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SubjectRe: [PATCH 1/2] mm, thp: introduce dedicated transparent huge page allocation interfaces
[CC Kirill]

On Mon 16-10-17 17:19:16, changbin.du@intel.com wrote:
> From: Changbin Du <changbin.du@intel.com>
>
> This patch introduced 4 new interfaces to allocate a prepared
> transparent huge page.
> - alloc_transhuge_page_vma
> - alloc_transhuge_page_nodemask
> - alloc_transhuge_page_node
> - alloc_transhuge_page
>
> The aim is to remove duplicated code and simplify transparent
> huge page allocation. These are similar to alloc_hugepage_xxx
> which are for hugetlbfs pages. This patch does below changes:
> - define alloc_transhuge_page_xxx interfaces
> - apply them to all existing code
> - declare prep_transhuge_page as static since no others use it
> - remove alloc_hugepage_vma definition since it no longer has users

So what exactly is the advantage of the new API? The diffstat doesn't
sound very convincing to me.

> Signed-off-by: Changbin Du <changbin.du@intel.com>
> ---
> include/linux/gfp.h | 4 ----
> include/linux/huge_mm.h | 13 ++++++++++++-
> include/linux/migrate.h | 14 +++++---------
> mm/huge_memory.c | 50 ++++++++++++++++++++++++++++++++++++++++++-------
> mm/khugepaged.c | 11 ++---------
> mm/mempolicy.c | 10 +++-------
> mm/migrate.c | 12 ++++--------
> mm/shmem.c | 6 ++----
> 8 files changed, 71 insertions(+), 49 deletions(-)
>
> diff --git a/include/linux/gfp.h b/include/linux/gfp.h
> index f780718..855c72e 100644
> --- a/include/linux/gfp.h
> +++ b/include/linux/gfp.h
> @@ -507,15 +507,11 @@ alloc_pages(gfp_t gfp_mask, unsigned int order)
> extern struct page *alloc_pages_vma(gfp_t gfp_mask, int order,
> struct vm_area_struct *vma, unsigned long addr,
> int node, bool hugepage);
> -#define alloc_hugepage_vma(gfp_mask, vma, addr, order) \
> - alloc_pages_vma(gfp_mask, order, vma, addr, numa_node_id(), true)
> #else
> #define alloc_pages(gfp_mask, order) \
> alloc_pages_node(numa_node_id(), gfp_mask, order)
> #define alloc_pages_vma(gfp_mask, order, vma, addr, node, false)\
> alloc_pages(gfp_mask, order)
> -#define alloc_hugepage_vma(gfp_mask, vma, addr, order) \
> - alloc_pages(gfp_mask, order)
> #endif
> #define alloc_page(gfp_mask) alloc_pages(gfp_mask, 0)
> #define alloc_page_vma(gfp_mask, vma, addr) \
> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
> index 14bc21c..1dd2c33 100644
> --- a/include/linux/huge_mm.h
> +++ b/include/linux/huge_mm.h
> @@ -130,9 +130,20 @@ extern unsigned long thp_get_unmapped_area(struct file *filp,
> unsigned long addr, unsigned long len, unsigned long pgoff,
> unsigned long flags);
>
> -extern void prep_transhuge_page(struct page *page);
> extern void free_transhuge_page(struct page *page);
>
> +struct page *alloc_transhuge_page_vma(gfp_t gfp_mask,
> + struct vm_area_struct *vma, unsigned long addr);
> +struct page *alloc_transhuge_page_nodemask(gfp_t gfp_mask,
> + int preferred_nid, nodemask_t *nmask);
> +
> +static inline struct page *alloc_transhuge_page_node(int nid, gfp_t gfp_mask)
> +{
> + return alloc_transhuge_page_nodemask(gfp_mask, nid, NULL);
> +}
> +
> +struct page *alloc_transhuge_page(gfp_t gfp_mask);
> +
> bool can_split_huge_page(struct page *page, int *pextra_pins);
> int split_huge_page_to_list(struct page *page, struct list_head *list);
> static inline int split_huge_page(struct page *page)
> diff --git a/include/linux/migrate.h b/include/linux/migrate.h
> index 643c7ae..70a00f3 100644
> --- a/include/linux/migrate.h
> +++ b/include/linux/migrate.h
> @@ -42,19 +42,15 @@ static inline struct page *new_page_nodemask(struct page *page,
> return alloc_huge_page_nodemask(page_hstate(compound_head(page)),
> preferred_nid, nodemask);
>
> - if (thp_migration_supported() && PageTransHuge(page)) {
> - order = HPAGE_PMD_ORDER;
> - gfp_mask |= GFP_TRANSHUGE;
> - }
> -
> if (PageHighMem(page) || (zone_idx(page_zone(page)) == ZONE_MOVABLE))
> gfp_mask |= __GFP_HIGHMEM;
>
> - new_page = __alloc_pages_nodemask(gfp_mask, order,
> + if (thp_migration_supported() && PageTransHuge(page))
> + return alloc_transhuge_page_nodemask(gfp_mask | GFP_TRANSHUGE,
> + preferred_nid, nodemask);
> + else
> + return __alloc_pages_nodemask(gfp_mask, order,
> preferred_nid, nodemask);
> -
> - if (new_page && PageTransHuge(page))
> - prep_transhuge_page(new_page);
>
> return new_page;
> }
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 269b5df..e267488 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -490,7 +490,7 @@ static inline struct list_head *page_deferred_list(struct page *page)
> return (struct list_head *)&page[2].mapping;
> }
>
> -void prep_transhuge_page(struct page *page)
> +static void prep_transhuge_page(struct page *page)
> {
> /*
> * we use page->mapping and page->indexlru in second tail page
> @@ -501,6 +501,45 @@ void prep_transhuge_page(struct page *page)
> set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
> }
>
> +struct page *alloc_transhuge_page_vma(gfp_t gfp_mask,
> + struct vm_area_struct *vma, unsigned long addr)
> +{
> + struct page *page;
> +
> + page = alloc_pages_vma(gfp_mask | __GFP_COMP, HPAGE_PMD_ORDER,
> + vma, addr, numa_node_id(), true);
> + if (unlikely(!page))
> + return NULL;
> + prep_transhuge_page(page);
> + return page;
> +}
> +
> +struct page *alloc_transhuge_page_nodemask(gfp_t gfp_mask,
> + int preferred_nid, nodemask_t *nmask)
> +{
> + struct page *page;
> +
> + page = __alloc_pages_nodemask(gfp_mask | __GFP_COMP, HPAGE_PMD_ORDER,
> + preferred_nid, nmask);
> + if (unlikely(!page))
> + return NULL;
> + prep_transhuge_page(page);
> + return page;
> +}
> +
> +struct page *alloc_transhuge_page(gfp_t gfp_mask)
> +{
> + struct page *page;
> +
> + VM_BUG_ON(!(gfp_mask & __GFP_COMP));
> +
> + page = alloc_pages(gfp_mask | __GFP_COMP, HPAGE_PMD_ORDER);
> + if (unlikely(!page))
> + return NULL;
> + prep_transhuge_page(page);
> + return page;
> +}
> +
> unsigned long __thp_get_unmapped_area(struct file *filp, unsigned long len,
> loff_t off, unsigned long flags, unsigned long size)
> {
> @@ -719,12 +758,11 @@ int do_huge_pmd_anonymous_page(struct vm_fault *vmf)
> return ret;
> }
> gfp = alloc_hugepage_direct_gfpmask(vma);
> - page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
> + page = alloc_transhuge_page_vma(gfp, vma, haddr);
> if (unlikely(!page)) {
> count_vm_event(THP_FAULT_FALLBACK);
> return VM_FAULT_FALLBACK;
> }
> - prep_transhuge_page(page);
> return __do_huge_pmd_anonymous_page(vmf, page, gfp);
> }
>
> @@ -1288,13 +1326,11 @@ int do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd)
> if (transparent_hugepage_enabled(vma) &&
> !transparent_hugepage_debug_cow()) {
> huge_gfp = alloc_hugepage_direct_gfpmask(vma);
> - new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER);
> + new_page = alloc_transhuge_page_vma(huge_gfp, vma, haddr);
> } else
> new_page = NULL;
>
> - if (likely(new_page)) {
> - prep_transhuge_page(new_page);
> - } else {
> + if (unlikely(!new_page)) {
> if (!page) {
> split_huge_pmd(vma, vmf->pmd, vmf->address);
> ret |= VM_FAULT_FALLBACK;
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index c01f177..d17a694 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -745,14 +745,13 @@ khugepaged_alloc_page(struct page **hpage, gfp_t gfp, int node)
> {
> VM_BUG_ON_PAGE(*hpage, *hpage);
>
