Re: [PATCH v2 1/2] mm: disable LRU pagevec during the migration temporarily
From: kernel test robot
Date: Tue Mar 09 2021 - 02:58:09 EST
Hi Minchan,
I love your patch! Perhaps something to improve:
[auto build test WARNING on linux/master]
[also build test WARNING 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: arm64-randconfig-r023-20210308 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 820f508b08d7c94b2dd7847e9710d2bc36d3dd45)
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
# install arm64 cross compiling tool for clang build
# apt-get install binutils-aarch64-linux-gnu
# https://github.com/0day-ci/linux/commit/e746db1a2ab13441890fa2cad8604bbec190b401
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 e746db1a2ab13441890fa2cad8604bbec190b401
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=arm64
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>
All warnings (new ones prefixed by >>):
mm/swap.c:244:4: error: implicit declaration of function 'lru_cache_disabled' [-Werror,-Wimplicit-function-declaration]
lru_cache_disabled())
^
mm/swap.c:244:4: note: did you mean 'lru_cache_disable'?
include/linux/swap.h:342:13: note: 'lru_cache_disable' declared here
extern void lru_cache_disable(void);
^
>> mm/swap.c:743:6: warning: no previous prototype for function '__lru_add_drain_all' [-Wmissing-prototypes]
void __lru_add_drain_all(bool force_all_cpus)
^
mm/swap.c:743:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
void __lru_add_drain_all(bool force_all_cpus)
^
static
mm/swap.c:858:6: error: conflicting types for 'lru_cache_disabled'
bool lru_cache_disabled(void)
^
mm/swap.c:244:4: note: previous implicit declaration is here
lru_cache_disabled())
^
1 warning and 2 errors generated.
vim +/__lru_add_drain_all +743 mm/swap.c
742
> 743 void __lru_add_drain_all(bool force_all_cpus)
744 {
745 /*
746 * lru_drain_gen - Global pages generation number
747 *
748 * (A) Definition: global lru_drain_gen = x implies that all generations
749 * 0 < n <= x are already *scheduled* for draining.
750 *
751 * This is an optimization for the highly-contended use case where a
752 * user space workload keeps constantly generating a flow of pages for
753 * each CPU.
754 */
755 static unsigned int lru_drain_gen;
756 static struct cpumask has_work;
757 static DEFINE_MUTEX(lock);
758 unsigned cpu, this_gen;
759
760 /*
761 * Make sure nobody triggers this path before mm_percpu_wq is fully
762 * initialized.
763 */
764 if (WARN_ON(!mm_percpu_wq))
765 return;
766
767 /*
768 * Guarantee pagevec counter stores visible by this CPU are visible to
769 * other CPUs before loading the current drain generation.
770 */
771 smp_mb();
772
773 /*
774 * (B) Locally cache global LRU draining generation number
775 *
776 * The read barrier ensures that the counter is loaded before the mutex
777 * is taken. It pairs with smp_mb() inside the mutex critical section
778 * at (D).
779 */
780 this_gen = smp_load_acquire(&lru_drain_gen);
781
782 mutex_lock(&lock);
783
784 /*
785 * (C) Exit the draining operation if a newer generation, from another
786 * lru_add_drain_all(), was already scheduled for draining. Check (A).
787 */
788 if (unlikely(this_gen != lru_drain_gen && !force_all_cpus))
789 goto done;
790
791 /*
792 * (D) Increment global generation number
793 *
794 * Pairs with smp_load_acquire() at (B), outside of the critical
795 * section. Use a full memory barrier to guarantee that the new global
796 * drain generation number is stored before loading pagevec counters.
797 *
798 * This pairing must be done here, before the for_each_online_cpu loop
799 * below which drains the page vectors.
800 *
801 * Let x, y, and z represent some system CPU numbers, where x < y < z.
802 * Assume CPU #z is is in the middle of the for_each_online_cpu loop
803 * below and has already reached CPU #y's per-cpu data. CPU #x comes
804 * along, adds some pages to its per-cpu vectors, then calls
805 * lru_add_drain_all().
806 *
807 * If the paired barrier is done at any later step, e.g. after the
808 * loop, CPU #x will just exit at (C) and miss flushing out all of its
809 * added pages.
810 */
811 WRITE_ONCE(lru_drain_gen, lru_drain_gen + 1);
812 smp_mb();
813
814 cpumask_clear(&has_work);
815 for_each_online_cpu(cpu) {
816 struct work_struct *work = &per_cpu(lru_add_drain_work, cpu);
817
818 if (force_all_cpus ||
819 pagevec_count(&per_cpu(lru_pvecs.lru_add, cpu)) ||
820 data_race(pagevec_count(&per_cpu(lru_rotate.pvec, cpu))) ||
821 pagevec_count(&per_cpu(lru_pvecs.lru_deactivate_file, cpu)) ||
822 pagevec_count(&per_cpu(lru_pvecs.lru_deactivate, cpu)) ||
823 pagevec_count(&per_cpu(lru_pvecs.lru_lazyfree, cpu)) ||
824 need_activate_page_drain(cpu)) {
825 INIT_WORK(work, lru_add_drain_per_cpu);
826 queue_work_on(cpu, mm_percpu_wq, work);
827 __cpumask_set_cpu(cpu, &has_work);
828 }
829 }
830
831 for_each_cpu(cpu, &has_work)
832 flush_work(&per_cpu(lru_add_drain_work, cpu));
833
834 done:
835 mutex_unlock(&lock);
836 }
837
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx
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