INFO: task syz.4.1902:14226 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.1902 state:D stack:26232 pid:14226 tgid:14222 ppid:12555 task_flags:0x400140 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5325 [inline]
__schedule+0x1190/0x5de0 kernel/sched/core.c:6929
__schedule_loop kernel/sched/core.c:7011 [inline]
schedule+0xe7/0x3a0 kernel/sched/core.c:7026
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7083
__mutex_lock_common kernel/locking/mutex.c:676 [inline]
__mutex_lock+0x818/0x1060 kernel/locking/mutex.c:760
expkey_flush+0x20/0x90 fs/nfsd/export.c:250
write_flush.constprop.0+0x2af/0x3d0 net/sunrpc/cache.c:1550
pde_write fs/proc/inode.c:330 [inline]
proc_reg_write+0x240/0x330 fs/proc/inode.c:342
do_loop_readv_writev fs/read_write.c:850 [inline]
do_loop_readv_writev fs/read_write.c:835 [inline]
vfs_writev+0x5df/0xde0 fs/read_write.c:1059
do_writev+0x132/0x340 fs/read_write.c:1103
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f98af58f749
RSP: 002b:00007f98b03be038 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 00007f98af7e6090 RCX: 00007f98af58f749
RDX: 000000000000000a RSI: 0000200000000200 RDI: 0000000000000005
RBP: 00007f98af613f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f98af7e6128 R14: 00007f98af7e6090 R15: 00007ffc8ef82508
Showing all locks held in the system:
1 lock held by khungtaskd/31:
#0: ffffffff8e3c45e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
#0: ffffffff8e3c45e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
#0: ffffffff8e3c45e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6775
2 locks held by getty/5590:
#0: ffff888030dee0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
#1: ffffc9000332b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x41b/0x14f0 drivers/tty/n_tty.c:2222
2 locks held by syz-executor/5829:
#0: ffff88807af040e0 (&type->s_umount_key#51){+.+.}-{4:4}, at: __super_lock fs/super.c:57 [inline]
#0: ffff88807af040e0 (&type->s_umount_key#51){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
#0: ffff88807af040e0 (&type->s_umount_key#51){+.+.}-{4:4}, at: deactivate_super fs/super.c:505 [inline]
#0: ffff88807af040e0 (&type->s_umount_key#51){+.+.}-{4:4}, at: deactivate_super+0xd6/0x100 fs/super.c:502
#1: ffffffff8e7ed348 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:593
2 locks held by kworker/u8:8/7218:
#0: ffff888147691148 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3238
#1: ffffc900181ffd00 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3239
4 locks held by kworker/u8:16/7228:
#0: ffff88801ba9f148 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3238
#1: ffffc9001845fd00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3239
#2: ffffffff900d4e90 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xad/0x8b0 net/core/net_namespace.c:669
#3: ffffffff8e3cfb78 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x284/0x3c0 kernel/rcu/tree_exp.h:311
2 locks held by kworker/u8:34/12222:
#0: ffff888147691148 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3238
#1: ffffc90003927d00 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3239
2 locks held by syz.2.1444/12245:
#0: ffffffff9018f090 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
#1: ffffffff8e7ed348 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0xd5/0x1b10 fs/nfsd/nfsctl.c:1880
3 locks held by syz.4.1902/14226:
#0: ffff8880292d2b78 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2a2/0x370 fs/file.c:1232
#1: ffff88802f954420 (sb_writers#3){.+.+}-{0:0}, at: do_writev+0x132/0x340 fs/read_write.c:1103
#2: ffffffff8e7ed348 (nfsd_mutex){+.+.}-{4:4}, at: expkey_flush+0x20/0x90 fs/nfsd/export.c:250
2 locks held by syz-executor/14328:
#0: ffff888057b300e0 (&type->s_umount_key#51){+.+.}-{4:4}, at: __super_lock fs/super.c:57 [inline]
#0: ffff888057b300e0 (&type->s_umount_key#51){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
#0: ffff888057b300e0 (&type->s_umount_key#51){+.+.}-{4:4}, at: deactivate_super fs/super.c:505 [inline]
#0: ffff888057b300e0 (&type->s_umount_key#51){+.+.}-{4:4}, at: deactivate_super+0xd6/0x100 fs/super.c:502
#1: ffffffff8e7ed348 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:593
2 locks held by syz.6.2214/15754:
#0: ffffffff9018f090 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
#1: ffffffff8e7ed348 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x687/0xbc0 fs/nfsd/nfsctl.c:1590
2 locks held by syz-executor/15983:
#0: ffff88805d1e40e0 (&type->s_umount_key#51){+.+.}-{4:4}, at: __super_lock fs/super.c:57 [inline]
#0: ffff88805d1e40e0 (&type->s_umount_key#51){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
#0: ffff88805d1e40e0 (&type->s_umount_key#51){+.+.}-{4:4}, at: deactivate_super fs/super.c:505 [inline]
#0: ffff88805d1e40e0 (&type->s_umount_key#51){+.+.}-{4:4}, at: deactivate_super+0xd6/0x100 fs/super.c:502
#1: ffffffff8e7ed348 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:593
2 locks held by syz-executor/16043:
#0: ffff8880299740e0 (&type->s_umount_key#51){+.+.}-{4:4}, at: __super_lock fs/super.c:57 [inline]
#0: ffff8880299740e0 (&type->s_umount_key#51){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
#0: ffff8880299740e0 (&type->s_umount_key#51){+.+.}-{4:4}, at: deactivate_super fs/super.c:505 [inline]
#0: ffff8880299740e0 (&type->s_umount_key#51){+.+.}-{4:4}, at: deactivate_super+0xd6/0x100 fs/super.c:502
#1: ffffffff8e7ed348 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:593
4 locks held by syz.3.2304/16266:
=============================================
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
nmi_cpu_backtrace+0x27b/0x390 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x29c/0x300 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:332 [inline]
watchdog+0xf3f/0x1170 kernel/hung_task.c:495
kthread+0x3c5/0x780 kernel/kthread.c:463
ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 16266 Comm: syz.3.2304 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:27 [inline]
RIP: 0010:check_kcov_mode kernel/kcov.c:183 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x10/0x70 kernel/kcov.c:217
Code: 00 00 5b e9 f2 83 e5 02 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 8b 34 24 65 48 8b 15 88 d8 e4 11 <65> 8b 05 99 d8 e4 11 a9 00 01 ff 00 74 1d f6 c4 01 74 43 a9 00 00
RSP: 0018:ffffc9000475da38 EFLAGS: 00000202
RAX: 0000000000000000 RBX: 0000000000000040 RCX: ffffffff84aa83cb
RDX: ffff888034901e40 RSI: ffffffff84aa749e RDI: 0000000000000001
RBP: ffffffff8eecefe1 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000040 R11: ffff888034990030 R12: 0000000000000001
R13: dffffc0000000000 R14: 0000000000000008 R15: 0000000000000000
FS: 00007fe33d0516c0(0000) GS:ffff888124a0d000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe33c3b5000 CR3: 000000006727e000 CR4: 00000000003526f0
Call Trace:
add_template lib/842/842_compress.c:290 [inline]
process_next lib/842/842_compress.c:460 [inline]
sw842_compress+0x1d9e/0x46b0 lib/842/842_compress.c:545
crypto_scomp_decompress include/crypto/internal/scompress.h:79 [inline]
scomp_acomp_comp_decomp+0x719/0xd20 crypto/scompress.c:256
crypto_acomp_compress+0x14c/0x520 crypto/acompress.c:291
zswap_compress mm/zswap.c:886 [inline]
zswap_store_page mm/zswap.c:1429 [inline]
zswap_store+0xab3/0x2830 mm/zswap.c:1540
swap_writeout+0x3f4/0x1090 mm/page_io.c:275
shmem_writeout+0xc29/0x1140 mm/shmem.c:1642
writeout mm/vmscan.c:660 [inline]
pageout mm/vmscan.c:721 [inline]
shrink_folio_list+0x2f45/0x4800 mm/vmscan.c:1453
shrink_inactive_list mm/vmscan.c:2051 [inline]
shrink_list mm/vmscan.c:2288 [inline]
shrink_lruvec+0xf46/0x2b00 mm/vmscan.c:5852
shrink_node_memcgs mm/vmscan.c:6054 [inline]
shrink_node+0x982/0x3d80 mm/vmscan.c:6095
shrink_zones mm/vmscan.c:6339 [inline]
do_try_to_free_pages+0x362/0x1920 mm/vmscan.c:6401
try_to_free_mem_cgroup_pages+0x31b/0x790 mm/vmscan.c:6729
try_charge_memcg+0x42a/0xd30 mm/memcontrol.c:2356
try_charge mm/memcontrol.c:2498 [inline]
charge_memcg+0x8a/0x230 mm/memcontrol.c:4701
__mem_cgroup_charge+0x2b/0x1e0 mm/memcontrol.c:4718
mem_cgroup_charge include/linux/memcontrol.h:662 [inline]
shmem_alloc_and_add_folio+0x50c/0xc20 mm/shmem.c:1922
shmem_get_folio_gfp+0x67f/0x1610 mm/shmem.c:2535
shmem_get_folio mm/shmem.c:2641 [inline]
shmem_write_begin+0x160/0x300 mm/shmem.c:3291
generic_perform_write+0x3c4/0x900 mm/filemap.c:4254
shmem_file_write_iter+0x10e/0x140 mm/shmem.c:3466
__kernel_write_iter+0x31a/0xb10 fs/read_write.c:619
dump_emit_page fs/coredump.c:1298 [inline]
dump_user_range+0x413/0xb70 fs/coredump.c:1372
elf_core_dump+0x29c3/0x3c00 fs/binfmt_elf.c:2111
coredump_write fs/coredump.c:1049 [inline]
vfs_coredump+0x2b9f/0x5670 fs/coredump.c:1170
get_signal+0x22e1/0x26d0 kernel/signal.c:3019
arch_do_signal_or_restart+0x8f/0x790 arch/x86/kernel/signal.c:337
exit_to_user_mode_loop kernel/entry/common.c:40 [inline]
exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
irqentry_exit_to_user_mode+0x176/0x310 kernel/entry/common.c:73
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
RIP: 0033:0x0
Code: Unable to access opcode bytes at 0xffffffffffffffd6.
RSP: 002b:000000000000000a EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007fe33c3e6360 RCX: 00007fe33c18f749
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000020003b46
RBP: 00007fe33c213f91 R08: 0000000000000002 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe33c3e63f8 R14: 00007fe33c3e6360 R15: 00007ffd6959a188