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possible deadlock in dqget (2)

Status: upstream: reported on 2026/01/24 00:53
Subsystems: ocfs2
[Documentation on labels]
Reported-by: syzbot+e7e874621d086b64b4ca@syzkaller.appspotmail.com
First crash: 85d, last: 3d15h
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [fs?] possible deadlock in dqget (2) 1 (2) 2026/02/01 04:21
▶ ▼ Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 possible deadlock in dqget 4 28 36d 299d 0/2 upstream: reported on 2025/06/20 12:37
linux-6.1 possible deadlock in dqget 4 1 442d 442d 0/3 auto-obsoleted due to no activity on 2025/05/07 22:20
upstream possible deadlock in dqget ocfs2 ext4 4 C error 100357 107d 561d 29/29 fixed on 2026/01/07 12:29
linux-5.15 possible deadlock in dqget 4 1 81d 81d 0/3 upstream: reported on 2026/01/23 21:59
linux-6.1 possible deadlock in dqget (2) 4 11 174d 288d 0/3 auto-obsoleted due to no activity on 2026/01/30 18:00

Sample crash report:
EXT4-fs (loop6): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: writeback.
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
syz.6.3213/14478 is trying to acquire lock:
ffff888052e41768 (&dquot->dq_lock){+.+.}-{4:4}, at: wait_on_dquot fs/quota/dquot.c:357 [inline]
ffff888052e41768 (&dquot->dq_lock){+.+.}-{4:4}, at: dqget+0x72a/0xf10 fs/quota/dquot.c:975

but task is already holding lock:
ffff888052cb2728 (&ei->xattr_sem){++++}-{4:4}, at: ext4_setattr+0x884/0x1da0 fs/ext4/inode.c:5846

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #11 (&ei->xattr_sem){++++}-{4:4}:
       down_read+0x47/0x2e0 kernel/locking/rwsem.c:1537
       ext4_readpage_inline+0x36/0x6a0 fs/ext4/inline.c:549
       ext4_read_folio+0x15e/0x550 fs/ext4/readpage.c:404
       filemap_read_folio+0x137/0x3b0 mm/filemap.c:2501
       filemap_create_folio mm/filemap.c:2639 [inline]
       filemap_get_pages+0xcbb/0x1f10 mm/filemap.c:2701
       filemap_read+0x447/0x1230 mm/filemap.c:2805
       __kernel_read+0x504/0x9b0 fs/read_write.c:532
       integrity_kernel_read+0x89/0xd0 security/integrity/iint.c:28
       ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:480 [inline]
       ima_calc_file_shash security/integrity/ima/ima_crypto.c:511 [inline]
       ima_calc_file_hash+0x12c3/0x17f0 security/integrity/ima/ima_crypto.c:568
       ima_collect_measurement+0x48b/0x930 security/integrity/ima/ima_api.c:295
       process_measurement+0x12cd/0x1c80 security/integrity/ima/ima_main.c:407
       ima_file_check+0xe1/0x130 security/integrity/ima/ima_main.c:667
       security_file_post_open+0xb3/0x260 security/security.c:2653
       do_open fs/namei.c:4679 [inline]
       path_openat+0x2e4d/0x3860 fs/namei.c:4836
       do_file_open+0x23e/0x4a0 fs/namei.c:4865
       do_sys_openat2+0x113/0x200 fs/open.c:1366
       do_sys_open fs/open.c:1372 [inline]
       __do_sys_openat fs/open.c:1388 [inline]
       __se_sys_openat fs/open.c:1383 [inline]
       __x64_sys_openat+0x138/0x170 fs/open.c:1383
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #10 (mapping.invalidate_lock#2){++++}-{4:4}:
       down_read+0x47/0x2e0 kernel/locking/rwsem.c:1537
       filemap_invalidate_lock_shared include/linux/fs.h:1093 [inline]
       do_page_cache_ra mm/readahead.c:333 [inline]
       page_cache_ra_order+0xae2/0xeb0 mm/readahead.c:538
       do_async_mmap_readahead mm/filemap.c:3441 [inline]
       filemap_fault+0x656/0x1320 mm/filemap.c:3540
