loop5: detected capacity change from 0 to 8192 ====================================================== WARNING: possible circular locking dependency detected 6.12.0-syzkaller-11930-g0e287d31b62b #0 Not tainted ------------------------------------------------------ syz.5.2049/20355 is trying to acquire lock: ffff88804d8140b0 (&sbi->fat_lock){+.+.}-{4:4}, at: lock_fat fs/fat/fatent.c:281 [inline] ffff88804d8140b0 (&sbi->fat_lock){+.+.}-{4:4}, at: fat_count_free_clusters+0x138/0x9d0 fs/fat/fatent.c:724 but task is already holding lock: ffff88814330df00 (&q->limits_lock){+.+.}-{4:4}, at: queue_limits_start_update include/linux/blkdev.h:945 [inline] ffff88814330df00 (&q->limits_lock){+.+.}-{4:4}, at: loop_reconfigure_limits+0x2da/0x8d0 drivers/block/loop.c:1003 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&q->limits_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:585 [inline] __mutex_lock+0x19b/0xa60 kernel/locking/mutex.c:735 queue_limits_start_update include/linux/blkdev.h:945 [inline] loop_reconfigure_limits+0x2da/0x8d0 drivers/block/loop.c:1003 loop_set_block_size drivers/block/loop.c:1473 [inline] lo_simple_ioctl drivers/block/loop.c:1496 [inline] lo_ioctl+0x901/0x18b0 drivers/block/loop.c:1559 blkdev_ioctl+0x279/0x6d0 block/ioctl.c:693 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl fs/ioctl.c:892 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:892 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 -> #1 (&q->q_usage_counter(io) #24){++++}-{0:0}: bio_queue_enter block/blk.h:75 [inline] blk_mq_submit_bio+0x1fb6/0x24c0 block/blk-mq.c:3092 __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 submit_bh fs/buffer.c:2819 [inline] __bread_slow fs/buffer.c:1264 [inline] __bread_gfp+0x189/0x340 fs/buffer.c:1488 sb_bread include/linux/buffer_head.h:346 [inline] fat12_ent_bread+0x141/0x410 fs/fat/fatent.c:77 fat_ent_read+0x6a4/0xb90 fs/fat/fatent.c:368 fat_free_clusters+0x1b7/0xa60 fs/fat/fatent.c:568 fat_free fs/fat/file.c:376 [inline] fat_truncate_blocks+0x53a/0xbe0 fs/fat/file.c:394 fat_evict_inode+0x8d/0x280 fs/fat/inode.c:656 evict+0x40c/0x960 fs/inode.c:796 iput_final fs/inode.c:1946 [inline] iput fs/inode.c:1972 [inline] iput+0x52a/0x890 fs/inode.c:1958 do_unlinkat+0x5c3/0x760 fs/namei.c:4594 __do_sys_unlinkat fs/namei.c:4630 [inline] __se_sys_unlinkat fs/namei.c:4623 [inline] __x64_sys_unlinkat+0xbf/0x130 fs/namei.c:4623 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 -> #0 (&sbi->fat_lock){+.+.}-{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 lock_fat fs/fat/fatent.c:281 [inline] fat_count_free_clusters+0x138/0x9d0 fs/fat/fatent.c:724 fat_statfs+0x3c2/0x4d0 fs/fat/inode.c:834 statfs_by_dentry+0x12e/0x210 fs/statfs.c:66 vfs_statfs+0x3a/0xa0 fs/statfs.c:90 loop_config_discard drivers/block/loop.c:798 [inline] loop_reconfigure_limits+0x5b7/0x8d0 drivers/block/loop.c:1012 loop_configure+0x7a0/0x11f0 drivers/block/loop.c:1093 lo_ioctl+0xa6a/0x18b0 drivers/block/loop.c:1532 blkdev_ioctl+0x279/0x6d0 block/ioctl.c:693 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl fs/ioctl.c:892 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:892 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 other info that might help us debug this: Chain exists of: &sbi->fat_lock --> &q->q_usage_counter(io)#24 --> &q->limits_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&q->limits_lock); lock(&q->q_usage_counter(io)#24); lock(&q->limits_lock); lock(&sbi->fat_lock); *** DEADLOCK *** 2 locks held by syz.5.2049/20355: #0: ffff888145ac7360 (&lo->lo_mutex){+.+.}-{4:4}, at: loop_global_lock_killable drivers/block/loop.c:120 [inline] #0: ffff888145ac7360 (&lo->lo_mutex){+.+.}-{4:4}, at: loop_configure+0x22f/0x11f0 drivers/block/loop.c:1044 #1: ffff88814330df00 (&q->limits_lock){+.+.}-{4:4}, at: queue_limits_start_update include/linux/blkdev.h:945 [inline] #1: ffff88814330df00 (&q->limits_lock){+.+.}-{4:4}, at: loop_reconfigure_limits+0x2da/0x8d0 drivers/block/loop.c:1003 stack backtrace: CPU: 1 UID: 0 PID: 20355 Comm: syz.5.2049 Not tainted 6.12.0-syzkaller-11930-g0e287d31b62b #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_circular_bug+0x419/0x5d0 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 lock_fat fs/fat/fatent.c:281 [inline] fat_count_free_clusters+0x138/0x9d0 fs/fat/fatent.c:724 fat_statfs+0x3c2/0x4d0 fs/fat/inode.c:834 statfs_by_dentry+0x12e/0x210 fs/statfs.c:66 vfs_statfs+0x3a/0xa0 fs/statfs.c:90 loop_config_discard drivers/block/loop.c:798 [inline] loop_reconfigure_limits+0x5b7/0x8d0 drivers/block/loop.c:1012 loop_configure+0x7a0/0x11f0 drivers/block/loop.c:1093 lo_ioctl+0xa6a/0x18b0 drivers/block/loop.c:1532 blkdev_ioctl+0x279/0x6d0 block/ioctl.c:693 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl fs/ioctl.c:892 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:892 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 RIP: 0033:0x7fe588180849 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:00007fe589035058 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fe588345fa0 RCX: 00007fe588180849 RDX: 00000000200002c0 RSI: 0000000000004c0a RDI: 0000000000000004 RBP: 00007fe5881f3986 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007fe588345fa0 R15: 00007fff267de898