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

[syzbot <syzbot+293a57918b36cfae3d48@syzkaller.appspotmail.com>]

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