[PATCH] crash: Support high memory reservation for range syntax

[kernel test robot]

Hi Youling,

kernel test robot noticed the following build warnings:

[auto build test WARNING on akpm-mm/mm-everything]
[also build test WARNING on linus/master v7.0 next-20260414]
[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/Youling-Tang/crash-Support-high-memory-reservation-for-range-syntax/20260414-205035
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/20260404074103.506793-1-youling.tang%40linux.dev
patch subject: [PATCH] crash: Support high memory reservation for range syntax
config: loongarch-randconfig-001-20260415 (https://download.01.org/0day-ci/archive/20260415/202604150808.7HxFp5b4-lkp@intel.com/config)
compiler: clang version 18.1.8 (https://github.com/llvm/llvm-project 3b5b5c1ec4a3095ab096dd780e84d7ab81f3d7ff)
rustc: rustc 1.88.0 (6b00bc388 2025-06-23)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260415/202604150808.7HxFp5b4-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 at intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202604150808.7HxFp5b4-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> kernel/crash_reserve.c:264:19: warning: expression which evaluates to zero treated as a null pointer constant of type 'char *' [-Wnon-literal-null-conversion]
     264 |         char *first_gt = false;
         |                          ^~~~~
   1 warning generated.


vim +264 kernel/crash_reserve.c

   254	
   255	/*
   256	 * This function parses command lines in the format
   257	 *
   258	 *   crashkernel=ramsize-range:size[,...][@offset],>boundary
   259	 */
   260	static void __init parse_crashkernel_boundary(char *ck_cmdline,
   261						unsigned long long *boundary)
   262	{
   263		char *cur = ck_cmdline, *next;
 > 264		char *first_gt = false;
   265	
   266		first_gt = strchr(cur, '>');
   267		if (!first_gt)
   268			return;
   269	
   270		cur = first_gt + 1;
   271		if (*cur == '\0' || *cur == ' ' || *cur == ',') {
   272			pr_warn("crashkernel: '>' specified without boundary size, ignoring\n");
   273			return;
   274		}
   275	
   276		*boundary = memparse(cur, &next);
   277		if (cur == next) {
   278			pr_warn("crashkernel: invalid boundary size after '>'\n");
   279			return;
   280		}
   281	}
   282	

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