Hello. This seems to be an example of https://lkml.kernel.org/r/49925af7-78a8-a3dd-bce6-cfc02e1a9236@xxxxxxxxxxxxxxxxxxx introduced by "ext4: truncate during setxattr leads to kernel panic". Please don't use schedule_work() if you need to use flush_scheduled_work(). On 2022/03/30 6:23, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 8515d05bf6bc Add linux-next specific files for 20220328 > git tree: linux-next > console output: https://syzkaller.appspot.com/x/log.txt?x=155abcc3700000 > kernel config: https://syzkaller.appspot.com/x/.config?x=530c68bef4e2b8a8 > dashboard link: https://syzkaller.appspot.com/bug?extid=bde0f89deacca7c765b8 > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > > 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+bde0f89deacca7c765b8@xxxxxxxxxxxxxxxxxxxxxxxxx > > ====================================================== > WARNING: possible circular locking dependency detected > 5.17.0-next-20220328-syzkaller #0 Not tainted > ------------------------------------------------------ > kworker/1:1/26 is trying to acquire lock: > ffff88807eece460 (sb_writers#3){.+.+}-{0:0}, at: p9_fd_write net/9p/trans_fd.c:428 [inline] > ffff88807eece460 (sb_writers#3){.+.+}-{0:0}, at: p9_write_work+0x25e/0xca0 net/9p/trans_fd.c:479 > > but task is already holding lock: > ffffc90000a1fda8 ((work_completion)(&m->wq)){+.+.}-{0:0}, at: process_one_work+0x8ae/0x1610 kernel/workqueue.c:2264 > > which lock already depends on the new lock. > > > the existing dependency chain (in reverse order) is: > > -> #3 ((work_completion)(&m->wq)){+.+.}-{0:0}: > process_one_work+0x905/0x1610 kernel/workqueue.c:2265 > worker_thread+0x665/0x1080 kernel/workqueue.c:2436 > kthread+0x2e9/0x3a0 kernel/kthread.c:376 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298 > > -> #2 ((wq_completion)events){+.+.}-{0:0}: > flush_workqueue+0x164/0x1440 kernel/workqueue.c:2831 > flush_scheduled_work include/linux/workqueue.h:583 [inline] > ext4_put_super+0x99/0x1150 fs/ext4/super.c:1202 > generic_shutdown_super+0x14c/0x400 fs/super.c:462 > kill_block_super+0x97/0xf0 fs/super.c:1394 > deactivate_locked_super+0x94/0x160 fs/super.c:332 > deactivate_super+0xad/0xd0 fs/super.c:363 > cleanup_mnt+0x3a2/0x540 fs/namespace.c:1186 > task_work_run+0xdd/0x1a0 kernel/task_work.c:164 > resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] > exit_to_user_mode_loop kernel/entry/common.c:183 [inline] > exit_to_user_mode_prepare+0x23c/0x250 kernel/entry/common.c:215 > __syscall_exit_to_user_mode_work kernel/entry/common.c:297 [inline] > syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:308 > do_syscall_64+0x42/0x80 arch/x86/entry/common.c:86 > entry_SYSCALL_64_after_hwframe+0x44/0xae > > -> #1 (&type->s_umount_key#32){++++}-{3:3}: > down_read+0x98/0x440 kernel/locking/rwsem.c:1461 > iterate_supers+0xdb/0x290 fs/super.c:692 > drop_caches_sysctl_handler+0xdb/0x110 fs/drop_caches.c:62 > proc_sys_call_handler+0x4a1/0x6e0 fs/proc/proc_sysctl.c:604 > call_write_iter include/linux/fs.h:2080 [inline] > do_iter_readv_writev+0x3d1/0x640 fs/read_write.c:726 > do_iter_write+0x182/0x700 fs/read_write.c:852 > vfs_iter_write+0x70/0xa0 fs/read_write.c:893 > iter_file_splice_write+0x723/0xc70 fs/splice.c:689 > do_splice_from fs/splice.c:767 [inline] > direct_splice_actor+0x110/0x180 fs/splice.c:936 > splice_direct_to_actor+0x34b/0x8c0 fs/splice.c:891 > do_splice_direct+0x1a7/0x270 fs/splice.c:979 > do_sendfile+0xae0/0x1240 fs/read_write.c:1246 > __do_sys_sendfile64 fs/read_write.c:1305 [inline] > __se_sys_sendfile64 fs/read_write.c:1297 [inline] > __x64_sys_sendfile64+0x149/0x210 fs/read_write.c:1297 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x44/0xae > > -> #0 (sb_writers#3){.+.