On Tue, 20 Feb 2024 at 08:35, kernel test robot <[email protected]> wrote: > > > > Hello, > > we noticed this is a revert commit, below report is for an issue we observed > on this commit but not on its parent. just FYI. > > 113edefd366346b3 187292be96ae2be247807fac1c3 > ---------------- --------------------------- > fail:runs %reproduction fail:runs > | | | > :6 100% 6:6 > dmesg.WARNING:suspicious_RCU_usage > > > kernel test robot noticed "WARNING:suspicious_RCU_usage" on: > > commit: 187292be96ae2be247807fac1c3a6d89a7cc2a84 ("kasan: revert eviction of > stack traces in generic mode") > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
This commit didn't touch rcutorture or the rcu subsystem in any way, so I currently don't understand how rcutorture would be affected. While stackdepot has started to use RCU, this already happened in a previous commit, and this particular commit actually reduced RCU usage (no more evictions and re-allocations of stacktraces). The only explanation I have is that it improved performance of a KASAN-enabled kernel (which the config here has enabled) so much that previously undiscovered issues have now become much more likely to occur. [+Cc rcu folks] > in testcase: rcutorture > version: > with following parameters: > > runtime: 300s > test: cpuhotplug > torture_type: busted_srcud > > > > compiler: clang-17 > test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G > > (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 <[email protected]> > | Closes: > https://lore.kernel.org/oe-lkp/[email protected] > > > [ 292.513535][ T653] WARNING: suspicious RCU usage > [ 292.514923][ T653] 6.8.0-rc4-00126-g187292be96ae #1 Not tainted > [ 292.516369][ T653] ----------------------------- > [ 292.517743][ T653] kernel/rcu/rcutorture.c:1983 suspicious > rcu_dereference_check() usage! > [ 292.519310][ T653] > [ 292.519310][ T653] other info that might help us debug this: > [ 292.519310][ T653] > [ 292.523130][ T653] > [ 292.523130][ T653] rcu_scheduler_active = 2, debug_locks = 1 > [ 292.525644][ T653] no locks held by rcu_torture_rea/653. > [ 292.526974][ T653] > [ 292.526974][ T653] stack backtrace: > [ 292.529271][ T653] CPU: 0 PID: 653 Comm: rcu_torture_rea Not tainted > 6.8.0-rc4-00126-g187292be96ae #1 > [ 292.530780][ T653] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), > BIOS 1.16.2-debian-1.16.2-1 04/01/2014 > [ 292.532329][ T653] Call Trace: > [ 292.533524][ T653] <TASK> > [ 292.534696][ T653] dump_stack_lvl (lib/dump_stack.c:?) > [ 292.535941][ T653] ? __cfi_dump_stack_lvl (lib/dump_stack.c:98) > [ 292.537221][ T653] ? lockdep_rcu_suspicious (kernel/locking/lockdep.c:6712) > [ 292.538523][ T653] rcu_torture_one_read (kernel/rcu/rcutorture.c:?) > rcutorture > [ 292.539887][ T653] ? __cfi_lockdep_hardirqs_on_prepare > (kernel/locking/lockdep.c:4312) > [ 292.541226][ T653] ? rcu_torture_timer (kernel/rcu/rcutorture.c:1955) > rcutorture > [ 292.542621][ T653] ? __cfi_rcu_torture_timer (kernel/rcu/rcutorture.c:2055) > rcutorture > [ 292.544012][ T653] ? init_timer_key (include/linux/lockdep.h:135 > include/linux/lockdep.h:142 include/linux/lockdep.h:148 > kernel/time/timer.c:847 kernel/time/timer.c:867) > [ 292.545262][ T653] rcu_torture_reader (kernel/rcu/rcutorture.c:2093) > rcutorture > [ 292.546579][ T653] ? __cfi_rcu_torture_reader > (kernel/rcu/rcutorture.c:2076) rcutorture > [ 292.547872][ T653] ? __cfi__raw_spin_unlock_irqrestore > (kernel/locking/spinlock.c:193) > [ 292.549108][ T653] ? __cfi_rcu_torture_timer (kernel/rcu/rcutorture.c:2055) > rcutorture > [ 292.550341][ T653] ? __kthread_parkme (kernel/kthread.c:?) > [ 292.551425][ T653] ? __kthread_parkme (include/linux/instrumented.h:? > include/asm-generic/bitops/instrumented-non-atomic.h:141 kernel/kthread.c:280) > [ 292.552489][ T653] kthread (kernel/kthread.c:390) > [ 292.553504][ T653] ? __cfi_rcu_torture_reader > (kernel/rcu/rcutorture.c:2076) rcutorture > [ 292.554689][ T653] ? __cfi_kthread (kernel/kthread.c:341) > [ 292.555749][ T653] ret_from_fork (arch/x86/kernel/process.c:153) > [ 292.556792][ T653] ? __cfi_kthread (kernel/kthread.c:341) > [ 292.557852][ T653] ret_from_fork_asm (arch/x86/entry/entry_64.S:250) > [ 292.558920][ T653] </TASK> > > > > The kernel config and materials to reproduce are available at: > https://download.01.org/0day-ci/archive/20240220/[email protected] > > > > -- > 0-DAY CI Kernel Test Service > https://github.com/intel/lkp-tests/wiki >
