syzbot


INFO: task hung in exit_mmap

Status: upstream: reported C repro on 2025/09/26 08:35
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+29425e599d1d7f33029b@syzkaller.appspotmail.com
First crash: 13d, last: 52m
Bug presence (1)
Date Name Commit Repro Result
2025/09/27 upstream (ToT) 51a24b7deaae C [report] INFO: task hung in exit_mmap
Similar bugs (5)
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 20 13h56m 167d 0/29 upstream: reported C repro on 2025/04/25 07:09
linux-6.1 INFO: task hung in exit_mmap (3) origin:upstream 1 C 9 1d21h 114d 0/3 upstream: reported C repro on 2025/06/17 05:04
linux-6.1 INFO: task hung in exit_mmap 1 43 339d 419d 0/3 auto-obsoleted due to no activity on 2025/01/13 01:54
upstream INFO: task hung in exit_mmap mm 1 236 335d 363d 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 227d 227d 0/3 auto-obsoleted due to no activity on 2025/06/04 11:18

Sample crash report:
INFO: task syz.3.20:6036 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.20        state:D stack:24656 pid:6036  ppid:5928   flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6832
 rwsem_down_write_slowpath+0xbd2/0xfa0 kernel/locking/rwsem.c:1178
 __down_write_common kernel/locking/rwsem.c:1306 [inline]
 __down_write kernel/locking/rwsem.c:1315 [inline]
 down_write+0x1a7/0x1f0 kernel/locking/rwsem.c:1574
 mmap_write_lock include/linux/mmap_lock.h:108 [inline]
 exit_mmap+0x245/0xb50 mm/mmap.c:3310
 __mmput+0x118/0x3c0 kernel/fork.c:1355
 exit_mm+0x1da/0x2c0 kernel/exit.c:569
 do_exit+0x88e/0x23c0 kernel/exit.c:870
 do_group_exit+0x21b/0x2d0 kernel/exit.c:1024
 __do_sys_exit_group kernel/exit.c:1035 [inline]
 __se_sys_exit_group kernel/exit.c:1033 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1033
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7ff1a118eec9
RSP: 002b:00007ffc429aab68 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007ff1a118eec9
RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000003 R08: 00000005429aac5f R09: 00007ff1a13b1280
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff1a13b1280 R14: 0000000000000003 R15: 00007ffc429aac20
 </TASK>
INFO: task syz.0.27:6037 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.27        state:D stack:24496 pid:6037  ppid:5921   flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6832
 rwsem_down_write_slowpath+0xbd2/0xfa0 kernel/locking/rwsem.c:1178
 __down_write_common kernel/locking/rwsem.c:1306 [inline]
 __down_write kernel/locking/rwsem.c:1315 [inline]
 down_write+0x1a7/0x1f0 kernel/locking/rwsem.c:1574
 mmap_write_lock include/linux/mmap_lock.h:108 [inline]
 exit_mmap+0x245/0xb50 mm/mmap.c:3310
 __mmput+0x118/0x3c0 kernel/fork.c:1355
 exit_mm+0x1da/0x2c0 kernel/exit.c:569
 do_exit+0x88e/0x23c0 kernel/exit.c:870
 do_group_exit+0x21b/0x2d0 kernel/exit.c:1024
 __do_sys_exit_group kernel/exit.c:1035 [inline]
 __se_sys_exit_group kernel/exit.c:1033 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1033
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f040098eec9
RSP: 002b:00007fffcc915b88 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f040098eec9
RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fffcc915bec R08: 00000005cc915c7f R09: 00000000000927c0
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000006
R13: 00000000000927c0 R14: 00000000000277a0 R15: 00007fffcc915c40
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/29:
 #0: ffffffff8cd2ff20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 #0: ffffffff8cd2ff20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
 #0: ffffffff8cd2ff20 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
2 locks held by getty/5548:
 #0: ffff88823bd960a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x425/0x1380 drivers/tty/n_tty.c:2217
1 lock held by syz-executor/5814:
 #0: ffff88807e9101a0 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:124 [inline]
 #0: ffff88807e9101a0 (&mm->mmap_lock){++++}-{3:3}, at: vm_mmap_pgoff+0x168/0x400 mm/util.c:554
2 locks held by syz-executor/5923:
 #0: ffffffff8cdd2090 (dup_mmap_sem){.+.+}-{0:0}, at: dup_mmap kernel/fork.c:657 [inline]
 #0: ffffffff8cdd2090 (dup_mmap_sem){.+.+}-{0:0}, at: dup_mm kernel/fork.c:1692 [inline]
 #0: ffffffff8cdd2090 (dup_mmap_sem){.+.+}-{0:0}, at: copy_mm+0x266/0x1c20 kernel/fork.c:1741
 #1: ffff888024b2cda0 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:124 [inline]
 #1: ffff888024b2cda0 (&mm->mmap_lock){++++}-{3:3}, at: dup_mmap kernel/fork.c:658 [inline]
 #1: ffff888024b2cda0 (&mm->mmap_lock){++++}-{3:3}, at: dup_mm kernel/fork.c:1692 [inline]
 #1: ffff888024b2cda0 (&mm->mmap_lock){++++}-{3:3}, at: copy_mm+0x281/0x1c20 kernel/fork.c:1741
1 lock held by syz-executor/5928:
 #0: ffff8880259a8b20 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock include/linux/mmap_lock.h:108 [inline]
 #0: ffff8880259a8b20 (&mm->mmap_lock){++++}-{3:3}, at: exit_mmap+0x245/0xb50 mm/mmap.c:3310
1 lock held by syz.3.20/6036:
 #0: ffff88802ef973a0 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock include/linux/mmap_lock.h:108 [inline]
 #0: ffff88802ef973a0 (&mm->mmap_lock){++++}-{3:3}, at: exit_mmap+0x245/0xb50 mm/mmap.c:3310
1 lock held by syz.0.27/6037:
 #0: ffff88802ef960a0 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock include/linux/mmap_lock.h:108 [inline]
 #0: ffff88802ef960a0 (&mm->mmap_lock){++++}-{3:3}, at: exit_mmap+0x245/0xb50 mm/mmap.c:3310

