syzbot


INFO: task hung in exit_mmap (3)

Status: upstream: reported on 2025/06/17 05:04
Reported-by: syzbot+4ae44039c268079df003@syzkaller.appspotmail.com
First crash: 44d, last: 44d
Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in exit_mmap (2) mm 1 C done error 12 6h40m 97d 0/29 upstream: reported C repro on 2025/04/25 07:09
linux-6.1 INFO: task hung in exit_mmap 1 43 269d 350d 0/3 auto-obsoleted due to no activity on 2025/01/13 01:54
upstream INFO: task hung in exit_mmap mm 1 236 265d 294d 0/29 auto-obsoleted due to no activity on 2025/01/17 10:18
linux-6.1 INFO: task hung in exit_mmap (2) 1 1 157d 157d 0/3 auto-obsoleted due to no activity on 2025/06/04 11:18

Sample crash report:
INFO: task syz.0.11456:5394 blocked for more than 143 seconds.
      Not tainted 6.1.141-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.11456     state:D stack:25440 pid:5394  ppid:4255   flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10e9/0x40d0 kernel/sched/core.c:6561
 schedule+0xb9/0x180 kernel/sched/core.c:6637
 rwsem_down_write_slowpath+0xbed/0x1090 kernel/locking/rwsem.c:1189
 mmap_write_lock include/linux/mmap_lock.h:71 [inline]
 exit_mmap+0x20f/0x8e0 mm/mmap.c:3246
 __mmput+0x118/0x3c0 kernel/fork.c:1200
 exit_mm+0x1e6/0x2c0 kernel/exit.c:565
 do_exit+0x8b9/0x2400 kernel/exit.c:858
 do_group_exit+0x217/0x2d0 kernel/exit.c:1021
 __do_sys_exit_group kernel/exit.c:1032 [inline]
 __se_sys_exit_group kernel/exit.c:1030 [inline]
 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1030
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f980118e929
RSP: 002b:00007ffdc59feab8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f980118e929
RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ffdc59feb1c R08: 0000001cc59febaf R09: 00000000000927c0
R10: 00000000000014bc R11: 0000000000000246 R12: 00000000000008cf
R13: 00000000000927c0 R14: 000000000018df9c R15: 00007ffdc59feb70
 </TASK>
INFO: task syz.3.11460:5406 blocked for more than 143 seconds.
      Not tainted 6.1.141-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.11460     state:D stack:25352 pid:5406  ppid:4250   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10e9/0x40d0 kernel/sched/core.c:6561
 schedule+0xb9/0x180 kernel/sched/core.c:6637
 rwsem_down_write_slowpath+0xbed/0x1090 kernel/locking/rwsem.c:1189
 mmap_write_lock include/linux/mmap_lock.h:71 [inline]
 exit_mmap+0x20f/0x8e0 mm/mmap.c:3246
 __mmput+0x118/0x3c0 kernel/fork.c:1200
 exit_mm+0x1e6/0x2c0 kernel/exit.c:565
 do_exit+0x8b9/0x2400 kernel/exit.c:858
 do_group_exit+0x217/0x2d0 kernel/exit.c:1021
 get_signal+0x1272/0x1350 kernel/signal.c:2871
 arch_do_signal_or_restart+0xb0/0x1230 arch/x86/kernel/signal.c:871
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7faec4d8e929
RSP: 002b:00007faec5bbbfe8 EFLAGS: 00000206 ORIG_RAX: 0000000000000038
RAX: fffffffffffffff4 RBX: 00007faec4fb5fa0 RCX: 00007faec4d8e929
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020083400
RBP: 00007faec4e10b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 0000000000000000 R14: 00007faec4fb5fa0 R15: 00007ffeb64d1638
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
 #0: ffffffff8c92b430 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xf00 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
 #0: ffffffff8c92bc50 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xf00 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/27:
 #0: ffffffff8c92aaa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8c92aaa0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8c92aaa0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6513
1 lock held by syslogd/3605:
 #0: ffff8880b8f3aa98 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x26/0x140 kernel/sched/core.c:537
2 locks held by getty/4011:
 #0: ffff88802fe63098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
 #1: ffffc9000326b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x41b/0x1380 drivers/tty/n_tty.c:2198
1 lock held by syz-executor/4239:
 #0: ffff88807a06d3d8 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:87 [inline]
 #0: ffff88807a06d3d8 (&mm->mmap_lock){++++}-{3:3}, at: vm_mmap_pgoff+0x15d/0x2b0 mm/util.c:518
1 lock held by syz-executor/4255:
 #0: ffff8880305062d8 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock include/linux/mmap_lock.h:71 [inline]
 #0: ffff8880305062d8 (&mm->mmap_lock){++++}-{3:3}, at: exit_mmap+0x20f/0x8e0 mm/mmap.c:3246
2 locks held by syz-executor/4259:
 #0: ffffffff8c9c6c70 (dup_mmap_sem){++++}-{0:0}, at: dup_mmap kernel/fork.c:593 [inline]
 #0: ffffffff8c9c6c70 (dup_mmap_sem){++++}-{0:0}, at: dup_mm kernel/fork.c:1541 [inline]
 #0: ffffffff8c9c6c70 (dup_mmap_sem){++++}-{0:0}, at: copy_mm+0x2a9/0x15c0 kernel/fork.c:1590
 #1: ffff88807bf34c58 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:87 [inline]
 #1: ffff88807bf34c58 (&mm->mmap_lock){++++}-{3:3}, at: dup_mmap kernel/fork.c:594 [inline]
 #1: ffff88807bf34c58 (&mm->mmap_lock){++++}-{3:3}, at: dup_mm kernel/fork.c:1541 [inline]
 #1: ffff88807bf34c58 (&mm->mmap_lock){++++}-{3:3}, at: copy_mm+0x2c3/0x15c0 kernel/fork.c:1590
2 locks held by syz-executor/4265:
 #0: ffffffff8c9c6c70 (dup_mmap_sem){++++}-{0:0}, at: dup_mmap kernel/fork.c:593 [inline]
 #0: ffffffff8c9c6c70 (dup_mmap_sem){++++}-{0:0}, at: dup_mm kernel/fork.c:1541 [inline]
 #0: ffffffff8c9c6c70 (dup_mmap_sem){++++}-{0:0}, at: copy_mm+0x2a9/0x15c0 kernel/fork.c:1590
 #1: ffff88807bf35b58 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:87 [inline]
 #1: ffff88807bf35b58 (&mm->mmap_lock){++++}-{3:3}, at: dup_mmap kernel/fork.c:594 [inline]
 #1: ffff88807bf35b58 (&mm->mmap_lock){++++}-{3:3}, at: dup_mm kernel/fork.c:1541 [inline]
 #1: ffff88807bf35b58 (&mm->mmap_lock){++++}-{3:3}, at: copy_mm+0x2c3/0x15c0 kernel/fork.c:1590
1 lock held by syz.0.11456/5394:
 #0: ffff88802470cc58 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock include/linux/mmap_lock.h:71 [inline]
 #0: ffff88802470cc58 (&mm->mmap_lock){++++}-{3:3}, at: exit_mmap+0x20f/0x8e0 mm/mmap.c:3246
1 lock held by syz.3.11460/5406:
 #0: ffff888075b488d8 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock include/linux/mmap_lock.h:71 [inline]
 #0: ffff888075b488d8 (&mm->mmap_lock){++++}-{3:3}, at: exit_mmap+0x20f/0x8e0 mm/mmap.c:3246

