Re: [PATCH 9/9] remove /proc/sys/vm/hugepages_treat_as_movable

[Michal Hocko]

On Thu 21-02-13 14:41:48, Naoya Horiguchi wrote:
> Now hugepages are definitely movable. So allocating hugepages from
> ZONE_MOVABLE is natural and we have no reason to keep this parameter.

The sysctl is a part of user interface so you shouldn't remove it right
away. What we can do is to make it noop and only WARN() that the
interface will be removed later so that userspace can prepare for that.

> Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
> ---
>  Documentation/sysctl/vm.txt | 16 ----------------
>  include/linux/hugetlb.h     |  2 --
>  kernel/sysctl.c             |  7 -------
>  mm/hugetlb.c                | 23 +++++------------------
>  4 files changed, 5 insertions(+), 43 deletions(-)
> 
> diff --git v3.8.orig/Documentation/sysctl/vm.txt v3.8/Documentation/sysctl/vm.txt
> index 078701f..997350a 100644
> --- v3.8.orig/Documentation/sysctl/vm.txt
> +++ v3.8/Documentation/sysctl/vm.txt
> @@ -167,22 +167,6 @@ fragmentation index is <= extfrag_threshold. The default value is 500.
>  
>  ==============================================================
>  
> -hugepages_treat_as_movable
> -
> -This parameter is only useful when kernelcore= is specified at boot time to
> -create ZONE_MOVABLE for pages that may be reclaimed or migrated. Huge pages
> -are not movable so are not normally allocated from ZONE_MOVABLE. A non-zero
> -value written to hugepages_treat_as_movable allows huge pages to be allocated
> -from ZONE_MOVABLE.
> -
> -Once enabled, the ZONE_MOVABLE is treated as an area of memory the huge
> -pages pool can easily grow or shrink within. Assuming that applications are
> -not running that mlock() a lot of memory, it is likely the huge pages pool
> -can grow to the size of ZONE_MOVABLE by repeatedly entering the desired value
> -into nr_hugepages and triggering page reclaim.
> -
> -==============================================================
> -
>  hugetlb_shm_group
>  
>  hugetlb_shm_group contains group id that is allowed to create SysV
> diff --git v3.8.orig/include/linux/hugetlb.h v3.8/include/linux/hugetlb.h
> index e33f07f..c97e5c5 100644
> --- v3.8.orig/include/linux/hugetlb.h
> +++ v3.8/include/linux/hugetlb.h
> @@ -35,7 +35,6 @@ int PageHuge(struct page *page);
>  void reset_vma_resv_huge_pages(struct vm_area_struct *vma);
>  int hugetlb_sysctl_handler(struct ctl_table *, int, void __user *, size_t *, loff_t *);
>  int hugetlb_overcommit_handler(struct ctl_table *, int, void __user *, size_t *, loff_t *);
> -int hugetlb_treat_movable_handler(struct ctl_table *, int, void __user *, size_t *, loff_t *);
>  
>  #ifdef CONFIG_NUMA
>  int hugetlb_mempolicy_sysctl_handler(struct ctl_table *, int,
> @@ -73,7 +72,6 @@ void migrate_hugepage_add(struct page *page, struct list_head *list);
>  int is_hugepage_movable(struct page *page);
>  void copy_huge_page(struct page *dst, struct page *src);
>  
> -extern unsigned long hugepages_treat_as_movable;
>  extern const unsigned long hugetlb_zero, hugetlb_infinity;
>  extern int sysctl_hugetlb_shm_group;
>  extern struct list_head huge_boot_pages;
> diff --git v3.8.orig/kernel/sysctl.c v3.8/kernel/sysctl.c
> index c88878d..a98bcf2 100644
> --- v3.8.orig/kernel/sysctl.c
> +++ v3.8/kernel/sysctl.c
> @@ -1189,13 +1189,6 @@ static struct ctl_table vm_table[] = {
>  		.mode		= 0644,
>  		.proc_handler	= proc_dointvec,
>  	 },
> -	 {
> -		.procname	= "hugepages_treat_as_movable",
> -		.data		= &hugepages_treat_as_movable,
> -		.maxlen		= sizeof(int),
> -		.mode		= 0644,
> -		.proc_handler	= hugetlb_treat_movable_handler,
> -	},
>  	{
>  		.procname	= "nr_overcommit_hugepages",
>  		.data		= NULL,
> diff --git v3.8.orig/mm/hugetlb.c v3.8/mm/hugetlb.c
> index c28e6c9..c60d203 100644
> --- v3.8.orig/mm/hugetlb.c
> +++ v3.8/mm/hugetlb.c
> @@ -33,7 +33,6 @@
>  #include "internal.h"
>  
>  const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
> -static gfp_t htlb_alloc_mask = GFP_HIGHUSER;
>  unsigned long hugepages_treat_as_movable;
>  
>  int hugetlb_max_hstate __read_mostly;
> @@ -542,7 +541,7 @@ static struct page *dequeue_huge_page_vma(struct hstate *h,
>  retry_cpuset:
>  	cpuset_mems_cookie = get_mems_allowed();
>  	zonelist = huge_zonelist(vma, address,
> -					htlb_alloc_mask, &mpol, &nodemask);
> +					GFP_HIGHUSER_MOVABLE, &mpol, &nodemask);
>  	/*
>  	 * A child process with MAP_PRIVATE mappings created by their parent
>  	 * have no page reserves. This check ensures that reservations are
> @@ -558,7 +557,7 @@ static struct page *dequeue_huge_page_vma(struct hstate *h,
>  
>  	for_each_zone_zonelist_nodemask(zone, z, zonelist,
>  						MAX_NR_ZONES - 1, nodemask) {
> -		if (cpuset_zone_allowed_softwall(zone, htlb_alloc_mask)) {
> +		if (cpuset_zone_allowed_softwall(zone, GFP_HIGHUSER_MOVABLE)) {
>  			page = dequeue_huge_page_node(h, zone_to_nid(zone));
>  			if (page) {
>  				if (!avoid_reserve)
> @@ -698,7 +697,7 @@ static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid)
>  		return NULL;
>  
>  	page = alloc_pages_exact_node(nid,
> -		htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|
> +		GFP_HIGHUSER_MOVABLE|__GFP_COMP|__GFP_THISNODE|
>  						__GFP_REPEAT|__GFP_NOWARN,
>  		huge_page_order(h));
>  	if (page) {
> @@ -909,12 +908,12 @@ static struct page *alloc_buddy_huge_page(struct hstate *h, int nid)
>  	spin_unlock(&hugetlb_lock);
>  
>  	if (nid == NUMA_NO_NODE)
> -		page = alloc_pages(htlb_alloc_mask|__GFP_COMP|
> +		page = alloc_pages(GFP_HIGHUSER_MOVABLE|__GFP_COMP|
>  				   __GFP_REPEAT|__GFP_NOWARN,
>  				   huge_page_order(h));
>  	else
>  		page = alloc_pages_exact_node(nid,
> -			htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|
> +			GFP_HIGHUSER_MOVABLE|__GFP_COMP|__GFP_THISNODE|
>  			__GFP_REPEAT|__GFP_NOWARN, huge_page_order(h));
>  
>  	if (page && arch_prepare_hugepage(page)) {
> @@ -2078,18 +2077,6 @@ int hugetlb_mempolicy_sysctl_handler(struct ctl_table *table, int write,
>  }
>  #endif /* CONFIG_NUMA */
>  
> -int hugetlb_treat_movable_handler(struct ctl_table *table, int write,
> -			void __user *buffer,
> -			size_t *length, loff_t *ppos)
> -{
> -	proc_dointvec(table, write, buffer, length, ppos);
> -	if (hugepages_treat_as_movable)
> -		htlb_alloc_mask = GFP_HIGHUSER_MOVABLE;
> -	else
> -		htlb_alloc_mask = GFP_HIGHUSER;
> -	return 0;
> -}
> -
>  int hugetlb_overcommit_handler(struct ctl_table *table, int write,
>  			void __user *buffer,
>  			size_t *length, loff_t *ppos)
> -- 
> 1.7.11.7
> 
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-- 
Michal Hocko
SUSE Labs
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