IPVS: Creating netns size=2552 id=6 IPVS: Creating netns size=2552 id=7 IPVS: Creating netns size=2552 id=8 ====================================================== [ INFO: possible circular locking dependency detected ] 4.4.125-g38f41ec #21 Not tainted ------------------------------------------------------- syz-executor2/3883 is trying to acquire lock: (&bdev->bd_mutex){+.+.+.}, at: [] blkdev_reread_part+0x1e/0x40 block/ioctl.c:189 but task is already holding lock: (&lo->lo_ctl_mutex#2){+.+.+.}, at: [] lo_compat_ioctl+0x109/0x140 drivers/block/loop.c:1526 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: [] lock_acquire+0x15e/0x460 kernel/locking/lockdep.c:3592 [] __mutex_lock_common kernel/locking/mutex.c:521 [inline] [] mutex_lock_nested+0xbb/0x850 kernel/locking/mutex.c:621 [] __lo_release drivers/block/loop.c:1579 [inline] [] lo_release+0x85/0x160 drivers/block/loop.c:1602 [] __blkdev_put+0x5f7/0x7e0 fs/block_dev.c:1535 [] blkdev_put+0x85/0x550 fs/block_dev.c:1600 [] blkdev_close+0x8b/0xb0 fs/block_dev.c:1607 [] __fput+0x233/0x6d0 fs/file_table.c:208 [] ____fput+0x15/0x20 fs/file_table.c:244 [] task_work_run+0x104/0x180 kernel/task_work.c:115 [] tracehook_notify_resume include/linux/tracehook.h:191 [inline] [] exit_to_usermode_loop+0x13d/0x160 arch/x86/entry/common.c:252 [] prepare_exit_to_usermode arch/x86/entry/common.c:283 [inline] [] syscall_return_slowpath+0x1b5/0x1f0 arch/x86/entry/common.c:348 [] int_ret_from_sys_call+0x25/0xa3 [] lock_acquire+0x15e/0x460 kernel/locking/lockdep.c:3592 [] __mutex_lock_common kernel/locking/mutex.c:521 [inline] [] mutex_lock_nested+0xbb/0x850 kernel/locking/mutex.c:621 [] lo_open+0x1b/0xa0 drivers/block/loop.c:1559 [] __blkdev_get+0x2ac/0xdf0 fs/block_dev.c:1213 [] blkdev_get+0x33d/0x940 fs/block_dev.c:1353 [] blkdev_open+0x1a5/0x250 fs/block_dev.c:1508 [] do_dentry_open+0x59b/0xba0 fs/open.c:749 [] vfs_open+0x110/0x210 fs/open.c:862 [] do_last fs/namei.c:3221 [inline] [] path_openat+0x923/0x3940 fs/namei.c:3357 [] do_filp_open+0x197/0x290 fs/namei.c:3392 [] do_sys_open+0x369/0x660 fs/open.c:1038 [] SYSC_open fs/open.c:1056 [inline] [] SyS_open+0x2d/0x40 fs/open.c:1051 [] entry_SYSCALL_64_fastpath+0x22/0x9e [] check_prev_add kernel/locking/lockdep.c:1853 [inline] [] check_prevs_add kernel/locking/lockdep.c:1958 [inline] [] validate_chain kernel/locking/lockdep.c:2144 [inline] [] __lock_acquire+0x371f/0x4b50 kernel/locking/lockdep.c:3213 [] lock_acquire+0x15e/0x460 kernel/locking/lockdep.c:3592 [] __mutex_lock_common kernel/locking/mutex.c:521 [inline] [] mutex_lock_nested+0xbb/0x850 kernel/locking/mutex.c:621 [] blkdev_reread_part+0x1e/0x40 block/ioctl.c:189 [] loop_reread_partitions+0x78/0xe0 drivers/block/loop.c:645 [] loop_set_status+0x995/0xfc0 drivers/block/loop.c:1175 [] loop_set_status_compat+0x9a/0x100 drivers/block/loop.c:1499 [] lo_compat_ioctl+0x114/0x140 drivers/block/loop.c:1527 [] compat_blkdev_ioctl+0x3d4/0x3b10 block/compat_ioctl.c:751 [] C_SYSC_ioctl fs/compat_ioctl.c:1592 [inline] [] compat_SyS_ioctl+0x28a/0x2540 fs/compat_ioctl.c:1544 [] do_syscall_32_irqs_on arch/x86/entry/common.c:392 [inline] [] do_fast_syscall_32+0x321/0x8a0 arch/x86/entry/common.c:459 [] sysenter_flags_fixed+0xd/0x17 other info that might help us debug this: Chain exists of: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&lo->lo_ctl_mutex#2); lock(loop_index_mutex); lock(&lo->lo_ctl_mutex#2); lock(&bdev->bd_mutex); *** DEADLOCK *** 1 lock held by syz-executor2/3883: #0: (&lo->lo_ctl_mutex#2){+.+.+.}, at: [] lo_compat_ioctl+0x109/0x140 drivers/block/loop.c:1526 stack backtrace: CPU: 1 PID: 3883 Comm: syz-executor2 Not tainted 4.4.125-g38f41ec #21 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 0000000000000000 baf479a3d3540d59 ffff8800ac9475e8 ffffffff81d067bd ffffffff85188b10 ffffffff851880f0 ffffffff851b0e00 ffff8800ac95d108 ffff8800ac95c800 ffff8800ac947630 ffffffff81234081 ffff8800ac95d108 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0xc1/0x124 lib/dump_stack.c:51 [] print_circular_bug+0x271/0x310 kernel/locking/lockdep.c:1226 [] check_prev_add kernel/locking/lockdep.c:1853 [inline] [] check_prevs_add kernel/locking/lockdep.c:1958 [inline] [] validate_chain kernel/locking/lockdep.c:2144 [inline] [] __lock_acquire+0x371f/0x4b50 kernel/locking/lockdep.c:3213 [] lock_acquire+0x15e/0x460 kernel/locking/lockdep.c:3592 [] __mutex_lock_common kernel/locking/mutex.c:521 [inline] [] mutex_lock_nested+0xbb/0x850 kernel/locking/mutex.c:621 [] blkdev_reread_part+0x1e/0x40 block/ioctl.c:189 [] loop_reread_partitions+0x78/0xe0 drivers/block/loop.c:645 [] loop_set_status+0x995/0xfc0 drivers/block/loop.c:1175 [] loop_set_status_compat+0x9a/0x100 drivers/block/loop.c:1499 [] lo_compat_ioctl+0x114/0x140 drivers/block/loop.c:1527 [] compat_blkdev_ioctl+0x3d4/0x3b10 block/compat_ioctl.c:751 [] C_SYSC_ioctl fs/compat_ioctl.c:1592 [inline] [] compat_SyS_ioctl+0x28a/0x2540 fs/compat_ioctl.c:1544 [] do_syscall_32_irqs_on arch/x86/entry/common.c:392 [inline] [] do_fast_syscall_32+0x321/0x8a0 arch/x86/entry/common.c:459 [] sysenter_flags_fixed+0xd/0x17