kernel BUG in btrfs_free_tree_block (2)

Status: upstream: reported syz repro on 2026/07/29 07:23
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+1e47e820a43a89a9e5e4@syzkaller.appspotmail.com
First crash: 103d, last: 5h52m
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2026/11/06 linux-5.15.y (ToT) 700e62ea909a syz [report] WARNING in __btrfs_free_extent
2026/11/06 upstream (ToT) a91337fb5e8e syz Didn't crash
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream kernel BUG in btrfs_free_tree_block btrfs -1 syz, C error 150 818d 1504d 27/29 fixed on 2024/08/14 03:44
linux-6.1 kernel BUG in btrfs_free_tree_block origin:upstream missing-backport -1 syz, C inconclusive 47 9d23h 1184d 0/3 upstream: reported C repro on 2023/08/12 21:44
linux-5.15 kernel BUG in btrfs_free_tree_block origin:upstream -1 syz, C error 3 625d 1225d 0/3 auto-obsoleted due to no activity on 2025/09/21 10:08
▶ ▼ Last patch testing requests (1)
Created Duration User Patch Repo Result
2026/10/08 13:04 20m retest repro linux-5.15.y report job log log

Sample crash report:
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f37c1c97038 R14: 00007f37c1c96fa0 R15: 00007ffcfa1bdc68
 </TASK>
------------[ cut here ]------------
kernel BUG at fs/btrfs/extent-tree.c:3311!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 4566 Comm: syz.0.23 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/06/2026
RIP: 0010:btrfs_free_tree_block+0xb71/0xb80 fs/btrfs/extent-tree.c:3311
Code: e9 02 f9 ff ff 44 89 e1 80 e1 07 38 c1 0f 8c 07 f9 ff ff be 08 00 00 00 4c 89 e7 e8 69 fb 78 fe e9 f5 f8 ff ff e8 6f b2 33 fe <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 55 41 57 41 56 41 55
RSP: 0018:ffffc9000384f5a0 EFLAGS: 00010293
RAX: ffffffff83457b21 RBX: 1ffff11005a58c62 RCX: ffff88802d345940
RDX: 0000000000000000 RSI: 00000000fffffff4 RDI: 0000000000000000
RBP: ffffc9000384f6f0 R08: ffffffff9104720f R09: 1ffffffff2208e41
R10: dffffc0000000000 R11: fffffbfff2208e42 R12: ffff88806150b064
R13: ffff88802d2c6310 R14: 00000000fffffff4 R15: 0000000000000005
FS:  00007f37c106f6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f37c1a5e200 CR3: 000000005fae7000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 btrfs_force_cow_block+0xc4d/0x1760 fs/btrfs/ctree.c:480
 btrfs_cow_block+0x33e/0x7d0 fs/btrfs/ctree.c:598
 btrfs_search_slot+0x9d4/0x2090 fs/btrfs/ctree.c:-1
 btrfs_insert_empty_items+0x32c/0x3e0 fs/btrfs/ctree.c:4012
 btrfs_new_inode+0x908/0x1830 fs/btrfs/inode.c:6674
 btrfs_mkdir+0x2ac/0x5b0 fs/btrfs/inode.c:7072
 vfs_mkdir+0x386/0x570 fs/namei.c:4116
 do_mkdirat+0x1dd/0x5c0 fs/namei.c:4141
 __do_sys_mkdirat fs/namei.c:4156 [inline]
 __se_sys_mkdirat fs/namei.c:4154 [inline]
 __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4154
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f37c1a10b19
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:00007f37c106f028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f37c1c96fa0 RCX: 00007f37c1a10b19
RDX: 00000000000001ff RSI: 0000200000007040 RDI: ffffffffffffff9c
RBP: 00007f37c1aa8b70 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f37c1c97038 R14: 00007f37c1c96fa0 R15: 00007ffcfa1bdc68
 </TASK>
Modules linked in:
---[ end trace a5d16897b868bc91 ]---
RIP: 0010:btrfs_free_tree_block+0xb71/0xb80 fs/btrfs/extent-tree.c:3311
Code: e9 02 f9 ff ff 44 89 e1 80 e1 07 38 c1 0f 8c 07 f9 ff ff be 08 00 00 00 4c 89 e7 e8 69 fb 78 fe e9 f5 f8 ff ff e8 6f b2 33 fe <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 55 41 57 41 56 41 55
RSP: 0018:ffffc9000384f5a0 EFLAGS: 00010293
RAX: ffffffff83457b21 RBX: 1ffff11005a58c62 RCX: ffff88802d345940
RDX: 0000000000000000 RSI: 00000000fffffff4 RDI: 0000000000000000
RBP: ffffc9000384f6f0 R08: ffffffff9104720f R09: 1ffffffff2208e41
R10: dffffc0000000000 R11: fffffbfff2208e42 R12: ffff88806150b064
R13: ffff88802d2c6310 R14: 00000000fffffff4 R15: 0000000000000005
FS:  00007f37c106f6c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005561572a6160 CR3: 000000005fae7000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Crashes (17):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/11/09 06:42 linux-5.15.y 29c6cdaac04a 5cecaf1f .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (clean fs)] [mounted in repro #3 (clean fs)] ci2-linux-5-15-kasan kernel BUG in btrfs_free_tree_block
2026/11/08 15:01 linux-5.15.y 29c6cdaac04a 5cecaf1f .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (clean fs)] ci2-linux-5-15-kasan kernel BUG in btrfs_free_tree_block
2026/09/20 00:31 linux-5.15.y 0248c33e835e 853b104b .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci2-linux-5-15-kasan kernel BUG in btrfs_free_tree_block
2026/11/09 02:13 linux-5.15.y 29c6cdaac04a 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan kernel BUG in btrfs_free_tree_block
2026/11/09 02:00 linux-5.15.y 29c6cdaac04a 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan kernel BUG in btrfs_free_tree_block
2026/11/08 13:49 linux-5.15.y 29c6cdaac04a 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan kernel BUG in btrfs_free_tree_block
2026/11/08 13:41 linux-5.15.y 29c6cdaac04a 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan kernel BUG in btrfs_free_tree_block
2026/11/08 13:38 linux-5.15.y 29c6cdaac04a 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan kernel BUG in btrfs_free_tree_block
2026/11/08 13:35 linux-5.15.y 29c6cdaac04a 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan kernel BUG in btrfs_free_tree_block
2026/11/08 13:10 linux-5.15.y 29c6cdaac04a 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan kernel BUG in btrfs_free_tree_block
2026/11/06 15:16 linux-5.15.y 700e62ea909a 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan kernel BUG in btrfs_free_tree_block
2026/11/02 18:42 linux-5.15.y 700e62ea909a 6969b601 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan kernel BUG in btrfs_free_tree_block
2026/11/02 18:41 linux-5.15.y 700e62ea909a 6969b601 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan kernel BUG in btrfs_free_tree_block
2026/11/02 00:54 linux-5.15.y 700e62ea909a 25a0ae84 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan kernel BUG in btrfs_free_tree_block
2026/11/01 11:22 linux-5.15.y 700e62ea909a 25a0ae84 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan kernel BUG in btrfs_free_tree_block
2026/09/19 23:29 linux-5.15.y 0248c33e835e 853b104b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan kernel BUG in btrfs_free_tree_block
2026/07/29 07:23 linux-5.15.y 674f684f7c61 19622d9d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan kernel BUG in btrfs_free_tree_block
* Struck through repros no longer work on HEAD.