Re: [PATCH 3/4] mm/hotplug: free zone->pageset when a zone becomes empty

[Bob Liu <lliubbo@gmail.com>]

On Thu, Jul 5, 2012 at 5:45 PM, Jiang Liu <jiang.liu@huawei.com> wrote:
> When a zone becomes empty after memory offlining, free zone->pageset.
> Otherwise it will cause memory leak when adding memory to the empty
> zone again because build_all_zonelists() will allocate zone->pageset
> for an empty zone.
>

What about other area allocated to the zone?  eg. wait_table?

> Signed-off-by: Jiang Liu <liuj97@gmail.com>
> Signed-off-by: Wei Wang <Bessel.Wang@huawei.com>
> ---
>  include/linux/mm.h  |    1 +
>  mm/memory_hotplug.c |    3 +++
>  mm/page_alloc.c     |   13 +++++++++++++
>  3 files changed, 17 insertions(+), 0 deletions(-)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index b36d08c..f8b62f2 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1331,6 +1331,7 @@ void warn_alloc_failed(gfp_t gfp_mask, int order, const char *fmt, ...);
>  extern void setup_per_cpu_pageset(void);
>
>  extern void zone_pcp_update(struct zone *zone);
> +extern void zone_pcp_reset(struct zone *zone);
>
>  /* nommu.c */
>  extern atomic_long_t mmap_pages_allocated;
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index bce80c7..998b792 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -966,6 +966,9 @@ repeat:
>
>         init_per_zone_wmark_min();
>
> +       if (!populated_zone(zone))
> +               zone_pcp_reset(zone);
> +
>         if (!node_present_pages(node)) {
>                 node_clear_state(node, N_HIGH_MEMORY);
>                 kswapd_stop(node);
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index ebf319d..5964b7a 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5872,6 +5872,19 @@ void free_contig_range(unsigned long pfn, unsigned nr_pages)
>  #endif
>
>  #ifdef CONFIG_MEMORY_HOTREMOVE
> +void zone_pcp_reset(struct zone *zone)
> +{
> +       unsigned long flags;
> +
> +       /* avoid races with drain_pages()  */
> +       local_irq_save(flags);
> +       if (zone->pageset != &boot_pageset) {
> +               free_percpu(zone->pageset);
> +               zone->pageset = &boot_pageset;
> +       }
> +       local_irq_restore(flags);
> +}
> +
>  /*
>   * All pages in the range must be isolated before calling this.
>   */
> --
> 1.7.1
>
>
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-- 
Regards,
--Bob

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