KCSAN: data-race in caching_thread / find_free_extent

Status: auto-closed as invalid on 2021/05/10 04:01
Subsystems: btrfs
[Documentation on labels]
Reported-by: syzbot+0f296fc55bac260ff919@syzkaller.appspotmail.com
First crash: 2163d, last: 1962d

Sample crash report:
==================================================================
BUG: KCSAN: data-race in caching_thread / find_free_extent

write to 0xffff888107fbe8a4 of 4 bytes by task 17541 on cpu 0:
 caching_thread+0xe5/0x8d0 fs/btrfs/block-group.c:672
 btrfs_work_helper+0x1e2/0x380 fs/btrfs/async-thread.c:318
 process_one_work+0x3e1/0x950 kernel/workqueue.c:2275
 worker_thread+0x616/0xa70 kernel/workqueue.c:2421
 kthread+0x20b/0x230 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

read to 0xffff888107fbe8a4 of 4 bytes by task 8385 on cpu 1:
 find_free_extent+0x15db/0x22a0 fs/btrfs/extent-tree.c:4305
 btrfs_reserve_extent+0x135/0x2e0 fs/btrfs/extent-tree.c:4441
 btrfs_alloc_tree_block+0xfe/0x880 fs/btrfs/extent-tree.c:4840
 alloc_tree_block_no_bg_flush fs/btrfs/ctree.c:992 [inline]
 __btrfs_cow_block+0x2f2/0xac0 fs/btrfs/ctree.c:1048
 btrfs_cow_block+0x252/0x3a0 fs/btrfs/ctree.c:1495
 commit_cowonly_roots+0x94/0x590 fs/btrfs/transaction.c:1233
 btrfs_commit_transaction+0x99f/0x1980 fs/btrfs/transaction.c:2293
 btrfs_commit_super+0x8f/0xa0 fs/btrfs/disk-io.c:4210
 close_ctree+0x1c0/0x52d fs/btrfs/disk-io.c:4275
 btrfs_put_super+0x21/0x30 fs/btrfs/super.c:325
 generic_shutdown_super+0xde/0x210 fs/super.c:464
 kill_anon_super+0x23/0x40 fs/super.c:1056
 btrfs_kill_super+0x26/0x40 fs/btrfs/super.c:2353
 deactivate_locked_super+0x6a/0xb0 fs/super.c:335
 deactivate_super+0x85/0x90 fs/super.c:366
 cleanup_mnt+0x277/0x2e0 fs/namespace.c:1136
 __cleanup_mnt+0x15/0x20 fs/namespace.c:1143
 task_work_run+0x8e/0x110 kernel/task_work.c:140
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
 exit_to_user_mode_prepare+0x17c/0x1b0 kernel/entry/common.c:208
 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:301
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8385 Comm: syz-executor.3 Not tainted 5.12.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (42):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2021/04/05 04:01 upstream e49d033bddf5 6a81331a .config console log report info ci2-upstream-kcsan-gce KCSAN: data-race in caching_thread / find_free_extent
2021/03/20 19:11 upstream 1c273e10bc0c e45f5621 .config console log report info ci2-upstream-kcsan-gce KCSAN: data-race in caching_thread / find_free_extent
2021/03/18 10:50 upstream 6417f03132a6 7216542e .config console log report info ci2-upstream-kcsan-gce KCSAN: data-race in caching_thread / find_free_extent
2021/03/07 08:58 upstream a38fd8748464 c599ed12 .config console log report info ci2-upstream-kcsan-gce KCSAN: data-race in caching_thread / find_free_extent
2021/02/22 16:04 upstream 31caf8b2a847 c26fb06b .config console log report info ci2-upstream-kcsan-gce KCSAN: data-race in caching_thread / find_free_extent
2021/02/21 19:41 upstream 55f62bc87347 a659b3f1 .config console log report info ci2-upstream-kcsan-gce KCSAN: data-race in caching_thread / find_free_extent
2021/02/15 15:25 upstream f40ddce88593 98682e5e .config console log report info ci2-upstream-kcsan-gce KCSAN: data-race in caching_thread / find_free_extent
2021/02/14 08:42 upstream ac30d8ce28d6 98682e5e .config console log report info ci2-upstream-kcsan-gce KCSAN: data-race in caching_thread / find_free_extent
2021/02/08 08:58 upstream b75dba7f472c 2ce644fc .config console log report info ci2-upstream-kcsan-gce KCSAN: data-race in caching_thread / find_free_extent
2021/02/05 21:22 upstream dd86e7fa07a3 23a562df .config console log report info ci2-upstream-kcsan-gce KCSAN: data-race in caching_thread / find_free_extent
