked for more than 143 seconds. Not tainted 6.12.0-next-20241126-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor246 state:D stack:22584 pid:5857 tgid:5857 ppid:5854 flags:0x00004006 Call Trace: <TASK> context_switch kernel/sched/core.c:5369 [inline] __schedule+0x1850/0x4c30 kernel/sched/core.c:6756 __schedule_loop kernel/sched/core.c:6833 [inline] schedule+0x14b/0x320 kernel/sched/core.c:6848 bit_wait+0x12/0xd0 kernel/sched/wait_bit.c:237 __wait_on_bit+0xb0/0x2f0 kernel/sched/wait_bit.c:49 out_of_line_wait_on_bit+0x1d5/0x260 kernel/sched/wait_bit.c:64 wait_on_bit include/linux/wait_bit.h:77 [inline] netfs_dispatch_unbuffered_reads fs/netfs/direct_read.c:107 [inline] netfs_unbuffered_read fs/netfs/direct_read.c:146 [inline] netfs_unbuffered_read_iter_locked+0xd7e/0x1560 fs/netfs/direct_read.c:231 netfs_unbuffered_read_iter+0xbf/0xe0 fs/netfs/direct_read.c:266 new_sync_read fs/read_write.c:484 [inline] vfs_read+0x991/0xb70 fs/read_write.c:565 ksys_read+0x18f/0x2b0 fs/read_write.c:708 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: 0033:0x7f1999cb4f79 RSP: 002b:00007ffef9ec4f98 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 0030656c69662f2e RCX: 00007f1999cb4f79 RDX: 0000000000002020 RSI: 000000002001b640 RDI: 0000000000000006 RBP: 00007f1999cfe04e R08: 0000000000000006 R09: 0000000000000006 R10: 0000000000000006 R11: 0000000000000246 R12: 00007ffef9ec4fac R13: 431bde82d7b634db R14: 0000000000000001 R15: 0000000000000001 </TASK> Showing all locks held in the system: 1 lock held by khungtaskd/30: #0: ffffffff8e937ae0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline] #0: ffffffff8e937ae0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffffffff8e937ae0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x55/0x2a0 kernel/locking/lockdep.c:6744 5 locks held by kworker/u8:2/35: 2 locks held by getty/5592: #0: ffff888034e320a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243 #1: ffffc90002fde2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x6a6/0x1e00 drivers/tty/n_tty.c:2211 1 lock held by syz-executor246/5857: #0: ffff888072050148 (&sb->s_type->i_mutex_key#15){++++}-{4:4}, at: netfs_start_io_direct+0x1d4/0x210 fs/netfs/locking.c:188 ============================================= NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 30 Comm: khungtaskd Not tainted 6.12.0-next-20241126-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 nmi_cpu_backtrace+0x49c/0x4d0 lib/nmi_backtrace.c:113 nmi_trigger_cpumask_backtrace+0x198/0x320 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:234 [inline] watchdog+0xffb/0x1040 kernel/hung_task.c:397 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> Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 35 Comm: kworker/u8:2 Not tainted 6.12.0-next-20241126-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Workqueue: events_unbound toggle_allocation_gate RIP: 0010:insn_get_sib arch/x86/lib/insn.c:447 [inline] RIP: 0010:insn_get_displacement+0x2ca/0x9a0 arch/x86/lib/insn.c:484 Code: cb f5 49 bc 00 00 00 00 00 fc ff df e9 12 04 00 00 49 8d 5d 25 48 89 d8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df 0f b6 04 08 <84> c0 0f 85 95 05 00 00 0f b6 1b 31 ff 89 de e8 72 c9 cb f5 85 db RSP: 0018:ffffc90000ab7790 EFLAGS: 00000a07 RAX: 0000000000000000 RBX: ffffc90000ab7945 RCX: dffffc0000000000 RDX: ffff888020a81e00 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffc90000ab794c R08: ffffffff8bd3c21d R09: ffffffff8bd395b6 R10: 0000000000000002 R11: ffff888020a81e00 R12: 1ffff92000156f29 R13: ffffc90000ab7920 R14: 1ffff92000156f2a R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fbd0e4b4580 CR3: 000000000e736000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <NMI> </NMI> <TASK> insn_get_immediate+0x62/0x11f0 arch/x86/lib/insn.c:650 insn_get_length arch/x86/lib/insn.c:723 [inline] insn_decode+0x2d6/0x4c0 arch/x86/lib/insn.c:762 text_poke_loc_init+0xed/0x870 arch/x86/kernel/alternative.c:2432 arch_jump_label_transform_queue+0x8f/0x100 arch/x86/kernel/jump_label.c:138 __jump_label_update+0x177/0x3a0 kernel/jump_label.c:513 static_key_disable_cpuslocked+0xd2/0x1c0 kernel/jump_label.c:240 static_key_disable+0x1a/0x20 kernel/jump_label.c:248 toggle_allocation_gate+0x1bf/0x260 mm/kfence/core.c:854 process_one_work kernel/workqueue.c:3229 [inline] process_scheduled_works+0xa63/0x1850 kernel/workqueue.c:3310 worker_thread+0x870/0xd30 kernel/workqueue.c:3391 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> INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.344 msecs --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. For information about bisection process see: https://goo.gl/tpsmEJ#bisection If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title 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. If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup
