[v6.1] INFO: task hung in set_blocksize

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8ce36b2849ef Linux 6.1.163
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=169ca722580000
kernel config: https://syzkaller.appspot.com/x/.config?x=b1adc0bfde2d8a4a
dashboard link: https://syzkaller.appspot.com/bug?extid=f0f2bb3bfa0eb2e0f004
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
userspace arch: arm64

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e71ac74ccc11/disk-8ce36b28.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a090f33b3222/vmlinux-8ce36b28.xz
kernel image: https://storage.googleapis.com/syzbot-assets/13fb3beccc73/Image-8ce36b28.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f0f2bb...@syzkaller.appspotmail.com

INFO: task syz.0.924:7403 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.924 state:D stack:0 pid:7403 ppid:4321 flags:0x00000009
Call trace:
__switch_to+0x2f4/0x550 arch/arm64/kernel/process.c:555
context_switch kernel/sched/core.c:5245 [inline]
__schedule+0xdd0/0x1b0c kernel/sched/core.c:6562
schedule+0xc4/0x170 kernel/sched/core.c:6638
rwsem_down_write_slowpath+0xb60/0x1280 kernel/locking/rwsem.c:1189
__down_write_common kernel/locking/rwsem.c:1314 [inline]
__down_write kernel/locking/rwsem.c:1323 [inline]
down_write+0x84/0x88 kernel/locking/rwsem.c:1574
filemap_invalidate_lock include/linux/fs.h:803 [inline]
set_blocksize+0x1c8/0x3f8 block/bdev.c:161
sb_set_blocksize block/bdev.c:178 [inline]
sb_min_blocksize+0xb8/0x184 block/bdev.c:194
fat_fill_super+0x1570/0x3d30 fs/fat/inode.c:1650
msdos_fill_super+0x40/0x54 fs/fat/namei_msdos.c:655
mount_bdev+0x264/0x358 fs/super.c:1443
msdos_mount+0x44/0x58 fs/fat/namei_msdos.c:662
legacy_get_tree+0xd4/0x16c fs/fs_context.c:632
vfs_get_tree+0x90/0x274 fs/super.c:1573
do_new_mount+0x228/0x810 fs/namespace.c:3078
path_mount+0x5bc/0xe80 fs/namespace.c:3408
do_mount fs/namespace.c:3421 [inline]
__do_sys_mount fs/namespace.c:3629 [inline]
__se_sys_mount fs/namespace.c:3606 [inline]
__arm64_sys_mount+0x49c/0x59c fs/namespace.c:3606
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b4 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204
el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
#0: ffff8000153e7c30 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x40/0xbb4 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
#0: ffff8000153e8450 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x40/0xbb4 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/28:
#0: ffff8000153e72c0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0xc/0x44 include/linux/rcupdate.h:349
1 lock held by udevd/3936:
2 locks held by getty/4078:
#0: ffff0000d8d68098 (&tty->ldisc_sem){++++}-{0:0}, at: ldsem_down_read+0x3c/0x4c drivers/tty/tty_ldsem.c:340
#1: ffff80001cfe62f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x2ec/0xfa0 drivers/tty/n_tty.c:2198
3 locks held by kworker/u4:6/4419:
#0: ffff0000c0029138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x6b8/0x13a4 kernel/workqueue.c:2265
#1: ffff800020f47c20 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x6fc/0x13a4 kernel/workqueue.c:2267
#2: ffff80001787f1c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock+0x20/0x2c net/core/rtnetlink.c:74
1 lock held by syz.3.742/6774:
3 locks held by syz.0.924/7403:
#0: ffff0001112380e0 (&type->s_umount_key#61/1){+.+.}-{3:3}, at: alloc_super+0x1a4/0x800 fs/super.c:228
#1: ffff0000c04a5f38 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
#1: ffff0000c04a5f38 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: set_blocksize+0x190/0x3f8 block/bdev.c:160
#2: ffff0000c04a60d8 (mapping.invalidate_lock){++++}-{3:3}, at: filemap_invalidate_lock include/linux/fs.h:803 [inline]
#2: ffff0000c04a60d8 (mapping.invalidate_lock){++++}-{3:3}, at: set_blocksize+0x1c8/0x3f8 block/bdev.c:161
1 lock held by udevd/10037:
#0: ffff00019f578198 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:538 [inline]
#0: ffff00019f578198 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock kernel/sched/sched.h:1362 [inline]
#0: ffff00019f578198 (&rq->__lock){-.-.}-{2:2}, at: rq_lock kernel/sched/sched.h:1652 [inline]
#0: ffff00019f578198 (&rq->__lock){-.-.}-{2:2}, at: __schedule+0x2b8/0x1b0c kernel/sched/core.c:6478
1 lock held by udevd/10039:
#0: ffff00019f557198 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:538 [inline]
#0: ffff00019f557198 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock kernel/sched/sched.h:1362 [inline]
#0: ffff00019f557198 (&rq->__lock){-.-.}-{2:2}, at: rq_lock kernel/sched/sched.h:1652 [inline]
#0: ffff00019f557198 (&rq->__lock){-.-.}-{2:2}, at: __schedule+0x2b8/0x1b0c kernel/sched/core.c:6478
1 lock held by syz.2.1800/10042:
#0: ffff80001787f1c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock+0x20/0x2c net/core/rtnetlink.c:74
2 locks held by syz.1.1805/10059:
#0: ffff0000d20aa0f0 (&smc->clcsock_release_lock){+.+.}-{3:3}, at: smc_setsockopt+0x158/0xbfc net/smc/af_smc.c:2977
#1: ffff80001787f1c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock+0x20/0x2c net/core/rtnetlink.c:74
1 lock held by syz.1.1805/10062:
#0: ffff0000d20aa0f0 (&smc->clcsock_release_lock){+.+.}-{3:3}, at: smc_getsockopt+0x15c/0x460 net/smc/af_smc.c:3057
1 lock held by syz.6.1808/10067:
#0: ffff80001787f1c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
#0: ffff80001787f1c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x650/0xcdc net/core/rtnetlink.c:6147
1 lock held by syz.6.1808/10071:
#0: ffff80001787f1c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
#0: ffff80001787f1c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x650/0xcdc net/core/rtnetlink.c:6147
1 lock held by syz.5.1809/10069:
#0: ffff80001787f1c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock+0x20/0x2c net/core/rtnetlink.c:74
1 lock held by syz.5.1809/10074:
#0: ffff80001787f1c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock+0x20/0x2c net/core/rtnetlink.c:74
4 locks held by syz.4.1811/10080:
#0: ffff0000d4192098 (&tty->ldisc_sem){++++}-{0:0}, at: ldsem_down_write+0x3c/0x4c drivers/tty/tty_ldsem.c:366
#1: ffff0000d46a7098 (&tty->ldisc_sem/1){+.+.}-{0:0}, at: ldsem_down_write_nested+0x44/0x58 drivers/tty/tty_ldsem.c:427
#2: ffff0000f84920b0 (&gsm->mutex){+.+.}-{3:3}, at: gsm_cleanup_mux+0xac/0x7e4 drivers/tty/n_gsm.c:2542
#3: ffff0000c0023148 (&root->kernfs_rwsem){++++}-{3:3}, at: kernfs_remove_by_name_ns+0x78/0x180 fs/kernfs/dir.c:1662

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