syzbot


WARNING: suspicious RCU usage in bch2_bucket_ref_update

Status: upstream: reported C repro on 2024/07/09 14:58
Subsystems: bcachefs
[Documentation on labels]
Reported-by: syzbot+e74fea078710bbca6f4b@syzkaller.appspotmail.com
Fix commit: 6f692b1672bd bcachefs: Fix RCU splat
Patched on: [ci-qemu-upstream ci-qemu-upstream-386 ci-qemu2-arm32 ci-qemu2-arm64 ci-qemu2-arm64-compat ci-qemu2-arm64-mte ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce ci-upstream-gce-leak ci-upstream-kasan-badwrites-root ci-upstream-kasan-gce ci-upstream-kasan-gce-386 ci-upstream-kasan-gce-root ci-upstream-kasan-gce-selinux-root ci-upstream-kasan-gce-smack-root ci-upstream-kmsan-gce-386-root ci-upstream-kmsan-gce-root ci-upstream-linux-next-kasan-gce-root ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci2-upstream-fs ci2-upstream-kcsan-gce ci2-upstream-net-next-test-gce], missing on: [ci-qemu-native-arm64-kvm ci-qemu2-riscv64 ci-upstream-gce-arm64 ci2-upstream-usb]
First crash: 11d, last: 10d
Cause bisection: introduced by (bisect log) :
commit f7643bc9749f270d487c32dc35b578575bf1adb0
Author: Kent Overstreet <kent.overstreet@linux.dev>
Date: Wed Apr 17 05:26:02 2024 +0000

  bcachefs: make btree read errors silent during scan

Crash: WARNING: suspicious RCU usage in bch2_check_bucket_ref (log)
Repro: C syz .config
  
Discussions (2)
Title Replies (including bot) Last reply
[syzbot] [bcachefs?] WARNING: suspicious RCU usage in bch2_bucket_ref_update 1 (4) 2024/07/12 17:36
[PATCH] Fix WARNING: suspicious RCU usage in bch2_bucket_ref_update 2 (2) 2024/07/10 16:45
Last patch testing requests (2)
Created Duration User Patch Repo Result
2024/07/10 05:31 26m peili.dev@gmail.com patch upstream OK log
2024/07/10 04:48 17m peili.dev@gmail.com patch upstream error

Sample crash report:
bcachefs (loop0): done starting filesystem
=============================
WARNING: suspicious RCU usage
6.10.0-rc7-syzkaller #0 Not tainted
-----------------------------
fs/bcachefs/buckets.h:107 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
9 locks held by syz-executor107/5084:
 #0: ffff88807441c420 (sb_writers#9){.+.+}-{0:0}, at: mnt_want_write+0x3f/0x90 fs/namespace.c:409
 #1: ffff88807441c730 (&type->s_vfs_rename_key){+.+.}-{3:3}, at: lock_rename fs/namei.c:3078 [inline]
 #1: ffff88807441c730 (&type->s_vfs_rename_key){+.+.}-{3:3}, at: do_renameat2+0x5cf/0x13f0 fs/namei.c:4985
 #2: ffff88807a278150 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:826 [inline]
 #2: ffff88807a278150 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: lock_two_directories+0x145/0x220 fs/namei.c:3044
 #3: ffff88807a2788b8 (&type->i_mutex_dir_key#6/5){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:826 [inline]
 #3: ffff88807a2788b8 (&type->i_mutex_dir_key#6/5){+.+.}-{3:3}, at: lock_two_directories+0x16f/0x220 fs/namei.c:3045
 #4: ffff888077f842d8 (&c->btree_trans_barrier){.+.+}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:116 [inline]
 #4: ffff888077f842d8 (&c->btree_trans_barrier){.+.+}-{0:0}, at: srcu_read_lock include/linux/srcu.h:215 [inline]
 #4: ffff888077f842d8 (&c->btree_trans_barrier){.+.+}-{0:0}, at: __bch2_trans_get+0x840/0xce0 fs/bcachefs/btree_iter.c:3193
 #5: ffff88802fc93070 (&dev->mutex){....}-{3:3}, at: six_relock_type fs/bcachefs/six.h:289 [inline]
 #5: ffff88802fc93070 (&dev->mutex){....}-{3:3}, at: __bch2_btree_node_relock+0x142/0x9c0 fs/bcachefs/btree_locking.c:507
 #6: ffff88802fc93070 (&dev->mutex){....}-{3:3}, at: btree_node_lock_increment fs/bcachefs/btree_locking.h:248 [inline]
 #6: ffff88802fc93070 (&dev->mutex){....}-{3:3}, at: __bch2_btree_node_relock+0x675/0x9c0 fs/bcachefs/btree_locking.c:509
 #7: ffff88807a0db340 (&dev->mutex){....}-{3:3}, at: six_relock_type fs/bcachefs/six.h:289 [inline]
 #7: ffff88807a0db340 (&dev->mutex){....}-{3:3}, at: __bch2_btree_node_relock+0x142/0x9c0 fs/bcachefs/btree_locking.c:507
 #8: ffff88802b279870 (&dev->mutex){....}-{3:3}, at: six_relock_type fs/bcachefs/six.h:289 [inline]
 #8: ffff88802b279870 (&dev->mutex){....}-{3:3}, at: __bch2_btree_node_relock+0x142/0x9c0 fs/bcachefs/btree_locking.c:507

