INFO: task hung in __lru_add_drain_all (2)

Status: premoderation: reported on 2026/05/21 15:31
Reported-by: syzbot+01f1cb4fc5c3861d3e97@syzkaller.appspotmail.com
First crash: 74d, last: 15d
▶ ▼ Similar bugs (10)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: task hung in __lru_add_drain_all (3) 1 5 79d 146d 0/3 upstream: reported on 2026/03/10 22:55
linux-5.15 INFO: task hung in __lru_add_drain_all (3) 1 5 74d 95d 0/3 upstream: reported on 2026/05/01 08:27
linux-6.6 INFO: task hung in __lru_add_drain_all 1 1 273d 273d 0/2 auto-obsoleted due to no activity on 2026/02/12 06:31
linux-6.1 INFO: task hung in __lru_add_drain_all (2) 1 1 428d 428d 0/3 auto-obsoleted due to no activity on 2025/09/09 22:30
linux-5.15 INFO: task hung in __lru_add_drain_all 1 1 1199d 1199d 0/3 auto-obsoleted due to no activity on 2023/08/21 02:18
linux-6.1 INFO: task hung in __lru_add_drain_all 1 1 808d 808d 0/3 auto-obsoleted due to no activity on 2024/08/25 20:43
upstream INFO: task hung in __lru_add_drain_all (2) mm 1 syz error 272 470d 808d 0/29 auto-obsoleted due to no activity on 2025/06/29 18:01
upstream INFO: task hung in __lru_add_drain_all net 1 syz, C done error 71 996d 1796d 0/29 auto-obsoleted due to no activity on 2024/02/20 10:46
linux-5.15 INFO: task hung in __lru_add_drain_all (2) 1 1 739d 739d 0/3 auto-obsoleted due to no activity on 2024/11/03 03:56
android-6-12 INFO: task hung in __lru_add_drain_all 1 1 273d 273d 0/1 auto-obsoleted due to no activity on 2026/02/01 19:21

Sample crash report:
INFO: task khugepaged:41 blocked for more than 122 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:khugepaged      state:D
 stack:0     pid:41    tgid:41    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:6054 [inline]
 __schedule+0x1496/0x20b0 kernel/sched/core.c:7867
 __schedule_loop kernel/sched/core.c:7944 [inline]
 schedule+0xc5/0x240 kernel/sched/core.c:7959
 schedule_timeout+0xc7/0x3b0 kernel/time/timer.c:2596
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common+0x368/0x650 kernel/sched/completion.c:127
 wait_for_completion+0x1c/0x40 kernel/sched/completion.c:148
 __flush_work+0x6a8/0xaa0 kernel/workqueue.c:4290
 flush_work+0x1b/0x40 kernel/workqueue.c:4312
 __lru_add_drain_all+0x51c/0x580 mm/swap.c:923
 lru_add_drain_all+0x14/0x30 mm/swap.c:931
 khugepaged_do_scan mm/khugepaged.c:2531 [inline]
 khugepaged+0x18a/0x1930 mm/khugepaged.c:2600
 kthread+0x2c7/0x360 kernel/kthread.c:389
 ret_from_fork+0x67/0xa0 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
INFO: task syz-executor:296 blocked for more than 124 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D
 stack:0     pid:296   tgid:296   ppid:1      flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:6054 [inline]
 __schedule+0x1496/0x20b0 kernel/sched/core.c:7867
 __schedule_loop kernel/sched/core.c:7944 [inline]
 schedule+0xc5/0x240 kernel/sched/core.c:7959
 schedule_preempt_disabled+0x14/0x30 kernel/sched/core.c:8016
 __mutex_lock_common kernel/locking/mutex.c:707 [inline]
 __mutex_lock+0x902/0x1b90 kernel/locking/mutex.c:806
 __mutex_lock_slowpath+0xe/0x20 kernel/locking/mutex.c:1136
 mutex_lock+0x113/0x1d0 kernel/locking/mutex.c:285
 rtnl_lock+0x19/0x20 net/core/rtnetlink.c:79
 tun_detach drivers/net/tun.c:698 [inline]
 tun_chr_close+0x41/0x150 drivers/net/tun.c:3520
 __fput+0x20b/0xa30 fs/file_table.c:447
 ____fput+0x20/0x30 fs/file_table.c:475
 task_work_run+0x1e8/0x260 kernel/task_work.c:246
