syzbot


INFO: task hung in iterate_supers

Status: upstream: reported C repro on 2025/06/20 00:37
Bug presence: origin:upstream
Labels: missing-backport
[Documentation on labels]
Reported-by: syzbot+739c128b5557abb9f816@syzkaller.appspotmail.com
First crash: 143d, last: 14h33m
Bug presence (3)
Date Name Commit Repro Result
2025/11/08 linux-6.6.y (ToT) 0a805b6ea8cd C [report] INFO: task hung in iterate_supers
2025/09/20 upstream (ToT) cd89d487374c C [report] INFO: task hung in __iterate_supers
2025/11/08 upstream (ToT) e811c33b1f13 C Didn't crash
Similar bugs (13)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-6-12 INFO: task hung in iterate_supers origin:upstream 1 C 1340 1h54m 141d 0/1 premoderation: reported C repro on 2025/06/21 16:44
android-414 INFO: task hung in iterate_supers 1 1 2568d 2405d 0/1 auto-closed as invalid on 2019/04/28 09:45
linux-4.14 INFO: task hung in iterate_supers 1 16 1776d 2390d 0/1 auto-closed as invalid on 2021/04/29 12:11
linux-4.19 INFO: task hung in iterate_supers (2) 1 1 1978d 1978d 0/1 auto-closed as invalid on 2020/10/09 12:15
upstream INFO: task hung in iterate_supers 9p 1 C error error 5804 58d 2680d 0/29 upstream: reported C repro on 2018/07/10 10:30
linux-5.15 INFO: task hung in iterate_supers origin:lts-only 1 C 346 4d00h 977d 0/3 upstream: reported C repro on 2023/03/08 18:22
linux-6.1 INFO: task hung in iterate_supers origin:upstream 1 C 318 3d11h 975d 0/3 upstream: reported C repro on 2023/03/10 21:24
linux-4.14 INFO: task hung in iterate_supers (2) 1 1 989d 989d 0/1 upstream: reported on 2023/02/24 15:59
linux-4.19 INFO: task hung in iterate_supers 1 7 2110d 2297d 0/1 auto-closed as invalid on 2020/05/29 21:42
linux-4.19 INFO: task hung in iterate_supers (3) vfs reiserfs ntfs 1 syz 378 979d 1786d 0/1 upstream: reported syz repro on 2020/12/20 03:38
android-49 INFO: task hung in iterate_supers 1 19 2629d 2730d 0/3 auto-closed as invalid on 2019/02/25 14:49
android-414 INFO: task hung in iterate_supers (2) 1 1 2387d 2387d 0/1 auto-closed as invalid on 2019/10/25 08:49
upstream INFO: task can't die in iterate_supers (2) ceph fs 1 1 1610d 1606d 0/29 auto-closed as invalid on 2021/08/13 03:51

