Re: [PATCH v2 2/2] locking: mutex: Fix proxy-exec potentially deactivating tasks marked TASK_RUNNING

[kernel test robot]

Hi John,

kernel test robot noticed the following build warnings:

[auto build test WARNING on tip/sched/core]
[also build test WARNING on tip/master next-20260430]
[cannot apply to tip/locking/core tip/auto-latest linus/master v6.16-rc1]
[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/John-Stultz/sched-proxy-exec-Close-race-causing-workqueue-work-being-delayed/20260504-045026
base:   tip/sched/core
patch link:    https://lore.kernel.org/r/20260430215103.2978955-3-jstultz%40google.com
patch subject: [PATCH v2 2/2] locking: mutex: Fix proxy-exec potentially deactivating tasks marked TASK_RUNNING
config: x86_64-rhel-9.4-rust (https://download.01.org/0day-ci/archive/20260505/202605050032.Sh1SUziK-lkp@xxxxxxxxx/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
rustc: rustc 1.88.0 (6b00bc388 2025-06-23)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260505/202605050032.Sh1SUziK-lkp@xxxxxxxxx/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@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-kbuild-all/202605050032.Sh1SUziK-lkp@xxxxxxxxx/

All warnings (new ones prefixed by >>):

   In file included from arch/x86/kernel/asm-offsets.c:9:
   In file included from include/linux/crypto.h:18:
   In file included from include/linux/slab.h:17:
   In file included from include/linux/gfp.h:7:
   In file included from include/linux/mmzone.h:22:
   In file included from include/linux/mm_types.h:11:
   In file included from include/linux/rbtree.h:24:
   In file included from include/linux/rcupdate.h:27:
>> include/linux/sched.h:2209:10: warning: expression which evaluates to zero treated as a null pointer constant of type 'struct mutex *' [-Wnon-literal-null-conversion]
    2209 |                 return false;
         |                        ^~~~~
   1 warning generated.
--
>> clang diag: include/linux/sched.h:2209:10: warning: expression which evaluates to zero treated as a null pointer constant of type 'struct mutex *' [-Wnon-literal-null-conversion]


vim +2209 include/linux/sched.h

  2205	
  2206	static inline struct mutex *task_is_blocked_on(struct task_struct *p)
  2207	{
  2208		if (!sched_proxy_exec())
> 2209			return false;
  2210		return (struct mutex *)((unsigned long)p->blocked_on & PROXY_BLOCKED_LATCH);
  2211	}
  2212	

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