INFO: task hung in exit_mm

Status: closed as dup on 2021/01/21 05:51
Subsystems: perf
[Documentation on labels]
Reported-by: syzbot+8cc1843d4eec9c0dfb35@syzkaller.appspotmail.com
First crash: 2583d, last: 1674d
Cause bisection: the issue happens on the oldest tested release (bisect log)
Crash: INFO: task hung in khugepaged (log)
Repro: syz .config
  
Fix bisection: failed (error log, bisect log)
  
▶ ▼ Duplicate of
Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported
INFO: task hung in do_exit 1 syz done error 125 1636d 2658d
▶ ▼ Discussions (3)
Title Replies (including bot) Last reply
Reminder: 19 open syzbot bugs in perf subsystem 2 (2) 2019/07/24 13:22
Reminder: 22 open syzbot bugs in perf subsystem 7 (7) 2019/07/03 11:34
INFO: task hung in exit_mm 3 (4) 2019/07/02 09:36
▶ ▼ Similar bugs (6)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 INFO: task hung in exit_mm (2) 1 1 94d 94d 0/3 upstream: reported on 2026/04/20 20:34
linux-5.15 INFO: task hung in exit_mm 1 3 198d 288d 0/3 auto-obsoleted due to no activity on 2026/04/16 07:42
upstream INFO: task hung in exit_mm (5) prio:high kernel 1 C done 1265 38d 366d 0/29 upstream: reported C repro on 2025/07/22 15:17
upstream INFO: task hung in exit_mm (3) kernel 1 1 876d 876d 0/29 auto-obsoleted due to no activity on 2024/05/28 14:48
upstream INFO: task hung in exit_mm (2) arm 1 8 1224d 1350d 0/29 auto-obsoleted due to no activity on 2023/06/14 23:13
upstream INFO: task hung in exit_mm (4) kernel 1 11 575d 728d 0/29 auto-obsoleted due to no activity on 2025/03/24 22:19
▶ ▼ Fix bisection attempts (8)
Created Duration User Patch Repo Result
2020/05/25 10:53 0m bisect fix upstream error job log
2020/04/22 23:14 26m bisect fix upstream OK (0) job log log
2020/03/23 22:49 24m bisect fix upstream OK (0) job log log
2020/02/13 02:21 25m bisect fix upstream OK (0) job log log
2020/01/14 01:56 24m bisect fix upstream OK (0) job log log
2019/11/12 00:28 24m bisect fix upstream OK (0) job log log
2019/10/12 20:34 24m bisect fix upstream OK (0) job log log
2019/09/12 20:07 26m bisect fix upstream OK (0) job log log

