[syzbot] [ext4?] kernel BUG in ext4_write_inline_data_end (3)

[syzbot] [ext4?] kernel BUG in ext4_write_inline_data_end (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    a13c140cc289 Linux 7.2-rc3
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=11d48789580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ecdef466b08b9772
dashboard link: https://syzkaller.appspot.com/bug?extid=293a57918b36cfae3d48
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=16e444b9580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b40dd0e99ac8/disk-a13c140c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7ef230d7959b/vmlinux-a13c140c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a593476d5c20/Image-a13c140c.gz.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/172c5a39071b/mount_0.gz
  fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=12e444b9580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+293a57918b36cfae3d48@syzkaller.appspotmail.com

------------[ cut here ]------------
kernel BUG at fs/ext4/inline.c:815!
Internal error: Oops - BUG: 00000000f2000800 [#1]  SMP
Modules linked in:
CPU: 1 UID: 0 PID: 20668 Comm: syz.0.3283 Not tainted syzkaller #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/02/2026
pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : ext4_write_inline_data_end+0x8fc/0x9d8 fs/ext4/ext4.h:3790
lr : ext4_has_inline_data fs/ext4/ext4.h:3790 [inline]
lr : ext4_write_inline_data_end+0x8fc/0x9d8 fs/ext4/inline.c:815
sp : ffff800090e575c0
x29: ffff800090e57670 x28: dfff800000000000 x27: ffff7000121caebc
x26: 0000000000000000 x25: ffff0000e01554b0 x24: fffffdffc3c2a340
x23: ffff800090e575e0 x22: 0000000000000023 x21: 0000000600080000
x20: ffff0000e01556a0 x19: 0000000000000023 x18: 0000000000000000
x17: 0000000000000000 x16: 0000000000000000 x15: 00000000200000c0
x14: 0000000000000000 x13: 0000000000000001 x12: 0000000000000000
x11: 0000000000000000 x10: ffff60001c02aa97 x9 : 0000000000000000
x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff8000810066e8
x2 : 0000000000000000 x1 : ffff0000c4c28000 x0 : 0000000000000000
Call trace:
 ext4_has_inline_data fs/ext4/ext4.h:3790 [inline] (P)
 ext4_write_inline_data_end+0x8fc/0x9d8 fs/ext4/inline.c:815 (P)
 ext4_write_end+0x320/0x9e0 fs/ext4/inode.c:1455
 ext4_da_write_end+0x90/0xba0 fs/ext4/inode.c:3297
 generic_perform_write+0x504/0x7a4 mm/filemap.c:4379
 ext4_buffered_write_iter+0xd0/0x2ec fs/ext4/file.c:316
 ext4_file_write_iter+0x1dc/0x134c fs/ext4/file.c:-1
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x51c/0xa0c fs/read_write.c:687
 ksys_write+0x12c/0x228 fs/read_write.c:739
 __do_sys_write fs/read_write.c:750 [inline]
 __se_sys_write fs/read_write.c:747 [inline]
 __arm64_sys_write+0x7c/0x90 fs/read_write.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:736
 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594
Code: c8097f28 35ffffa9 17fffe38 97d939e6 (d4210000) 
---[ end trace 0000000000000000 ]---


---
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#syz undup

Re: [syzbot] [ext4?] kernel BUG in ext4_write_inline_data_end (3)

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
possible deadlock in ext4_write_inline_data_end

loop0: detected capacity change from 0 to 1024
EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.0.17/5361 is trying to acquire lock:
ffff0000ee0c30f8 (&ei->i_data_sem#2){++++}-{4:4}, at: ext4_update_i_disksize fs/ext4/ext4.h:3569 [inline]
ffff0000ee0c30f8 (&ei->i_data_sem#2){++++}-{4:4}, at: ext4_update_inode_size fs/ext4/ext4.h:3585 [inline]
ffff0000ee0c30f8 (&ei->i_data_sem#2){++++}-{4:4}, at: ext4_write_inline_data_end+0x500/0x9d8 fs/ext4/inline.c:839

but task is already holding lock:
ffff0000ee0c30f8 (&ei->i_data_sem#2){++++}-{4:4}, at: ext4_write_end+0x16c/0x9fc fs/ext4/inode.c:1453

