js1304@xxxxxxxxx writes:
> From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
>
> Freepage on ZONE_HIGHMEM doesn't work for kernel memory so it's not that
> important to reserve. When ZONE_MOVABLE is used, this problem would
> theorectically cause to decrease usable memory for GFP_HIGHUSER_MOVABLE
> allocation request which is mainly used for page cache and anon page
> allocation. So, fix it.
>
> And, defining sysctl_lowmem_reserve_ratio array by MAX_NR_ZONES - 1 size
> makes code complex. For example, if there is highmem system, following
> reserve ratio is activated for *NORMAL ZONE* which would be easyily
> misleading people.
>
> #ifdef CONFIG_HIGHMEM
> 32
> #endif
>
> This patch also fix this situation by defining sysctl_lowmem_reserve_ratio
> array by MAX_NR_ZONES and place "#ifdef" to right place.
>
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
> ---
> include/linux/mmzone.h | 2 +-
> mm/page_alloc.c | 7 ++++---
> 2 files changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index d572b78..e3f39af 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -877,7 +877,7 @@ int min_free_kbytes_sysctl_handler(struct ctl_table *, int,
> void __user *, size_t *, loff_t *);
> int watermark_scale_factor_sysctl_handler(struct ctl_table *, int,
> void __user *, size_t *, loff_t *);
> -extern int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1];
> +extern int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES];
> int lowmem_reserve_ratio_sysctl_handler(struct ctl_table *, int,
> void __user *, size_t *, loff_t *);
> int percpu_pagelist_fraction_sysctl_handler(struct ctl_table *, int,
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 4f7d5d7..a8310de 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -198,17 +198,18 @@ static void __free_pages_ok(struct page *page, unsigned int order);
> * TBD: should special case ZONE_DMA32 machines here - in those we normally
> * don't need any ZONE_NORMAL reservation
> */
> -int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1] = {
> +int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES] = {
> #ifdef CONFIG_ZONE_DMA
> 256,
> #endif
> #ifdef CONFIG_ZONE_DMA32
> 256,
> #endif
> -#ifdef CONFIG_HIGHMEM
> 32,
> +#ifdef CONFIG_HIGHMEM
> + INT_MAX,
> #endif
> - 32,
> + INT_MAX,
> };
>
> EXPORT_SYMBOL(totalram_pages);
> --
> 1.9.1
We can also do things like below to make it readable ?
#ifdef CONFIG_ZONE_DMA
[ZONE_DMA] = 256,
#endif
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
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