Message-ID: <20200609132438.GE22623@dhcp22.suse.cz>
Date:   Tue, 9 Jun 2020 15:24:38 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     js1304@...il.com
Cc:     Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, kernel-team@....com,
        Vlastimil Babka <vbabka@...e.cz>,
        Christoph Hellwig <hch@...radead.org>,
        Roman Gushchin <guro@...com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [PATCH v2 03/12] mm/hugetlb: introduce alloc_control structure
 to simplify migration target allocation APIs

On Wed 27-05-20 15:44:54, Joonsoo Kim wrote:
> From: Joonsoo Kim <iamjoonsoo.kim@....com>
> 
> Currently, page allocation functions for migration requires some arguments.
> More worse, in the following patch, more argument will be needed to unify
> the similar functions. To simplify them, in this patch, unified data
> structure that controls allocation behaviour is introduced.
> 
> For clean-up, function declarations are re-ordered.

This is really hard to review without having a clear picture of the
resulting code so bear with me. I can see some reasons why allocation
callbacks might benefit from a agragated argument but you seem to touch
the internal hugetlb dequeue_huge_page_vma which shouldn't really need
that. I wouldn't mind much but I remember the hugetlb allocation
functions layering is quite complex for hugetlb specific reasons (see
0c397daea1d4 ("mm, hugetlb: further simplify hugetlb allocation API")
for more background).

Is there any reason why the agregated argument cannot be limited only to
migration callbacks. That would be alloc_huge_page_node, alloc_huge_page_nodemask
and alloc_huge_page_vma.

> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@....com>
> ---
>  include/linux/hugetlb.h | 35 +++++++++++++++-------------
>  mm/gup.c                | 11 ++++++---
>  mm/hugetlb.c            | 62 ++++++++++++++++++++++++-------------------------
>  mm/internal.h           |  7 ++++++
>  mm/mempolicy.c          | 13 +++++++----
>  mm/migrate.c            | 13 +++++++----
>  6 files changed, 83 insertions(+), 58 deletions(-)
> 
> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> index 50650d0..15c8fb8 100644
> --- a/include/linux/hugetlb.h
> +++ b/include/linux/hugetlb.h
> @@ -14,6 +14,7 @@
>  struct ctl_table;
>  struct user_struct;
>  struct mmu_gather;
> +struct alloc_control;
>  
>  #ifndef is_hugepd
>  typedef struct { unsigned long pd; } hugepd_t;
> @@ -502,15 +503,16 @@ struct huge_bootmem_page {
>  	struct hstate *hstate;
>  };
>  
> -struct page *alloc_huge_page(struct vm_area_struct *vma,
> -				unsigned long addr, int avoid_reserve);
> -struct page *alloc_huge_page_node(struct hstate *h, int nid);
> -struct page *alloc_huge_page_nodemask(struct hstate *h, int preferred_nid,
> -				nodemask_t *nmask);
> +struct page *alloc_migrate_huge_page(struct hstate *h,
> +				struct alloc_control *ac);
> +struct page *alloc_huge_page_node(struct hstate *h,
> +				struct alloc_control *ac);
> +struct page *alloc_huge_page_nodemask(struct hstate *h,
> +				struct alloc_control *ac);
>  struct page *alloc_huge_page_vma(struct hstate *h, struct vm_area_struct *vma,
>  				unsigned long address);
> -struct page *alloc_migrate_huge_page(struct hstate *h, gfp_t gfp_mask,
> -				     int nid, nodemask_t *nmask);
> +struct page *alloc_huge_page(struct vm_area_struct *vma,
> +				unsigned long addr, int avoid_reserve);
>  int huge_add_to_page_cache(struct page *page, struct address_space *mapping,
>  			pgoff_t idx);
>  
> @@ -752,20 +754,14 @@ static inline void huge_ptep_modify_prot_commit(struct vm_area_struct *vma,
>  #else	/* CONFIG_HUGETLB_PAGE */
>  struct hstate {};
>  
> -static inline struct page *alloc_huge_page(struct vm_area_struct *vma,
> -					   unsigned long addr,
> -					   int avoid_reserve)
> -{
> -	return NULL;
> -}
> -
> -static inline struct page *alloc_huge_page_node(struct hstate *h, int nid)
> +static inline struct page *
> +alloc_huge_page_node(struct hstate *h, struct alloc_control *ac)
>  {
>  	return NULL;
>  }
>  
>  static inline struct page *
> -alloc_huge_page_nodemask(struct hstate *h, int preferred_nid, nodemask_t *nmask)
> +alloc_huge_page_nodemask(struct hstate *h, struct alloc_control *ac)
>  {
>  	return NULL;
>  }
> @@ -777,6 +773,13 @@ static inline struct page *alloc_huge_page_vma(struct hstate *h,
>  	return NULL;
>  }
>  
> +static inline struct page *alloc_huge_page(struct vm_area_struct *vma,
> +					   unsigned long addr,
> +					   int avoid_reserve)
> +{
> +	return NULL;
> +}
> +
>  static inline int __alloc_bootmem_huge_page(struct hstate *h)
>  {
>  	return 0;
> diff --git a/mm/gup.c b/mm/gup.c
> index ee039d4..6b78f11 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -1612,16 +1612,21 @@ static struct page *new_non_cma_page(struct page *page, unsigned long private)
>  	if (PageHighMem(page))
>  		gfp_mask |= __GFP_HIGHMEM;
>  
> -#ifdef CONFIG_HUGETLB_PAGE
>  	if (PageHuge(page)) {
>  		struct hstate *h = page_hstate(page);
> +		struct alloc_control ac = {
> +			.nid = nid,
> +			.nmask = NULL,
> +			.gfp_mask = gfp_mask,
> +		};
> +
>  		/*
>  		 * We don't want to dequeue from the pool because pool pages will
>  		 * mostly be from the CMA region.
>  		 */
> -		return alloc_migrate_huge_page(h, gfp_mask, nid, NULL);
> +		return alloc_migrate_huge_page(h, &ac);
>  	}
> -#endif
> +
>  	if (PageTransHuge(page)) {
>  		struct page *thp;
>  		/*
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 57ece74..453ba94 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1053,8 +1053,8 @@ static struct page *dequeue_huge_page_node_exact(struct hstate *h, int nid)
>  	return page;
>  }
>  
> -static struct page *dequeue_huge_page_nodemask(struct hstate *h, gfp_t gfp_mask, int nid,
> -		nodemask_t *nmask)
> +static struct page *dequeue_huge_page_nodemask(struct hstate *h,
> +				struct alloc_control *ac)
>  {
>  	unsigned int cpuset_mems_cookie;
>  	struct zonelist *zonelist;
> @@ -1062,14 +1062,15 @@ static struct page *dequeue_huge_page_nodemask(struct hstate *h, gfp_t gfp_mask,
>  	struct zoneref *z;
>  	int node = NUMA_NO_NODE;
>  
> -	zonelist = node_zonelist(nid, gfp_mask);
> +	zonelist = node_zonelist(ac->nid, ac->gfp_mask);
>  
>  retry_cpuset:
>  	cpuset_mems_cookie = read_mems_allowed_begin();
> -	for_each_zone_zonelist_nodemask(zone, z, zonelist, gfp_zone(gfp_mask), nmask) {
> +	for_each_zone_zonelist_nodemask(zone, z, zonelist,
> +			gfp_zone(ac->gfp_mask), ac->nmask) {
>  		struct page *page;
>  
> -		if (!cpuset_zone_allowed(zone, gfp_mask))
> +		if (!cpuset_zone_allowed(zone, ac->gfp_mask))
>  			continue;
>  		/*
>  		 * no need to ask again on the same node. Pool is node rather than
> @@ -1105,9 +1106,7 @@ static struct page *dequeue_huge_page_vma(struct hstate *h,
>  {
>  	struct page *page;
>  	struct mempolicy *mpol;
> -	gfp_t gfp_mask;
> -	nodemask_t *nodemask;
> -	int nid;
> +	struct alloc_control ac = {0};
>  
>  	/*
>  	 * A child process with MAP_PRIVATE mappings created by their parent
> @@ -1122,9 +1121,10 @@ static struct page *dequeue_huge_page_vma(struct hstate *h,
>  	if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
>  		goto err;
>  
> -	gfp_mask = htlb_alloc_mask(h);
> -	nid = huge_node(vma, address, gfp_mask, &mpol, &nodemask);
> -	page = dequeue_huge_page_nodemask(h, gfp_mask, nid, nodemask);
> +	ac.gfp_mask = htlb_alloc_mask(h);
> +	ac.nid = huge_node(vma, address, ac.gfp_mask, &mpol, &ac.nmask);
> +
> +	page = dequeue_huge_page_nodemask(h, &ac);
>  	if (page && !avoid_reserve && vma_has_reserves(vma, chg)) {
>  		SetPagePrivate(page);
>  		h->resv_huge_pages--;
> @@ -1937,15 +1937,16 @@ static struct page *alloc_surplus_huge_page(struct hstate *h, gfp_t gfp_mask,
>  	return page;
>  }
>  
> -struct page *alloc_migrate_huge_page(struct hstate *h, gfp_t gfp_mask,
> -				     int nid, nodemask_t *nmask)
> +struct page *alloc_migrate_huge_page(struct hstate *h,
> +				struct alloc_control *ac)
>  {
>  	struct page *page;
>  
>  	if (hstate_is_gigantic(h))
>  		return NULL;
>  
> -	page = alloc_fresh_huge_page(h, gfp_mask, nid, nmask, NULL);
> +	page = alloc_fresh_huge_page(h, ac->gfp_mask,
> +				ac->nid, ac->nmask, NULL);
>  	if (!page)
>  		return NULL;
>  
> @@ -1979,36 +1980,37 @@ struct page *alloc_buddy_huge_page_with_mpol(struct hstate *h,
>  }
>  
>  /* page migration callback function */
> -struct page *alloc_huge_page_node(struct hstate *h, int nid)
> +struct page *alloc_huge_page_node(struct hstate *h,
> +				struct alloc_control *ac)
>  {
> -	gfp_t gfp_mask = htlb_alloc_mask(h);
>  	struct page *page = NULL;
>  
> -	if (nid != NUMA_NO_NODE)
> -		gfp_mask |= __GFP_THISNODE;
> +	ac->gfp_mask = htlb_alloc_mask(h);
> +	if (ac->nid != NUMA_NO_NODE)
> +		ac->gfp_mask |= __GFP_THISNODE;
>  
>  	spin_lock(&hugetlb_lock);
>  	if (h->free_huge_pages - h->resv_huge_pages > 0)
> -		page = dequeue_huge_page_nodemask(h, gfp_mask, nid, NULL);
> +		page = dequeue_huge_page_nodemask(h, ac);
>  	spin_unlock(&hugetlb_lock);
>  
>  	if (!page)
> -		page = alloc_migrate_huge_page(h, gfp_mask, nid, NULL);
> +		page = alloc_migrate_huge_page(h, ac);
>  
>  	return page;
>  }
>  
>  /* page migration callback function */
> -struct page *alloc_huge_page_nodemask(struct hstate *h, int preferred_nid,
> -		nodemask_t *nmask)
> +struct page *alloc_huge_page_nodemask(struct hstate *h,
> +				struct alloc_control *ac)
>  {
> -	gfp_t gfp_mask = htlb_alloc_mask(h);
> +	ac->gfp_mask = htlb_alloc_mask(h);
>  
>  	spin_lock(&hugetlb_lock);
>  	if (h->free_huge_pages - h->resv_huge_pages > 0) {
>  		struct page *page;
>  