2021/02/05 04:59 upstream 5c279c4cf206 23a562df .config console log report info ci2-upstream-kcsan-gce KCSAN: data-race in caching_thread / find_free_extent
2021/01/28 17:13 upstream 76c057c84d28 eefc07f2 .config console log report info ci2-upstream-kcsan-gce KCSAN: data-race in caching_thread / find_free_extent
2021/01/24 20:48 upstream e68061375f79 52e37319 .config console log report info ci2-upstream-kcsan-gce KCSAN: data-race in caching_thread / find_free_extent
2021/01/24 04:36 upstream e1ae4b0be158 52e37319 .config console log report info ci2-upstream-kcsan-gce KCSAN: data-race in caching_thread / find_free_extent
2021/01/22 20:23 upstream 83d09ad4b950 52e37319 .config console log report info ci2-upstream-kcsan-gce KCSAN: data-race in caching_thread / find_free_extent
2021/01/18 23:35 upstream 1e2a199f6ccd 63631df1 .config console log report info ci2-upstream-kcsan-gce KCSAN: data-race in caching_thread / find_free_extent
2021/01/15 14:26 upstream 146620506274 65a7a854 .config console log report info ci2-upstream-kcsan-gce
2021/01/14 12:17 upstream 65f0d2414b70 269d24e8 .config console log report info ci2-upstream-kcsan-gce
2021/01/07 19:30 upstream 71c061d24438 c104d4a3 .config console log report info ci2-upstream-kcsan-gce
2020/12/10 00:53 upstream ca4bbdaf1716 c090b4da .config console log report info ci2-upstream-kcsan-gce
2020/12/08 12:13 upstream cd796ed33450 9af51e31 .config console log report info ci2-upstream-kcsan-gce
2020/11/24 07:48 upstream d5beb3140f91 1ab681a4 .config console log report info ci2-upstream-kcsan-gce
2020/11/23 00:36 upstream 68d3fa235fd8 0d27f508 .config console log report info ci2-upstream-kcsan-gce
2020/11/21 11:02 upstream 27bba9c532a8 c7ec2d19 .config console log report info ci2-upstream-kcsan-gce
2020/11/15 12:12 upstream e28c0d7c92c8 1bf9a662 .config console log report info ci2-upstream-kcsan-gce
2020/11/14 13:44 upstream f01c30de86f1 1bf9a662 .config console log report info ci2-upstream-kcsan-gce
2020/11/11 17:51 upstream eccc87672492 cca87986 .config console log report info ci2-upstream-kcsan-gce
2020/11/09 10:08 upstream f8394f232b1e cba33199 .config console log report info ci2-upstream-kcsan-gce
2020/11/04 22:09 upstream 4ef8451b3326 cba33199 .config console log report info ci2-upstream-kcsan-gce
2020/11/03 00:26 upstream 495023e4e49e 7f344fa6 .config console log report info ci2-upstream-kcsan-gce
2020/11/01 04:13 upstream c2dc4c073fb7 8bc4594f .config console log report info ci2-upstream-kcsan-gce
2020/10/29 08:40 upstream 23859ae44402 f24824d3 .config console log report info ci2-upstream-kcsan-gce
2020/10/19 19:29 upstream 7cf726a59435 ff4a3345 .config console log report info ci2-upstream-kcsan-gce
2020/10/19 07:16 upstream 7cf726a59435 fea47c01 .config console log report info ci2-upstream-kcsan-gce
2020/10/12 09:38 upstream bbf5c979011a 4a77ae0b .config console log report info ci2-upstream-kcsan-gce
2020/09/30 11:52 upstream 02de58b24d2e 8516f6d3 .config console log report info ci2-upstream-kcsan-gce
2020/09/25 02:23 upstream 171d4ff79f96 54289b08 .config console log report info ci2-upstream-kcsan-gce
2020/09/21 10:54 upstream ba4f184e126b c81d99c8 .config console log report info ci2-upstream-kcsan-gce
2020/09/20 22:44 upstream bdcf11de8f77 9564d2e9 .config console log report info ci2-upstream-kcsan-gce
2020/09/20 17:52 upstream 325d0eab4f31 9564d2e9 .config console log report info ci2-upstream-kcsan-gce
2020/09/17 17:27 upstream 5925fa68fe82 8247808b .config console log report info ci2-upstream-kcsan-gce
2020/09/16 17:22 upstream fc4f28bb3daf 77507d02 .config console log report info ci2-upstream-kcsan-gce
* Struck through repros no longer work on HEAD.