       __do_fault+0x138/0x390 mm/memory.c:5364
       do_read_fault mm/memory.c:5799 [inline]
       do_fault mm/memory.c:5933 [inline]
       do_pte_missing+0x228f/0x3490 mm/memory.c:4477
       handle_pte_fault mm/memory.c:6317 [inline]
       __handle_mm_fault mm/memory.c:6455 [inline]
       handle_mm_fault+0x1bec/0x3310 mm/memory.c:6624
       faultin_page mm/gup.c:1126 [inline]
       __get_user_pages+0x165b/0x29d0 mm/gup.c:1428
       __get_user_pages_locked mm/gup.c:1692 [inline]
       get_dump_page+0x1b5/0x410 mm/gup.c:2192
       dump_user_range+0x20a/0x12d0 fs/coredump.c:1367
       elf_core_dump+0x34c2/0x3ad0 fs/binfmt_elf.c:2110
       coredump_write+0x1216/0x1910 fs/coredump.c:1050
       do_coredump fs/coredump.c:1127 [inline]
       vfs_coredump+0x36a9/0x4280 fs/coredump.c:1201
       get_signal+0x1107/0x1330 kernel/signal.c:3019
       arch_do_signal_or_restart+0xbc/0x830 arch/x86/kernel/signal.c:337
       __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
       exit_to_user_mode_loop kernel/entry/common.c:98 [inline]
       __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
       irqentry_exit_to_user_mode_prepare include/linux/irq-entry-common.h:270 [inline]
       irqentry_exit_to_user_mode include/linux/irq-entry-common.h:339 [inline]
       irqentry_exit+0x176/0x620 kernel/entry/common.c:219
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618

-> #9 (&mm->mmap_lock){++++}-{4:4}:
       __might_fault+0xcb/0x130 mm/memory.c:7230
       _copy_from_iter+0x100/0x1670 lib/iov_iter.c:271
       copy_from_iter include/linux/uio.h:228 [inline]
       copy_from_iter_full include/linux/uio.h:245 [inline]
       skb_do_copy_data_nocache include/net/sock.h:2300 [inline]
       skb_copy_to_page_nocache include/net/sock.h:2326 [inline]
       tcp_sendmsg_locked+0x2151/0x5490 net/ipv4/tcp.c:1324
       tcp_sendmsg+0x2f/0x50 net/ipv4/tcp.c:1465
       sock_sendmsg_nosec net/socket.c:727 [inline]
       __sock_sendmsg net/socket.c:742 [inline]
       sock_write_iter+0x406/0x4f0 net/socket.c:1195
       new_sync_write fs/read_write.c:595 [inline]
       vfs_write+0x61d/0xb90 fs/read_write.c:688
       ksys_write+0x150/0x270 fs/read_write.c:740
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #8 (sk_lock-AF_INET){+.+.}-{0:0}:
       lock_sock_nested+0x48/0x100 net/core/sock.c:3780
       lock_sock include/net/sock.h:1709 [inline]
       tcp_sendmsg+0x21/0x50 net/ipv4/tcp.c:1464
       sock_sendmsg_nosec net/socket.c:727 [inline]
       __sock_sendmsg net/socket.c:742 [inline]
       sock_sendmsg+0x379/0x450 net/socket.c:765
       __sock_xmit+0x251/0x510 drivers/block/nbd.c:576
       sock_xmit drivers/block/nbd.c:605 [inline]
       send_disconnects drivers/block/nbd.c:1406 [inline]
       nbd_disconnect+0x3b7/0x560 drivers/block/nbd.c:1421
       __nbd_ioctl drivers/block/nbd.c:1601 [inline]
       nbd_ioctl+0xc79/0xe40 drivers/block/nbd.c:1663
       blkdev_ioctl+0x5e3/0x740 block/ioctl.c:804
       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+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #7 (&nsock->tx_lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:614 [inline]
       __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776
       nbd_handle_cmd drivers/block/nbd.c:1143 [inline]
       nbd_queue_rq+0x37b/0x1100 drivers/block/nbd.c:1207
       blk_mq_dispatch_rq_list+0xa70/0x1910 block/blk-mq.c:2148