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&ei->i_data_sem#2);
  lock(&ei->i_data_sem#2);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

4 locks held by syz.0.17/5361:
 #0: ffff0000d18615f0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x100/0x144 fs/file.c:1259
 #1: ffff0000db5fc450 (sb_writers#3){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2733 [inline]
 #1: ffff0000db5fc450 (sb_writers#3){.+.+}-{0:0}, at: vfs_write+0x248/0xa0c fs/read_write.c:683
 #2: ffff0000ee0c3260 (&sb->s_type->i_mutex_key#10){++++}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline]
 #2: ffff0000ee0c3260 (&sb->s_type->i_mutex_key#10){++++}-{4:4}, at: ext4_buffered_write_iter+0xa0/0x2ec fs/ext4/file.c:311
 #3: ffff0000ee0c30f8 (&ei->i_data_sem#2){++++}-{4:4}, at: ext4_write_end+0x16c/0x9fc fs/ext4/inode.c:1453

stack backtrace:
CPU: 0 UID: 0 PID: 5361 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/02/2026
Call trace:
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (C)
 __dump_stack+0x30/0x40 lib/dump_stack.c:94
 dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120
 dump_stack+0x1c/0x28 lib/dump_stack.c:129
 print_deadlock_bug+0x2e8/0x2f0 kernel/locking/lockdep.c:3041
 check_deadlock kernel/locking/lockdep.c:3093 [inline]
 validate_chain kernel/locking/lockdep.c:3895 [inline]
 __lock_acquire+0x2764/0x2ebc kernel/locking/lockdep.c:5237
 lock_acquire+0x140/0x364 kernel/locking/lockdep.c:5868
 down_write+0x50/0xc0 kernel/locking/rwsem.c:1631
 ext4_update_i_disksize fs/ext4/ext4.h:3569 [inline]
 ext4_update_inode_size fs/ext4/ext4.h:3585 [inline]
 ext4_write_inline_data_end+0x500/0x9d8 fs/ext4/inline.c:839
 ext4_write_end+0x328/0x9fc fs/ext4/inode.c:1457
 ext4_da_write_end+0x90/0xba0 fs/ext4/inode.c:3303
 generic_perform_write+0x504/0x7a4 mm/filemap.c:4379
 ext4_buffered_write_iter+0xd0/0x2ec fs/ext4/file.c:316
 ext4_file_write_iter+0x1dc/0x134c fs/ext4/file.c:-1
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x51c/0xa0c fs/read_write.c:687
 ksys_write+0x12c/0x228 fs/read_write.c:739
 __do_sys_write fs/read_write.c:750 [inline]
 __se_sys_write fs/read_write.c:747 [inline]
 __arm64_sys_write+0x7c/0x90 fs/read_write.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:736
 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594


Tested on:

commit:         a13c140c Linux 7.2-rc3
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=13068cb9580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ecdef466b08b9772
dashboard link: https://syzkaller.appspot.com/bug?extid=293a57918b36cfae3d48
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
userspace arch: arm64
patch:          https://syzkaller.appspot.com/x/patch.diff?x=17dfcc32580000

Re: [syzbot] [ext4?] kernel BUG in ext4_write_inline_data_end (3)

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING: lock held when returning to user space in ext4_write_inline_data_end

loop0: detected capacity change from 0 to 1024
================================================
WARNING: lock held when returning to user space!
syzkaller #0 Not tainted
------------------------------------------------
syz.0.999/10153 is leaving the kernel with locks still held!
1 lock held by syz.0.999/10153:
 #0: ffff0000e0bc67e0 (&ei->xattr_sem){++++}-{4:4}, at: ext4_write_lock_xattr fs/ext4/xattr.h:157 [inline]
 #0: ffff0000e0bc67e0 (&ei->xattr_sem){++++}-{4:4}, at: ext4_write_inline_data_end+0x198/0x9f8 fs/ext4/inline.c:814