+}-{0:0}: > check_prev_add kernel/locking/lockdep.c:3096 [inline] > check_prevs_add kernel/locking/lockdep.c:3219 [inline] > validate_chain kernel/locking/lockdep.c:3834 [inline] > __lock_acquire+0x2ac6/0x56c0 kernel/locking/lockdep.c:5060 > lock_acquire kernel/locking/lockdep.c:5672 [inline] > lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5637 > percpu_down_read include/linux/percpu-rwsem.h:51 [inline] > __sb_start_write include/linux/fs.h:1728 [inline] > sb_start_write include/linux/fs.h:1798 [inline] > file_start_write include/linux/fs.h:2815 [inline] > kernel_write fs/read_write.c:564 [inline] > kernel_write+0x2ac/0x540 fs/read_write.c:555 > p9_fd_write net/9p/trans_fd.c:428 [inline] > p9_write_work+0x25e/0xca0 net/9p/trans_fd.c:479 > process_one_work+0x996/0x1610 kernel/workqueue.c:2289 > worker_thread+0x665/0x1080 kernel/workqueue.c:2436 > kthread+0x2e9/0x3a0 kernel/kthread.c:376 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298 > > other info that might help us debug this: > > Chain exists of: > sb_writers#3 --> (wq_completion)events --> (work_completion)(&m->wq) > > Possible unsafe locking scenario: > > CPU0 CPU1 > ---- ---- > lock((work_completion)(&m->wq)); > lock((wq_completion)events); > lock((work_completion)(&m->wq)); > lock(sb_writers#3); > > *** DEADLOCK *** > > 2 locks held by kworker/1:1/26: > #0: ffff888010c64d38 ((wq_completion)events){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] > #0: ffff888010c64d38 ((wq_completion)events){+.+.}-{0:0}, at: arch_atomic_long_set include/linux/atomic/atomic-long.h:41 [inline] > #0: ffff888010c64d38 ((wq_completion)events){+.+.}-{0:0}, at: atomic_long_set include/linux/atomic/atomic-instrumented.h:1280 [inline] > #0: ffff888010c64d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:636 [inline] > #0: ffff888010c64d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:663 [inline] > #0: ffff888010c64d38 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x87a/0x1610 kernel/workqueue.c:2260 > #1: ffffc90000a1fda8 ((work_completion)(&m->wq)){+.+.}-{0:0}, at: process_one_work+0x8ae/0x1610 kernel/workqueue.c:2264 > > stack backtrace: > CPU: 1 PID: 26 Comm: kworker/1:1 Not tainted 5.17.0-next-20220328-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Workqueue: events p9_write_work > Call Trace: > <TASK> > __dump_stack lib/dump_stack.c:88 [inline] > dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 > check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2176 > check_prev_add kernel/locking/lockdep.c:3096 [inline] > check_prevs_add kernel/locking/lockdep.c:3219 [inline] > validate_chain kernel/locking/lockdep.c:3834 [inline] > __lock_acquire+0x2ac6/0x56c0 kernel/locking/lockdep.c:5060 > lock_acquire kernel/locking/lockdep.c:5672 [inline] > lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5637 > percpu_down_read include/linux/percpu-rwsem.h:51 [inline] > __sb_start_write include/linux/fs.h:1728 [inline] > sb_start_write include/linux/fs.h:1798 [inline] > file_start_write include/linux/fs.h:2815 [inline] > kernel_write fs/read_write.c:564 [inline] > kernel_write+0x2ac/0x540 fs/read_write.c:555 > p9_fd_write net/9p/trans_fd.c:428 [inline] > p9_write_work+0x25e/0xca0 net/9p/trans_fd.c:479 > process_one_work+0x996/0x1610 kernel/workqueue.c:2289 > worker_thread+0x665/0x1080 kernel/workqueue.c:2436 > kthread+0x2e9/0x3a0 kernel/kthread.c:376 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298 > </TASK> > usb 4-1: new high-speed USB device number 72 using dummy_hcd > usb 4-1: New USB device found, idVendor=1b3d, idProduct=0193, bcdDevice= 8.4d > usb 4-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0 > usb 4-1: config 0 descriptor?? > ftdi_sio 4-1:0.0: FTDI USB Serial Device converter detected > usb 4-1: Detected FT232RL > ftdi_sio ttyUSB0: Unable to read latency timer: -71 > ftdi_sio ttyUSB0: Unable to write latency timer: -71 > ftdi_sio 4-1:0.0: GPIO initialisation failed: -71 > usb 4-1: FTDI USB Serial Device converter now attached to ttyUSB0 > usb 4-1: USB disconnect, device number 72 > ftdi_sio ttyUSB0: FTDI USB Serial Device converter now disconnected from ttyUSB0 > ftdi_sio 4-1:0.0: device disconnected > usb 4-1: new high-speed USB device number 73 using dummy_hcd > usb 4-1: New USB device found, idVendor=1b3d, idProduct=0193, bcdDevice= 8.4d > usb 4-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0 > usb 4-1: config 0 descriptor?? > ftdi_sio 4-1:0.0: FTDI USB Serial Device converter detected > usb 4-1: Detected FT232RL > ftdi_sio ttyUSB0: Unable to read latency timer: -71 > ftdi_sio ttyUSB0: Unable to write latency timer: -71 > ftdi_sio 4-1:0.0: GPIO initialisation failed: -71 > usb 4-1: FTDI USB Serial Device converter now attached to ttyUSB0 > usb 4-1: USB disconnect, device number 73 > ftdi_sio ttyUSB0: FTDI USB Serial Device converter now disconnected from ttyUSB0 > ftdi_sio 4-1:0.0: device disconnected > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. >