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

NMI backtrace for cpu 1
CPU: 1 PID: 29 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x39b/0x3d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x2f0 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline]
 watchdog+0xf41/0xf80 kernel/hung_task.c:379
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 1138 Comm: kworker/u4:7 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Workqueue: events_unbound cfg80211_wiphy_work
RIP: 0010:hlist_add_head include/linux/list.h:1026 [inline]
RIP: 0010:alloc_object+0x583/0x650 lib/debugobjects.c:275
Code: 48 c1 e8 03 80 3c 28 00 74 08 4c 89 e7 e8 55 d6 b6 fd 49 89 1c 24 48 85 db 74 1c 48 83 c3 08 48 89 d8 48 c1 e8 03 80 3c 28 00 <74> 08 48 89 df e8 33 d6 b6 fd 4c 89 23 41 80 3c 2e 00 74 08 4c 89
RSP: 0018:ffffc9000466f0b0 EFLAGS: 00000046
RAX: 1ffff11005d56ac5 RBX: ffff88802eab5628 RCX: dffffc0000000000
RDX: ffffffff8aabd000 RSI: ffffffff8afc63a0 RDI: ffff88805d702588
RBP: dffffc0000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff520008cde04 R12: ffff88805d702578
R13: 1ffff1100bae04b0 R14: 1ffffffff2e12912 R15: ffffffff97094890
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055cead549010 CR3: 000000000cb30000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 lookup_object_or_alloc lib/debugobjects.c:588 [inline]
 debug_object_activate+0x14a/0x4b0 lib/debugobjects.c:711
 debug_rcu_head_queue kernel/rcu/rcu.h:227 [inline]
 kvfree_call_rcu+0x99/0x780 kernel/rcu/tree.c:3443
 cfg80211_update_known_bss+0x175/0x930 net/wireless/scan.c:-1
 __cfg80211_bss_update+0x144/0x21f0 net/wireless/scan.c:1872
 cfg80211_inform_single_bss_frame_data net/wireless/scan.c:2982 [inline]
 cfg80211_inform_bss_frame_data+0xaea/0x12b0 net/wireless/scan.c:3013
 ieee80211_bss_info_update+0x70b/0x930 net/mac80211/scan.c:211
 ieee80211_rx_bss_info net/mac80211/ibss.c:1124 [inline]
 ieee80211_rx_mgmt_probe_beacon net/mac80211/ibss.c:1613 [inline]
 ieee80211_ibss_rx_queued_mgmt+0x17c9/0x2ac0 net/mac80211/ibss.c:1642
 ieee80211_iface_process_skb net/mac80211/iface.c:1643 [inline]
 ieee80211_iface_work+0x717/0xc70 net/mac80211/iface.c:1697
 cfg80211_wiphy_work+0x225/0x260 net/wireless/core.c:437
 process_one_work kernel/workqueue.c:2634 [inline]
 process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>

Crashes (9):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/10/09 11:03 linux-6.6.y e617101e5626 7e2882b3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: task hung in exit_mmap
2025/10/08 04:24 linux-6.6.y e617101e5626 7e2882b3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: task hung in exit_mmap
2025/10/07 07:47 linux-6.6.y e617101e5626 8ef35d49 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: task hung in exit_mmap
2025/10/06 02:10 linux-6.6.y f34f16e5c632 49379ee0 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: task hung in exit_mmap
2025/10/05 15:19 linux-6.6.y f34f16e5c632 49379ee0 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: task hung in exit_mmap
2025/10/05 07:32 linux-6.6.y f34f16e5c632 49379ee0 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: task hung in exit_mmap
2025/10/04 16:29 linux-6.6.y f34f16e5c632 49379ee0 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: task hung in exit_mmap
2025/10/04 12:15 linux-6.6.y f34f16e5c632 49379ee0 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: task hung in exit_mmap
2025/09/26 08:35 linux-6.6.y 147338df3487 0abd0691 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: task hung in exit_mmap
* Struck through repros no longer work on HEAD.