Tested on:

commit:         a13c140c Linux 7.2-rc3
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=1730b4b9580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ecdef466b08b9772
dashboard link: https://syzkaller.appspot.com/bug?extid=293a57918b36cfae3d48
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
userspace arch: arm64
patch:          https://syzkaller.appspot.com/x/patch.diff?x=134f6789580000

Re: [syzbot] [ext4?] kernel BUG in ext4_write_inline_data_end (3)

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
INFO: task hung in ext4_page_mkwrite

INFO: task syz.0.914:9735 block
INFO: task syz.0.914:9735 blocked in I/O wait for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.914       state:D stack:0     pid:9735  tgid:9731  ppid:8204   task_flags:0x400140 flags:0x00000001
Call trace:
 __switch_to+0x2b0/0x6e0 arch/arm64/kernel/process.c:775 (T)
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x1370/0x2d80 kernel/sched/core.c:7234
 __schedule_loop kernel/sched/core.c:7311 [inline]
 schedule+0x13c/0x20c kernel/sched/core.c:7326
 io_schedule+0x1c/0xe0 kernel/sched/core.c:8154
 folio_wait_bit_common+0x6b8/0xa30 mm/filemap.c:1323
 __folio_lock+0x2c/0x3c mm/filemap.c:1704
 folio_lock include/linux/pagemap.h:1157 [inline]
 ext4_page_mkwrite+0x864/0xd1c fs/ext4/inode.c:6833
 do_page_mkwrite+0x138/0x2b8 mm/memory.c:3684
 wp_page_shared mm/memory.c:4085 [inline]
 do_wp_page+0x1270/0x4074 mm/memory.c:4304
 handle_pte_fault mm/memory.c:6395 [inline]
 __handle_mm_fault mm/memory.c:6517 [inline]
 handle_mm_fault+0x123c/0x253c mm/memory.c:6686
 do_page_fault+0x4b0/0xb88 arch/arm64/mm/fault.c:751
 do_mem_abort+0x70/0x194 arch/arm64/mm/fault.c:984
 el1_abort+0x50/0x74 arch/arm64/kernel/entry-common.c:322
 el1h_64_sync_handler+0xdc/0x130 arch/arm64/kernel/entry-common.c:449
 el1h_64_sync+0x6c/0x70 arch/arm64/kernel/entry.S:589
 __arch_copy_to_user+0xf0/0x240 arch/arm64/lib/copy_template.S:129 (P)
 processcompl_compat+0x160/0x8dc drivers/usb/core/devio.c:2222
 proc_reapurb_compat drivers/usb/core/devio.c:2256 [inline]
 usbdev_do_ioctl drivers/usb/core/devio.c:2627 [inline]
 usbdev_ioctl+0x324/0x1990 drivers/usb/core/devio.c:2826
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl fs/ioctl.c:583 [inline]
 __arm64_sys_ioctl+0x14c/0x1c4 fs/ioctl.c:583
 __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:736
 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594
INFO: task syz.1.915:9774 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.915       state:D stack:0     pid:9774  tgid:9773  ppid:9739   task_flags:0x400140 flags:0x00800001
Call trace:
 __switch_to+0x2b0/0x6e0 arch/arm64/kernel/process.c:775 (T)
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x1370/0x2d80 kernel/sched/core.c:7234
 __schedule_loop kernel/sched/core.c:7311 [inline]
 schedule+0x13c/0x20c kernel/sched/core.c:7326
 schedule_preempt_disabled+0x18/0x2c kernel/sched/core.c:7383
 __mutex_lock_common kernel/locking/mutex.c:726 [inline]
 __mutex_lock+0x4ec/0xf14 kernel/locking/mutex.c:821
 mutex_lock_nested+0x24/0x30 kernel/locking/mutex.c:874
 device_lock include/linux/device.h:1102 [inline]
 usbdev_open+0x138/0x674 drivers/usb/core/devio.c:1054
 chrdev_open+0x398/0x3e8 fs/char_dev.c:411
 do_dentry_open+0x5c4/0xfc0 fs/open.c:947
 vfs_open+0x44/0x2dc fs/open.c:1052
 do_open fs/namei.c:4700 [inline]
 path_openat+0x21fc/0x2a60 fs/namei.c:4863
 do_file_open+0x1c8/0x2e8 fs/namei.c:4892
 do_sys_openat2+0x114/0x1e8 fs/open.c:1368
 do_sys_open+0xb0/0xe0 fs/open.c:1374
 __do_sys_openat fs/open.c:1390 [inline]
 __se_sys_openat fs/open.c:1385 [inline]
 __arm64_sys_openat+0xa0/0xbc fs/open.c:1385
 __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:736
 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffff800088cb6f20 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #0: ffff800088cb6f20 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline]
 #0: ffff800088cb6f20 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x4c/0x188 kernel/locking/lockdep.c:6775
2 locks held by pr/ttyAMA-1/41:
2 locks held by getty/4492:
 #0: ffff0000c882d0a0 (&tty->ldisc_sem){++++}-{0:0}, at: ldsem_down_read+0x3c/0x4c drivers/tty/tty_ldsem.c:340
 #1: ffff80009248b2e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x348/0xf78 drivers/tty/n_tty.c:2211
2 locks held by kworker/0:4/5327:
4 locks held by syz.0.914/9735:
 #0: ffff0000cb2331d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1102 [inline]
 #0: ffff0000cb2331d8 (&dev->mutex){....}-{4:4}, at: usbdev_do_ioctl drivers/usb/core/devio.c:2610 [inline]
 #0: ffff0000cb2331d8 (&dev->mutex){....}-{4:4}, at: usbdev_ioctl+0x120/0x1990 drivers/usb/core/devio.c:2826
 #1: ffff0000d08c8378 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_trylock include/linux/mmap_lock.h:611 [inline]
 #1: ffff0000d08c8378 (&mm->mmap_lock){++++}-{4:4}, at: get_mmap_lock_carefully mm/mmap_lock.c:441 [inline]
 #1: ffff0000d08c8378 (&mm->mmap_lock){++++}-{4:4}, at: lock_mm_and_find_vma+0x38/0x2c0 mm/mmap_lock.c:501
 #2: ffff0000cac7e548 (sb_pagefaults){.+.+}-{0:0}, at: percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline]
 #2: ffff0000cac7e548 (sb_pagefaults){.+.+}-{0:0}, at: __sb_start_write include/linux/fs/super.h:19 [inline]
 #2: ffff0000cac7e548 (sb_pagefaults){.+.+}-{0:0}, at: sb_start_pagefault include/linux/fs/super.h:159 [inline]
 #2: ffff0000cac7e548 (sb_pagefaults){.+.+}-{0:0}, at: ext4_page_mkwrite+0x1a4/0xd1c fs/ext4/inode.c:6804
 #3: ffff0000ddfcb3f8 (mapping.invalidate_lock#2){++++}-{4:4}, at: filemap_invalidate_lock_shared include/linux/fs.h:1089 [inline]
 #3: ffff0000ddfcb3f8 (mapping.invalidate_lock#2){++++}-{4:4}, at: ext4_page_mkwrite+0x1c8/0xd1c fs/ext4/inode.c:6807
1 lock held by syz.1.915/9774:
 #0: ffff0000cb2331d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1102 [inline]
 #0: ffff0000cb2331d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x138/0x674 drivers/usb/core/devio.c:1054
1 lock held by syz.2.916/9817:
 #0: ffff0000cb2331d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1102 [inline]
 #0: ffff0000cb2331d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x138/0x674 drivers/usb/core/devio.c:1054
1 lock held by syz.3.917/9862:
 #0: ffff0000cb2331d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1102 [inline]
 #0: ffff0000cb2331d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x138/0x674 drivers/usb/core/devio.c:1054
1 lock held by syz.4.918/9912:
 #0: ffff0000cb2331d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1102 [inline]
 #0: ffff0000cb2331d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x138/0x674 drivers/usb/core/devio.c:1054
1 lock held by syz.5.919/9959:
 #0: ffff0000cb2331d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1102 [inline]
 #0: ffff0000cb2331d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x138/0x674 drivers/usb/core/devio.c:1054
1 lock held by syz.6.920/10007:
 #0: ffff0000cb2331d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1102 [inline]
 #0: ffff0000cb2331d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x138/0x674 drivers/usb/core/devio.c:1054
1 lock held by syz.7.921/10056:
 #0: ffff0000cb2331d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1102 [inline]
 #0: ffff0000cb2331d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x138/0x674 drivers/usb/core/devio.c:1054
1 lock held by syz.8.922/10108:
 #0: ffff0000cb2331d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1102 [inline]
 #0: ffff0000cb2331d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x138/0x674 drivers/usb/core/devio.c:1054
1 lock held by syz.9.923/10156:
 #0: ffff0000cb2331d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1102 [inline]
 #0: ffff0000cb2331d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x138/0x674 drivers/usb/core/devio.c:1054
1 lock held by syz.0.924/10197:
 #0: ffff0000cb2331d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1102 [inline]
 #0: ffff0000cb2331d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x138/0x674 drivers/usb/core/devio.c:1054

