Re: [PATCH] mm/huge_memory: consolidate order-related checks into folio_split_supported()

[Wei Yang <richard.weiyang@gmail.com>]

On Wed, Nov 19, 2025 at 03:37:09PM +0300, Dan Carpenter wrote:
>Hi Wei,
>
>kernel test robot noticed the following build warnings:
>
>url:    https://github.com/intel-lab-lkp/linux/commits/Wei-Yang/mm-huge_memory-consolidate-order-related-checks-into-folio_split_supported/20251114-155833
>base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
>patch link:    https://lore.kernel.org/r/20251114075703.10434-1-richard.weiyang%40gmail.com
>patch subject: [PATCH] mm/huge_memory: consolidate order-related checks into folio_split_supported()
>config: i386-randconfig-141-20251115 (https://download.01.org/0day-ci/archive/20251115/202511151652.GKPwEctt-lkp@intel.com/config)
>compiler: gcc-12 (Debian 12.4.0-5) 12.4.0
>
>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>
>| Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
>| Closes: https://lore.kernel.org/r/202511151652.GKPwEctt-lkp@intel.com/
>
>smatch warnings:
>mm/huge_memory.c:3696 folio_split_supported() warn: signedness bug returning '(-22)'
>
>vim +3696 mm/huge_memory.c
>
>aa27253af32c74 Wei Yang 2025-11-06  3690  bool folio_split_supported(struct folio *folio, unsigned int new_order,
>                                          ^^^^
>This is a bool function.
>
>aa27253af32c74 Wei Yang 2025-11-06  3691  		enum split_type split_type, bool warns)
>58729c04cf1092 Zi Yan   2025-03-07  3692  {
>ab62f1bb0caaa5 Wei Yang 2025-11-14  3693  	const int old_order = folio_order(folio);
>ab62f1bb0caaa5 Wei Yang 2025-11-14  3694  
>ab62f1bb0caaa5 Wei Yang 2025-11-14  3695  	if (new_order >= old_order)
>ab62f1bb0caaa5 Wei Yang 2025-11-14 @3696  		return -EINVAL;

Thanks, this is noticed.

>
>s/-EINVAL/false/
>
>ab62f1bb0caaa5 Wei Yang 2025-11-14  3697  
>58729c04cf1092 Zi Yan   2025-03-07  3698  	if (folio_test_anon(folio)) {
>58729c04cf1092 Zi Yan   2025-03-07  3699  		/* order-1 is not supported for anonymous THP. */
>58729c04cf1092 Zi Yan   2025-03-07  3700  		VM_WARN_ONCE(warns && new_order == 1,
>58729c04cf1092 Zi Yan   2025-03-07  3701  				"Cannot split to order-1 folio");
>28753037121116 Zi Yan   2025-11-05  3702  		if (new_order == 1)
>28753037121116 Zi Yan   2025-11-05  3703  			return false;
>
>-- 
>0-DAY CI Kernel Test Service
>https://github.com/intel/lkp-tests/wiki

-- 
Wei Yang
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