Sample crash report:
INFO: task syz.0.17:5967 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.17        state:D stack:27248 pid:5967  ppid:5915   flags:0x00004006
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_read_slowpath+0x4f8/0x840 kernel/locking/rwsem.c:1086
 __down_read_common kernel/locking/rwsem.c:1250 [inline]
 __down_read kernel/locking/rwsem.c:1263 [inline]
 down_read+0x98/0x2e0 kernel/locking/rwsem.c:1522
 __super_lock fs/super.c:58 [inline]
 super_lock+0x167/0x360 fs/super.c:117
 super_lock_shared fs/super.c:146 [inline]
 iterate_supers+0x80/0x170 fs/super.c:977
 ksys_sync+0x95/0x150 fs/sync.c:102
 __ia32_sys_sync+0xe/0x20 fs/sync.c:113
 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: 0033:0x7f40b738efc9
RSP: 002b:00007f40b8197038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f40b75e6090 RCX: 00007f40b738efc9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f40b75e6090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f40b75e6128 R14: 00007f40b75e6090 R15: 00007fff36640c28
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/28:
 #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
3 locks held by klogd/5150:
 #0: ffff8880b8f3c218 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:558
 #1: ffff8880b8f289c0 (psi_seq){-.-.}-{0:0}, at: psi_sched_switch kernel/sched/stats.h:189 [inline]
 #1: ffff8880b8f289c0 (psi_seq){-.-.}-{0:0}, at: __schedule+0x20ee/0x44d0 kernel/sched/core.c:6694
 #2: ffff8880b8f289c0 (psi_seq){-.-.}-{0:0}, at: psi_sched_switch kernel/sched/stats.h:189 [inline]
 #2: ffff8880b8f289c0 (psi_seq){-.-.}-{0:0}, at: __schedule+0x20ee/0x44d0 kernel/sched/core.c:6694
2 locks held by getty/5549:
 #0: ffff88814ca550a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc900015d72f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x425/0x1380 drivers/tty/n_tty.c:2217
1 lock held by syz.0.17/5966:
 #0: ffff88802be980e0 (&type->s_umount_key#55/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x920 fs/super.c:352
1 lock held by syz.0.17/5967:
 #0: ffff88802be980e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88802be980e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
1 lock held by syz.1.18/5989:
 #0: ffff88802092e0e0 (&type->s_umount_key#55/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x920 fs/super.c:352
1 lock held by syz.1.18/5990:
 #0: ffff88802be980e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88802be980e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
1 lock held by syz.2.19/6019:
 #0: ffff88801f7960e0 (&type->s_umount_key#55/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x920 fs/super.c:352
1 lock held by syz.2.19/6020:
 #0: ffff88802be980e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88802be980e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
1 lock held by syz.3.20/6043:
 #0: ffff88801e2560e0 (&type->s_umount_key#55/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x920 fs/super.c:352
1 lock held by syz.3.20/6044:
 #0: ffff88802be980e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88802be980e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
1 lock held by syz.4.21/6072:
 #0: ffff8880223780e0 (&type->s_umount_key#55/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x920 fs/super.c:352
1 lock held by syz.4.21/6073:
 #0: ffff88802be980e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88802be980e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
1 lock held by syz.5.22/6104:
 #0: ffff88807c81a0e0 (&type->s_umount_key#55/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x920 fs/super.c:352
1 lock held by syz.5.22/6106:
 #0: ffff88802be980e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88802be980e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
1 lock held by syz.6.23/6138:
 #0: ffff88805af540e0 (&type->s_umount_key#55/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x920 fs/super.c:352
1 lock held by syz.6.23/6139:
 #0: ffff88802be980e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88802be980e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
1 lock held by syz.7.24/6167:
 #0: ffff88807f73e0e0 (&type->s_umount_key#55/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x920 fs/super.c:352
1 lock held by syz.7.24/6168:
 #0: ffff88802be980e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88802be980e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
1 lock held by syz.8.25/6197:
 #0: ffff8880617960e0 (&type->s_umount_key#55/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x920 fs/super.c:352
1 lock held by syz.8.25/6198:
 #0: ffff88802be980e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88802be980e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
1 lock held by syz-executor/6207:
2 locks held by dhcpcd/6206:
 #0: ffff88805fbaa130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1767 [inline]
 #0: ffff88805fbaa130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x32/0xcc0 net/packet/af_packet.c:3258
 #1: ffffffff8cd358f8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:292 [inline]
 #1: ffffffff8cd358f8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x448/0x830 kernel/rcu/tree_exp.h:1004