=============================================

NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted 6.1.141-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3f4/0x470 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x1d4/0x450 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
 watchdog+0xeee/0xf30 kernel/hung_task.c:377
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 26574 Comm: kworker/u4:8 Not tainted 6.1.141-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:insn_complete arch/x86/lib/insn.c:722 [inline]
RIP: 0010:insn_decode+0x347/0x520 arch/x86/lib/insn.c:751
Code: 03 42 0f b6 04 20 84 c0 0f 85 bd 01 00 00 41 0f b6 2e 31 ff 89 ee e8 98 ec 7c f7 85 ed 74 69 48 83 c3 3c 48 89 d8 48 c1 e8 03 <42> 0f b6 04 20 84 c0 0f 85 af 01 00 00 0f b6 03 0f b6 d8 31 ff 89
RSP: 0018:ffffc900042b78e8 EFLAGS: 00000a07
RAX: 1ffff92000856f33 RBX: ffffc900042b799c RCX: 0000000000000000
RDX: ffff88807cbf9dc0 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000001 R08: ffff88807cbf9dc0 R09: 0000000000000003
R10: 0000000000000008 R11: 0000000000000000 R12: dffffc0000000000
R13: 1ffff92000856f36 R14: ffffc900042b7994 R15: ffffc900042b79b8
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f38e8c00218 CR3: 000000007e20d000 CR4: 00000000003506e0
DR0: fffffffffffffffc DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 arch_jump_entry_size arch/x86/kernel/jump_label.c:24 [inline]
 __jump_label_patch+0xd8/0x430 arch/x86/kernel/jump_label.c:45
 arch_jump_label_transform_queue+0x48/0xd0 arch/x86/kernel/jump_label.c:137
 __jump_label_update+0x17d/0x390 kernel/jump_label.c:510
 static_key_disable_cpuslocked+0xc1/0x1a0 kernel/jump_label.c:237
 static_key_disable+0x16/0x20 kernel/jump_label.c:245
 toggle_allocation_gate+0x38f/0x430 mm/kfence/core.c:819
 process_one_work+0x898/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaa2/0x1250 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/06/17 05:03 linux-6.1.y 58485ff1a74f cfebc887 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: task hung in exit_mmap
* Struck through repros no longer work on HEAD.