====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.8.6117/23697 is trying to acquire lock: ffff88801e3b7698 (set->srcu){.+.+}-{0:0}, at: srcu_lock_sync include/linux/srcu.h:197 [inline] ffff88801e3b7698 (set->srcu){.+.+}-{0:0}, at: __synchronize_srcu+0x82/0x390 kernel/rcu/srcutree.c:1503 but task is already holding lock: ffff888027b54558 (&q->q_usage_counter(io)#71){++++}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:954 [inline] ffff888027b54558 (&q->q_usage_counter(io)#71){++++}-{0:0}, at: blk_throtl_init+0x27a/0x410 block/blk-throttle.c:1323 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&q->q_usage_counter(io)#71){++++}-{0:0}: blk_alloc_queue+0x538/0x620 block/blk-core.c:461 blk_mq_alloc_queue block/blk-mq.c:4410 [inline] __blk_mq_alloc_disk+0x15c/0x340 block/blk-mq.c:4457 loop_add+0x411/0xad0 drivers/block/loop.c:2206 blk_probe_dev block/genhd.c:884 [inline] blk_request_module+0x27d/0x2a0 block/genhd.c:-1 blkdev_get_no_open+0x3f/0xe0 block/bdev.c:842 blkdev_open+0x1de/0x600 block/fops.c:694 do_dentry_open+0x7ce/0x1420 fs/open.c:962 vfs_open+0x3b/0x340 fs/open.c:1094 do_open fs/namei.c:4597 [inline] path_openat+0x33ce/0x3d90 fs/namei.c:4756 do_filp_open+0x1fa/0x410 fs/namei.c:4783 do_sys_openat2+0x121/0x200 fs/open.c:1430 do_sys_open fs/open.c:1436 [inline] __do_sys_openat fs/open.c:1452 [inline] __se_sys_openat fs/open.c:1447 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1447 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (fs_reclaim){+.+.}-{0:0}: __fs_reclaim_acquire mm/page_alloc.c:4301 [inline] fs_reclaim_acquire+0x72/0x100 mm/page_alloc.c:4315 might_alloc include/linux/sched/mm.h:317 [inline] mempool_alloc_noprof+0xab/0x2f0 mm/mempool.c:559 bio_alloc_bioset+0x241/0x12a0 block/bio.c:559 __blkdev_direct_IO_async block/fops.c:338 [inline] blkdev_direct_IO+0x9c0/0x17e0 block/fops.c:437 blkdev_read_iter+0x23d/0x440 block/fops.c:845 lo_submit_rw_aio+0x488/0x620 drivers/block/loop.c:-1 lo_rw_aio_nowait drivers/block/loop.c:513 [inline] loop_queue_rq+0x6c5/0x8d0 drivers/block/loop.c:2036 __blk_mq_issue_directly block/blk-mq.c:2714 [inline] blk_mq_request_issue_directly+0x3c1/0x710 block/blk-mq.c:2801 blk_mq_issue_direct+0x2a0/0x660 block/blk-mq.c:2822 blk_mq_dispatch_queue_requests+0x621/0x800 block/blk-mq.c:2897 blk_mq_flush_plug_list+0x432/0x550 block/blk-mq.c:2980 __blk_flush_plug+0x3d3/0x4b0 block/blk-core.c:1225 blk_finish_plug block/blk-core.c:1252 [inline] __submit_bio+0x2d3/0x5a0 block/blk-core.c:651 __submit_bio_noacct_mq block/blk-core.c:724 [inline] submit_bio_noacct_nocheck+0x2eb/0xa30 block/blk-core.c:755 submit_bh fs/buffer.c:2829 [inline] block_read_full_folio+0x7b7/0x830 fs/buffer.c:2461 filemap_read_folio+0x117/0x380 mm/filemap.c:2496 do_read_cache_folio+0x358/0x590 mm/filemap.c:4096 read_mapping_folio include/linux/pagemap.h:1017 [inline] read_part_sector+0xb6/0x2b0 block/partitions/core.c:722 adfspart_check_ICS+0xa4/0xa50 block/partitions/acorn.c:360 check_partition block/partitions/core.c:141 [inline] blk_add_partitions block/partitions/core.c:589 [inline] bdev_disk_changed+0x75f/0x14b0 block/partitions/core.c:693 loop_reread_partitions+0x5f/0xf0 drivers/block/loop.c:554 loop_configure+0xbd6/0xe50 drivers/block/loop.c:1248 lo_ioctl+0x806/0x1c50 drivers/block/loop.c:-1 blkdev_ioctl+0x60e/0x710 block/ioctl.c:707 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (set->srcu){.+.+}-{0:0}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x15a6/0x2cf0 kernel/locking/lockdep.c:5237 lock_sync+0xba/0x160 kernel/locking/lockdep.c:5916 srcu_lock_sync include/linux/srcu.h:197 [inline] __synchronize_srcu+0x96/0x390 kernel/rcu/srcutree.c:1503 blk_throtl_init+0x298/0x410 block/blk-throttle.c:1324 tg_set_conf+0x1c6/0x4b0 block/blk-throttle.c:1359 cgroup_file_write+0x3a1/0x740 kernel/cgroup/cgroup.c:4312 kernfs_fop_write_iter+0x3af/0x540 fs/kernfs/file.c:352 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x5c9/0xb30 fs/read_write.c:686 ksys_write+0x145/0x250 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Chain exists of: set->srcu --> fs_reclaim --> &q->q_usage_counter(io)#71 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&q->q_usage_counter(io)#71); lock(fs_reclaim); lock(&q->q_usage_counter(io)#71); sync(set->srcu); *** DEADLOCK *** 7 locks held by syz.8.6117/23697: #0: ffff88805d413cf8 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x247/0x320 fs/file.c:1255 #1: ffff88803423e420 (sb_writers#10){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2681 [inline] #1: ffff88803423e420 (sb_writers#10){.+.+}-{0:0}, at: vfs_write+0x211/0xb30 fs/read_write.c:682 #2: ffff888032e2ac88 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1de/0x540 fs/kernfs/file.c:343 #3: ffff88805db6dc38 (kn->active#90){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline] #3: ffff88805db6dc38 (kn->active#90){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x231/0x540 fs/kernfs/file.c:344 #4: ffff888027b54760 (&q->rq_qos_mutex){+.+.}-{4:4}, at: blkg_conf_open_bdev+0x2a2/0x3d0 block/blk-cgroup.c:802 #5: ffff888027b54558 (&q->q_usage_counter(io)#71){++++}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:954 [inline] #5: ffff888027b54558 (&q->q_usage_counter(io)#71){++++}-{0:0}, at: blk_throtl_init+0x27a/0x410 block/blk-throttle.c:1323 #6: ffff888027b54590 (&q->q_usage_counter(queue)#53){+.+.}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:954 [inline] #6: ffff888027b54590 (&q->q_usage_counter(queue)#53){+.+.}-{0:0}, at: blk_throtl_init+0x27a/0x410 block/blk-throttle.c:1323 stack backtrace: CPU: 0 UID: 0 PID: 23697 Comm: syz.8.6117 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_circular_bug+0x2e2/0x300 kernel/locking/lockdep.c:2043 check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x15a6/0x2cf0 kernel/locking/lockdep.c:5237 lock_sync+0xba/0x160 kernel/locking/lockdep.c:5916 srcu_lock_sync include/linux/srcu.h:197 [inline] __synchronize_srcu+0x96/0x390 kernel/rcu/srcutree.c:1503 blk_throtl_init+0x298/0x410 block/blk-throttle.c:1324 tg_set_conf+0x1c6/0x4b0 block/blk-throttle.c:1359 cgroup_file_write+0x3a1/0x740 kernel/cgroup/cgroup.c:4312 kernfs_fop_write_iter+0x3af/0x540 fs/kernfs/file.c:352 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x5c9/0xb30 fs/read_write.c:686 ksys_write+0x145/0x250 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f663d18f749 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f663b3f6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f663d3e5fa0 RCX: 00007f663d18f749 RDX: 000000000000006a RSI: 00002000000000c0 RDI: 0000000000000007 RBP: 00007f663d213f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f663d3e6038 R14: 00007f663d3e5fa0 R15: 00007fffe895d598