[syzbot] [crypto?] INFO: task hung in hwrng_fillfn

From: syzbot
Date: Sat Nov 25 2023 - 08:21:33 EST

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Hello,

syzbot found the following issue on:

HEAD commit: 98b1cc82c4af Linux 6.7-rc2
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12e89e10e80000
kernel config: https://syzkaller.appspot.com/x/.config?x=6ae1a4ee971a7305
dashboard link: https://syzkaller.appspot.com/bug?extid=c52ab18308964d248092
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=174f0bd4e80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14b83b84e80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/39c6cdad13fc/disk-98b1cc82.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5a77b5daef9b/vmlinux-98b1cc82.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5e09ae712e0d/bzImage-98b1cc82.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c52ab18308964d248092@xxxxxxxxxxxxxxxxxxxxxxxxx

INFO: task hwrng:749 blocked for more than 143 seconds.
Not tainted 6.7.0-rc2-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:hwrng state:D stack:29040 pid:749 tgid:749 ppid:2 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5376 [inline]
__schedule+0xedb/0x5af0 kernel/sched/core.c:6688
__schedule_loop kernel/sched/core.c:6763 [inline]
schedule+0xe9/0x270 kernel/sched/core.c:6778
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6835
__mutex_lock_common kernel/locking/mutex.c:679 [inline]
__mutex_lock+0x5b9/0x9d0 kernel/locking/mutex.c:747
hwrng_fillfn+0x145/0x430 drivers/char/hw_random/core.c:504
kthread+0x2c6/0x3a0 kernel/kthread.c:388
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242
</TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/29:
#0: ffffffff8cfabce0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:301 [inline]
#0: ffffffff8cfabce0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:747 [inline]
#0: ffffffff8cfabce0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x75/0x340 kernel/locking/lockdep.c:6613
2 locks held by kswapd0/86:
1 lock held by hwrng/749:
#0: ffffffff8dbafee8 (reading_mutex){+.+.}-{3:3}, at: hwrng_fillfn+0x145/0x430 drivers/char/hw_random/core.c:504
2 locks held by getty/4824:
#0: ffff888025fa10a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
#1: ffffc90002f062f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0xfc6/0x1490 drivers/tty/n_tty.c:2201
2 locks held by syz-executor391/5105:
2 locks held by syz-executor391/5106:

