possible deadlock in btrfs_search_slot (3)

Status: auto-obsoleted due to no activity on 2025/04/24 08:43
Subsystems: btrfs
[Documentation on labels]
Reported-by: syzbot+7791482179507f327138@syzkaller.appspotmail.com
First crash: 619d, last: 571d
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [btrfs?] possible deadlock in btrfs_search_slot (3) 0 (1) 2024/12/01 19:56
▶ ▼ Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in btrfs_search_slot (2) btrfs 4 syz, C error 2 1083d 1079d 25/29 fixed on 2023/12/21 03:45
upstream possible deadlock in btrfs_search_slot btrfs 4 syz, C error done 188 1095d 1370d 23/29 fixed on 2023/08/10 11:21

Sample crash report:
BTRFS info (device loop3): rebuilding free space tree
======================================================
WARNING: possible circular locking dependency detected
6.13.0-rc7-syzkaller-00019-gc45323b7560e #0 Not tainted
------------------------------------------------------
syz.3.877/11306 is trying to acquire lock:
ffff8880626cf3b8 (btrfs-tree-00){++++}-{4:4}, at: btrfs_tree_read_lock_nested+0x2f/0x250 fs/btrfs/locking.c:146

but task is already holding lock:
ffff8880626cfef8 (btrfs-tree-01){++++}-{4:4}, at: btrfs_tree_read_lock_nested+0x2f/0x250 fs/btrfs/locking.c:146

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #8 (btrfs-tree-01){++++}-{4:4}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
       down_read_nested+0xb5/0xa50 kernel/locking/rwsem.c:1649
       btrfs_tree_read_lock_nested+0x2f/0x250 fs/btrfs/locking.c:146
       btrfs_tree_read_lock fs/btrfs/locking.h:188 [inline]
       btrfs_read_lock_root_node+0x3f/0xd0 fs/btrfs/locking.c:267
       btrfs_search_slot_get_root fs/btrfs/ctree.c:1787 [inline]
       btrfs_search_slot+0x4f4/0x3180 fs/btrfs/ctree.c:2113
       btrfs_lookup_file_extent+0x14c/0x210 fs/btrfs/file-item.c:267
       btrfs_get_extent+0x3e9/0x1660 fs/btrfs/inode.c:6860
       btrfs_fallocate+0xcb7/0x2000 fs/btrfs/file.c:3046
       vfs_fallocate+0x56b/0x6e0 fs/open.c:327
       ksys_fallocate fs/open.c:351 [inline]
       __do_sys_fallocate fs/open.c:356 [inline]
       __se_sys_fallocate fs/open.c:354 [inline]
       __x64_sys_fallocate+0xbc/0x110 fs/open.c:354
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #7 (&ei->i_mmap_lock){++++}-{4:4}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
       down_read+0xb1/0xa40 kernel/locking/rwsem.c:1524
       btrfs_page_mkwrite+0x62a/0x1540 fs/btrfs/file.c:1843
       do_page_mkwrite+0x15e/0x350 mm/memory.c:3176
       do_shared_fault mm/memory.c:5398 [inline]
       do_fault mm/memory.c:5460 [inline]
       do_pte_missing mm/memory.c:3979 [inline]
       handle_pte_fault+0x10c6/0x5ed0 mm/memory.c:5801
       __handle_mm_fault mm/memory.c:5944 [inline]
       handle_mm_fault+0x1106/0x1bb0 mm/memory.c:6112
       do_user_addr_fault arch/x86/mm/fault.c:1389 [inline]
       handle_page_fault arch/x86/mm/fault.c:1481 [inline]
       exc_page_fault+0x2b9/0x8b0 arch/x86/mm/fault.c:1539
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

-> #6 (sb_pagefaults#2){.+.+}-{0:0}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1725 [inline]
       sb_start_pagefault include/linux/fs.h:1890 [inline]
       btrfs_page_mkwrite+0x323/0x1540 fs/btrfs/file.c:1814
       do_page_mkwrite+0x15e/0x350 mm/memory.c:3176
       do_shared_fault mm/memory.c:5398 [inline]
       do_fault mm/memory.c:5460 [inline]
       do_pte_missing mm/memory.c:3979 [inline]
       handle_pte_fault+0x10c6/0x5ed0 mm/memory.c:5801
       __handle_mm_fault mm/memory.c:5944 [inline]
       handle_mm_fault+0x1106/0x1bb0 mm/memory.c:6112
       do_user_addr_fault arch/x86/mm/fault.c:1389 [inline]
       handle_page_fault arch/x86/mm/fault.c:1481 [inline]
       exc_page_fault+0x2b9/0x8b0 arch/x86/mm/fault.c:1539
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

-> #5 (&mm->mmap_lock){++++}-{4:4}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
       __might_fault+0xc6/0x120 mm/memory.c:6751
       _inline_copy_from_user include/linux/uaccess.h:162 [inline]
       _copy_from_user+0x2a/0xc0 lib/usercopy.c:18
       copy_from_user include/linux/uaccess.h:212 [inline]
       __blk_trace_setup kernel/trace/blktrace.c:626 [inline]
       blk_trace_ioctl+0x1ad/0x9a0 kernel/trace/blktrace.c:740
       blkdev_ioctl+0x40c/0x6a0 block/ioctl.c:682
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:906 [inline]
       __se_sys_ioctl+0xf7/0x170 fs/ioctl.c:892
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #4 (&q->debugfs_mutex){+.+.}-{4:4}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
       __mutex_lock_common kernel/locking/mutex.c:585 [inline]
       __mutex_lock+0x1ac/0xee0 kernel/locking/mutex.c:735
       blk_mq_init_sched+0x3fa/0x830 block/blk-mq-sched.c:473
       elevator_init_mq+0x20e/0x320 block/elevator.c:610
       add_disk_fwnode+0x10d/0xf80 block/genhd.c:413
       sd_probe+0xba6/0x1100 drivers/scsi/sd.c:4024
       really_probe+0x2ba/0xad0 drivers/base/dd.c:658
       __driver_probe_device+0x1a2/0x390 drivers/base/dd.c:800
       driver_probe_device+0x50/0x430 drivers/base/dd.c:830
       __device_attach_driver+0x2d6/0x530 drivers/base/dd.c:958
       bus_for_each_drv+0x250/0x2e0 drivers/base/bus.c:459
       __device_attach_async_helper+0x22d/0x300 drivers/base/dd.c:987
       async_run_entry_fn+0xaa/0x420 kernel/async.c:129
       process_one_work kernel/workqueue.c:3236 [inline]
       process_scheduled_works+0xa68/0x1840 kernel/workqueue.c:3317
       worker_thread+0x870/0xd30 kernel/workqueue.c:3398
       kthread+0x2f2/0x390 kernel/kthread.c:389
       ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

-> #3 (&q->q_usage_counter(queue)#50){++++}-{0:0}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
       blk_queue_enter+0xe1/0x600 block/blk-core.c:328
       blk_mq_alloc_request+0x4fa/0xaa0 block/blk-mq.c:652
       scsi_alloc_request drivers/scsi/scsi_lib.c:1222 [inline]
       scsi_execute_cmd+0x177/0x1090 drivers/scsi/scsi_lib.c:304
       read_capacity_16+0x2b4/0x1450 drivers/scsi/sd.c:2655
       sd_read_capacity drivers/scsi/sd.c:2824 [inline]
       sd_revalidate_disk+0x1013/0xbce0 drivers/scsi/sd.c:3734
       sd_probe+0x9fa/0x1100 drivers/scsi/sd.c:4010
       really_probe+0x2ba/0xad0 drivers/base/dd.c:658
       __driver_probe_device+0x1a2/0x390 drivers/base/dd.c:800
       driver_probe_device+0x50/0x430 drivers/base/dd.c:830
       __device_attach_driver+0x2d6/0x530 drivers/base/dd.c:958
       bus_for_each_drv+0x250/0x2e0 drivers/base/bus.c:459
       __device_attach_async_helper+0x22d/0x300 drivers/base/dd.c:987
       async_run_entry_fn+0xaa/0x420 kernel/async.c:129
       process_one_work kernel/workqueue.c:3236 [inline]
       process_scheduled_works+0xa68/0x1840 kernel/workqueue.c:3317
       worker_thread+0x870/0xd30 kernel/workqueue.c:3398
       kthread+0x2f2/0x390 kernel/kthread.c:389
       ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

-> #2 (&q->limits_lock){+.+.}-{4:4}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
       __mutex_lock_common kernel/locking/mutex.c:585 [inline]
       __mutex_lock+0x1ac/0xee0 kernel/locking/mutex.c:735
       queue_limits_start_update include/linux/blkdev.h:947 [inline]
       loop_reconfigure_limits+0x43f/0x900 drivers/block/loop.c:998
       loop_set_block_size drivers/block/loop.c:1473 [inline]
       lo_simple_ioctl drivers/block/loop.c:1496 [inline]
       lo_ioctl+0x1351/0x1f50 drivers/block/loop.c:1559
       blkdev_ioctl+0x57f/0x6a0 block/ioctl.c:693
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:906 [inline]
       __se_sys_ioctl+0xf7/0x170 fs/ioctl.c:892
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&q->q_usage_counter(io)#23){++++}-{0:0}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
       bio_queue_enter block/blk.h:75 [inline]
       blk_mq_submit_bio+0x1536/0x2390 block/blk-mq.c:3090
       __submit_bio+0x2c6/0x560 block/blk-core.c:629
       __submit_bio_noacct_mq block/blk-core.c:710 [inline]
       submit_bio_noacct_nocheck+0x4d3/0xe30 block/blk-core.c:739
       btrfs_submit_chunk fs/btrfs/bio.c:763 [inline]
       btrfs_submit_bbio+0xf91/0x19c0 fs/btrfs/bio.c:792
       read_extent_buffer_pages+0x61f/0x7f0 fs/btrfs/extent_io.c:3558
       btrfs_read_extent_buffer+0xdb/0x730 fs/btrfs/disk-io.c:229
       read_block_for_search+0x79e/0xbb0 fs/btrfs/ctree.c:1616
       btrfs_search_slot+0x1274/0x3180 fs/btrfs/ctree.c:2237
       btrfs_init_root_free_objectid+0x148/0x330 fs/btrfs/disk-io.c:4846
       btrfs_init_fs_root fs/btrfs/disk-io.c:1137 [inline]
       btrfs_get_root_ref+0x5d7/0xc30 fs/btrfs/disk-io.c:1364
       btrfs_get_fs_root fs/btrfs/disk-io.c:1416 [inline]
       open_ctree+0x2470/0x2a30 fs/btrfs/disk-io.c:3532
       btrfs_fill_super fs/btrfs/super.c:972 [inline]
       btrfs_get_tree_super fs/btrfs/super.c:1898 [inline]
       btrfs_get_tree+0x12d8/0x1a30 fs/btrfs/super.c:2093
       vfs_get_tree+0x92/0x2b0 fs/super.c:1814
       fc_mount+0x1b/0xb0 fs/namespace.c:1231
       btrfs_get_tree_subvol fs/btrfs/super.c:2051 [inline]
       btrfs_get_tree+0x6b1/0x1a30 fs/btrfs/super.c:2094
       vfs_get_tree+0x92/0x2b0 fs/super.c:1814
       do_new_mount+0x2be/0xb40 fs/namespace.c:3511
       do_mount fs/namespace.c:3851 [inline]
       __do_sys_mount fs/namespace.c:4061 [inline]
       __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:4038
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (btrfs-tree-00){++++}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3161 [inline]
       check_prevs_add kernel/locking/lockdep.c:3280 [inline]
       validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904
       __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
       down_read_nested+0xb5/0xa50 kernel/locking/rwsem.c:1649
       btrfs_tree_read_lock_nested+0x2f/0x250 fs/btrfs/locking.c:146
       btrfs_tree_read_lock fs/btrfs/locking.h:188 [inline]
       btrfs_search_slot+0x13c4/0x3180 fs/btrfs/ctree.c:2261
       defrag_get_extent fs/btrfs/defrag.c:645 [inline]
       defrag_lookup_extent+0x402/0xf60 fs/btrfs/defrag.c:783
       defrag_collect_targets+0x148/0xeb0 fs/btrfs/defrag.c:978
       defrag_one_cluster fs/btrfs/defrag.c:1283 [inline]
       btrfs_defrag_file+0x793/0x2810 fs/btrfs/defrag.c:1435
       btrfs_ioctl_defrag+0x2cf/0x440 fs/btrfs/ioctl.c:2656
       btrfs_ioctl+0x9ce/0xcc0
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:906 [inline]
       __se_sys_ioctl+0xf7/0x170 fs/ioctl.c:892
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  btrfs-tree-00 --> &ei->i_mmap_lock --> btrfs-tree-01

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  rlock(btrfs-tree-01);
                               lock(&ei->i_mmap_lock);
                               lock(btrfs-tree-01);
  rlock(btrfs-tree-00);

 *** DEADLOCK ***

3 locks held by syz.3.877/11306:
 #0: ffff888044d96420 (sb_writers#17){.+.+}-{0:0}, at: mnt_want_write_file+0x5e/0x200 fs/namespace.c:560
 #1: ffff88805bed5b78 (&sb->s_type->i_mutex_key#23){++++}-{4:4}, at: inode_lock include/linux/fs.h:818 [inline]
 #1: ffff88805bed5b78 (&sb->s_type->i_mutex_key#23){++++}-{4:4}, at: btrfs_inode_lock+0x4d/0xe0 fs/btrfs/inode.c:362
 #2: ffff8880626cfef8 (btrfs-tree-01){++++}-{4:4}, at: btrfs_tree_read_lock_nested+0x2f/0x250 fs/btrfs/locking.c:146

stack backtrace:
CPU: 0 UID: 0 PID: 11306 Comm: syz.3.877 Not tainted 6.13.0-rc7-syzkaller-00019-gc45323b7560e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_circular_bug+0x13a/0x1b0 kernel/locking/lockdep.c:2074
 check_noncircular+0x36a/0x4a0 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+0x18ef/0x5920 kernel/locking/lockdep.c:3904
 __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
 down_read_nested+0xb5/0xa50 kernel/locking/rwsem.c:1649
 btrfs_tree_read_lock_nested+0x2f/0x250 fs/btrfs/locking.c:146
 btrfs_tree_read_lock fs/btrfs/locking.h:188 [inline]
 btrfs_search_slot+0x13c4/0x3180 fs/btrfs/ctree.c:2261
 defrag_get_extent fs/btrfs/defrag.c:645 [inline]
 defrag_lookup_extent+0x402/0xf60 fs/btrfs/defrag.c:783
 defrag_collect_targets+0x148/0xeb0 fs/btrfs/defrag.c:978
 defrag_one_cluster fs/btrfs/defrag.c:1283 [inline]
 btrfs_defrag_file+0x793/0x2810 fs/btrfs/defrag.c:1435
 btrfs_ioctl_defrag+0x2cf/0x440 fs/btrfs/ioctl.c:2656
 btrfs_ioctl+0x9ce/0xcc0
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl+0xf7/0x170 fs/ioctl.c:892
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f350c185d29
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:00007f350cf37038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f350c375fa0 RCX: 00007f350c185d29
RDX: 0000000020000080 RSI: 0000000040309410 RDI: 0000000000000008
RBP: 00007f350c201b08 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f350c375fa0 R15: 00007ffdfe2ba268
 </TASK>

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/01/14 08:42 upstream c45323b7560e b1f1cd88 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in btrfs_search_slot
2024/12/27 13:21 upstream d6ef8b40d075 d3ccff63 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in btrfs_search_slot
2024/12/25 17:26 upstream 9b2ffa6148b1 444551c4 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in btrfs_search_slot
2024/12/20 13:32 upstream 8faabc041a00 1d58202c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in btrfs_search_slot
2024/11/27 19:52 upstream aaf20f870da0 5df23865 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in btrfs_search_slot
* Struck through repros no longer work on HEAD.