Hello, syzbot found the following issue on: HEAD commit: e99d8a84 Add linux-next specific files for 20210409 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=13b01681d00000 kernel config: https://syzkaller.appspot.com/x/.config?x=7cd69574979bfeb7 dashboard link: https://syzkaller.appspot.com/bug?extid=61e04e51b7ac86930589 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=148265d9d00000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16a981a1d00000 The issue was bisected to: commit 997acaf6b4b59c6a9c259740312a69ea549cc684 Author: Mark Rutland <mark.rutland@xxxxxxx> Date: Mon Jan 11 15:37:07 2021 +0000 lockdep: report broken irq restoration bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=16a7e77ed00000 final oops: https://syzkaller.appspot.com/x/report.txt?x=15a7e77ed00000 console output: https://syzkaller.appspot.com/x/log.txt?x=11a7e77ed00000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+61e04e51b7ac86930589@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: 997acaf6b4b5 ("lockdep: report broken irq restoration") ====================================================== WARNING: possible circular locking dependency detected 5.12.0-rc6-next-20210409-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor104/8440 is trying to acquire lock: ffff888016e9dca0 (&bdev->bd_mutex){+.+.}-{3:3}, at: del_gendisk+0x250/0x9e0 block/genhd.c:618 but task is already holding lock: ffffffff8c7d9430 (bdev_lookup_sem){++++}-{3:3}, at: del_gendisk+0x222/0x9e0 block/genhd.c:616 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (bdev_lookup_sem){++++}-{3:3}: down_write+0x92/0x150 kernel/locking/rwsem.c:1406 del_gendisk+0x222/0x9e0 block/genhd.c:616 loop_remove drivers/block/loop.c:2191 [inline] loop_control_ioctl drivers/block/loop.c:2291 [inline] loop_control_ioctl+0x40d/0x4f0 drivers/block/loop.c:2251 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #1 (loop_ctl_mutex){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:949 [inline] __mutex_lock+0x139/0x1120 kernel/locking/mutex.c:1096 lo_open+0x1a/0x130 drivers/block/loop.c:1890 __blkdev_get+0x135/0xa30 fs/block_dev.c:1305 blkdev_get_by_dev fs/block_dev.c:1457 [inline] blkdev_get_by_dev+0x26c/0x600 fs/block_dev.c:1425 blkdev_open+0x154/0x2b0 fs/block_dev.c:1554 do_dentry_open+0x4b9/0x11b0 fs/open.c:826 do_open fs/namei.c:3361 [inline] path_openat+0x1c09/0x27d0 fs/namei.c:3494 do_filp_open+0x190/0x3d0 fs/namei.c:3521 do_sys_openat2+0x16d/0x420 fs/open.c:1187 do_sys_open fs/open.c:1203 [inline] __do_sys_open fs/open.c:1211 [inline] __se_sys_open fs/open.c:1207 [inline] __x64_sys_open+0x119/0x1c0 fs/open.c:1207 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #0 (&bdev->bd_mutex){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:2938 [inline] check_prevs_add kernel/locking/lockdep.c:3061 [inline] validate_chain kernel/locking/lockdep.c:3676 [inline] __lock_acquire+0x2a17/0x5230 kernel/locking/lockdep.c:4902 lock_acquire kernel/locking/lockdep.c:5512 [inline] lock_acquire+0x1ab/0x740 kernel/locking/lockdep.c:5477 __mutex_lock_common kernel/locking/mutex.c:949 [inline] __mutex_lock+0x139/0x1120 kernel/locking/mutex.c:1096 del_gendisk+0x250/0x9e0 block/genhd.c:618 loop_remove drivers/block/loop.c:2191 [inline] loop_control_ioctl drivers/block/loop.c:2291 [inline] loop_control_ioctl+0x40d/0x4f0 drivers/block/loop.c:2251 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae other info that might help us debug this: Chain exists of: &bdev->bd_mutex --> loop_ctl_mutex --> bdev_lookup_sem Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(bdev_lookup_sem); lock(loop_ctl_mutex); lock(bdev_lookup_sem); lock(&bdev->bd_mutex); *** DEADLOCK *** 2 locks held by syz-executor104/8440: #0: ffffffff8ca5f148 (loop_ctl_mutex){+.+.}-{3:3}, at: loop_control_ioctl+0x7b/0x4f0 drivers/block/loop.c:2257 #1: ffffffff8c7d9430 (bdev_lookup_sem){++++}-{3:3}, at: del_gendisk+0x222/0x9e0 block/genhd.c:616 stack backtrace: CPU: 1 PID: 8440 Comm: syz-executor104 Not tainted 5.12.0-rc6-next-20210409-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x141/0x1d7 lib/dump_stack.c:120 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2129 check_prev_add kernel/locking/lockdep.c:2938 [inline] check_prevs_add kernel/locking/lockdep.c:3061 [inline] validate_chain kernel/locking/lockdep.c:3676 [inline] __lock_acquire+0x2a17/0x5230 kernel/locking/lockdep.c:4902 lock_acquire kernel/locking/lockdep.c:5512 [inline] lock_acquire+0x1ab/0x740 kernel/locking/lockdep.c:5477 __mutex_lock_common kernel/locking/mutex.c:949 [inline] __mutex_lock+0x139/0x1120 kernel/locking/mutex.c:1096 del_gendisk+0x250/0x9e0 block/genhd.c:618 loop_remove drivers/block/loop.c:2191 [inline] loop_control_ioctl drivers/block/loop.c:2291 [inline] loop_control_ioctl+0x40d/0x4f0 drivers/block/loop.c:2251 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x43ee49 Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fff4d86c238 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000400488 RCX: 000000000043ee49 RDX: 0000000000000002 RSI: 0000000000004c81 RDI: 0000000000000003 RBP: 0000000000402e30 R08: 0000000000000000 R09: 0000000000400488 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000402ec0 R13: 0000000000000000 R14: 00000000004ac018 R15: 0000000000400488 --- 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. For information about bisection process see: https://goo.gl/tpsmEJ#bisection syzbot can test patches for this issue, for details see: https://goo.gl/tpsmEJ#testing-patches