stack backtrace:
CPU: 0 PID: 5084 Comm: syz-executor107 Not tainted 6.10.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 lockdep_rcu_suspicious+0x221/0x340 kernel/locking/lockdep.c:6712
 bucket_gens fs/bcachefs/buckets.h:103 [inline]
 bucket_gen fs/bcachefs/buckets.h:112 [inline]
 bch2_bucket_ref_update+0xbe1/0x1100 fs/bcachefs/buckets.c:808
 __mark_pointer fs/bcachefs/buckets.c:1000 [inline]
 bch2_trigger_pointer fs/bcachefs/buckets.c:1037 [inline]
 __trigger_extent+0x1524/0x6260 fs/bcachefs/buckets.c:1176
 bch2_trigger_extent+0x636/0x920 fs/bcachefs/buckets.c:1261
 bch2_key_trigger fs/bcachefs/bkey_methods.h:88 [inline]
 bch2_key_trigger_old fs/bcachefs/bkey_methods.h:102 [inline]
 run_one_trans_trigger fs/bcachefs/btree_trans_commit.c:514 [inline]
 run_btree_triggers+0xadb/0x11d0 fs/bcachefs/btree_trans_commit.c:544
 bch2_trans_commit_run_triggers fs/bcachefs/btree_trans_commit.c:576 [inline]
 __bch2_trans_commit+0x3a6/0x88e0 fs/bcachefs/btree_trans_commit.c:1022
 bch2_trans_commit fs/bcachefs/btree_update.h:170 [inline]
 bch2_inode_delete_keys+0xae8/0x1440 fs/bcachefs/inode.c:845
 bch2_inode_rm+0x165/0xd40 fs/bcachefs/inode.c:874
 bch2_evict_inode+0x21c/0x3c0 fs/bcachefs/fs.c:1588
 evict+0x2a8/0x630 fs/inode.c:667
 __dentry_kill+0x20d/0x630 fs/dcache.c:603
 dput+0x19f/0x2b0 fs/dcache.c:845
 do_renameat2+0xda1/0x13f0 fs/namei.c:5052
 __do_sys_renameat2 fs/namei.c:5084 [inline]
 __se_sys_renameat2 fs/namei.c:5081 [inline]
 __x64_sys_renameat2+0xd2/0xf0 fs/namei.c:5081
 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: 0033:0x7f491fe4ad59
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 17 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff84583f28 EFLAGS: 00000246 ORIG_RAX: 000000000000013c
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f491fe4ad59
RDX: 0000000000000004 RSI: 0000000020000080 RDI: 00000000ffffff9c
RBP: 00007f491fec45f0 R08: 0000000000000000 R09: 000055555e2ff4c0
R10: 0000000020000980 R11: 0000000000000246 R12: 00007fff84583f50
R13: 00007fff84584178 R14: 431bde82d7b634db R15: 00007f491fe9403b
 </TASK>
bucket 0:34 gen 7 (mem gen 0) data type user: stale dirty ptr (gen 0)
while marking u64s 7 type extent 536870913:8:U32_MAX len 8 ver 0: durability: 1 crc: c_size 8 size 8 offset 0 nonce 0 csum crc32c compress incompressible ptr: 0:34:0 gen 0, shutting down
bcachefs (loop0): inconsistency detected - emergency read only at journal seq 11
syz-executor107 (5084) used greatest stack depth: 18488 bytes left

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/07/08 17:47 upstream 256abd8e550c cde64f7d .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-upstream-fs WARNING: suspicious RCU usage in bch2_bucket_ref_update
2024/07/08 02:11 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 8a03d70c27fc bc4ebbb5 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-gce-arm64 WARNING: suspicious RCU usage in bch2_bucket_ref_update
2024/07/08 01:39 upstream c6653f49e4fd bc4ebbb5 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root WARNING: suspicious RCU usage in bch2_bucket_ref_update
2024/07/08 01:38 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 8a03d70c27fc bc4ebbb5 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 WARNING: suspicious RCU usage in bch2_bucket_ref_update
2024/07/08 01:38 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 8a03d70c27fc bc4ebbb5 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 WARNING: suspicious RCU usage in bch2_bucket_ref_update
* Struck through repros no longer work on HEAD.