Re: [PATCH v5] mm: Add CONFIG_PAGE_BLOCK_ORDER to select page block order

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

Hi Juan,

kernel test robot noticed the following build warnings:

[auto build test WARNING on akpm-mm/mm-everything]

url:    https://github.com/intel-lab-lkp/linux/commits/Juan-Yescas/mm-Add-CONFIG_PAGE_BLOCK_ORDER-to-select-page-block-order/20250517-072434
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/20250516232341.659513-1-jyescas%40google.com
patch subject: [PATCH v5] mm: Add CONFIG_PAGE_BLOCK_ORDER to select page block order
config: i386-randconfig-r073-20250518 (https://download.01.org/0day-ci/archive/20250518/202505181321.IBrAyg7D-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0

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>
| Closes: https://lore.kernel.org/oe-kbuild-all/202505181321.IBrAyg7D-lkp@intel.com/

smatch warnings:
mm/compaction.c:849 skip_isolation_on_order() warn: always true condition '(order >= (((((22 - 12))) < ((0))) ?(((22 - 12))):((0)))) => (s32min-s32max >= 0)'
mm/page_alloc.c:730 __del_page_from_free_list() warn: always true condition '(order >= (((((22 - 12))) < ((0))) ?(((22 - 12))):((0)))) => (0-u32max >= 0)'
mm/page_alloc.c:679 __add_to_free_list() warn: always true condition '(order >= (((((22 - 12))) < ((0))) ?(((22 - 12))):((0)))) => (0-u32max >= 0)'
mm/page_alloc.c:704 move_to_free_list() warn: always true condition '(order >= (((((22 - 12))) < ((0))) ?(((22 - 12))):((0)))) => (0-u32max >= 0)'
mm/page_alloc.c:2036 should_try_claim_block() warn: always true condition '(order >= (((((22 - 12))) < ((0))) ?(((22 - 12))):((0)))) => (0-u32max >= 0)'
mm/page_alloc.c:2043 should_try_claim_block() warn: always true condition '(order >= (((((22 - 12))) < ((0))) ?(((22 - 12))):((0))) / 2) => (0-u32max >= 0)'
mm/page_alloc.c:2112 try_to_claim_block() warn: always true condition '(current_order >= (((((22 - 12))) < ((0))) ?(((22 - 12))):((0)))) => (s32min-s32max >= 0)'
mm/page_alloc.c:2192 __rmqueue_claim() warn: unsigned 'order' is never less than zero.
mm/page_alloc.c:3200 reserve_highatomic_pageblock() warn: unsigned 'order' is never less than zero.
mm/page_alloc.c:3273 unreserve_highatomic_pageblock() warn: unsigned 'order' is never less than zero.

vim +849 mm/compaction.c

748446bb6b5a93 Mel Gorman 2010-05-24  825  
ee6f62fd34f0bb Zi Yan     2024-02-20  826  /**
ee6f62fd34f0bb Zi Yan     2024-02-20  827   * skip_isolation_on_order() - determine when to skip folio isolation based on
ee6f62fd34f0bb Zi Yan     2024-02-20  828   *			       folio order and compaction target order
ee6f62fd34f0bb Zi Yan     2024-02-20  829   * @order:		to-be-isolated folio order
ee6f62fd34f0bb Zi Yan     2024-02-20  830   * @target_order:	compaction target order
ee6f62fd34f0bb Zi Yan     2024-02-20  831   *
ee6f62fd34f0bb Zi Yan     2024-02-20  832   * This avoids unnecessary folio isolations during compaction.
ee6f62fd34f0bb Zi Yan     2024-02-20  833   */
ee6f62fd34f0bb Zi Yan     2024-02-20  834  static bool skip_isolation_on_order(int order, int target_order)
ee6f62fd34f0bb Zi Yan     2024-02-20  835  {
ee6f62fd34f0bb Zi Yan     2024-02-20  836  	/*
ee6f62fd34f0bb Zi Yan     2024-02-20  837  	 * Unless we are performing global compaction (i.e.,
ee6f62fd34f0bb Zi Yan     2024-02-20  838  	 * is_via_compact_memory), skip any folios that are larger than the
ee6f62fd34f0bb Zi Yan     2024-02-20  839  	 * target order: we wouldn't be here if we'd have a free folio with
ee6f62fd34f0bb Zi Yan     2024-02-20  840  	 * the desired target_order, so migrating this folio would likely fail
ee6f62fd34f0bb Zi Yan     2024-02-20  841  	 * later.
ee6f62fd34f0bb Zi Yan     2024-02-20  842  	 */
ee6f62fd34f0bb Zi Yan     2024-02-20  843  	if (!is_via_compact_memory(target_order) && order >= target_order)
ee6f62fd34f0bb Zi Yan     2024-02-20  844  		return true;
ee6f62fd34f0bb Zi Yan     2024-02-20  845  	/*
ee6f62fd34f0bb Zi Yan     2024-02-20  846  	 * We limit memory compaction to pageblocks and won't try
ee6f62fd34f0bb Zi Yan     2024-02-20  847  	 * creating free blocks of memory that are larger than that.
ee6f62fd34f0bb Zi Yan     2024-02-20  848  	 */
ee6f62fd34f0bb Zi Yan     2024-02-20 @849  	return order >= pageblock_order;
ee6f62fd34f0bb Zi Yan     2024-02-20  850  }
ee6f62fd34f0bb Zi Yan     2024-02-20  851  

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