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From:   Pavel Tatashin <pasha.tatashin@soleen.com>
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Subject: [PATCH v4 02/10] mm cma: rename PF_MEMALLOC_NOCMA to PF_MEMALLOC_PIN
Date:   Thu, 17 Dec 2020 13:52:35 -0500
Message-Id: <20201217185243.3288048-3-pasha.tatashin@soleen.com>
In-Reply-To: <20201217185243.3288048-1-pasha.tatashin@soleen.com>
References: <20201217185243.3288048-1-pasha.tatashin@soleen.com>
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PF_MEMALLOC_NOCMA is used ot guarantee that the allocator will not return
pages that might belong to CMA region. This is currently used for long
term gup to make sure that such pins are not going to be done on any CMA
pages.

When PF_MEMALLOC_NOCMA has been introduced we haven't realized that it is
focusing on CMA pages too much and that there is larger class of pages that
need the same treatment. MOVABLE zone cannot contain any long term pins as
well so it makes sense to reuse and redefine this flag for that usecase as
well. Rename the flag to PF_MEMALLOC_PIN which defines an allocation
context which can only get pages suitable for long-term pins.

Also re-name:
memalloc_nocma_save()/memalloc_nocma_restore
to
memalloc_pin_save()/memalloc_pin_restore()
and make the new functions common.

Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Acked-by: Michal Hocko <mhocko@suse.com>
---
 include/linux/sched.h    |  2 +-
 include/linux/sched/mm.h | 21 +++++----------------
 mm/gup.c                 |  4 ++--
 mm/hugetlb.c             |  4 ++--
 mm/page_alloc.c          |  4 ++--
 5 files changed, 12 insertions(+), 23 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index e5ad6d354b7b..e30d5511ccc0 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1576,7 +1576,7 @@ extern struct pid *cad_pid;
 #define PF_SWAPWRITE		0x00800000	/* Allowed to write to swap */
 #define PF_NO_SETAFFINITY	0x04000000	/* Userland is not allowed to meddle with cpus_mask */
 #define PF_MCE_EARLY		0x08000000      /* Early kill for mce process policy */
-#define PF_MEMALLOC_NOCMA	0x10000000	/* All allocation request will have _GFP_MOVABLE cleared */
+#define PF_MEMALLOC_PIN		0x10000000	/* Allocation context constrained to zones which allow long term pinning. */
 #define PF_FREEZER_SKIP		0x40000000	/* Freezer should not count it as freezable */
 #define PF_SUSPEND_TASK		0x80000000      /* This thread called freeze_processes() and should not be frozen */
 
diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index 1ae08b8462a4..5f4dd3274734 100644
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -270,29 +270,18 @@ static inline void memalloc_noreclaim_restore(unsigned int flags)
 	current->flags = (current->flags & ~PF_MEMALLOC) | flags;
 }
 
-#ifdef CONFIG_CMA
-static inline unsigned int memalloc_nocma_save(void)
+static inline unsigned int memalloc_pin_save(void)
 {
-	unsigned int flags = current->flags & PF_MEMALLOC_NOCMA;
+	unsigned int flags = current->flags & PF_MEMALLOC_PIN;
 
-	current->flags |= PF_MEMALLOC_NOCMA;
+	current->flags |= PF_MEMALLOC_PIN;
 	return flags;
 }
 
-static inline void memalloc_nocma_restore(unsigned int flags)
+static inline void memalloc_pin_restore(unsigned int flags)
 {
-	current->flags = (current->flags & ~PF_MEMALLOC_NOCMA) | flags;
+	current->flags = (current->flags & ~PF_MEMALLOC_PIN) | flags;
 }
-#else
-static inline unsigned int memalloc_nocma_save(void)
-{
-	return 0;
-}
-
-static inline void memalloc_nocma_restore(unsigned int flags)
-{
-}
-#endif
 
 #ifdef CONFIG_MEMCG
 DECLARE_PER_CPU(struct mem_cgroup *, int_active_memcg);
diff --git a/mm/gup.c b/mm/gup.c
index f2e50cdd7d67..04602e94856b 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1671,7 +1671,7 @@ static long __gup_longterm_locked(struct mm_struct *mm,
 	long rc;
 
 	if (gup_flags & FOLL_LONGTERM)
-		flags = memalloc_nocma_save();
+		flags = memalloc_pin_save();
 
 	rc = __get_user_pages_locked(mm, start, nr_pages, pages, vmas, NULL,
 				     gup_flags);
@@ -1680,7 +1680,7 @@ static long __gup_longterm_locked(struct mm_struct *mm,
 		if (rc > 0)
 			rc = check_and_migrate_cma_pages(mm, start, rc, pages,
 							 vmas, gup_flags);
-		memalloc_nocma_restore(flags);
+		memalloc_pin_restore(flags);
 	}
 	return rc;
 }
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index cbf32d2824fd..3f5ddac5de8a 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1033,10 +1033,10 @@ 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 = !!(current->flags & PF_MEMALLOC_NOCMA);
+	bool pin = !!(current->flags & PF_MEMALLOC_PIN);
 
 	list_for_each_entry(page, &h->hugepage_freelists[nid], lru) {
-		if (nocma && is_migrate_cma_page(page))
+		if (pin && is_migrate_cma_page(page))
 			continue;
 
 		if (PageHWPoison(page))
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 774542e1483e..ec05396a597b 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3808,8 +3808,8 @@ static inline unsigned int current_alloc_flags(gfp_t gfp_mask,
 #ifdef CONFIG_CMA
 	unsigned int pflags = current->flags;
 
-	if (!(pflags & PF_MEMALLOC_NOCMA) &&
-			gfp_migratetype(gfp_mask) == MIGRATE_MOVABLE)
+	if (!(pflags & PF_MEMALLOC_PIN) &&
+	    gfp_migratetype(gfp_mask) == MIGRATE_MOVABLE)
 		alloc_flags |= ALLOC_CMA;
 
 #endif
-- 
2.25.1