Sample crash report:
INFO: task syz-executor.0:9648 blocked for more than 143 seconds.
      Not tainted 5.3.0-rc4 #73
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0  D28624  9648   9627 0x80004004
Call Trace:
 context_switch kernel/sched/core.c:3254 [inline]
 __schedule+0x877/0xc50 kernel/sched/core.c:3880
 schedule+0x131/0x1e0 kernel/sched/core.c:3944
 rwsem_down_read_slowpath+0x5c5/0xa00 kernel/locking/rwsem.c:1090
 __down_read+0x6e/0x330 kernel/locking/rwsem.c:1320
 down_read+0x45/0x50 kernel/locking/rwsem.c:1463
 exit_mm+0x90/0x590 kernel/exit.c:513
 do_exit+0x565/0x21a0 kernel/exit.c:866
 do_group_exit+0x15c/0x2b0 kernel/exit.c:983
 get_signal+0x4ac/0x1d60 kernel/signal.c:2729
 do_signal+0x37/0x640 arch/x86/kernel/signal.c:815
 exit_to_usermode_loop arch/x86/entry/common.c:159 [inline]
 prepare_exit_to_usermode+0x303/0x580 arch/x86/entry/common.c:194
 syscall_return_slowpath+0x113/0x4a0 arch/x86/entry/common.c:274
 do_syscall_64+0x126/0x140 arch/x86/entry/common.c:299
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45987a
Code: Bad RIP value.
RSP: 002b:00007ffc3f0c90a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: fffffffffffffffc RBX: 0000000000000003 RCX: 000000000045987a
RDX: 0000000000000003 RSI: 0000000000021000 RDI: 0000000000000000
RBP: ffffffffffffffff R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000020022 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000021000 R14: 0000000000020022 R15: 0000000000000000
INFO: task syz-executor.0:9649 blocked for more than 143 seconds.
      Not tainted 5.3.0-rc4 #73
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0  D28760  9649   9627 0x80004004
Call Trace:
 context_switch kernel/sched/core.c:3254 [inline]
 __schedule+0x877/0xc50 kernel/sched/core.c:3880
 schedule+0x131/0x1e0 kernel/sched/core.c:3944
 rwsem_down_read_slowpath+0x5c5/0xa00 kernel/locking/rwsem.c:1090
 __down_read+0x6e/0x330 kernel/locking/rwsem.c:1320
 down_read+0x45/0x50 kernel/locking/rwsem.c:1463
 exit_mm+0x90/0x590 kernel/exit.c:513
 do_exit+0x565/0x21a0 kernel/exit.c:866
 do_group_exit+0x15c/0x2b0 kernel/exit.c:983
 get_signal+0x4ac/0x1d60 kernel/signal.c:2729
 do_signal+0x37/0x640 arch/x86/kernel/signal.c:815
 exit_to_usermode_loop arch/x86/entry/common.c:159 [inline]
 prepare_exit_to_usermode+0x303/0x580 arch/x86/entry/common.c:194
 syscall_return_slowpath+0x113/0x4a0 arch/x86/entry/common.c:274
 do_syscall_64+0x126/0x140 arch/x86/entry/common.c:299
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459829
Code: Bad RIP value.
RSP: 002b:00007f2b4b0b0cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 000000000075bf28 RCX: 0000000000459829
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000075bf28
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000075bf2c
R13: 00007ffc3f0c914f R14: 00007f2b4b0b19c0 R15: 000000000075bf2c
INFO: task syz-executor.0:9651 blocked for more than 143 seconds.
      Not tainted 5.3.0-rc4 #73
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0  D28888  9651   9627 0x80004004
Call Trace:
 context_switch kernel/sched/core.c:3254 [inline]
 __schedule+0x877/0xc50 kernel/sched/core.c:3880
 schedule+0x131/0x1e0 kernel/sched/core.c:3944
 rwsem_down_read_slowpath+0x5c5/0xa00 kernel/locking/rwsem.c:1090
 __down_read+0x6e/0x330 kernel/locking/rwsem.c:1320
 down_read+0x45/0x50 kernel/locking/rwsem.c:1463
 acct_collect+0xa3/0x5f0 kernel/acct.c:542
 do_exit+0x4fa/0x21a0 kernel/exit.c:858
 do_group_exit+0x15c/0x2b0 kernel/exit.c:983
 get_signal+0x4ac/0x1d60 kernel/signal.c:2729
 do_signal+0x37/0x640 arch/x86/kernel/signal.c:815
 exit_to_usermode_loop arch/x86/entry/common.c:159 [inline]
 prepare_exit_to_usermode+0x303/0x580 arch/x86/entry/common.c:194
 syscall_return_slowpath+0x113/0x4a0 arch/x86/entry/common.c:274
 do_syscall_64+0x126/0x140 arch/x86/entry/common.c:299
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459829
Code: Bad RIP value.
RSP: 002b:00007f2b4b08fcf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 000000000075bfd0 RCX: 0000000000459829
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000075bfd0
RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000075bfd4
R13: 00007ffc3f0c914f R14: 00007f2b4b0909c0 R15: 000000000075bfd4
INFO: task syz-executor.0:9652 blocked for more than 143 seconds.
      Not tainted 5.3.0-rc4 #73
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0  D30200  9652   9651 0x80004000
Call Trace:
 context_switch kernel/sched/core.c:3254 [inline]
