Re: mmotm 2020-05-11-15-43 uploaded (mm/memcontrol.c, huge pages)

[Naresh Kamboju]

> The THP page size macros are CONFIG_TRANSPARENT_HUGEPAGE only.
>
> We already ifdef most THP-related code in memcg, but not these
> particular stats. Memcg used to track the pages as they came in, and
> PageTransHuge() + hpage_nr_pages() work when THP is not compiled in.
>
> Switching to native vmstat counters, memcg doesn't see the pages, it
> only gets a count of THPs. To translate that to bytes, it has to know
> how big the THPs are - and that's only available for CONFIG_THP.
>
> Add the necessary ifdefs. /proc/meminfo, smaps etc. also don't show
> the THP counters when the feature is compiled out. The event counts
> (THP_FAULT_ALLOC, THP_COLLAPSE_ALLOC) were already conditional also.
>
> Style touchup: HPAGE_PMD_NR * PAGE_SIZE is silly. Use HPAGE_PMD_SIZE.

Build tested and build pass on x86_64.

>
> Reported-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>

Tested-by: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx>

> ---
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 738d071ba1ef..47c685088a2c 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -1401,9 +1401,11 @@ static char *memory_stat_format(struct mem_cgroup *memcg)
>                        (u64)memcg_page_state(memcg, NR_WRITEBACK) *
>                        PAGE_SIZE);
>
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
>         seq_buf_printf(&s, "anon_thp %llu\n",
>                        (u64)memcg_page_state(memcg, NR_ANON_THPS) *
> -                      HPAGE_PMD_NR * PAGE_SIZE);
> +                      HPAGE_PMD_SIZE);
> +#endif
>
>         for (i = 0; i < NR_LRU_LISTS; i++)
>                 seq_buf_printf(&s, "%s %llu\n", lru_list_name(i),
> @@ -3752,7 +3754,9 @@ static int memcg_numa_stat_show(struct seq_file *m, void *v)
>  static const unsigned int memcg1_stats[] = {
>         NR_FILE_PAGES,
>         NR_ANON_MAPPED,
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
>         NR_ANON_THPS,
> +#endif
>         NR_SHMEM,
>         NR_FILE_MAPPED,
>         NR_FILE_DIRTY,
> @@ -3763,7 +3767,9 @@ static const unsigned int memcg1_stats[] = {
>  static const char *const memcg1_stat_names[] = {
>         "cache",
>         "rss",
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
>         "rss_huge",
> +#endif
>         "shmem",
>         "mapped_file",
>         "dirty",
> @@ -3794,8 +3800,10 @@ static int memcg_stat_show(struct seq_file *m, void *v)
>                 if (memcg1_stats[i] == MEMCG_SWAP && !do_memsw_account())
>                         continue;
>                 nr = memcg_page_state_local(memcg, memcg1_stats[i]);
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
>                 if (memcg1_stats[i] == NR_ANON_THPS)
>                         nr *= HPAGE_PMD_NR;
> +#endif
>                 seq_printf(m, "%s %lu\n", memcg1_stat_names[i], nr * PAGE_SIZE);
>         }
>


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