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



Tested on:

commit:         a13c140c Linux 7.2-rc3
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=16504cb9580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ecdef466b08b9772
dashboard link: https://syzkaller.appspot.com/bug?extid=293a57918b36cfae3d48
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
userspace arch: arm64
patch:          https://syzkaller.appspot.com/x/patch.diff?x=17546cb9580000

Re: [syzbot] [ext4?] kernel BUG in ext4_write_inline_data_end (3)

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
INFO: task hung in ext4_page_mkwrite

I
INFO: task syz.0.1038:10254 blocked in I/O wait for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.1038      state:D stack:0     pid:10254 tgid:10250 ppid:8212   task_flags:0x400140 flags:0x00000001
Call trace:
 __switch_to+0x2b0/0x6e0 arch/arm64/kernel/process.c:775 (T)
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x1370/0x2d80 kernel/sched/core.c:7234
 __schedule_loop kernel/sched/core.c:7311 [inline]
 schedule+0x13c/0x20c kernel/sched/core.c:7326
 io_schedule+0x1c/0xe0 kernel/sched/core.c:8154
 folio_wait_bit_common+0x6b8/0xa30 mm/filemap.c:1323
 __folio_lock+0x2c/0x3c mm/filemap.c:1704
 folio_lock include/linux/pagemap.h:1157 [inline]
 ext4_page_mkwrite+0x864/0xd1c fs/ext4/inode.c:6833
 do_page_mkwrite+0x138/0x2b8 mm/memory.c:3684
 wp_page_shared mm/memory.c:4085 [inline]
 do_wp_page+0x1270/0x4074 mm/memory.c:4304
 handle_pte_fault mm/memory.c:6395 [inline]
 __handle_mm_fault mm/memory.c:6517 [inline]
 handle_mm_fault+0x123c/0x253c mm/memory.c:6686
 do_page_fault+0x4b0/0xb88 arch/arm64/mm/fault.c:751
 do_mem_abort+0x70/0x194 arch/arm64/mm/fault.c:984
 el1_abort+0x50/0x74 arch/arm64/kernel/entry-common.c:322
 el1h_64_sync_handler+0xdc/0x130 arch/arm64/kernel/entry-common.c:449
 el1h_64_sync+0x6c/0x70 arch/arm64/kernel/entry.S:589
 __arch_copy_to_user+0xf0/0x240 arch/arm64/lib/copy_template.S:129 (P)
 processcompl_compat+0x160/0x8dc drivers/usb/core/devio.c:2222
 proc_reapurb_compat drivers/usb/core/devio.c:2256 [inline]
 usbdev_do_ioctl drivers/usb/core/devio.c:2627 [inline]
 usbdev_ioctl+0x324/0x1990 drivers/usb/core/devio.c:2826
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl fs/ioctl.c:583 [inline]
 __arm64_sys_ioctl+0x14c/0x1c4 fs/ioctl.c:583
 __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:736
 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594

Showing all locks held in the system:
1 lock held by ksoftirqd/0/14:
1 lock held by khungtaskd/31:
 #0: ffff800088cb6f20 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #0: ffff800088cb6f20 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline]
 #0: ffff800088cb6f20 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x4c/0x188 kernel/locking/lockdep.c:6775
3 locks held by kworker/u8:3/40:
 #0: ffff0000ccf96140 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
 #0: ffff0000ccf96140 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x734/0x10b8 kernel/workqueue.c:3405
 #1: ffff80008eff7c40 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
 #1: ffff80008eff7c40 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x73c/0x10b8 kernel/workqueue.c:3405
 #2: ffff800089d93380 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock+0x20/0x2c net/core/rtnetlink.c:80
3 locks held by kworker/u8:7/3673:
3 locks held by kworker/1:3/4460:
 #0: ffff0000c002b540 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
 #0: ffff0000c002b540 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x734/0x10b8 kernel/workqueue.c:3405
 #1: ffff800096067c40 (deferred_process_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
 #1: ffff800096067c40 (deferred_process_work){+.+.}-{0:0}, at: process_scheduled_works+0x73c/0x10b8 kernel/workqueue.c:3405
 #2: ffff800089d93380 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock+0x20/0x2c net/core/rtnetlink.c:80
2 locks held by getty/4493:
 #0: ffff0000cf2630a0 (&tty->ldisc_sem){++++}-{0:0}, at: ldsem_down_read+0x3c/0x4c drivers/tty/tty_ldsem.c:340
 #1: ffff80009248b2e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x348/0xf78 drivers/tty/n_tty.c:2211
3 locks held by kworker/0:3/4757:
 #0: ffff0000c002b540 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
 #0: ffff0000c002b540 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x734/0x10b8 kernel/workqueue.c:3405
 #1: ffff800094407c40 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
 #1: ffff800094407c40 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_scheduled_works+0x73c/0x10b8 kernel/workqueue.c:3405
 #2: ffff0000c8e4a250 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x198/0x320 drivers/net/netdevsim/fib.c:1490
4 locks held by kworker/1:5/4810:
 #0: ffff0000c002b540 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
 #0: ffff0000c002b540 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x734/0x10b8 kernel/workqueue.c:3405
 #1: ffff800097867c40 ((work_completion)(&helper->damage_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
 #1: ffff800097867c40 ((work_completion)(&helper->damage_work)){+.+.}-{0:0}, at: process_scheduled_works+0x73c/0x10b8 kernel/workqueue.c:3405
 #2: ffff0000c4db6a70 (&helper->lock){+.+.}-{4:4}, at: drm_fb_helper_fb_dirty drivers/gpu/drm/drm_fb_helper.c:324 [inline]
 #2: ffff0000c4db6a70 (&helper->lock){+.+.}-{4:4}, at: drm_fb_helper_damage_work+0x120/0xbc0 drivers/gpu/drm/drm_fb_helper.c:365
 #3: ffff0000c6e2c128 (&dev->master_mutex){+.+.}-{4:4}, at: drm_master_internal_acquire+0x24/0x78 drivers/gpu/drm/drm_auth.c:435
4 locks held by syz.0.1038/10254:
 #0: ffff0000ca8ea1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1102 [inline]
 #0: ffff0000ca8ea1d8 (&dev->mutex){....}-{4:4}, at: usbdev_do_ioctl drivers/usb/core/devio.c:2610 [inline]
 #0: ffff0000ca8ea1d8 (&dev->mutex){....}-{4:4}, at: usbdev_ioctl+0x120/0x1990 drivers/usb/core/devio.c:2826
 #1: ffff0000d2f8d078 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_trylock include/linux/mmap_lock.h:611 [inline]