> -		page = dequeue_huge_page_nodemask(h, gfp_mask, preferred_nid, nmask);
> +		page = dequeue_huge_page_nodemask(h, ac);
>  		if (page) {
>  			spin_unlock(&hugetlb_lock);
>  			return page;
> @@ -2016,22 +2018,20 @@ struct page *alloc_huge_page_nodemask(struct hstate *h, int preferred_nid,
>  	}
>  	spin_unlock(&hugetlb_lock);
>  
> -	return alloc_migrate_huge_page(h, gfp_mask, preferred_nid, nmask);
> +	return alloc_migrate_huge_page(h, ac);
>  }
>  
>  /* mempolicy aware migration callback */
>  struct page *alloc_huge_page_vma(struct hstate *h, struct vm_area_struct *vma,
>  		unsigned long address)
>  {
> +	struct alloc_control ac = {0};
>  	struct mempolicy *mpol;
> -	nodemask_t *nodemask;
>  	struct page *page;
> -	gfp_t gfp_mask;
> -	int node;
>  
> -	gfp_mask = htlb_alloc_mask(h);
> -	node = huge_node(vma, address, gfp_mask, &mpol, &nodemask);
> -	page = alloc_huge_page_nodemask(h, node, nodemask);
> +	ac.gfp_mask = htlb_alloc_mask(h);
> +	ac.nid = huge_node(vma, address, ac.gfp_mask, &mpol, &ac.nmask);
> +	page = alloc_huge_page_nodemask(h, &ac);
>  	mpol_cond_put(mpol);
>  
>  	return page;
> diff --git a/mm/internal.h b/mm/internal.h
> index 9886db2..6e613ce 100644
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -613,4 +613,11 @@ static inline bool is_migrate_highatomic_page(struct page *page)
>  
>  void setup_zone_pageset(struct zone *zone);
>  extern struct page *alloc_new_node_page(struct page *page, unsigned long node);
> +
> +struct alloc_control {
> +	int nid;		/* preferred node id */
> +	nodemask_t *nmask;
> +	gfp_t gfp_mask;
> +};
> +
>  #endif	/* __MM_INTERNAL_H */
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index 3813206..3b6b551 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -1068,10 +1068,15 @@ static int migrate_page_add(struct page *page, struct list_head *pagelist,
>  /* page allocation callback for NUMA node migration */
>  struct page *alloc_new_node_page(struct page *page, unsigned long node)
>  {
> -	if (PageHuge(page))
> -		return alloc_huge_page_node(page_hstate(compound_head(page)),
> -					node);
> -	else if (PageTransHuge(page)) {
> +	if (PageHuge(page)) {
> +		struct hstate *h = page_hstate(compound_head(page));
> +		struct alloc_control ac = {
> +			.nid = node,
> +			.nmask = NULL,
> +		};
> +
> +		return alloc_huge_page_node(h, &ac);
> +	} else if (PageTransHuge(page)) {
>  		struct page *thp;
>  
>  		thp = alloc_pages_node(node,
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 824c22e..30217537 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1544,10 +1544,15 @@ struct page *new_page_nodemask(struct page *page,
>  	unsigned int order = 0;
>  	struct page *new_page = NULL;
>  
> -	if (PageHuge(page))
> -		return alloc_huge_page_nodemask(
> -				page_hstate(compound_head(page)),
> -				preferred_nid, nodemask);
> +	if (PageHuge(page)) {
> +		struct hstate *h = page_hstate(compound_head(page));
> +		struct alloc_control ac = {
> +			.nid = preferred_nid,
> +			.nmask = nodemask,
> +		};
> +
> +		return alloc_huge_page_nodemask(h, &ac);
> +	}
>  
>  	if (PageTransHuge(page)) {
>  		gfp_mask |= GFP_TRANSHUGE;
> -- 
> 2.7.4
> 

-- 
Michal Hocko
SUSE Labs

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