 __schedule+0x877/0xc50 kernel/sched/core.c:3880
 schedule+0x131/0x1e0 kernel/sched/core.c:3944
 rwsem_down_read_slowpath+0x5c5/0xa00 kernel/locking/rwsem.c:1090
 __down_read+0x6e/0x330 kernel/locking/rwsem.c:1320
 down_read+0x45/0x50 kernel/locking/rwsem.c:1463
 acct_collect+0xa3/0x5f0 kernel/acct.c:542
 do_exit+0x4fa/0x21a0 kernel/exit.c:858
 do_group_exit+0x15c/0x2b0 kernel/exit.c:983
 __do_sys_exit_group+0x17/0x20 kernel/exit.c:994
 __se_sys_exit_group+0x14/0x20 kernel/exit.c:992
 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:992
 do_syscall_64+0xfe/0x140 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459829
Code: Bad RIP value.
RSP: 002b:00007f2b4b08f688 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 000000000000000b RCX: 0000000000459829
RDX: 0000000000459829 RSI: 00007f2b4b08f6c0 RDI: 000000000000000b
RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000246 R12: 00007f2b4b0906d4
R13: 00000000004bfce6 R14: 00000000004d1a38 R15: 00000000ffffffff
INFO: lockdep is turned off.
NMI backtrace for cpu 0
CPU: 0 PID: 1057 Comm: khungtaskd Not tainted 5.3.0-rc4 #73
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1d8/0x2f8 lib/dump_stack.c:113
 nmi_cpu_backtrace+0xaf/0x1a0 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x174/0x290 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x10/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_all_cpu_backtrace+0x17/0x20 include/linux/nmi.h:146
 check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline]
 watchdog+0xbb9/0xbd0 kernel/hung_task.c:289
 kthread+0x332/0x350 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 9650 Comm: syz-executor.0 Not tainted 5.3.0-rc4 #73
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:atomic_fetch_add_unless include/linux/atomic-fallback.h:1089 [inline]
RIP: 0010:atomic_add_unless include/linux/atomic-fallback.h:1111 [inline]
RIP: 0010:atomic_inc_not_zero include/linux/atomic-fallback.h:1127 [inline]
RIP: 0010:perf_mmap+0x5d5/0x1530 kernel/events/core.c:5707
Code: 04 30 84 c0 0f 85 66 01 00 00 45 8b 3c 24 49 89 dd 4c 8b 75 a0 41 8a 04 1e 84 c0 0f 85 6d 01 00 00 44 89 7d cc 31 ff 44 89 fe <e8> c6 81 e5 ff 45 85 ff 75 21 e8 1c 7e e5 ff 4c 8b 7d c0 e9 d0 00
RSP: 0018:ffff8880a7cb7b78 EFLAGS: 00000246
RAX: 1ffff11012c43b00 RBX: dffffc0000000000 RCX: ffffffff818e0622
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff8880a7cb7c40 R08: dffffc0000000000 R09: ffffed1012c43bb6
R10: ffffed1012c43bb6 R11: 0000000000000000 R12: ffff88809621dda8
R13: dffffc0000000000 R14: 1ffff11014f96f81 R15: 0000000000000000
FS:  00007f2b4b0b1700(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffff600400 CR3: 0000000091061000 CR4: 00000000001406e0
Call Trace:
 call_mmap include/linux/fs.h:1875 [inline]
 mmap_region+0x17a4/0x1cb0 mm/mmap.c:1788
 do_mmap+0x9ef/0x1020 mm/mmap.c:1561
 do_mmap_pgoff include/linux/mm.h:2374 [inline]
 vm_mmap_pgoff+0x13d/0x1d0 mm/util.c:391
 ksys_mmap_pgoff+0x46b/0x560 mm/mmap.c:1611
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:91 [inline]
 __x64_sys_mmap+0x103/0x120 arch/x86/kernel/sys_x86_64.c:91
 do_syscall_64+0xfe/0x140 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459829
Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f2b4b0b0c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 0000000000459829
RDX: 0000000000000000 RSI: 0000000000003000 RDI: 0000000020ffd000
RBP: 000000000075bf20 R08: 0000000000000003 R09: 0000000000000000
R10: 0000000000000011 R11: 0000000000000246 R12: 00007f2b4b0b16d4
R13: 00000000004c5d1b R14: 00000000004da750 R15: 00000000ffffffff

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2019/08/13 16:00 upstream d45331b00ddb 8620c2c2 .config console log report syz ci-upstream-kasan-gce-smack-root
2019/07/28 05:19 upstream 5168afe6ef59 c85e1c5b .config console log report syz ci-upstream-kasan-gce-smack-root
2019/06/27 06:45 upstream 249155c20f9b 7509bf36 .config console log report syz ci-upstream-kasan-gce-smack-root
2021/12/22 10:05 upstream 2f47a9a4dfa3 6caa12e4 .config console log report info ci-upstream-kasan-gce-smack-root INFO: task hung in exit_mm
2021/12/22 08:48 upstream 2f47a9a4dfa3 6caa12e4 .config console log report info ci-upstream-kasan-gce-smack-root INFO: task hung in exit_mm
2019/07/30 23:41 upstream 629f8205a6cc 7c7ded69 .config console log report ci-upstream-kasan-gce-smack-root
2019/06/27 07:58 upstream 249155c20f9b 7509bf36 .config console log report ci-upstream-kasan-gce-smack-root
* Struck through repros no longer work on HEAD.