Re: [v5 6/7] mm: Defer TLB flush by keeping both src and dst folios at migration

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

Hi Byungchul,

kernel test robot noticed the following build warnings:

[auto build test WARNING on akpm-mm/mm-everything]
[also build test WARNING on tip/sched/core tip/x86/core arm64/for-next/core tip/x86/mm linus/master v6.7 next-20240111]
[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/Byungchul-Park/x86-tlb-Add-APIs-manipulating-tlb-batch-s-arch-data/20240111-141049
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/20240111060757.13563-7-byungchul%40sk.com
patch subject: [v5 6/7] mm: Defer TLB flush by keeping both src and dst folios at migration
config: x86_64-randconfig-161-20240111 (https://download.01.org/0day-ci/archive/20240112/202401120637.ZuSqfagi-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240112/202401120637.ZuSqfagi-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/202401120637.ZuSqfagi-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> mm/migrate.c:152:6: warning: no previous prototype for 'migrc_flush_start' [-Wmissing-prototypes]
     152 | void migrc_flush_start(void)
         |      ^~~~~~~~~~~~~~~~~
>> mm/migrate.c:161:6: warning: no previous prototype for 'migrc_flush_end' [-Wmissing-prototypes]
     161 | void migrc_flush_end(struct arch_tlbflush_unmap_batch *arch)
         |      ^~~~~~~~~~~~~~~


vim +/migrc_flush_start +152 mm/migrate.c

   151	
 > 152	void migrc_flush_start(void)
   153	{
   154		unsigned long flags;
   155	
   156		spin_lock_irqsave(&migrc_lock, flags);
   157		migrc_flushing++;
   158		spin_unlock_irqrestore(&migrc_lock, flags);
   159	}
   160	
 > 161	void migrc_flush_end(struct arch_tlbflush_unmap_batch *arch)
   162	{
   163		LIST_HEAD(folios);
   164		struct folio *f, *f2;
   165		unsigned long flags;
   166	
   167		spin_lock_irqsave(&migrc_lock, flags);
   168		if (!arch_tlbbatch_done(&migrc_ubc.arch, arch)) {
   169			list_splice_init(&migrc_folios, &folios);
   170			migrc_ubc.flush_required = false;
   171			migrc_ubc.writable = false;
   172		}
   173		migrc_flushing--;
   174		spin_unlock_irqrestore(&migrc_lock, flags);
   175	
   176		list_for_each_entry_safe(f, f2, &folios, lru) {
   177			folio_put_small_nopcp(f);
   178			atomic_dec(&folio_zone(f)->migrc_pending_nr);
   179		}
   180	}
   181	

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