[syzbot] [fuse?] [ext4?] INFO: task hung in do_new_mount (4)

[syzbot <syzbot+2cb543a665f5f76997cb@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    38872197cae2 Merge branch 'for-next/fixes' into for-kernelci
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=126f64c9580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=56ed23170c168d4c
dashboard link: https://syzkaller.appspot.com/bug?extid=2cb543a665f5f76997cb
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
userspace arch: arm64
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1674e005580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c5963fdd6790/disk-38872197.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a8c2cab00c45/vmlinux-38872197.xz
kernel image: https://storage.googleapis.com/syzbot-assets/bde15d173380/Image-38872197.gz.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/47713ec0651b/mount_0.gz
  fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=146f64c9580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2cb543a665f5f76997cb@syzkaller.appspotmail.com

INFO: task syz.0.17:4913 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:0     pid:4913  tgid:4912  ppid:4820   task_flags:0x400140 flags:0x00800011
Call trace:
 __switch_to+0x2b4/0x6e4 arch/arm64/kernel/process.c:775 (T)
 context_switch kernel/sched/core.c:5526 [inline]
 __schedule+0x1370/0x2d80 kernel/sched/core.c:7277
 __schedule_loop kernel/sched/core.c:7354 [inline]
 schedule+0x13c/0x20c kernel/sched/core.c:7369
 schedule_preempt_disabled+0x18/0x2c kernel/sched/core.c:7426
 rwsem_down_write_slowpath+0x6ec/0x1174 kernel/locking/rwsem.c:1215
 __down_write_common kernel/locking/rwsem.c:1347 [inline]
 __down_write kernel/locking/rwsem.c:1356 [inline]
 down_write+0xb4/0xc0 kernel/locking/rwsem.c:1632
 inode_lock include/linux/fs.h:1024 [inline]
 do_lock_mount+0x158/0x63c fs/namespace.c:2768
 do_new_mount_fc fs/namespace.c:3790 [inline]
 do_new_mount+0x360/0x538 fs/namespace.c:3848
 path_mount+0x5f0/0xa88 fs/namespace.c:4168
 do_mount+0xe8/0x148 fs/namespace.c:4181
 __do_sys_mount fs/namespace.c:4397 [inline]
 __se_sys_mount fs/namespace.c:4374 [inline]
 __arm64_sys_mount+0x33c/0x388 fs/namespace.c:4374
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:758
 el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:777
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:590
INFO: task syz.0.17:4914 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:0     pid:4914  tgid:4912  ppid:4820   task_flags:0x400140 flags:0x00000011
Call trace:
 __switch_to+0x2b4/0x6e4 arch/arm64/kernel/process.c:775 (T)
 context_switch kernel/sched/core.c:5526 [inline]
 __schedule+0x1370/0x2d80 kernel/sched/core.c:7277
 __schedule_loop kernel/sched/core.c:7354 [inline]
 schedule+0x13c/0x20c kernel/sched/core.c:7369
 request_wait_answer fs/fuse/dev.c:749 [inline]
 __fuse_request_send fs/fuse/dev.c:768 [inline]
 fuse_chan_send+0x840/0xf60 fs/fuse/dev.c:844
 __fuse_simple_request+0xa0/0xb8 fs/fuse/req.c:69
 fuse_simple_request fs/fuse/fuse_i.h:1012 [inline]
 fuse_do_setattr+0xb34/0x1468 fs/fuse/dir.c:2248
 fuse_setattr+0x1f4/0x5e0 fs/fuse/dir.c:2373
 notify_change+0x928/0xb7c fs/attr.c:556
 chmod_common+0x200/0x3a4 fs/open.c:686
 do_fchmodat+0x10c/0x1f8 fs/open.c:731
 __do_sys_fchmodat fs/open.c:750 [inline]
 __se_sys_fchmodat fs/open.c:747 [inline]
 __arm64_sys_fchmodat+0x88/0xa0 fs/open.c:747
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:758
 el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:777
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:590