 exit_task_work include/linux/task_work.h:43 [inline]
 do_exit+0xa46/0x2850 kernel/exit.c:955
 do_group_exit+0x21f/0x2f0 kernel/exit.c:1098
 get_signal+0x134c/0x1490 kernel/signal.c:2933
 arch_do_signal_or_restart+0xbc/0x700 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x57/0xb0 kernel/entry/common.c:218
 do_syscall_64+0x63/0xf0 arch/x86/entry/common.c:84
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f7e94359017
RSP: 002b:00007ffd84c27a90 EFLAGS: 00000202 ORIG_RAX: 000000000000003d
RAX: fffffffffffffe00 RBX: 000055558bcf4500 RCX: 00007f7e94359017
RDX: 0000000040000000 RSI: 00007ffd84c27b1c RDI: ffffffffffffffff
RBP: 00007ffd84c27b1c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000047
R13: 000055558bd078e0 R14: 0000000000000005 R15: 00007ffd84c27b70
 </TASK>
INFO: task syz.1.142:913 blocked for more than 125 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.142       state:D stack:0     pid:913   tgid:913   ppid:293    flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:6054 [inline]
 __schedule+0x1496/0x20b0 kernel/sched/core.c:7867
 __schedule_loop kernel/sched/core.c:7944 [inline]
 schedule+0xc5/0x240 kernel/sched/core.c:7959
 schedule_preempt_disabled+0x14/0x30 kernel/sched/core.c:8016
 __mutex_lock_common kernel/locking/mutex.c:707 [inline]
 __mutex_lock+0x902/0x1b90 kernel/locking/mutex.c:806
 __mutex_lock_slowpath+0xe/0x20 kernel/locking/mutex.c:1136
 mutex_lock+0x113/0x1d0 kernel/locking/mutex.c:285
 rtnl_lock+0x19/0x20 net/core/rtnetlink.c:79
 tun_detach drivers/net/tun.c:698 [inline]
 tun_chr_close+0x41/0x150 drivers/net/tun.c:3520
 __fput+0x20b/0xa30 fs/file_table.c:447
 ____fput+0x20/0x30 fs/file_table.c:475
 task_work_run+0x1e8/0x260 kernel/task_work.c:246
 exit_task_work include/linux/task_work.h:43 [inline]
 do_exit+0xa46/0x2850 kernel/exit.c:955
 do_group_exit+0x21f/0x2f0 kernel/exit.c:1098
 get_signal+0x134c/0x1490 kernel/signal.c:2933
 arch_do_signal_or_restart+0xbc/0x700 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x57/0xb0 kernel/entry/common.c:218
 do_syscall_64+0x63/0xf0 arch/x86/entry/common.c:84
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7ff96995e6ce
RSP: 002b:00007ff96a808f58 EFLAGS: 00000246
 ORIG_RAX: 00000000000000e6
RAX: fffffffffffffdfc RBX: 00007ff96a8096c0 RCX: 00007ff96995e6ce
RDX: 00007ff96a808fb0 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ff969a33eaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff969c26038 R14: 00007ff969c25fa0 R15: 00007ffdbbe03728
 </TASK>
INFO: task syz-executor:1317 blocked for more than 126 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:0     pid:1317  tgid:1317  ppid:1      flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:6054 [inline]
 __schedule+0x1496/0x20b0 kernel/sched/core.c:7867
 __schedule_loop kernel/sched/core.c:7944 [inline]
 schedule+0xc5/0x240 kernel/sched/core.c:7959
 schedule_preempt_disabled+0x14/0x30 kernel/sched/core.c:8016
 __mutex_lock_common kernel/locking/mutex.c:707 [inline]
 __mutex_lock+0x902/0x1b90 kernel/locking/mutex.c:806
 __mutex_lock_slowpath+0xe/0x20 kernel/locking/mutex.c:1136
 mutex_lock+0x113/0x1d0 kernel/locking/mutex.c:285
 rtnl_lock net/core/rtnetlink.c:79 [inline]
 rtnetlink_rcv_msg+0x79e/0xa40 net/core/rtnetlink.c:6676
 netlink_rcv_skb+0x24a/0x4e0 net/netlink/af_netlink.c:2545
 rtnetlink_rcv+0x20/0x30 net/core/rtnetlink.c:6697
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x8bc/0xa70 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x7d1/0xad0 net/netlink/af_netlink.c:1889
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 __sys_sendto+0x68a/0x700 net/socket.c:2216
 __do_sys_sendto net/socket.c:2228 [inline]
 __se_sys_sendto net/socket.c:2224 [inline]
 __x64_sys_sendto+0xe9/0x100 net/socket.c:2224
 x64_sys_call+0x2c2c/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:45
 do_syscall_x64 arch/x86/entry/common.c:47 [inline]
 do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f8bded59017
RSP: 002b:00007ffde98232d0 EFLAGS: 00000202 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 0000555584c24500 RCX: 00007f8bded59017
RDX: 0000000000000028 RSI: 00007f8bdfb54670 RDI: 0000000000000003
RBP: 0000000000000001 R08: 00007ffde9823334 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000003
R13: 0000000000000000 R14: 00007f8bdfb54670 R15: 0000000000000000
 </TASK>
INFO: task syz-executor:1319 blocked for more than 126 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:0     pid:1319  tgid:1319  ppid:1      flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:6054 [inline]
 __schedule+0x1496/0x20b0 kernel/sched/core.c:7867
 __schedule_loop kernel/sched/core.c:7944 [inline]
 schedule+0xc5/0x240 kernel/sched/core.c:7959
 schedule_preempt_disabled+0x14/0x30 kernel/sched/core.c:8016
 __mutex_lock_common kernel/locking/mutex.c:707 [inline]
 __mutex_lock+0x902/0x1b90 kernel/locking/mutex.c:806
 __mutex_lock_slowpath+0xe/0x20 kernel/locking/mutex.c:1136
 mutex_lock+0x113/0x1d0 kernel/locking/mutex.c:285
 rtnl_lock net/core/rtnetlink.c:79 [inline]
 rtnetlink_rcv_msg+0x79e/0xa40 net/core/rtnetlink.c:6676
 netlink_rcv_skb+0x24a/0x4e0 net/netlink/af_netlink.c:2545
 rtnetlink_rcv+0x20/0x30 net/core/rtnetlink.c:6697
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x8bc/0xa70 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x7d1/0xad0 net/netlink/af_netlink.c:1889
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 __sys_sendto+0x68a/0x700 net/socket.c:2216
 __do_sys_sendto net/socket.c:2228 [inline]
 __se_sys_sendto net/socket.c:2224 [inline]
 __x64_sys_sendto+0xe9/0x100 net/socket.c:2224
 x64_sys_call+0x2c2c/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:45
 do_syscall_x64 arch/x86/entry/common.c:47 [inline]
 do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7fac6c559017
RSP: 002b:00007ffe65bbf330 EFLAGS: 00000202 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 0000555589af0500 RCX: 00007fac6c559017
RDX: 0000000000000028 RSI: 00007fac6d354670 RDI: 0000000000000003
RBP: 0000000000000001 R08: 00007ffe65bbf394 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000003
R13: 0000000000000000 R14: 00007fac6d354670 R15: 0000000000000000
 </TASK>
INFO: task syz-executor:1321 blocked for more than 127 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:R  running task     stack:0     pid:1321  tgid:1321  ppid:1      flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:6054 [inline]
 __schedule+0x1496/0x20b0 kernel/sched/core.c:7867
 __schedule_loop kernel/sched/core.c:7944 [inline]
 schedule+0xc5/0x240 kernel/sched/core.c:7959
 exp_funnel_lock kernel/rcu/tree_exp.h:322 [inline]
 synchronize_rcu_expedited+0x50e/0x960 kernel/rcu/tree_exp.h:978
 namespace_unlock+0x248/0x450 fs/namespace.c:1720
 drop_collected_mounts fs/namespace.c:2248 [inline]
 put_mnt_ns+0xad/0xf0 fs/namespace.c:5655
 free_nsproxy+0x52/0x290 kernel/nsproxy.c:193
 put_nsproxy include/linux/nsproxy.h:118 [inline]
 switch_task_namespaces kernel/nsproxy.c:251 [inline]
 exit_task_namespaces+0x99/0xe0 kernel/nsproxy.c:256
 do_exit+0xa41/0x2850 kernel/exit.c:954
 do_group_exit+0x21f/0x2f0 kernel/exit.c:1098
 get_signal+0x134c/0x1490 kernel/signal.c:2933
 arch_do_signal_or_restart+0xbc/0x700 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x57/0xb0 kernel/entry/common.c:218
 do_syscall_64+0x63/0xf0 arch/x86/entry/common.c:84
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f19fab59017
RSP: 002b:00007ffee978fda0 EFLAGS: 00000202 ORIG_RAX: 000000000000002c
RAX: 0000000000000028 RBX: 000055556048e500 RCX: 00007f19fab59017
RDX: 0000000000000028 RSI: 00007f19fb954670 RDI: 0000000000000003
RBP: 0000000000000001 R08: 00007ffee978fe04 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000003
R13: 0000000000000000 R14: 00007f19fb954670 R15: 0000000000000000
 </TASK>
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 37 Comm: khungtaskd Not tainted syzkaller #0 5adf726ab28801c07fd45706e49e1b3a66128c4b
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:94
 dump_stack_lvl+0x140/0x1c0 lib/dump_stack.c:120
 dump_stack+0x19/0x20 lib/dump_stack.c:129
 nmi_cpu_backtrace+0x2ba/0x2d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x142/0x2c0 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:41
 trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:267 [inline]
 watchdog+0xe45/0xf90 kernel/hung_task.c:423
 kthread+0x2c7/0x360 kernel/kthread.c:389
 ret_from_fork+0x67/0xa0 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted syzkaller #0 5adf726ab28801c07fd45706e49e1b3a66128c4b
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:116
Code: cc cc cc cc cc cc cc b8 97 4a eb 13 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 23 d9 43 00 55 48 89 e5 fb f4 <5d> c3 cc cc cc cc cc cc cc cc cc cc cc b8 00 00 00 00 90 90 90 90
RSP: 0018:ffffc900001a7e00 EFLAGS: 000002c2
RAX: ffff8881f6f00000 RBX: ffff888103669300 RCX: ffffffff85a384fd
RDX: 0000000000000001 RSI: 0000000000000004 RDI: 000000000015786c
RBP: ffffc900001a7e00 R08: ffff8881f6f395eb R09: 1ffff1103ede72bd
R10: dffffc0000000000 R11: ffffed103ede72be R12: 0000000000000000
R13: 1ffff110206cd260 R14: dffffc0000000000 R15: ffffffff87ecb2a8
FS:  0000000000000000(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000562c64f91af8 CR3: 000000010cb3a000 CR4: 00000000003526b0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:-1 [inline]
 default_idle+0x17/0x30 arch/x86/kernel/process.c:754
 arch_cpu_idle+0xd/0x20 arch/x86/kernel/process.c:791
 default_idle_call+0x3e/0x80 kernel/sched/idle.c:117
 cpuidle_idle_call kernel/sched/idle.c:193 [inline]
 do_idle+0x2fc/0x570 kernel/sched/idle.c:346
 cpu_startup_entry+0x47/0x60 kernel/sched/idle.c:445
 start_secondary+0x12e/0x140 arch/x86/kernel/smpboot.c:314
 common_startup_64+0x13b/0x157
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/20 05:42 android16-6.12 0fd55a309793 72524a66 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in __lru_add_drain_all
2026/05/21 15:30 android16-6.12 9d40b257ba08 e195359d .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in __lru_add_drain_all
* Struck through repros no longer work on HEAD.