[3/4] mm/hugetlb: make hugetlb migration callback CMA aware
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Message ID 1594789529-6206-3-git-send-email-iamjoonsoo.kim@lge.com
State New
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Series
  • [1/4] mm/page_alloc: fix non cma alloc context
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Commit Message

Joonsoo Kim July 15, 2020, 5:05 a.m. UTC
From: Joonsoo Kim <iamjoonsoo.kim@lge.com>

new_non_cma_page() in gup.c requires to allocate the new page that is not
on the CMA area. new_non_cma_page() implements it by using allocation
scope APIs.

However, there is a work-around for hugetlb. Normal hugetlb page
allocation API for migration is alloc_huge_page_nodemask(). It consists
of two steps. First is dequeing from the pool. Second is, if there is no
available page on the queue, allocating by using the page allocator.

new_non_cma_page() can't use this API since first step (deque) isn't
aware of scope API to exclude CMA area. So, new_non_cma_page() exports
hugetlb internal function for the second step, alloc_migrate_huge_page(),
to global scope and uses it directly. This is suboptimal since hugetlb
pages on the queue cannot be utilized.

This patch tries to fix this situation by making the deque function on
hugetlb CMA aware. In the deque function, CMA memory is skipped if
PF_MEMALLOC_NOCMA flag is found.

Acked-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
---
 include/linux/hugetlb.h |  2 --
 mm/gup.c                |  6 +-----
 mm/hugetlb.c            | 11 +++++++++--
 3 files changed, 10 insertions(+), 9 deletions(-)

Comments

Michal Hocko July 15, 2020, 8:33 a.m. UTC | #1
On Wed 15-07-20 14:05:28, Joonsoo Kim wrote:
> From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> 
> new_non_cma_page() in gup.c requires to allocate the new page that is not
> on the CMA area. new_non_cma_page() implements it by using allocation
> scope APIs.
> 
> However, there is a work-around for hugetlb. Normal hugetlb page
> allocation API for migration is alloc_huge_page_nodemask(). It consists
> of two steps. First is dequeing from the pool. Second is, if there is no
> available page on the queue, allocating by using the page allocator.
> 
> new_non_cma_page() can't use this API since first step (deque) isn't
> aware of scope API to exclude CMA area. So, new_non_cma_page() exports
> hugetlb internal function for the second step, alloc_migrate_huge_page(),
> to global scope and uses it directly. This is suboptimal since hugetlb
> pages on the queue cannot be utilized.
> 
> This patch tries to fix this situation by making the deque function on
> hugetlb CMA aware. In the deque function, CMA memory is skipped if
> PF_MEMALLOC_NOCMA flag is found.

Now that this is in sync with the global case I do not have any
objections.

> Acked-by: Mike Kravetz <mike.kravetz@oracle.com>
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>

Acked-by: Michal Hocko <mhocko@suse.com>

Minor nit below

[...]
> @@ -1036,10 +1037,16 @@ static void enqueue_huge_page(struct hstate *h, struct page *page)
>  static struct page *dequeue_huge_page_node_exact(struct hstate *h, int nid)
>  {
>  	struct page *page;
> +	bool nocma = !!(READ_ONCE(current->flags) & PF_MEMALLOC_NOCMA);

READ_ONCE is not really needed because current->flags are always set on
the current so no race is possible.

> +
> +	list_for_each_entry(page, &h->hugepage_freelists[nid], lru) {
> +		if (nocma && is_migrate_cma_page(page))
> +			continue;
>  
> -	list_for_each_entry(page, &h->hugepage_freelists[nid], lru)
>  		if (!PageHWPoison(page))
>  			break;
> +	}
> +
>  	/*
>  	 * if 'non-isolated free hugepage' not found on the list,
>  	 * the allocation fails.
> @@ -1928,7 +1935,7 @@ 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,
> +static struct page *alloc_migrate_huge_page(struct hstate *h, gfp_t gfp_mask,
>  				     int nid, nodemask_t *nmask)
>  {
>  	struct page *page;
> -- 
> 2.7.4
Vlastimil Babka July 15, 2020, 9:51 a.m. UTC | #2
On 7/15/20 7:05 AM, js1304@gmail.com wrote:
> From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> 
> new_non_cma_page() in gup.c requires to allocate the new page that is not
> on the CMA area. new_non_cma_page() implements it by using allocation
> scope APIs.
> 
> However, there is a work-around for hugetlb. Normal hugetlb page
> allocation API for migration is alloc_huge_page_nodemask(). It consists
> of two steps. First is dequeing from the pool. Second is, if there is no
> available page on the queue, allocating by using the page allocator.
> 
> new_non_cma_page() can't use this API since first step (deque) isn't
> aware of scope API to exclude CMA area. So, new_non_cma_page() exports
> hugetlb internal function for the second step, alloc_migrate_huge_page(),
> to global scope and uses it directly. This is suboptimal since hugetlb
> pages on the queue cannot be utilized.
> 
> This patch tries to fix this situation by making the deque function on
> hugetlb CMA aware. In the deque function, CMA memory is skipped if
> PF_MEMALLOC_NOCMA flag is found.
> 
> Acked-by: Mike Kravetz <mike.kravetz@oracle.com>
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>

Acked-by: Vlastimil Babka <vbabka@suse.cz>

Patch
diff mbox series

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 2660b04..fb2b5aa 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -509,8 +509,6 @@  struct page *alloc_huge_page_nodemask(struct hstate *h, int preferred_nid,
 				nodemask_t *nmask, gfp_t gfp_mask);
 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);
 int huge_add_to_page_cache(struct page *page, struct address_space *mapping,
 			pgoff_t idx);
 
diff --git a/mm/gup.c b/mm/gup.c
index bbd36a1..4ba822a 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1634,11 +1634,7 @@  static struct page *new_non_cma_page(struct page *page, unsigned long private)
 		struct hstate *h = page_hstate(page);
 
 		gfp_mask = htlb_modify_alloc_mask(h, 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_huge_page_nodemask(h, nid, NULL, gfp_mask);
 	}
 #endif
 	if (PageTransHuge(page)) {
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 3245aa0..514e29c 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -29,6 +29,7 @@ 
 #include <linux/numa.h>
 #include <linux/llist.h>
 #include <linux/cma.h>
+#include <linux/sched/mm.h>
 
 #include <asm/page.h>
 #include <asm/tlb.h>
@@ -1036,10 +1037,16 @@  static void enqueue_huge_page(struct hstate *h, struct page *page)
 static struct page *dequeue_huge_page_node_exact(struct hstate *h, int nid)
 {
 	struct page *page;
+	bool nocma = !!(READ_ONCE(current->flags) & PF_MEMALLOC_NOCMA);
+
+	list_for_each_entry(page, &h->hugepage_freelists[nid], lru) {
+		if (nocma && is_migrate_cma_page(page))
+			continue;
 
-	list_for_each_entry(page, &h->hugepage_freelists[nid], lru)
 		if (!PageHWPoison(page))
 			break;
+	}
+
 	/*
 	 * if 'non-isolated free hugepage' not found on the list,
 	 * the allocation fails.
@@ -1928,7 +1935,7 @@  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,
+static struct page *alloc_migrate_huge_page(struct hstate *h, gfp_t gfp_mask,
 				     int nid, nodemask_t *nmask)
 {
 	struct page *page;