[linux-next:master 12137/12319] include/linux/kstack_erase.h:29:37: error: passing 'const struct task_struct *' to parameter of type 'struct task_struct *' discards qualifiers

[linux-next:master 12137/12319] include/linux/kstack_erase.h:29:37: error: passing 'const struct task_struct *' to parameter of type 'struct task_struct *' discards qualifiers

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   d7af19298454ed155f5cf67201a70f5cf836c842
commit: 897627bc44d228f00cc8595c9b2fa747d3e8c64f [12137/12319] kstack_erase: Support Clang stack depth tracking
config: loongarch-allyesconfig (https://download.01.org/0day-ci/archive/20250726/202507261908.eBMSznZw-lkp@intel.com/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 853c343b45b3e83cc5eeef5a52fc8cc9d8a09252)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250726/202507261908.eBMSznZw-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/202507261908.eBMSznZw-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from kernel/fork.c:96:
>> include/linux/kstack_erase.h:29:37: error: passing 'const struct task_struct *' to parameter of type 'struct task_struct *' discards qualifiers [-Werror,-Wincompatible-pointer-types-discards-qualifiers]
      29 |         return (unsigned long)end_of_stack(tsk) + sizeof(unsigned long);
         |                                            ^~~
   include/linux/sched/task_stack.h:56:63: note: passing argument to parameter 'p' here
      56 | static inline unsigned long *end_of_stack(struct task_struct *p)
         |                                                               ^
   1 error generated.


vim +29 include/linux/kstack_erase.h

afaef01c001537 include/linux/stackleak.h Alexander Popov 2018-08-17  18  
9ec79840d6afaf include/linux/stackleak.h Mark Rutland    2022-04-27  19  /*
9ec79840d6afaf include/linux/stackleak.h Mark Rutland    2022-04-27  20   * The lowest address on tsk's stack which we can plausibly erase.
9ec79840d6afaf include/linux/stackleak.h Mark Rutland    2022-04-27  21   */
9ec79840d6afaf include/linux/stackleak.h Mark Rutland    2022-04-27  22  static __always_inline unsigned long
9ec79840d6afaf include/linux/stackleak.h Mark Rutland    2022-04-27  23  stackleak_task_low_bound(const struct task_struct *tsk)
9ec79840d6afaf include/linux/stackleak.h Mark Rutland    2022-04-27  24  {
9ec79840d6afaf include/linux/stackleak.h Mark Rutland    2022-04-27  25  	/*
9ec79840d6afaf include/linux/stackleak.h Mark Rutland    2022-04-27  26  	 * The lowest unsigned long on the task stack contains STACK_END_MAGIC,
9ec79840d6afaf include/linux/stackleak.h Mark Rutland    2022-04-27  27  	 * which we must not corrupt.
9ec79840d6afaf include/linux/stackleak.h Mark Rutland    2022-04-27  28  	 */
9ec79840d6afaf include/linux/stackleak.h Mark Rutland    2022-04-27 @29  	return (unsigned long)end_of_stack(tsk) + sizeof(unsigned long);
9ec79840d6afaf include/linux/stackleak.h Mark Rutland    2022-04-27  30  }
9ec79840d6afaf include/linux/stackleak.h Mark Rutland    2022-04-27  31  

:::::: The code at line 29 was first introduced by commit
:::::: 9ec79840d6afaf472294588a6bbe145bcdffa28b stackleak: rework stack low bound handling

:::::: TO: Mark Rutland <mark.rutland@arm.com>
:::::: CC: Kees Cook <keescook@chromium.org>

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