====================================================== WARNING: possible circular locking dependency detected 6.13.0-rc2-syzkaller-00333-ga0e3919a2df2 #0 Not tainted ------------------------------------------------------ syz.3.2174/14795 is trying to acquire lock: ffff8880440fc3c8 (&q->debugfs_mutex){+.+.}-{4:4} , at: blk_mq_exit_sched+0xd1/0x310 block/blk-mq-sched.c:531 but task is already holding lock: ffff88801f5970b8 (&eq->sysfs_lock){+.+.}-{4:4}, at: elevator_exit block/elevator.c:158 [inline] ffff88801f5970b8 (&eq->sysfs_lock){+.+.}-{4:4}, at: elevator_disable+0xb5/0x490 block/elevator.c:674 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (&eq->sysfs_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:585 [inline] __mutex_lock+0x19b/0xa60 kernel/locking/mutex.c:735 elevator_exit block/elevator.c:158 [inline] elevator_disable+0xb5/0x490 block/elevator.c:674 blk_mq_elv_switch_none block/blk-mq.c:4942 [inline] __blk_mq_update_nr_hw_queues+0x41e/0x1500 block/blk-mq.c:5005 blk_mq_update_nr_hw_queues+0x2a/0x40 block/blk-mq.c:5068 nbd_start_device+0x15b/0xd70 drivers/block/nbd.c:1413 nbd_start_device_ioctl drivers/block/nbd.c:1464 [inline] __nbd_ioctl drivers/block/nbd.c:1539 [inline] nbd_ioctl+0x21a/0xfd0 drivers/block/nbd.c:1579 compat_blkdev_ioctl+0x2f7/0x750 block/ioctl.c:749 __do_compat_sys_ioctl+0x1cb/0x2c0 fs/ioctl.c:1004 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline] __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #3 (&q->q_usage_counter(io)#52){++++}-{0:0}: bio_queue_enter block/blk.h:75 [inline] blk_mq_submit_bio+0x1fb6/0x24c0 block/blk-mq.c:3090 __submit_bio+0x384/0x540 block/blk-core.c:629 __submit_bio_noacct_mq block/blk-core.c:710 [inline] submit_bio_noacct_nocheck+0x698/0xd70 block/blk-core.c:739 submit_bio_noacct+0x93a/0x1e20 block/blk-core.c:868 mpage_bio_submit_read fs/mpage.c:75 [inline] mpage_readahead+0x41d/0x590 fs/mpage.c:377 read_pages+0x1a8/0xdc0 mm/readahead.c:160 page_cache_ra_unbounded+0x3dc/0x750 mm/readahead.c:295 do_page_cache_ra mm/readahead.c:325 [inline] force_page_cache_ra+0x24b/0x340 mm/readahead.c:354 page_cache_sync_ra+0x110/0x9c0 mm/readahead.c:566 page_cache_sync_readahead include/linux/pagemap.h:1397 [inline] filemap_get_pages+0xd7b/0x1be0 mm/filemap.c:2546 filemap_read+0x3ca/0xd70 mm/filemap.c:2646 blkdev_read_iter+0x187/0x480 block/fops.c:770 new_sync_read fs/read_write.c:484 [inline] vfs_read+0x87f/0xbe0 fs/read_write.c:565 ksys_read+0x12b/0x250 fs/read_write.c:708 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #2 (mapping.invalidate_lock#2){++++}-{4:4}: down_read+0x9a/0x330 kernel/locking/rwsem.c:1524 filemap_invalidate_lock_shared include/linux/fs.h:873 [inline] filemap_fault+0x62c/0x2820 mm/filemap.c:3351 __do_fault+0x10a/0x490 mm/memory.c:4907 do_cow_fault mm/memory.c:5352 [inline] do_fault mm/memory.c:5458 [inline] do_pte_missing+0x99f/0x3e00 mm/memory.c:3979 handle_pte_fault mm/memory.c:5801 [inline] __handle_mm_fault+0x103c/0x2a40 mm/memory.c:5944 handle_mm_fault+0x3fa/0xaa0 mm/memory.c:6112 faultin_page mm/gup.c:1196 [inline] __get_user_pages+0x8d9/0x3b50 mm/gup.c:1494 populate_vma_page_range+0x27f/0x3a0 mm/gup.c:1932 __mm_populate+0x1d6/0x380 mm/gup.c:2035 do_mlock+0x40a/0x7d0 mm/mlock.c:653 __do_sys_mlock mm/mlock.c:661 [inline] __se_sys_mlock mm/mlock.c:659 [inline] __ia32_sys_mlock+0x57/0x80 mm/mlock.c:659 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline] __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #1 (&mm->mmap_lock){++++}-{4:4}: __might_fault mm/memory.c:6751 [inline] __might_fault+0x11b/0x190 mm/memory.c:6744 _inline_copy_from_user include/linux/uaccess.h:162 [inline] _copy_from_user+0x29/0xd0 lib/usercopy.c:18 copy_from_user include/linux/uaccess.h:212 [inline] compat_blk_trace_setup+0xc9/0x200 kernel/trace/blktrace.c:664 blk_trace_ioctl+0x24a/0x290 kernel/trace/blktrace.c:745 compat_blkdev_ioctl+0x13c/0x750 block/ioctl.c:742 __do_compat_sys_ioctl+0x1cb/0x2c0 fs/ioctl.c:1004 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline] __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #0 (&q->debugfs_mutex){+.+.}-{4:4}: check_prev_add kernel/locking/lockdep.c:3161 [inline] check_prevs_add kernel/locking/lockdep.c:3280 [inline] validate_chain kernel/locking/lockdep.c:3904 [inline] __lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5226 lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5849 __mutex_lock_common kernel/locking/mutex.c:585 [inline] __mutex_lock+0x19b/0xa60 kernel/locking/mutex.c:735 blk_mq_exit_sched+0xd1/0x310 block/blk-mq-sched.c:531 elevator_exit block/elevator.c:159 [inline] elevator_disable+0xc0/0x490 block/elevator.c:674 blk_mq_elv_switch_none block/blk-mq.c:4942 [inline] __blk_mq_update_nr_hw_queues+0x41e/0x1500 block/blk-mq.c:5005 blk_mq_update_nr_hw_queues+0x2a/0x40 block/blk-mq.c:5068 nbd_start_device+0x15b/0xd70 drivers/block/nbd.c:1413 nbd_start_device_ioctl drivers/block/nbd.c:1464 [inline] __nbd_ioctl drivers/block/nbd.c:1539 [inline] nbd_ioctl+0x21a/0xfd0 drivers/block/nbd.c:1579 compat_blkdev_ioctl+0x2f7/0x750 block/ioctl.c:749 __do_compat_sys_ioctl+0x1cb/0x2c0 fs/ioctl.c:1004 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline] __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411 entry_SYSENTER_compat_after_hwframe+0x84/0x8e other info that might help us debug this: Chain exists of: &q->debugfs_mutex --> &q->q_usage_counter(io)#52 --> &eq->sysfs_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&eq->sysfs_lock); lock(&q->q_usage_counter(io)#52); lock(&eq->sysfs_lock); lock(&q->debugfs_mutex); *** DEADLOCK *** 7 locks held by syz.3.2174/14795: #0: ffff88801f591198 (&nbd->config_lock){+.+.}-{4:4}, at: nbd_ioctl+0x151/0xfd0 drivers/block/nbd.c:1572 #1: ffff88801f5910d8 (&set->tag_list_lock){+.+.}-{4:4}, at: blk_mq_update_nr_hw_queues+0x20/0x40 block/blk-mq.c:5067 #2: ffff8880440fc118 (&q->sysfs_dir_lock){+.+.}-{4:4}, at: __blk_mq_update_nr_hw_queues+0x205/0x1500 block/blk-mq.c:4995 #3: ffff8880440fc088 (&q->sysfs_lock){+.+.