       __blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline]
       blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline]
       __blk_mq_sched_dispatch_requests+0xdcc/0x1600 block/blk-mq-sched.c:307
       blk_mq_sched_dispatch_requests+0xd7/0x190 block/blk-mq-sched.c:329
       blk_mq_run_hw_queue+0x348/0x4f0 block/blk-mq.c:2386
       blk_mq_dispatch_list+0xd16/0xe10 include/linux/spinlock.h:-1
       blk_mq_flush_plug_list+0x48d/0x570 block/blk-mq.c:2997
       __blk_flush_plug+0x3ed/0x4d0 block/blk-core.c:1230
       blk_finish_plug block/blk-core.c:1257 [inline]
       __submit_bio+0x28d/0x580 block/blk-core.c:649
       __submit_bio_noacct_mq block/blk-core.c:722 [inline]
       submit_bio_noacct_nocheck+0x2f4/0xa70 block/blk-core.c:753
       submit_bh fs/buffer.c:2826 [inline]
       block_read_full_folio+0x599/0x830 fs/buffer.c:2444
       filemap_read_folio+0x137/0x3b0 mm/filemap.c:2501
       do_read_cache_folio+0x358/0x590 mm/filemap.c:4106
       read_mapping_folio include/linux/pagemap.h:1017 [inline]
       read_part_sector+0xb6/0x2b0 block/partitions/core.c:723
       adfspart_check_ICS+0xa5/0xa40 block/partitions/acorn.c:360
       check_partition block/partitions/core.c:142 [inline]
       blk_add_partitions block/partitions/core.c:590 [inline]
       bdev_disk_changed+0x7ba/0x1550 block/partitions/core.c:694
       blkdev_get_whole+0x380/0x510 block/bdev.c:764
       bdev_open+0x31e/0xd30 block/bdev.c:973
       blkdev_open+0x470/0x610 block/fops.c:697
       do_dentry_open+0x785/0x14e0 fs/open.c:949
       vfs_open+0x3b/0x340 fs/open.c:1081
       do_open fs/namei.c:4677 [inline]
       path_openat+0x2e08/0x3860 fs/namei.c:4836
       do_file_open+0x23e/0x4a0 fs/namei.c:4865
       do_sys_openat2+0x113/0x200 fs/open.c:1366
       do_sys_open fs/open.c:1372 [inline]
       __do_sys_openat fs/open.c:1388 [inline]
       __se_sys_openat fs/open.c:1383 [inline]
       __x64_sys_openat+0x138/0x170 fs/open.c:1383
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #6 (&cmd->lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:614 [inline]
       __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776
       nbd_queue_rq+0xc6/0x1100 drivers/block/nbd.c:1199
       blk_mq_dispatch_rq_list+0xa70/0x1910 block/blk-mq.c:2148
       __blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline]
       blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline]
       __blk_mq_sched_dispatch_requests+0xdcc/0x1600 block/blk-mq-sched.c:307
       blk_mq_sched_dispatch_requests+0xd7/0x190 block/blk-mq-sched.c:329
       blk_mq_run_hw_queue+0x348/0x4f0 block/blk-mq.c:2386
       blk_mq_dispatch_list+0xd16/0xe10 include/linux/spinlock.h:-1
       blk_mq_flush_plug_list+0x48d/0x570 block/blk-mq.c:2997
       __blk_flush_plug+0x3ed/0x4d0 block/blk-core.c:1230
       blk_finish_plug block/blk-core.c:1257 [inline]
       __submit_bio+0x28d/0x580 block/blk-core.c:649
       __submit_bio_noacct_mq block/blk-core.c:722 [inline]
       submit_bio_noacct_nocheck+0x2f4/0xa70 block/blk-core.c:753
       submit_bh fs/buffer.c:2826 [inline]
       block_read_full_folio+0x599/0x830 fs/buffer.c:2444
       filemap_read_folio+0x137/0x3b0 mm/filemap.c:2501
       do_read_cache_folio+0x358/0x590 mm/filemap.c:4106
       read_mapping_folio include/linux/pagemap.h:1017 [inline]
       read_part_sector+0xb6/0x2b0 block/partitions/core.c:723
       adfspart_check_ICS+0xa5/0xa40 block/partitions/acorn.c:360
       check_partition block/partitions/core.c:142 [inline]
       blk_add_partitions block/partitions/core.c:590 [inline]
       bdev_disk_changed+0x7ba/0x1550 block/partitions/core.c:694
       blkdev_get_whole+0x380/0x510 block/bdev.c:764
       bdev_open+0x31e/0xd30 block/bdev.c:973
       blkdev_open+0x470/0x610 block/fops.c:697
       do_dentry_open+0x785/0x14e0 fs/open.c:949
       vfs_open+0x3b/0x340 fs/open.c:1081
       do_open fs/namei.c:4677 [inline]
       path_openat+0x2e08/0x3860 fs/namei.c:4836
       do_file_open+0x23e/0x4a0 fs/namei.c:4865
       do_sys_openat2+0x113/0x200 fs/open.c:1366
       do_sys_open fs/open.c:1372 [inline]
       __do_sys_openat fs/open.c:1388 [inline]
       __se_sys_openat fs/open.c:1383 [inline]
       __x64_sys_openat+0x138/0x170 fs/open.c:1383
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #5 (set->srcu){.+.+}-{0:0}:
       srcu_lock_sync include/linux/srcu.h:199 [inline]
       __synchronize_srcu+0xca/0x300 kernel/rcu/srcutree.c:1481
       elevator_switch+0x1e8/0x7a0 block/elevator.c:576
       elevator_change+0x2cc/0x450 block/elevator.c:681
       elevator_set_default+0x36c/0x430 block/elevator.c:754
       blk_register_queue+0x366/0x430 block/blk-sysfs.c:946
       __add_disk+0x677/0xd50 block/genhd.c:528
       add_disk_fwnode+0xfb/0x480 block/genhd.c:597
       add_disk include/linux/blkdev.h:785 [inline]
       nbd_dev_add+0x72c/0xb50 drivers/block/nbd.c:1984
       nbd_init+0x168/0x1f0 drivers/block/nbd.c:2692
       do_one_initcall+0x250/0x8d0 init/main.c:1382
       do_initcall_level+0x104/0x190 init/main.c:1444
       do_initcalls+0x59/0xa0 init/main.c:1460
       kernel_init_freeable+0x2a6/0x3e0 init/main.c:1692
       kernel_init+0x1d/0x1d0 init/main.c:1582
       ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #4 (&q->elevator_lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:614 [inline]
       __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776
       elevator_change+0x1b3/0x450 block/elevator.c:679
       elevator_set_none+0xb5/0x140 block/elevator.c:769
       blk_mq_elv_switch_none block/blk-mq.c:5110 [inline]
       __blk_mq_update_nr_hw_queues block/blk-mq.c:5155 [inline]
       blk_mq_update_nr_hw_queues+0x5e7/0x1a60 block/blk-mq.c:5220
       nbd_start_device+0x17f/0xb10 drivers/block/nbd.c:1489
       nbd_genl_connect+0x165b/0x1cf0 drivers/block/nbd.c:2239
       genl_family_rcv_msg_doit+0x22a/0x330 net/netlink/genetlink.c:1114
       genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline]
       genl_rcv_msg+0x61c/0x7a0 net/netlink/genetlink.c:1209
       netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550
       genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
       netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
       netlink_unicast+0x80f/0x9b0 net/netlink/af_netlink.c:1344
       netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
       sock_sendmsg_nosec net/socket.c:727 [inline]
       __sock_sendmsg net/socket.c:742 [inline]
       ____sys_sendmsg+0x972/0x9f0 net/socket.c:2592
       ___sys_sendmsg+0x2a5/0x360 net/socket.c:2646
       __sys_sendmsg net/socket.c:2678 [inline]
       __do_sys_sendmsg net/socket.c:2683 [inline]
       __se_sys_sendmsg net/socket.c:2681 [inline]
