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Message-ID: <202103091952.Nlz922lP-lkp@intel.com>
Date:   Tue, 9 Mar 2021 19:11:35 +0800
From:   kernel test robot <lkp@...el.com>
To:     Minchan Kim <minchan@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     kbuild-all@...org,
        Linux Memory Management List <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>, joaodias@...gle.com,
        surenb@...gle.com, cgoldswo@...eaurora.org, willy@...radead.org,
        mhocko@...e.com, david@...hat.com, vbabka@...e.cz
Subject: Re: [PATCH v2 2/2] mm: fs: Invalidate BH LRU during page migration

Hi Minchan,

I love your patch! Yet something to improve:

[auto build test ERROR on linux/master]
[also build test ERROR on linus/master v5.12-rc2 next-20210309]
[cannot apply to hnaz-linux-mm/master]
[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]

url:    https://github.com/0day-ci/linux/commits/Minchan-Kim/mm-disable-LRU-pagevec-during-the-migration-temporarily/20210309-131826
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 144c79ef33536b4ecb4951e07dbc1f2b7fa99d32
config: openrisc-randconfig-r026-20210308 (attached as .config)
compiler: or1k-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/dfca8699b8fb8cf3bed2297e261fca53c0fc523c
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Minchan-Kim/mm-disable-LRU-pagevec-during-the-migration-temporarily/20210309-131826
        git checkout dfca8699b8fb8cf3bed2297e261fca53c0fc523c
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=openrisc 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@...el.com>

All errors (new ones prefixed by >>):

   mm/swap.c:745:6: warning: no previous prototype for '__lru_add_drain_all' [-Wmissing-prototypes]
     745 | void __lru_add_drain_all(bool force_all_cpus)
         |      ^~~~~~~~~~~~~~~~~~~
   mm/swap.c: In function '__lru_add_drain_all':
>> mm/swap.c:827:7: error: implicit declaration of function 'has_bh_in_lru' [-Werror=implicit-function-declaration]
     827 |       has_bh_in_lru(cpu, NULL)) {
         |       ^~~~~~~~~~~~~
   cc1: some warnings being treated as errors


vim +/has_bh_in_lru +827 mm/swap.c

   744	
   745	void __lru_add_drain_all(bool force_all_cpus)
   746	{
   747		/*
   748		 * lru_drain_gen - Global pages generation number
   749		 *
   750		 * (A) Definition: global lru_drain_gen = x implies that all generations
   751		 *     0 < n <= x are already *scheduled* for draining.
   752		 *
   753		 * This is an optimization for the highly-contended use case where a
   754		 * user space workload keeps constantly generating a flow of pages for
   755		 * each CPU.
   756		 */
   757		static unsigned int lru_drain_gen;
   758		static struct cpumask has_work;
   759		static DEFINE_MUTEX(lock);
   760		unsigned cpu, this_gen;
   761	
   762		/*
   763		 * Make sure nobody triggers this path before mm_percpu_wq is fully
   764		 * initialized.
   765		 */
   766		if (WARN_ON(!mm_percpu_wq))
   767			return;
   768	
   769		/*
   770		 * Guarantee pagevec counter stores visible by this CPU are visible to
   771		 * other CPUs before loading the current drain generation.
   772		 */
   773		smp_mb();
   774	
   775		/*
   776		 * (B) Locally cache global LRU draining generation number
   777		 *
   778		 * The read barrier ensures that the counter is loaded before the mutex
   779		 * is taken. It pairs with smp_mb() inside the mutex critical section
   780		 * at (D).
   781		 */
   782		this_gen = smp_load_acquire(&lru_drain_gen);
   783	
   784		mutex_lock(&lock);
   785	
   786		/*
   787		 * (C) Exit the draining operation if a newer generation, from another
   788		 * lru_add_drain_all(), was already scheduled for draining. Check (A).
   789		 */
   790		if (unlikely(this_gen != lru_drain_gen && !force_all_cpus))
   791			goto done;
   792	
   793		/*
   794		 * (D) Increment global generation number
   795		 *
   796		 * Pairs with smp_load_acquire() at (B), outside of the critical
   797		 * section. Use a full memory barrier to guarantee that the new global
   798		 * drain generation number is stored before loading pagevec counters.
   799		 *
   800		 * This pairing must be done here, before the for_each_online_cpu loop
   801		 * below which drains the page vectors.
   802		 *
   803		 * Let x, y, and z represent some system CPU numbers, where x < y < z.
   804		 * Assume CPU #z is is in the middle of the for_each_online_cpu loop
   805		 * below and has already reached CPU #y's per-cpu data. CPU #x comes
   806		 * along, adds some pages to its per-cpu vectors, then calls
   807		 * lru_add_drain_all().
   808		 *
   809		 * If the paired barrier is done at any later step, e.g. after the
   810		 * loop, CPU #x will just exit at (C) and miss flushing out all of its
   811		 * added pages.
   812		 */
   813		WRITE_ONCE(lru_drain_gen, lru_drain_gen + 1);
   814		smp_mb();
   815	
   816		cpumask_clear(&has_work);
   817		for_each_online_cpu(cpu) {
   818			struct work_struct *work = &per_cpu(lru_add_drain_work, cpu);
   819	
   820			if (force_all_cpus ||
   821			    pagevec_count(&per_cpu(lru_pvecs.lru_add, cpu)) ||
   822			    data_race(pagevec_count(&per_cpu(lru_rotate.pvec, cpu))) ||
   823			    pagevec_count(&per_cpu(lru_pvecs.lru_deactivate_file, cpu)) ||
   824			    pagevec_count(&per_cpu(lru_pvecs.lru_deactivate, cpu)) ||
   825			    pagevec_count(&per_cpu(lru_pvecs.lru_lazyfree, cpu)) ||
   826			    need_activate_page_drain(cpu) ||
 > 827			    has_bh_in_lru(cpu, NULL)) {
   828				INIT_WORK(work, lru_add_drain_per_cpu);
   829				queue_work_on(cpu, mm_percpu_wq, work);
   830				__cpumask_set_cpu(cpu, &has_work);
   831			}
   832		}
   833	
   834		for_each_cpu(cpu, &has_work)
   835			flush_work(&per_cpu(lru_add_drain_work, cpu));
   836	
   837	done:
   838		mutex_unlock(&lock);
   839	}
   840	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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