lkml.org 
[lkml]   [2021]   [Mar]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH v2 1/2] mm: disable LRU pagevec during the migration temporarily
    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@intel.com>

    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@lists.01.org
    [unhandled content-type:application/gzip]
    \
     
     \ /
      Last update: 2021-03-09 08:59    [W:3.081 / U:0.048 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site