       __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2681
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #3 (&q->q_usage_counter(io)#49){++++}-{0:0}:
       blk_alloc_queue+0x546/0x680 block/blk-core.c:461
       blk_mq_alloc_queue block/blk-mq.c:4429 [inline]
       __blk_mq_alloc_disk+0x197/0x390 block/blk-mq.c:4476
       nbd_dev_add+0x499/0xb50 drivers/block/nbd.c:1954
       nbd_init+0x168/0x1f0 drivers/block/nbd.c:2692
       do_one_initcall+0x250/0x8d0 init/main.c:1382
       do_initcall_level+0x104/0x190 init/main.c:1444
       do_initcalls+0x59/0xa0 init/main.c:1460
       kernel_init_freeable+0x2a6/0x3e0 init/main.c:1692
       kernel_init+0x1d/0x1d0 init/main.c:1582
       ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #2 (fs_reclaim){+.+.}-{0:0}:
       __fs_reclaim_acquire mm/page_alloc.c:4348 [inline]
       fs_reclaim_acquire+0x71/0x100 mm/page_alloc.c:4362
       might_alloc include/linux/sched/mm.h:317 [inline]
       slab_pre_alloc_hook mm/slub.c:4489 [inline]
       slab_alloc_node mm/slub.c:4843 [inline]
       __do_kmalloc_node mm/slub.c:5259 [inline]
       __kmalloc_noprof+0x9d/0x760 mm/slub.c:5272
       kmalloc_noprof include/linux/slab.h:954 [inline]
       find_tree_dqentry+0x5c/0x1070 fs/quota/quota_tree.c:663
       find_dqentry fs/quota/quota_tree.c:716 [inline]
       qtree_read_dquot+0x586/0x830 fs/quota/quota_tree.c:736
       ocfs2_acquire_dquot+0x2e9/0xb70 fs/ocfs2/quota_global.c:838
       dqget+0x7b1/0xf10 fs/quota/dquot.c:980
       __dquot_initialize+0x3ba/0xd30 fs/quota/dquot.c:1508
       ocfs2_get_init_inode+0x147/0x1c0 fs/ocfs2/namei.c:206
       ocfs2_mknod+0xa67/0x2290 fs/ocfs2/namei.c:314
       ocfs2_mkdir+0x181/0x490 fs/ocfs2/namei.c:660
       vfs_mkdir+0x413/0x630 fs/namei.c:5239
       filename_mkdirat+0x285/0x510 fs/namei.c:5272
       __do_sys_mkdir fs/namei.c:5299 [inline]
       __se_sys_mkdir+0x34/0x150 fs/namei.c:5296
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&ocfs2_quota_ip_alloc_sem_key){++++}-{4:4}:
       down_write+0x96/0x200 kernel/locking/rwsem.c:1590
       ocfs2_create_local_dquot+0x1a5/0x1af0 fs/ocfs2/quota_local.c:1227
       ocfs2_acquire_dquot+0x816/0xb70 fs/ocfs2/quota_global.c:883
       dqget+0x7b1/0xf10 fs/quota/dquot.c:980
       __dquot_initialize+0x3ba/0xd30 fs/quota/dquot.c:1508
       ocfs2_get_init_inode+0x147/0x1c0 fs/ocfs2/namei.c:206
       ocfs2_mknod+0xa67/0x2290 fs/ocfs2/namei.c:314
       vfs_mknod+0x447/0x610 fs/namei.c:5098
       filename_mknodat+0x3cb/0x660 fs/namei.c:-1
       __do_sys_mknod fs/namei.c:5185 [inline]
       __se_sys_mknod+0x3a/0x150 fs/namei.c:5182
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&dquot->dq_lock){+.+.}-{4:4}:
       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+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237
       lock_acquire+0xf0/0x2e0 kernel/locking/lockdep.c:5868
       __mutex_lock_common kernel/locking/mutex.c:614 [inline]
       __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776
       wait_on_dquot fs/quota/dquot.c:357 [inline]
       dqget+0x72a/0xf10 fs/quota/dquot.c:975
       dquot_transfer+0x451/0x660 fs/quota/dquot.c:2157
       ext4_setattr+0x894/0x1da0 fs/ext4/inode.c:5847
       notify_change+0xc1a/0xf40 fs/attr.c:556
       chown_common+0x466/0x6b0 fs/open.c:778
       vfs_fchown fs/open.c:843 [inline]
       ksys_fchown+0xe9/0x160 fs/open.c:855