> - *hpage = __alloc_pages_node(node, gfp, HPAGE_PMD_ORDER);
> + *hpage = alloc_transhuge_page_node(node, gfp);
> if (unlikely(!*hpage)) {
> count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
> *hpage = ERR_PTR(-ENOMEM);
> return NULL;
> }
>
> - prep_transhuge_page(*hpage);
> count_vm_event(THP_COLLAPSE_ALLOC);
> return *hpage;
> }
> @@ -764,13 +763,7 @@ static int khugepaged_find_target_node(void)
>
> static inline struct page *alloc_khugepaged_hugepage(void)
> {
> - struct page *page;
> -
> - page = alloc_pages(alloc_hugepage_khugepaged_gfpmask(),
> - HPAGE_PMD_ORDER);
> - if (page)
> - prep_transhuge_page(page);
> - return page;
> + return alloc_transhuge_page(alloc_hugepage_khugepaged_gfpmask());
> }
>
> static struct page *khugepaged_alloc_hugepage(bool *wait)
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index a2af6d5..aa24285 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -949,12 +949,10 @@ static struct page *new_node_page(struct page *page, unsigned long node, int **x
> else if (thp_migration_supported() && PageTransHuge(page)) {
> struct page *thp;
>
> - thp = alloc_pages_node(node,
> - (GFP_TRANSHUGE | __GFP_THISNODE),
> - HPAGE_PMD_ORDER);
> + thp = alloc_transhuge_page_node(node,
> + (GFP_TRANSHUGE | __GFP_THISNODE));
> if (!thp)
> return NULL;
> - prep_transhuge_page(thp);
> return thp;
> } else
> return __alloc_pages_node(node, GFP_HIGHUSER_MOVABLE |
> @@ -1125,11 +1123,9 @@ static struct page *new_page(struct page *page, unsigned long start, int **x)
> } else if (thp_migration_supported() && PageTransHuge(page)) {
> struct page *thp;
>
> - thp = alloc_hugepage_vma(GFP_TRANSHUGE, vma, address,
> - HPAGE_PMD_ORDER);
> + thp = alloc_transhuge_page_vma(GFP_TRANSHUGE, vma, address);
> if (!thp)
> return NULL;
> - prep_transhuge_page(thp);
> return thp;
> }
> /*
> diff --git a/mm/migrate.c b/mm/migrate.c
> index e00814c..7f0486f 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1472,12 +1472,10 @@ static struct page *new_page_node(struct page *p, unsigned long private,
> else if (thp_migration_supported() && PageTransHuge(p)) {
> struct page *thp;
>
> - thp = alloc_pages_node(pm->node,
> - (GFP_TRANSHUGE | __GFP_THISNODE) & ~__GFP_RECLAIM,
> - HPAGE_PMD_ORDER);
> + thp = alloc_transhuge_page_node(pm->node,
> + (GFP_TRANSHUGE | __GFP_THISNODE) & ~__GFP_RECLAIM);
> if (!thp)
> return NULL;
> - prep_transhuge_page(thp);
> return thp;
> } else
> return __alloc_pages_node(pm->node,
> @@ -2017,12 +2015,10 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm,
> if (numamigrate_update_ratelimit(pgdat, HPAGE_PMD_NR))
> goto out_dropref;
>
> - new_page = alloc_pages_node(node,
> - (GFP_TRANSHUGE_LIGHT | __GFP_THISNODE),
> - HPAGE_PMD_ORDER);
> + new_page = alloc_transhuge_page_node(node,
> + (GFP_TRANSHUGE_LIGHT | __GFP_THISNODE));
> if (!new_page)
> goto out_fail;
> - prep_transhuge_page(new_page);
>
> isolated = numamigrate_isolate_page(pgdat, page);
> if (!isolated) {
> diff --git a/mm/shmem.c b/mm/shmem.c
> index 07a1d22..52468f7 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -1444,11 +1444,9 @@ static struct page *shmem_alloc_hugepage(gfp_t gfp,
> rcu_read_unlock();
>
> shmem_pseudo_vma_init(&pvma, info, hindex);
> - page = alloc_pages_vma(gfp | __GFP_COMP | __GFP_NORETRY | __GFP_NOWARN,
> - HPAGE_PMD_ORDER, &pvma, 0, numa_node_id(), true);
> + gfp |= __GFP_COMP | __GFP_NORETRY | __GFP_NOWARN;
> + page = alloc_transhuge_page_vma(gfp, &pvma, 0);
> shmem_pseudo_vma_destroy(&pvma);
> - if (page)
> - prep_transhuge_page(page);
> return page;
> }
>
> --
> 2.7.4
>
> --
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--
Michal Hocko
SUSE Labs

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