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

NMI backtrace for cpu 1
CPU: 1 PID: 29 Comm: khungtaskd Not tainted 6.7.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
nmi_cpu_backtrace+0x277/0x390 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x299/0x300 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+0xf87/0x1210 kernel/hung_task.c:379
kthread+0x2c6/0x3a0 kernel/kthread.c:388
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242
</TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 5105 Comm: syz-executor391 Not tainted 6.7.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
RIP: 0010:__lock_acquire+0x30/0x3b10 kernel/locking/lockdep.c:4992
Code: f6 41 55 41 54 49 89 fc 55 89 d5 53 44 89 cb 48 81 ec f0 00 00 00 48 8b 84 24 28 01 00 00 48 c7 84 24 90 00 00 00 b3 8a b5 41 <44> 89 44 24 08 44 8b ac 24 48 01 00 00 48 c7 84 24 98 00 00 00 1b
RSP: 0018:ffffc900044271d8 EFLAGS: 00000086
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000002
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8cfabce0
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff8f1934d7 R11: 0000000000000002 R12: ffffffff8cfabce0
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS: 00007f3c785f96c0(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005565d7bb9be7 CR3: 000000001af30000 CR4: 0000000000350ef0
Call Trace:
<NMI>
</NMI>
<TASK>
lock_acquire kernel/locking/lockdep.c:5753 [inline]
lock_acquire+0x1ae/0x520 kernel/locking/lockdep.c:5718
rcu_lock_acquire include/linux/rcupdate.h:301 [inline]
rcu_read_lock include/linux/rcupdate.h:747 [inline]
get_mem_cgroup_from_mm+0x4b/0x4c0 mm/memcontrol.c:1081
__mem_cgroup_charge+0x1c/0x140 mm/memcontrol.c:7224
mem_cgroup_charge include/linux/memcontrol.h:684 [inline]
__filemap_add_folio+0x88c/0xed0 mm/filemap.c:854
filemap_add_folio+0xb1/0x1e0 mm/filemap.c:937
page_cache_ra_unbounded+0x1d0/0x5f0 mm/readahead.c:250
do_page_cache_ra mm/readahead.c:299 [inline]
page_cache_ra_order+0x72b/0xa80 mm/readahead.c:546
do_sync_mmap_readahead mm/filemap.c:3141 [inline]
filemap_fault+0x16a8/0x3570 mm/filemap.c:3233
__do_fault+0x107/0x600 mm/memory.c:4265
do_cow_fault mm/memory.c:4662 [inline]
do_fault mm/memory.c:4764 [inline]
do_pte_missing mm/memory.c:3730 [inline]
handle_pte_fault mm/memory.c:5038 [inline]
__handle_mm_fault+0x3a8d/0x3d70 mm/memory.c:5179
handle_mm_fault+0x47a/0xa10 mm/memory.c:5344
do_user_addr_fault+0x3d1/0x1000 arch/x86/mm/fault.c:1413
handle_page_fault arch/x86/mm/fault.c:1505 [inline]
exc_page_fault+0x5d/0xc0 arch/x86/mm/fault.c:1561
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570
RIP: 0010:rep_movs_alternative+0x57/0x70 arch/x86/lib/copy_user_64.S:80
Code: 00 66 90 48 8b 06 48 89 07 48 83 c6 08 48 83 c7 08 83 e9 08 74 df 83 f9 08 73 e8 eb c9 eb 01 c3 48 89 c8 48 c1 e9 03 83 e0 07 <f3> 48 a5 89 c1 85 c9 75 b3 c3 48 8d 0c c8 eb ac 66 0f 1f 84 00 00
RSP: 0018:ffffc90004427bb0 EFLAGS: 00050246
RAX: 0000000000000000 RBX: 0000000000000040 RCX: 0000000000000008
RDX: ffffed1028a4ab48 RSI: ffff888145255a00 RDI: 0000000020019980
RBP: 0000000020019980 R08: 0000000000000000 R09: ffffed1028a4ab47
R10: ffff888145255a3f R11: 0000000000000001 R12: ffff888145255a00
R13: 00000000200199c0 R14: 0000000000000000 R15: dffffc0000000000
copy_user_generic arch/x86/include/asm/uaccess_64.h:112 [inline]
raw_copy_to_user arch/x86/include/asm/uaccess_64.h:133 [inline]
_copy_to_user lib/usercopy.c:41 [inline]
_copy_to_user+0xa8/0xb0 lib/usercopy.c:34
copy_to_user include/linux/uaccess.h:191 [inline]
rng_dev_read+0x184/0x580 drivers/char/hw_random/core.c:255
do_loop_readv_writev fs/read_write.c:755 [inline]
do_loop_readv_writev fs/read_write.c:743 [inline]
do_iter_read+0x567/0x830 fs/read_write.c:797
vfs_readv+0x12d/0x1a0 fs/read_write.c:915
do_preadv fs/read_write.c:1007 [inline]
__do_sys_preadv fs/read_write.c:1057 [inline]
__se_sys_preadv fs/read_write.c:1052 [inline]
__x64_sys_preadv+0x228/0x300 fs/read_write.c:1052
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7f3c78638b29
Code: Unable to access opcode bytes at 0x7f3c78638aff.
RSP: 002b:00007f3c785f9168 EFLAGS: 00000246 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 00007f3c786c2328 RCX: 00007f3c78638b29
RDX: 0000000000000001 RSI: 0000000020001880 RDI: 0000000000000003
RBP: 00007f3c786c2320 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f3c786c232c
R13: 0000000000000000 R14: 00007ffc8a220310 R15: 00007ffc8a2203f8
</TASK>
INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.464 msecs

---
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