On Fri, Sep 16, 2016 at 08:44:17AM +0530, Aneesh Kumar K.V wrote:
> 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
It looks more readable! I will change it.
>
> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Thanks!
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