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

NMI backtrace for cpu 0
CPU: 0 PID: 28 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
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 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 6212 Comm: modprobe Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:mas_destroy+0x1889/0x1fc0 lib/maple_tree.c:5579
Code: 6d 35 81 f7 48 8b 73 18 48 89 df e8 a1 02 02 00 48 89 df e8 29 f2 01 00 43 0f b6 04 27 84 c0 0f 85 5e 03 00 00 41 80 65 00 fd <43> 0f b6 04 27 84 c0 0f 85 f8 02 00 00 80 63 3a fa 48 83 c3 30 49
RSP: 0018:ffffc90004a2f5c0 EFLAGS: 00000293
RAX: ffffffff8a5b9c5c RBX: ffffc90004a2fe40 RCX: ffff88801b701e00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90004a2f8b0 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff2e580bc R12: dffffc0000000000
R13: ffffc90004a2fe7a R14: 0000000000000000 R15: 1ffff92000945fcf
FS:  00007fcde5a97c80(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fcde5dff000 CR3: 000000002f4b5000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 mas_store_prealloc+0x2a4/0x3c0 lib/maple_tree.c:5463
 vma_complete+0x207/0xb40 mm/mmap.c:532
 __split_vma+0xa93/0xc00 mm/mmap.c:2425
 mprotect_fixup+0xaad/0xc90 mm/mprotect.c:650
 do_mprotect_pkey+0x76e/0xc30 mm/mprotect.c:819
 __do_sys_mprotect mm/mprotect.c:840 [inline]
 __se_sys_mprotect mm/mprotect.c:837 [inline]
 __x64_sys_mprotect+0x80/0x90 mm/mprotect.c:837
 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: 0033:0x7fcde5e262c7
Code: 89 3d fd 3f 01 00 eb 90 0f 1f 00 f7 d8 89 05 f0 3f 01 00 48 c7 c0 ff ff ff ff eb 91 0f 1f 80 00 00 00 00 b8 0a 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8d 0d c9 3f 01 00 f7 d8 89 01 48 83
RSP: 002b:00007ffff1758f18 EFLAGS: 00000206 ORIG_RAX: 000000000000000a
RAX: ffffffffffffffda RBX: 00007fcde5e39da0 RCX: 00007fcde5e262c7
RDX: 0000000000000001 RSI: 0000000000002000 RDI: 00007fcde5e37000
RBP: 00007ffff17591e0 R08: 000000003de00ec7 R09: 0000000000000000
R10: 00007fcde5b72c58 R11: 0000000000000206 R12: fffffffffffffff8
R13: 0000009b0de98e52 R14: 0000000000000000 R15: 00007fcde5e3a310
 </TASK>

Crashes (24):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/10/24 20:47 linux-6.6.y 4a243110dc88 c0460fcd .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/10/12 11:25 linux-6.6.y e617101e5626 ff1712fe .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/09/09 17:22 linux-6.6.y 355bd0b51d2f d291dd2d .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/11/09 22:41 linux-6.6.y 0a805b6ea8cd 4e1406b4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/10/25 12:13 linux-6.6.y 4a243110dc88 c0460fcd .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/10/20 22:09 linux-6.6.y f231f248323d d422939c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/10/19 22:50 linux-6.6.y f231f248323d 1c8c8cd8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/10/17 19:02 linux-6.6.y 0bbbd97a442d 7adf5298 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/10/17 18:25 linux-6.6.y 0bbbd97a442d 7adf5298 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/10/17 18:22 linux-6.6.y 0bbbd97a442d 7adf5298 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/10/17 02:52 linux-6.6.y 0bbbd97a442d 19568248 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/10/17 02:41 linux-6.6.y 0bbbd97a442d 19568248 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/09/14 17:36 linux-6.6.y 60a9e718726f e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/09/07 11:55 linux-6.6.y 355bd0b51d2f d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/08/31 10:57 linux-6.6.y cc1a1c5b404a 807a3b61 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/08/29 08:31 linux-6.6.y cc1a1c5b404a d401b9d7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/08/29 08:26 linux-6.6.y cc1a1c5b404a d401b9d7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/08/24 20:47 linux-6.6.y bb9c90ab9c5a bf27483f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/08/11 23:11 linux-6.6.y 3a8ababb8b6a c06e8995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/08/10 02:06 linux-6.6.y 3a8ababb8b6a 32a0e5ed .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/07/28 13:31 linux-6.6.y dbcb8d8e4163 fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/07/12 09:46 linux-6.6.y 59a2de10b81a 3cda49cf .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/07/09 01:03 linux-6.6.y a5df3a702b2c 4d9fdfa4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/06/20 00:37 linux-6.6.y 6282921b6825 ed3e87f7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
* Struck through repros no longer work on HEAD.