}-{4:4}, at: __blk_mq_update_nr_hw_queues+0x214/0x1500 block/blk-mq.c:4996 #4: ffff8880440fbb58 (&q->q_usage_counter(io)#52){++++}-{0:0}, at: blk_mq_freeze_queue block/blk-mq.c:213 [inline] #4: ffff8880440fbb58 (&q->q_usage_counter(io)#52){++++}-{0:0}, at: __blk_mq_update_nr_hw_queues+0x21c/0x1500 block/blk-mq.c:4997 #5: ffff8880440fbb90 (&q->q_usage_counter(queue)#36){+.+.}-{0:0}, at: blk_mq_freeze_queue block/blk-mq.c:213 [inline] #5: ffff8880440fbb90 (&q->q_usage_counter(queue)#36){+.+.}-{0:0}, at: __blk_mq_update_nr_hw_queues+0x21c/0x1500 block/blk-mq.c:4997 #6: ffff88801f5970b8 (&eq->sysfs_lock){+.+.}-{4:4}, at: elevator_exit block/elevator.c:158 [inline] #6: ffff88801f5970b8 (&eq->sysfs_lock){+.+.}-{4:4}, at: elevator_disable+0xb5/0x490 block/elevator.c:674 stack backtrace: CPU: 3 UID: 0 PID: 14795 Comm: syz.3.2174 Not tainted 6.13.0-rc2-syzkaller-00333-ga0e3919a2df2 #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_circular_bug+0x41c/0x610 kernel/locking/lockdep.c:2074 check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2206 check_prev_add kernel/locking/lockdep.c:3161 [inline] check_prevs_add kernel/locking/lockdep.c:3280 [inline] validate_chain kernel/locking/lockdep.c:3904 [inline] __lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5226 lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5849 __mutex_lock_common kernel/locking/mutex.c:585 [inline] __mutex_lock+0x19b/0xa60 kernel/locking/mutex.c:735 blk_mq_exit_sched+0xd1/0x310 block/blk-mq-sched.c:531 elevator_exit block/elevator.c:159 [inline] elevator_disable+0xc0/0x490 block/elevator.c:674 blk_mq_elv_switch_none block/blk-mq.c:4942 [inline] __blk_mq_update_nr_hw_queues+0x41e/0x1500 block/blk-mq.c:5005 blk_mq_update_nr_hw_queues+0x2a/0x40 block/blk-mq.c:5068 nbd_start_device+0x15b/0xd70 drivers/block/nbd.c:1413 nbd_start_device_ioctl drivers/block/nbd.c:1464 [inline] __nbd_ioctl drivers/block/nbd.c:1539 [inline] nbd_ioctl+0x21a/0xfd0 drivers/block/nbd.c:1579 compat_blkdev_ioctl+0x2f7/0x750 block/ioctl.c:749 __do_compat_sys_ioctl+0x1cb/0x2c0 fs/ioctl.c:1004 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline] __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411 entry_SYSENTER_compat_after_hwframe+0x84/0x8e RIP: 0023:0xf711e579 Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 RSP: 002b:00000000f50ef55c EFLAGS: 00000296 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 0000000000000008 RCX: 000000000000ab03 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 block nbd3: shutting down sockets ---------------- Code disassembly (best guess), 2 bytes skipped: 0: 10 06 adc %al,(%rsi) 2: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi 6: 10 07 adc %al,(%rdi) 8: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi c: 10 08 adc %cl,(%rax) e: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi 1e: 00 51 52 add %dl,0x52(%rcx) 21: 55 push %rbp 22: 89 e5 mov %esp,%ebp 24: 0f 34 sysenter 26: cd 80 int $0x80 * 28: 5d pop %rbp <-- trapping instruction 29: 5a pop %rdx 2a: 59 pop %rcx 2b: c3 ret 2c: 90 nop 2d: 90 nop 2e: 90 nop 2f: 90 nop 30: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi 37: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi