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Subject[PATCH v3] mm, thp: introduce generic transparent huge page allocation interfaces
Date
From: Changbin Du <changbin.du@intel.com>

This patch introduced 4 new interfaces to allocate a prepared transparent
huge page. These interfaces merge distributed two-step allocation as simple
single step. And they can avoid issue like forget to call prep_transhuge_page()
or call it on wrong page. A real fix:
40a899e ("mm: migrate: fix an incorrect call of prep_transhuge_page()")

Anyway, I just want to prove that expose direct allocation interfaces is
better than a interface only do the second part of it.

These are similar to alloc_hugepage_xxx which are for hugetlbfs pages. New
interfaces are:
- alloc_transhuge_page_vma
- alloc_transhuge_page_nodemask
- alloc_transhuge_page_node
- alloc_transhuge_page

These interfaces implicitly add __GFP_COMP gfp mask which is the minimum
flags used for huge page allocation. More flags leave to the callers.

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

Signed-off-by: Changbin Du <changbin.du@intel.com>

---
V3:
- Rebase to latest mainline.

v2:
Anshuman Khandu:
- Remove redundant 'VM_BUG_ON(!(gfp_mask & __GFP_COMP))'.
Andrew Morton:
- Fix build error if thp is disabled.
---
include/linux/gfp.h | 4 ----
include/linux/huge_mm.h | 18 ++++++++++++++++--
include/linux/migrate.h | 14 +++++---------
mm/huge_memory.c | 48 +++++++++++++++++++++++++++++++++++++++++-------
mm/khugepaged.c | 11 ++---------
mm/mempolicy.c | 14 +++-----------
mm/migrate.c | 14 ++++----------
mm/shmem.c | 6 ++----
8 files changed, 73 insertions(+), 56 deletions(-)

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 1a4582b..0220cbe 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -494,15 +494,11 @@ 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 a8a1262..211de7e 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -131,9 +131,20 @@ 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);

+extern struct page *alloc_transhuge_page_vma(gfp_t gfp_mask,
+ struct vm_area_struct *vma, unsigned long addr);
+extern 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);
+}
+
+extern 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)
@@ -261,7 +272,10 @@ static inline bool transparent_hugepage_enabled(struct vm_area_struct *vma)
return false;
}

-static inline void prep_transhuge_page(struct page *page) {}
+#define alloc_transhuge_page_vma(gfp_mask, vma, addr) NULL
+#define alloc_transhuge_page_nodemask(gfp_mask, preferred_nid, nmask) NULL
+#define alloc_transhuge_page_node(nid, gfp_maskg) NULL
+#define alloc_transhuge_page(gfp_mask) NULL

#define transparent_hugepage_flags 0UL

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index a2246cf..36c6a5c 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -43,19 +43,15 @@ 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(new_page))
- prep_transhuge_page(new_page);

return new_page;
}
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 2f2f5e7..f287d53 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 +501,43 @@ 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;
+
+ 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 +756,11 @@ 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);
}

@@ -1293,13 +1329,11 @@ 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 ea4ff25..c20d9cd 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -746,14 +746,13 @@ 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;
}
@@ -765,13 +764,7 @@ 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 4ce44d3..67ea208 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -950,12 +950,8 @@ 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);
- if (!thp)
- return NULL;
- prep_transhuge_page(thp);
+ thp = alloc_transhuge_page_node(node,
+ (GFP_TRANSHUGE | __GFP_THISNODE));
return thp;
} else
return __alloc_pages_node(node, GFP_HIGHUSER_MOVABLE |
@@ -1126,11 +1122,7 @@ 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);
- if (!thp)
- return NULL;
- prep_transhuge_page(thp);
+ thp = alloc_transhuge_page_vma(GFP_TRANSHUGE, vma, address);
return thp;
}
/*
diff --git a/mm/migrate.c b/mm/migrate.c
index 4d0be47..aeb6815 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1473,12 +1473,8 @@ 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);
- if (!thp)
- return NULL;
- prep_transhuge_page(thp);
+ thp = alloc_transhuge_page_node(pm->node,
+ (GFP_TRANSHUGE | __GFP_THISNODE) & ~__GFP_RECLAIM);
return thp;
} else
return __alloc_pages_node(pm->node,
@@ -2018,12 +2014,10 @@ 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 7fbe67b..14e9370 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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