 #1: ffff0000d2f8d078 (&mm->mmap_lock){++++}-{4:4}, at: get_mmap_lock_carefully mm/mmap_lock.c:441 [inline]
 #1: ffff0000d2f8d078 (&mm->mmap_lock){++++}-{4:4}, at: lock_mm_and_find_vma+0x38/0x2c0 mm/mmap_lock.c:501
 #2: ffff0000d5dd6548 (sb_pagefaults){.+.+}-{0:0}, at: percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline]
 #2: ffff0000d5dd6548 (sb_pagefaults){.+.+}-{0:0}, at: __sb_start_write include/linux/fs/super.h:19 [inline]
 #2: ffff0000d5dd6548 (sb_pagefaults){.+.+}-{0:0}, at: sb_start_pagefault include/linux/fs/super.h:159 [inline]
 #2: ffff0000d5dd6548 (sb_pagefaults){.+.+}-{0:0}, at: ext4_page_mkwrite+0x1a4/0xd1c fs/ext4/inode.c:6804
 #3: ffff0000daa87598 (mapping.invalidate_lock#2){++++}-{4:4}, at: filemap_invalidate_lock_shared include/linux/fs.h:1089 [inline]
 #3: ffff0000daa87598 (mapping.invalidate_lock#2){++++}-{4:4}, at: ext4_page_mkwrite+0x1c8/0xd1c fs/ext4/inode.c:6807
1 lock held by syz.1.1039/10291:
 #0: ffff0000ca8ea1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1102 [inline]
 #0: ffff0000ca8ea1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x138/0x674 drivers/usb/core/devio.c:1054
1 lock held by syz.2.1040/10332:
 #0: ffff0000ca8ea1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1102 [inline]
 #0: ffff0000ca8ea1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x138/0x674 drivers/usb/core/devio.c:1054
1 lock held by syz.3.1041/10378:
 #0: ffff0000ca8ea1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1102 [inline]
 #0: ffff0000ca8ea1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x138/0x674 drivers/usb/core/devio.c:1054
1 lock held by syz.4.1042/10425:
 #0: ffff0000ca8ea1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1102 [inline]
 #0: ffff0000ca8ea1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x138/0x674 drivers/usb/core/devio.c:1054
1 lock held by syz.5.1043/10473:
 #0: ffff0000ca8ea1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1102 [inline]
 #0: ffff0000ca8ea1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x138/0x674 drivers/usb/core/devio.c:1054
1 lock held by syz.6.1044/10520:
 #0: ffff0000ca8ea1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1102 [inline]
 #0: ffff0000ca8ea1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x138/0x674 drivers/usb/core/devio.c:1054
1 lock held by syz.7.1045/10574:
 #0: ffff0000ca8ea1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1102 [inline]
 #0: ffff0000ca8ea1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x138/0x674 drivers/usb/core/devio.c:1054
1 lock held by syz.8.1046/10621:
 #0: ffff0000ca8ea1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1102 [inline]
 #0: ffff0000ca8ea1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x138/0x674 drivers/usb/core/devio.c:1054
1 lock held by syz.9.1047/10670:
 #0: ffff0000ca8ea1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1102 [inline]
 #0: ffff0000ca8ea1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x138/0x674 drivers/usb/core/devio.c:1054
1 lock held by syz-executor/10677:
 #0: ffff800089d93380 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock+0x20/0x2c net/core/rtnetlink.c:80

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



Tested on:

commit:         a13c140c Linux 7.2-rc3
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=17924cb9580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ecdef466b08b9772
dashboard link: https://syzkaller.appspot.com/bug?extid=293a57918b36cfae3d48
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
userspace arch: arm64
patch:          https://syzkaller.appspot.com/x/patch.diff?x=11666cb9580000