Showing all locks held in the system:
locks held by khungtaskd/31: 1, last CPU#0:
 #0: ffff800088d82260 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffff800088d82260 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffff800088d82260 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x4c/0x188 kernel/locking/lockdep.c:6871
locks held by kworker/u9:0/50: 3, on CPU#1:
 #0: ffff0000d8e34140 ((wq_completion)hci2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3371 [inline]
 #0: ffff0000d8e34140 ((wq_completion)hci2){+.+.}-{0:0}, at: process_scheduled_works+0x8c8/0x1250 kernel/workqueue.c:3479
 #1: ffff8000902f7c40 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3371 [inline]
 #1: ffff8000902f7c40 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_scheduled_works+0x8d0/0x1250 kernel/workqueue.c:3479
 #2: ffff0000d0df0ea0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_cmd_sync_work+0x178/0x374 net/bluetooth/hci_sync.c:331
locks held by kworker/u8:3/54: 5, last CPU#1:
 #0: ffff0000c004c140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3371 [inline]
 #0: ffff0000c004c140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x8c8/0x1250 kernel/workqueue.c:3479
 #1: ffff800090337c40 ((work_completion)(&(&nsim_dev->trap_data->trap_report_dw)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3371 [inline]
 #1: ffff800090337c40 ((work_completion)(&(&nsim_dev->trap_data->trap_report_dw)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x8d0/0x1250 kernel/workqueue.c:3479
 #2: ffff0001add89cd8 (&base->lock){-.-.}-{2:2}, at: devl_trylock+0x24/0x34 net/devlink/core.c:314
 #3: ffff0000d3bb38e0 (&nsim_trap_data->trap_lock){+.+.}-{3:3}, at: spin_lock include/linux/spinlock.h:347 [inline]
 #3: ffff0000d3bb38e0 (&nsim_trap_data->trap_lock){+.+.}-{3:3}, at: nsim_dev_trap_report drivers/net/netdevsim/dev.c:787 [inline]
 #3: ffff0000d3bb38e0 (&nsim_trap_data->trap_lock){+.+.}-{3:3}, at: nsim_dev_trap_report_work+0x168/0x9cc drivers/net/netdevsim/dev.c:847
 #4: ffff800088d82320 (rcu_read_lock_sched){....}-{1:2}, at: spin_lock_bh include/linux/spinlock.h:353 [inline]
 #4: ffff800088d82320 (rcu_read_lock_sched){....}-{1:2}, at: nsim_dev_trap_report drivers/net/netdevsim/dev.c:812 [inline]
 #4: ffff800088d82320 (rcu_read_lock_sched){....}-{1:2}, at: nsim_dev_trap_report_work+0x5ec/0x9cc drivers/net/netdevsim/dev.c:847
locks held by kworker/u8:6/1181: 1, last CPU#1:
 #0: ffff800088d82260 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffff800088d82260 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffff800088d82260 (rcu_read_lock){....}-{1:3}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #0: ffff800088d82260 (rcu_read_lock){....}-{1:3}, at: process_scheduled_works+0x698/0x1250 kernel/workqueue.c:3479
locks held by getty/4488: 2, on CPU#1:
 #0: ffff0000c94b40a0 (&tty->ldisc_sem){++++}-{0:0}, at: ldsem_down_read+0x3c/0x4c drivers/tty/tty_ldsem.c:340
 #1: ffff80009257e2e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x348/0xf78 drivers/tty/n_tty.c:2211
locks held by kworker/1:5/4772: 3, on CPU#1:
 #0: ffff0000c002b540 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3371 [inline]
 #0: ffff0000c002b540 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x8c8/0x1250 kernel/workqueue.c:3479
 #1: ffff80009b387c40 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3371 [inline]
 #1: ffff80009b387c40 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_scheduled_works+0x8d0/0x1250 kernel/workqueue.c:3479
 #2: ffff0000d4d66250 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x198/0x320 drivers/net/netdevsim/fib.c:1490
locks held by syz.0.17/4913: 1, on CPU#0:
 #0: ffff0000eeb44b80 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline]
 #0: ffff0000eeb44b80 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: do_lock_mount+0x158/0x63c fs/namespace.c:2768
locks held by syz.0.17/4914: 2, on CPU#1:
 #0: ffff0000d33d6460 (sb_writers#11){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:494
 #1: ffff0000eeb44b80 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: inode_lock_killable include/linux/fs.h:1029 [inline]
 #1: ffff0000eeb44b80 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: chmod_common+0x140/0x3a4 fs/open.c:678
locks held by syz.1.18/4956: 1, on CPU#1:
 #0: ffff0000eeb444c0 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline]
 #0: ffff0000eeb444c0 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: do_lock_mount+0x158/0x63c fs/namespace.c:2768
locks held by syz.1.18/4957: 2, on CPU#0:
 #0: ffff0000cfc96460 (sb_writers#11){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:494
 #1: ffff0000eeb444c0 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: inode_lock_killable include/linux/fs.h:1029 [inline]
 #1: ffff0000eeb444c0 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: chmod_common+0x140/0x3a4 fs/open.c:678
locks held by syz.2.19/5003: 1, on CPU#1:
 #0: ffff0000e0a7a300 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline]
 #0: ffff0000e0a7a300 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: do_lock_mount+0x158/0x63c fs/namespace.c:2768
locks held by syz.2.19/5005: 2, on CPU#1:
