BUG: soft lockup in generic_file_write_iter

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: bf82d38c91f8 Merge tag 'for-linus' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17944a4b880000
kernel config: https://syzkaller.appspot.com/x/.config?x=fb4483b4e2bccae2
dashboard link: https://syzkaller.appspot.com/bug?extid=0637d73bbc422e2b91ba
compiler: aarch64-linux-gnu-gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64
CC: [ak...@linux-foundation.org linux-...@vger.kernel.org linux-...@vger.kernel.org linu...@kvack.org wi...@infradead.org]

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0637d7...@syzkaller.appspotmail.com

watchdog: BUG: soft lockup - CPU#0 stuck for 23s! [syz-executor.0:27335]
Modules linked in:
irq event stamp: 18338
hardirqs last enabled at (18337): [<ffff80000ca05bc8>] __exit_to_kernel_mode arch/arm64/kernel/entry-common.c:84 [inline]
hardirqs last enabled at (18337): [<ffff80000ca05bc8>] exit_to_kernel_mode+0x38/0x120 arch/arm64/kernel/entry-common.c:94
hardirqs last disabled at (18338): [<ffff80000ca07844>] __el1_irq arch/arm64/kernel/entry-common.c:468 [inline]
hardirqs last disabled at (18338): [<ffff80000ca07844>] el1_interrupt+0x24/0x54 arch/arm64/kernel/entry-common.c:486
softirqs last enabled at (18284): [<ffff8000080109d4>] _stext+0x9d4/0x107c
softirqs last disabled at (18107): [<ffff800008019cb0>] ____do_softirq+0x10/0x20 arch/arm64/kernel/irq.c:79
CPU: 0 PID: 27335 Comm: syz-executor.0 Not tainted 6.1.0-rc6-syzkaller-00337-gbf82d38c91f8 #0
Hardware name: linux,dummy-virt (DT)
pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : __arch_copy_from_user+0x1b0/0x230 arch/arm64/lib/copy_template.S:164
lr : copyin lib/iov_iter.c:183 [inline]
lr : copyin+0xb8/0x120 lib/iov_iter.c:175
sp : ffff800013f27830
x29: ffff800013f27830 x28: ffff800013f27c30 x27: ffff80000dc70d98
x26: 00000000000a6000 x25: ffff800013f27c38 x24: ffff00000619c000
x23: 0000ffff7ca00000 x22: 0000ffff7caa6000 x21: ffff00000619c000
x20: 0000ffff7caa6000 x19: 0000000000001000 x18: ffff00006a9a4c00
x17: ffff80005ca0e000 x16: ffff800010ce8000 x15: 0000ffff7caa6000
x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000
x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000000
x8 : 0000000000000000 x7 : 0000000000000000 x6 : ffff00000619c7c0
x5 : ffff00000619d000 x4 : 0000000000000000 x3 : ffff8000091077c8
x2 : 00000000000007c0 x1 : 0000ffff7caa6800 x0 : ffff00000619c000
Call trace:
__arch_copy_from_user+0x1b0/0x230 arch/arm64/lib/copy_template.S:158
copy_page_from_iter_atomic+0x1d8/0xd00 lib/iov_iter.c:820
generic_perform_write+0x218/0x3ec mm/filemap.c:3761
__generic_file_write_iter+0x1e8/0x394 mm/filemap.c:3881
generic_file_write_iter+0xc0/0x29c mm/filemap.c:3913
call_write_iter include/linux/fs.h:2191 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x4c4/0x740 fs/read_write.c:584
ksys_write+0xec/0x1d0 fs/read_write.c:637
__do_sys_write fs/read_write.c:649 [inline]
__se_sys_write fs/read_write.c:646 [inline]
__arm64_sys_write+0x6c/0xa0 fs/read_write.c:646
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x6c/0x260 arch/arm64/kernel/syscall.c:52
el0_svc_common.constprop.0+0xc4/0x254 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x50/0x14c arch/arm64/kernel/syscall.c:206
el0_svc+0x54/0x140 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0xb8/0xc0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.