linux-kernel - Re: [PATCH 2/6] x86,tlb: leave lazy TLB mode at page table free time

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Date:   Wed, 27 Jun 2018 14:03:45 +0800
From:   kbuild test robot <lkp@...el.com>
To:     Rik van Riel <riel@...riel.com>
Cc:     kbuild-all@...org, linux-kernel@...r.kernel.org, x86@...nel.org,
        luto@...nel.org, dave.hansen@...ux.intel.com, mingo@...nel.org,
        kernel-team@...com, tglx@...utronix.de, efault@....de,
        songliubraving@...com, Rik van Riel <riel@...riel.com>
Subject: Re: [PATCH 2/6] x86,tlb: leave lazy TLB mode at page table free time

Hi Rik,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linus/master]
[also build test ERROR on v4.18-rc2 next-20180626]
[cannot apply to tip/x86/core]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Rik-van-Riel/mm-allocate-mm_cpumask-dynamically-based-on-nr_cpu_ids/20180627-021116
config: arm-keystone_defconfig (attached as .config)
compiler: arm-linux-gnueabi-gcc (Debian 7.2.0-11) 7.2.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        GCC_VERSION=7.2.0 make.cross ARCH=arm 

All errors (new ones prefixed by >>):

   mm/memory.c: In function 'tlb_remove_table_smp_sync':
>> mm/memory.c:339:2: error: implicit declaration of function 'tlb_flush_remove_tables_local'; did you mean 'tlb_remove_table'? [-Werror=implicit-function-declaration]
     tlb_flush_remove_tables_local(mm);
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     tlb_remove_table
   mm/memory.c: In function 'tlb_table_flush':
>> mm/memory.c:372:2: error: implicit declaration of function 'tlb_flush_remove_tables'; did you mean 'tlb_remove_table'? [-Werror=implicit-function-declaration]
     tlb_flush_remove_tables(tlb->mm);
     ^~~~~~~~~~~~~~~~~~~~~~~
     tlb_remove_table
   cc1: some warnings being treated as errors

vim +339 mm/memory.c

   328	
   329	static void tlb_remove_table_smp_sync(void *arg)
   330	{
   331		struct mm_struct *mm = arg;
   332		/*
   333		 * On most architectures this does nothing. Simply delivering the
   334		 * interrupt is enough to prevent races with software page table
   335		 * walking like that done in get_user_pages_fast.
   336		 *
   337		 * See the comment near struct mmu_table_batch.
   338		 */
 > 339		tlb_flush_remove_tables_local(mm);
   340	}
   341	
   342	static void tlb_remove_table_one(void *table, struct mmu_gather *tlb)
   343	{
   344		/*
   345		 * This isn't an RCU grace period and hence the page-tables cannot be
   346		 * assumed to be actually RCU-freed.
   347		 *
   348		 * It is however sufficient for software page-table walkers that rely on
   349		 * IRQ disabling. See the comment near struct mmu_table_batch.
   350		 */
   351		smp_call_function(tlb_remove_table_smp_sync, tlb->mm, 1);
   352		__tlb_remove_table(table);
   353	}
   354	
   355	static void tlb_remove_table_rcu(struct rcu_head *head)
   356	{
   357		struct mmu_table_batch *batch;
   358		int i;
   359	
   360		batch = container_of(head, struct mmu_table_batch, rcu);
   361	
   362		for (i = 0; i < batch->nr; i++)
   363			__tlb_remove_table(batch->tables[i]);
   364	
   365		free_page((unsigned long)batch);
   366	}
   367	
   368	void tlb_table_flush(struct mmu_gather *tlb)
   369	{
   370		struct mmu_table_batch **batch = &tlb->batch;
   371	
 > 372		tlb_flush_remove_tables(tlb->mm);
   373	
   374		if (*batch) {
   375			call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
   376			*batch = NULL;
   377		}
   378	}
   379	

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