       __do_sys_fchown fs/open.c:860 [inline]
       __se_sys_fchown fs/open.c:858 [inline]
       __x64_sys_fchown+0x7a/0x90 fs/open.c:858
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x14d/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:
  &dquot->dq_lock --> mapping.invalidate_lock#2 --> &ei->xattr_sem

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  rlock(&ei->xattr_sem);
                               lock(mapping.invalidate_lock#2);
                               lock(&ei->xattr_sem);
  lock(&dquot->dq_lock);

 *** DEADLOCK ***

3 locks held by syz.6.3213/14478:
 #0: ffff88805226c420 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write_file+0x60/0x200 fs/namespace.c:537
 #1: ffff888052cb2a40 (&sb->s_type->i_mutex_key#12){++++}-{4:4}, at: inode_lock_killable include/linux/fs.h:1033 [inline]
 #1: ffff888052cb2a40 (&sb->s_type->i_mutex_key#12){++++}-{4:4}, at: chown_common+0x35e/0x6b0 fs/open.c:766
 #2: ffff888052cb2728 (&ei->xattr_sem){++++}-{4:4}, at: ext4_setattr+0x884/0x1da0 fs/ext4/inode.c:5846

stack backtrace:
CPU: 1 UID: 0 PID: 14478 Comm: syz.6.3213 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_circular_bug+0x2e1/0x300 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+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237
 lock_acquire+0xf0/0x2e0 kernel/locking/lockdep.c:5868
 __mutex_lock_common kernel/locking/mutex.c:614 [inline]
 __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776
 wait_on_dquot fs/quota/dquot.c:357 [inline]
 dqget+0x72a/0xf10 fs/quota/dquot.c:975
 dquot_transfer+0x451/0x660 fs/quota/dquot.c:2157
 ext4_setattr+0x894/0x1da0 fs/ext4/inode.c:5847
 notify_change+0xc1a/0xf40 fs/attr.c:556
 chown_common+0x466/0x6b0 fs/open.c:778
 vfs_fchown fs/open.c:843 [inline]
 ksys_fchown+0xe9/0x160 fs/open.c:855
 __do_sys_fchown fs/open.c:860 [inline]
 __se_sys_fchown fs/open.c:858 [inline]
 __x64_sys_fchown+0x7a/0x90 fs/open.c:858
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f744ed9c819
Code: ff c3 66 2e 0f 1f 84 00 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 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f744fbee028 EFLAGS: 00000246 ORIG_RAX: 000000000000005d
RAX: ffffffffffffffda RBX: 00007f744f015fa0 RCX: 00007f744ed9c819
RDX: 000000000000ee01 RSI: ffffffffffffffff RDI: 0000000000000004
RBP: 00007f744ee32c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f744f016038 R14: 00007f744f015fa0 R15: 00007ffc100e6d98
 </TASK>

Crashes (8):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/11 23:26 upstream e753c16cb3dd 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in dqget
2026/03/28 03:41 upstream 7df48e363130 356bdfc9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in dqget
2026/03/28 03:07 upstream 7df48e363130 356bdfc9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in dqget
2026/03/14 06:58 upstream 1c9982b49613 ee8d34d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in dqget
2026/02/25 11:31 upstream 7dff99b35460 94a9671e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in dqget
2026/01/20 00:51 upstream 24d479d26b25 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in dqget
2026/02/23 08:24 linux-next d4906ae14a5f 6e7b5511 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in dqget
2026/02/10 12:18 linux-next 132737e360b4 91d776d3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in dqget
* Struck through repros no longer work on HEAD.