Re: [PATCH v4 8/8] uprobes: switch to RCU Tasks Trace flavor for better performance

[kernel test robot <lkp@intel.com>]

Hi Andrii,

kernel test robot noticed the following build errors:

[auto build test ERROR on tip/perf/core]
[also build test ERROR on next-20240830]
[cannot apply to perf-tools-next/perf-tools-next perf-tools/perf-tools linus/master acme/perf/core v6.11-rc5]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Andrii-Nakryiko/uprobes-revamp-uprobe-refcounting-and-lifetime-management/20240830-024135
base:   tip/perf/core
patch link:    https://lore.kernel.org/r/20240829183741.3331213-9-andrii%40kernel.org
patch subject: [PATCH v4 8/8] uprobes: switch to RCU Tasks Trace flavor for better performance
config: x86_64-defconfig (https://download.01.org/0day-ci/archive/20240831/202408310111.2dkrylJ9-lkp@intel.com/config)
compiler: gcc-11 (Debian 11.3.0-12) 11.3.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240831/202408310111.2dkrylJ9-lkp@intel.com/reproduce)

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 <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202408310111.2dkrylJ9-lkp@intel.com/

All errors (new ones prefixed by >>):

   kernel/events/uprobes.c: In function 'uprobe_unregister_sync':
>> kernel/events/uprobes.c:1157:9: error: implicit declaration of function 'synchronize_rcu_tasks_trace'; did you mean 'synchronize_rcu_tasks'? [-Werror=implicit-function-declaration]
    1157 |         synchronize_rcu_tasks_trace();
         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~
         |         synchronize_rcu_tasks
   cc1: some warnings being treated as errors


vim +1157 kernel/events/uprobes.c

  1145	
  1146	void uprobe_unregister_sync(void)
  1147	{
  1148		/*
  1149		 * Now that handler_chain() and handle_uretprobe_chain() iterate over
  1150		 * uprobe->consumers list under RCU protection without holding
  1151		 * uprobe->register_rwsem, we need to wait for RCU grace period to
  1152		 * make sure that we can't call into just unregistered
  1153		 * uprobe_consumer's callbacks anymore. If we don't do that, fast and
  1154		 * unlucky enough caller can free consumer's memory and cause
  1155		 * handler_chain() or handle_uretprobe_chain() to do an use-after-free.
  1156		 */
> 1157		synchronize_rcu_tasks_trace();
  1158	}
  1159	EXPORT_SYMBOL_GPL(uprobe_unregister_sync);
  1160	

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