 #0: ffff0000c60bc460 (sb_writers#11){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:494
 #1: ffff0000e0a7a300 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: inode_lock_killable include/linux/fs.h:1029 [inline]
 #1: ffff0000e0a7a300 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: chmod_common+0x140/0x3a4 fs/open.c:678
locks held by syz.3.20/5051: 1, on CPU#0:
 #0: ffff0000e0a79c40 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline]
 #0: ffff0000e0a79c40 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: do_lock_mount+0x158/0x63c fs/namespace.c:2768
locks held by syz.3.20/5053: 2, on CPU#1:
 #0: ffff0000d120a460 (sb_writers#11){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:494
 #1: ffff0000e0a79c40 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: inode_lock_killable include/linux/fs.h:1029 [inline]
 #1: ffff0000e0a79c40 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: chmod_common+0x140/0x3a4 fs/open.c:678
locks held by syz.4.21/5105: 1, on CPU#0:
 #0: ffff0000eeb43e00 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline]
 #0: ffff0000eeb43e00 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: do_lock_mount+0x158/0x63c fs/namespace.c:2768
locks held by syz.4.21/5107: 2, on CPU#0:
 #0: ffff0000d9608460 (sb_writers#11){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:494
 #1: ffff0000eeb43e00 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: inode_lock_killable include/linux/fs.h:1029 [inline]
 #1: ffff0000eeb43e00 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: chmod_common+0x140/0x3a4 fs/open.c:678
locks held by syz.5.22/5154: 1, on CPU#1:
 #0: ffff0000e0a79580 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline]
 #0: ffff0000e0a79580 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: do_lock_mount+0x158/0x63c fs/namespace.c:2768
locks held by syz.5.22/5156: 2, on CPU#1:
 #0: ffff0000d4608460 (sb_writers#11){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:494
 #1: ffff0000e0a79580 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: inode_lock_killable include/linux/fs.h:1029 [inline]
 #1: ffff0000e0a79580 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: chmod_common+0x140/0x3a4 fs/open.c:678
locks held by syz.6.23/5202: 1, on CPU#0:
 #0: ffff0000e0a78ec0 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline]
 #0: ffff0000e0a78ec0 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: do_lock_mount+0x158/0x63c fs/namespace.c:2768
locks held by syz.6.23/5203: 2, on CPU#0:
 #0: ffff0000cb9ae460 (sb_writers#11){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:494
 #1: ffff0000e0a78ec0 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: inode_lock_killable include/linux/fs.h:1029 [inline]
 #1: ffff0000e0a78ec0 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: chmod_common+0x140/0x3a4 fs/open.c:678
locks held by syz.7.24/5256: 1, on CPU#1:
 #0: ffff0000e0a78800 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline]
 #0: ffff0000e0a78800 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: do_lock_mount+0x158/0x63c fs/namespace.c:2768
locks held by syz.7.24/5257: 2, on CPU#0:
 #0: ffff0000f2b3a460 (sb_writers#11){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:494
 #1: ffff0000e0a78800 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: inode_lock_killable include/linux/fs.h:1029 [inline]
 #1: ffff0000e0a78800 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: chmod_common+0x140/0x3a4 fs/open.c:678
locks held by syz.8.25/5304: 1, on CPU#1:
 #0: ffff0000eeb43740 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline]
 #0: ffff0000eeb43740 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: do_lock_mount+0x158/0x63c fs/namespace.c:2768
locks held by syz.8.25/5305: 2, on CPU#0:
 #0: ffff0000f2054460 (sb_writers#11){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:494
 #1: ffff0000eeb43740 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: inode_lock_killable include/linux/fs.h:1029 [inline]
 #1: ffff0000eeb43740 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: chmod_common+0x140/0x3a4 fs/open.c:678
locks held by syz.9.26/5354: 1, on CPU#1:
 #0: ffff0000eeb43080 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline]
 #0: ffff0000eeb43080 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: do_lock_mount+0x158/0x63c fs/namespace.c:2768
locks held by syz.9.26/5356: 2, on CPU#0:
 #0: ffff0000d454c460 (sb_writers#11){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:494
 #1: ffff0000eeb43080 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: inode_lock_killable include/linux/fs.h:1029 [inline]
 #1: ffff0000eeb43080 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: chmod_common+0x140/0x3a4 fs/open.c:678
locks held by syz.0.27/5397: 2, on CPU#0:
 #0: ffff0000ca324460 (sb_writers#11){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:494
 #1: ffff0000eeb429c0 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: inode_lock_killable include/linux/fs.h:1029 [inline]
 #1: ffff0000eeb429c0 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: chmod_common+0x140/0x3a4 fs/open.c:678

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



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