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KCSAN: data-race in __d_lookup_rcu / __d_rehash (6)

Status: auto-obsoleted due to no activity on 2023/12/25 18:18
Subsystems: ext4
[Documentation on labels]
Reported-by: syzbot+eda2491f39061694f590@syzkaller.appspotmail.com
First crash: 189d, last: 189d
Similar bugs (6)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in __d_lookup_rcu / __d_rehash fs 1 1578d 1578d 0/26 auto-closed as invalid on 2020/04/10 19:18
upstream KCSAN: data-race in __d_lookup_rcu / __d_rehash (2) fs 1 883d 883d 0/26 auto-closed as invalid on 2022/01/31 01:45
upstream KCSAN: data-race in __d_lookup_rcu / __d_rehash (3) ext4 3 768d 745d 0/26 auto-closed as invalid on 2022/05/28 02:05
upstream KCSAN: data-race in __d_lookup_rcu / __d_rehash (5) fs 1 453d 453d 0/26 auto-obsoleted due to no activity on 2023/04/05 19:44
upstream KCSAN: data-race in __d_lookup_rcu / __d_rehash (4) fs 1 613d 612d 0/26 auto-obsoleted due to no activity on 2022/10/27 12:04
upstream KCSAN: data-race in __d_lookup_rcu / __d_rehash (7) fs 1 88d 88d 0/26 auto-obsoleted due to no activity on 2024/04/05 04:37

Sample crash report:
==================================================================
BUG: KCSAN: data-race in __d_lookup_rcu / __d_rehash

read to 0xffff88811f17e6d0 of 8 bytes by task 3101 on cpu 1:
 hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
 d_unhashed include/linux/dcache.h:336 [inline]
 __d_lookup_rcu+0x120/0x290 fs/dcache.c:2399
 lookup_fast+0x8e/0x290 fs/namei.c:1629
 walk_component fs/namei.c:1998 [inline]
 link_path_walk+0x3f4/0x7e0 fs/namei.c:2329
 path_lookupat+0x72/0x2a0 fs/namei.c:2482
 filename_lookup+0x126/0x300 fs/namei.c:2512
 user_path_at_empty+0x42/0x110 fs/namei.c:2911
 user_path_at include/linux/namei.h:57 [inline]
 ksys_umount fs/namespace.c:1916 [inline]
 __do_sys_umount fs/namespace.c:1924 [inline]
 __se_sys_umount fs/namespace.c:1922 [inline]
 __x64_sys_umount+0x88/0xe0 fs/namespace.c:1922
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

write to 0xffff88811f17e6d0 of 8 bytes by task 3108 on cpu 0:
 hlist_bl_add_head_rcu include/linux/rculist_bl.h:81 [inline]
 __d_rehash+0xc4/0x220 fs/dcache.c:2578
 __d_add+0x36d/0x4a0 fs/dcache.c:2793
 d_splice_alias+0xd6/0x270 fs/dcache.c:3181
 ext4_lookup+0x199/0x390 fs/ext4/namei.c:1883
 lookup_one_qstr_excl+0xc0/0x180 fs/namei.c:1609
 filename_create+0x14d/0x2b0 fs/namei.c:3876
 do_mkdirat+0x63/0x2a0 fs/namei.c:4121
 __do_sys_mkdirat fs/namei.c:4144 [inline]
 __se_sys_mkdirat fs/namei.c:4142 [inline]
 __x64_sys_mkdirat+0x50/0x60 fs/namei.c:4142
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 3108 Comm: syz-executor.4 Not tainted 6.7.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/11/20 18:18 upstream 98b1cc82c4af cb976f63 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __d_lookup_rcu / __d_rehash
* Struck through repros no longer work on HEAD.