====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.5.1045/9390 is trying to acquire lock: ffff88805095c0a8 (&dquot->dq_lock){+.+.}-{3:3}, at: dquot_commit+0x5a/0x410 fs/quota/dquot.c:507 but task is already holding lock: ffff888055751698 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_map_blocks+0x910/0x1b70 fs/ext4/inode.c:672 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&ei->i_data_sem/2){++++}-{3:3}: down_write+0x36/0x60 kernel/locking/rwsem.c:1573 ext4_map_blocks+0x910/0x1b70 fs/ext4/inode.c:672 ext4_getblk+0x1cc/0x6f0 fs/ext4/inode.c:890 ext4_bread+0x26/0x170 fs/ext4/inode.c:946 ext4_quota_write+0x236/0x580 fs/ext4/super.c:7222 write_blk fs/quota/quota_tree.c:70 [inline] find_free_dqentry+0x673/0xc20 fs/quota/quota_tree.c:318 do_insert_tree+0x70d/0x1040 fs/quota/quota_tree.c:400 do_insert_tree+0x9eb/0x1040 fs/quota/quota_tree.c:402 do_insert_tree+0x9eb/0x1040 fs/quota/quota_tree.c:402 do_insert_tree+0x9eb/0x1040 fs/quota/quota_tree.c:402 dq_insert_tree fs/quota/quota_tree.c:432 [inline] qtree_write_dquot+0x49d/0x5d0 fs/quota/quota_tree.c:451 v2_write_dquot+0x108/0x190 fs/quota/quota_v2.c:361 dquot_acquire+0x2d5/0x520 fs/quota/dquot.c:472 ext4_acquire_dquot+0x2d9/0x4a0 fs/ext4/super.c:6831 dqget+0x778/0xeb0 fs/quota/dquot.c:988 __dquot_initialize+0x3c3/0xcd0 fs/quota/dquot.c:1517 ext4_process_orphan+0x54/0x300 fs/ext4/orphan.c:327 ext4_orphan_cleanup+0xbeb/0x1420 fs/ext4/orphan.c:472 __ext4_fill_super fs/ext4/super.c:5556 [inline] ext4_fill_super+0x7829/0x7dc0 fs/ext4/super.c:5687 get_tree_bdev+0x3f1/0x610 fs/super.c:1366 vfs_get_tree+0x88/0x270 fs/super.c:1573 do_new_mount+0x24a/0xa40 fs/namespace.c:3078 do_mount fs/namespace.c:3421 [inline] __do_sys_mount fs/namespace.c:3629 [inline] __se_sys_mount+0x2e3/0x3d0 fs/namespace.c:3606 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 -> #1 (&s->s_dquot.dqio_sem){++++}-{3:3}: down_read+0x42/0x2d0 kernel/locking/rwsem.c:1520 v2_read_dquot+0x4a/0x110 fs/quota/quota_v2.c:335 dquot_acquire+0x152/0x520 fs/quota/dquot.c:463 ext4_acquire_dquot+0x2d9/0x4a0 fs/ext4/super.c:6831 dqget+0x778/0xeb0 fs/quota/dquot.c:988 __dquot_initialize+0x3c3/0xcd0 fs/quota/dquot.c:1517 ext4_process_orphan+0x54/0x300 fs/ext4/orphan.c:327 ext4_orphan_cleanup+0xbeb/0x1420 fs/ext4/orphan.c:472 __ext4_fill_super fs/ext4/super.c:5556 [inline] ext4_fill_super+0x7829/0x7dc0 fs/ext4/super.c:5687 get_tree_bdev+0x3f1/0x610 fs/super.c:1366 vfs_get_tree+0x88/0x270 fs/super.c:1573 do_new_mount+0x24a/0xa40 fs/namespace.c:3078 do_mount fs/namespace.c:3421 [inline] __do_sys_mount fs/namespace.c:3629 [inline] __se_sys_mount+0x2e3/0x3d0 fs/namespace.c:3606 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 -> #0 (&dquot->dq_lock){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:3090 [inline] check_prevs_add kernel/locking/lockdep.c:3209 [inline] validate_chain kernel/locking/lockdep.c:3825 [inline] __lock_acquire+0x2d07/0x7d10 kernel/locking/lockdep.c:5049 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5662 __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x12d/0xaf0 kernel/locking/mutex.c:747 dquot_commit+0x5a/0x410 fs/quota/dquot.c:507 ext4_write_dquot+0x1f0/0x360 fs/ext4/super.c:6811 mark_dquot_dirty fs/quota/dquot.c:372 [inline] mark_all_dquot_dirty+0xf9/0x400 fs/quota/dquot.c:412 __dquot_alloc_space+0x5fc/0xe60 fs/quota/dquot.c:1752 dquot_alloc_space_nodirty include/linux/quotaops.h:300 [inline] dquot_alloc_space include/linux/quotaops.h:313 [inline] dquot_alloc_block include/linux/quotaops.h:337 [inline] ext4_mb_new_blocks+0xf8d/0x4760 fs/ext4/mballoc.c:5738 ext4_ext_map_blocks+0x195b/0x6810 fs/ext4/extents.c:4340 ext4_map_blocks+0x9de/0x1b70 fs/ext4/inode.c:679 _ext4_get_block+0x1e7/0x540 fs/ext4/inode.c:822 ext4_block_write_begin+0x644/0x1300 fs/ext4/inode.c:1124 ext4_write_begin+0x629/0xf80 fs/ext4/ext4_jbd2.h:-1 ext4_da_write_begin+0x30a/0x960 fs/ext4/inode.c:3000 generic_perform_write+0x2fa/0x5c0 mm/filemap.c:3862 ext4_buffered_write_iter+0x11a/0x390 fs/ext4/file.c:285 ext4_file_write_iter+0x1cf/0x1710 fs/ext4/file.c:-1 __kernel_write_iter+0x285/0x650 fs/read_write.c:517 __kernel_write+0x103/0x170 fs/read_write.c:537 __dump_emit+0x208/0x310 fs/coredump.c:873 elf_core_dump+0x2858/0x35d0 fs/binfmt_elf.c:2306 do_coredump+0x165b/0x22f0 fs/coredump.c:824 get_signal+0x10aa/0x1350 kernel/signal.c:2857 arch_do_signal_or_restart+0xc4/0x1350 arch/x86/kernel/signal.c:871 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210 irqentry_exit_to_user_mode+0x5/0x30 kernel/entry/common.c:316 exc_page_fault+0x88/0x100 arch/x86/mm/fault.c:1490 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:608 other info that might help us debug this: Chain exists of: &dquot->dq_lock --> &s->s_dquot.dqio_sem --> &ei->i_data_sem/2 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&ei->i_data_sem/2); lock(&s->s_dquot.dqio_sem); lock(&ei->i_data_sem/2); lock(&dquot->dq_lock); *** DEADLOCK *** 4 locks held by syz.5.1045/9390: #0: ffff88807a128460 (sb_writers#4){.+.+}-{0:0}, at: do_coredump+0x163a/0x22f0 fs/coredump.c:823 #1: ffff888055751810 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline] #1: ffff888055751810 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: ext4_buffered_write_iter+0xa1/0x390 fs/ext4/file.c:279 #2: ffff888055751698 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_map_blocks+0x910/0x1b70 fs/ext4/inode.c:672 #3: ffffffff8cc74988 (dquot_srcu){....}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline] #3: ffffffff8cc74988 (dquot_srcu){....}-{0:0}, at: srcu_read_lock include/linux/srcu.h:165 [inline] #3: ffffffff8cc74988 (dquot_srcu){....}-{0:0}, at: __dquot_alloc_space+0x173/0xe60 fs/quota/dquot.c:1716 stack backtrace: CPU: 0 PID: 9390 Comm: syz.5.1045 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106 check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2170 check_prev_add kernel/locking/lockdep.c:3090 [inline] check_prevs_add kernel/locking/lockdep.c:3209 [inline] validate_chain kernel/locking/lockdep.c:3825 [inline] __lock_acquire+0x2d07/0x7d10 kernel/locking/lockdep.c:5049 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5662 __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x12d/0xaf0 kernel/locking/mutex.c:747 dquot_commit+0x5a/0x410 fs/quota/dquot.c:507 ext4_write_dquot+0x1f0/0x360 fs/ext4/super.c:6811 mark_dquot_dirty fs/quota/dquot.c:372 [inline] mark_all_dquot_dirty+0xf9/0x400 fs/quota/dquot.c:412 __dquot_alloc_space+0x5fc/0xe60 fs/quota/dquot.c:1752 dquot_alloc_space_nodirty include/linux/quotaops.h:300 [inline] dquot_alloc_space include/linux/quotaops.h:313 [inline] dquot_alloc_block include/linux/quotaops.h:337 [inline] ext4_mb_new_blocks+0xf8d/0x4760 fs/ext4/mballoc.c:5738 ext4_ext_map_blocks+0x195b/0x6810 fs/ext4/extents.c:4340 ext4_map_blocks+0x9de/0x1b70 fs/ext4/inode.c:679 _ext4_get_block+0x1e7/0x540 fs/ext4/inode.c:822 ext4_block_write_begin+0x644/0x1300 fs/ext4/inode.c:1124 ext4_write_begin+0x629/0xf80 fs/ext4/ext4_jbd2.h:-1 ext4_da_write_begin+0x30a/0x960 fs/ext4/inode.c:3000 generic_perform_write+0x2fa/0x5c0 mm/filemap.c:3862 ext4_buffered_write_iter+0x11a/0x390 fs/ext4/file.c:285 ext4_file_write_iter+0x1cf/0x1710 fs/ext4/file.c:-1 __kernel_write_iter+0x285/0x650 fs/read_write.c:517 __kernel_write+0x103/0x170 fs/read_write.c:537 __dump_emit+0x208/0x310 fs/coredump.c:873 elf_core_dump+0x2858/0x35d0 fs/binfmt_elf.c:2306 do_coredump+0x165b/0x22f0 fs/coredump.c:824 get_signal+0x10aa/0x1350 kernel/signal.c:2857 arch_do_signal_or_restart+0xc4/0x1350 arch/x86/kernel/signal.c:871 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210 irqentry_exit_to_user_mode+0x5/0x30 kernel/entry/common.c:316 exc_page_fault+0x88/0x100 arch/x86/mm/fault.c:1490 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:608 RIP: 0033:0x7fe8cb19aec1 Code: 00 00 00 00 0f 1f 44 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 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f RSP: 002b:000000000000a420 EFLAGS: 00010217 RAX: 0000000000000000 RBX: 00007fe8cb416090 RCX: 00007fe8cb19aeb9 RDX: 0000000000000000 RSI: 000000000000a420 RDI: 0000000000022080 RBP: 00007fe8cb208c1f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 R13: 00007fe8cb416128 R14: 00007fe8cb416090 R15: 00007fff5807bd58 syz.5.1045 (9390) used greatest stack depth: 19312 bytes left