syzbot


INFO: task hung in do_madvise (2)

Status: auto-obsoleted due to no activity on 2026/06/13 19:12
Subsystems: mm
Labels: prio:high
[Documentation on labels]
First crash: 103d, last: 102d
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
0bdef709-66d9-49fe-ad80-aef15e006c94 assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ INFO: task hung in do_madvise (2) 2026/05/21 16:01 2026/05/21 16:01 2026/05/21 16:52 d57425845dbe663f86e1e54a4997e95bd557b624

			
		
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in do_madvise mm 1 3 334d 341d 0/29 auto-obsoleted due to no activity on 2025/10/24 18:25

Sample crash report:
INFO: task syz.5.1086:10093 blocked for more than 143 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.5.1086      state:D stack:27520 pid:10093 tgid:10089 ppid:8485   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5352 [inline]
 __schedule+0x1665/0x5590 kernel/sched/core.c:6964
 __schedule_loop kernel/sched/core.c:7047 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7062
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7119
 rwsem_down_read_slowpath+0x6d9/0x940 kernel/locking/rwsem.c:1114
 __down_read_common kernel/locking/rwsem.c:1291 [inline]
 __down_read kernel/locking/rwsem.c:1304 [inline]
 down_read+0x99/0x2e0 kernel/locking/rwsem.c:1570
 mmap_read_lock include/linux/mmap_lock.h:592 [inline]
 madvise_lock+0x152/0x2e0 mm/madvise.c:1779
 do_madvise+0x16d/0x2e0 mm/madvise.c:2016
 __do_sys_madvise mm/madvise.c:2029 [inline]
 __se_sys_madvise mm/madvise.c:2027 [inline]
 __x64_sys_madvise+0xa6/0xc0 mm/madvise.c:2027
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe91e19c799
RSP: 002b:00007fe91eff4028 EFLAGS: 00000246 ORIG_RAX: 000000000000001c
RAX: ffffffffffffffda RBX: 00007fe91e416180 RCX: 00007fe91e19c799
RDX: 0000000000000019 RSI: 0000000000600003 RDI: 0000200000000000
RBP: 00007fe91e232c99 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe91e416218 R14: 00007fe91e416180 R15: 00007ffe9b9a9288
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/30:
 #0: ffffffff8eb5d6a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 #0: ffffffff8eb5d6a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
 #0: ffffffff8eb5d6a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by getty/7272:
 #0: ffff888032ced0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc900067232e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13c0 drivers/tty/n_tty.c:2211
1 lock held by syz.5.1086/10093:
 #0: ffff8880768a8fb8 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock include/linux/mmap_lock.h:592 [inline]
 #0: ffff8880768a8fb8 (&mm->mmap_lock){++++}-{4:4}, at: madvise_lock+0x152/0x2e0 mm/madvise.c:1779
1 lock held by vhost-13548/13549:
1 lock held by syz.1.2042/13611:
 #0: ffffffff8eb637b8 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 30 Comm: khungtaskd Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
 __sys_info lib/sys_info.c:157 [inline]
 sys_info+0x135/0x170 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline]
 watchdog+0x1002/0x1060 kernel/hung_task.c:561
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 13549 Comm: vhost-13548 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:__lock_acquire+0x6d5/0x2cf0 kernel/locking/lockdep.c:5207
Code: ba 08 00 00 00 e8 6b 44 00 00 31 ed 85 c0 0f 84 6d 0d 00 00 83 3d 4a 77 cc 18 00 75 13 48 63 44 24 18 48 0f a3 05 5b e7 c8 12 <0f> 83 8a 1e 00 00 49 8b 9e 40 0b 00 00 48 83 7c 24 28 00 75 19 83
RSP: 0018:ffffc900037d7780 EFLAGS: 00000047
RAX: 000000000000099d RBX: ffff88807ee11e80 RCX: ffffffff941455d8
RDX: 0000000000000008 RSI: ffff88807ee129d0 RDI: ffff88807ee11e80
RBP: 0000000000000000 R08: ffffffff890c1890 R09: ffff88805e954c60
R10: ffffc900037d7a40 R11: fffff520006faf4d R12: ffffffffffffff05
R13: ffff88807ee129d0 R14: ffff88807ee11e80 R15: ffff88807ee129d0
FS:  00007f55006356c0(0000) GS:ffff888124de0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbb6f1e92f8 CR3: 000000004f494000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 lock_acquire+0xf0/0x2e0 kernel/locking/lockdep.c:5868
 __mutex_lock_common kernel/locking/mutex.c:632 [inline]
 __mutex_lock+0x19e/0x1420 kernel/locking/mutex.c:794
 vhost_vsock_handle_tx_kick+0x100/0x10a0 drivers/vhost/vsock.c:518
 vhost_run_work_list+0x14d/0x1e0 drivers/vhost/vhost.c:454
 vhost_task_fn+0x2ef/0x4a0 kernel/vhost_task.c:49
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/15 19:04 linux-next b84a0ebe421c ee8d34d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in do_madvise
2026/03/15 02:48 linux-next b84a0ebe421c ee8d34d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in do_madvise
* Struck through repros no longer work on HEAD.