[linus:master] [rculist_bl] 1ac252ad03: BUG:KCSAN:data-race_in__d_lookup_rcu/print_report

[linus:master] [rculist_bl] 1ac252ad03: BUG:KCSAN:data-race_in__d_lookup_rcu/print_report

[kernel test robot]

Hello,

as we understand, this commit is not the root cause of the issue, it just
changes the stats of the (random) issue:

=========================================================================================
tbox_group/testcase/rootfs/kconfig/compiler/sleep:
  vm-snb/boot/debian-11.1-i386-20220923.cgz/x86_64-randconfig-074-20260622/gcc-14/1

34a6a003d4e49313 1ac252ad036cdb18f5fb7f76bb6
---------------- ---------------------------
       fail:runs  %reproduction    fail:runs
           |             |             |
           :200         32%          65:200   dmesg.BUG:KCSAN:data-race_in__d_lookup_rcu/print_report
         69:200        -34%            :200   dmesg.BUG:KCSAN:data-race_in_hlist_bl_first_rcu/print_report


we still make out this report FYI in case it could supply any useful information
to solve any potential code problems. thanks



kernel test robot noticed "BUG:KCSAN:data-race_in__d_lookup_rcu/print_report" on:

commit: 1ac252ad036cdb18f5fb7f76bb6061adfed9cedf ("rculist_bl: add hlist_bl_for_each_entry_continue_rcu")
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master

[tail failed on linus/master      d2c9a99135da931377240942d44f3dea104cedb8]
[test failed on linux-next/master 6eb8711ece2ce27e52e327a5b7a628ed39b97f45]

in testcase: boot

config: x86_64-randconfig-074-20260622
compiler: gcc-14
test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 32G

(please refer to attached dmesg/kmsg for entire log/backtrace)



If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <oliver.sang@intel.com>
| Closes: https://lore.kernel.org/oe-lkp/202607101627.2909550e-lkp@intel.com



[   94.613216][  T178] BUG: KCSAN: data-race in __d_lookup_rcu / print_report
[   94.616584][  T178]
[   94.617709][  T178] read (marked) to 0xffff88881e358348 of 8 bytes by task 170 on cpu 0:
[   94.621462][  T178]  __d_lookup_rcu (dcache.c:2332 (discriminator 2))
[   94.623009][  T178]  lookup_fast (namei.c:1850)
[   94.624382][  T178]  link_path_walk (namei.c:2275 namei.c:2647)
[   94.625855][  T178]  path_openat (namei.c:4826 (discriminator 2))
[   94.627207][  T178]  do_file_open (namei.c:4859)
[   94.628575][  T178]  do_sys_openat2 (open.c:1366 (discriminator 1))
[   94.630019][  T178]  do_sys_open (open.c:1372)
[   94.631330][  T178]  __ia32_compat_sys_openat (open.c:1434 open.c:1432 open.c:1432)
[   94.632980][  T178]  ia32_sys_call (kbuild/obj/consumer/x86_64-randconfig-074-20260622/./arch/x86/include/generated/asm/syscalls_32.h:296)
[   94.634453][  T178]  __do_fast_syscall_32 (x86/entry/syscall_32.c:83 x86/entry/syscall_32.c:307)
[   94.636053][  T178]  do_fast_syscall_32 (x86/entry/syscall_32.c:332)
[   94.637566][  T178]  do_SYSENTER_32 (x86/entry/syscall_32.c:370)
[   94.638930][  T178]  entry_SYSENTER_compat_after_hwframe (x86/entry/entry_64_compat.S:126)
[   94.640851][  T178]
[   94.641599][  T178] write to 0xffff88881e358348 of 8 bytes by task 178 on cpu 1:
[   94.643871][  T178]  print_report (kcsan/report.c:399)
[   94.645239][  T178]  kcsan_report_known_origin (kcsan/report.c:697)
[   94.646960][  T178]  kcsan_setup_watchpoint (kcsan/core.c:678)
[   94.648580][  T178]  hlist_bl_unlock (linux/instrumented.h:42 asm-generic/bitops/instrumented-lock.h:42 linux/bit_spinlock.h:96 linux/list_bl.h:155)
[   94.650030][  T178]  ___d_drop (dcache.c:569)
[   94.651274][  T178]  __d_drop (dcache.c:575)
[   94.652486][  T178]  __dentry_kill (dcache.c:668)
[   94.653876][  T178]  finish_dput (dcache.c:879)
[   94.655196][  T178]  dput (dcache.c:928)
[   94.656362][  T178]  step_into_slowpath (namei.c:1748 namei.c:2101)
[   94.657897][  T178]  link_path_walk (namei.c:2149 namei.c:2285 namei.c:2647)
[   94.659316][  T178]  path_parentat (namei.c:2851)
[   94.660680][  T178]  __filename_parentat (namei.c:2875)
[   94.662217][  T178]  filename_parentat (namei.c:2893)
[   94.663649][  T178]  filename_unlinkat (namei.c:5509)
[   94.665114][  T178]  __do_sys_unlink (namei.c:5575)
[   94.666511][  T178]  __ia32_sys_unlink (namei.c:5572 namei.c:5572)
[   94.667941][  T178]  ia32_sys_call (kbuild/obj/consumer/x86_64-randconfig-074-20260622/./arch/x86/include/generated/asm/syscalls_32.h:11)
[   94.669382][  T178]  __do_fast_syscall_32 (x86/entry/syscall_32.c:83 x86/entry/syscall_32.c:307)
[   94.670950][  T178]  do_fast_syscall_32 (x86/entry/syscall_32.c:332)
[   94.672430][  T178]  do_SYSENTER_32 (x86/entry/syscall_32.c:370)
[   94.673797][  T178]  entry_SYSENTER_compat_after_hwframe (x86/entry/entry_64_compat.S:126)
[   94.675698][  T178]
[   94.676432][  T178] Reported by Kernel Concurrency Sanitizer on:
[   94.678270][  T178] CPU: 1 UID: 0 PID: 178 Comm: systemd-udevd Not tainted 7.0.0-rc1-00328-g1ac252ad036c #1 PREEMPT(lazy)
[   94.682170][  T178] ==================================================================


The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20260710/202607101627.2909550e-lkp@intel.com



-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki