[PATCH v6 07/14] mm: honor PF_MEMALLOC_PIN for all movable pages

Pavel Tatashin
2021-01-20T01:43:53Z

PF_MEMALLOC_PIN is only honored for CMA pages, extend
this flag to work for any allocations from ZONE_MOVABLE by removing
__GFP_MOVABLE from gfp_mask when this flag is passed in the current
context.

Add is_pinnable_page() to return true if page is in a pinnable page.
A pinnable page is not in ZONE_MOVABLE and not of MIGRATE_CMA type.

Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Acked-by: Michal Hocko <mhocko@suse.com>
---
include/linux/mm.h | 11 +++++++++++
include/linux/sched/mm.h | 6 +++++-
mm/hugetlb.c | 2 +-
mm/page_alloc.c | 20 +++++++++-----------
4 files changed, 26 insertions(+), 13 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index a5d618d08506..0990a76d5e6f 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1117,6 +1117,17 @@ static inline bool is_zone_device_page(const struct page *page)
}
#endif

+static inline bool is_zone_movable_page(const struct page *page)
+{
+ return page_zonenum(page) == ZONE_MOVABLE;
+}
+
+/* MIGRATE_CMA and ZONE_MOVABLE do not allow pin pages */
+static inline bool is_pinnable_page(struct page *page)
+{
+ return !is_zone_movable_page(page) && !is_migrate_cma_page(page);
+}
+
#ifdef CONFIG_DEV_PAGEMAP_OPS
void free_devmap_managed_page(struct page *page);
DECLARE_STATIC_KEY_FALSE(devmap_managed_key);
diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index 5f4dd3274734..a55277b0d475 100644
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -150,12 +150,13 @@ static inline bool in_vfork(struct task_struct *tsk)
* Applies per-task gfp context to the given allocation flags.
* PF_MEMALLOC_NOIO implies GFP_NOIO
* PF_MEMALLOC_NOFS implies GFP_NOFS
+ * PF_MEMALLOC_PIN implies !GFP_MOVABLE
*/
static inline gfp_t current_gfp_context(gfp_t flags)
{
unsigned int pflags = READ_ONCE(current->flags);

- if (unlikely(pflags & (PF_MEMALLOC_NOIO | PF_MEMALLOC_NOFS))) {
+ if (unlikely(pflags & (PF_MEMALLOC_NOIO | PF_MEMALLOC_NOFS | PF_MEMALLOC_PIN))) {
/*
* NOIO implies both NOIO and NOFS and it is a weaker context
* so always make sure it makes precedence
@@ -164,6 +165,9 @@ static inline gfp_t current_gfp_context(gfp_t flags)
flags &= ~(__GFP_IO | __GFP_FS);
else if (pflags & PF_MEMALLOC_NOFS)
flags &= ~__GFP_FS;
+
+ if (pflags & PF_MEMALLOC_PIN)
+ flags &= ~__GFP_MOVABLE;
}
return flags;
}
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 006eccfa23d7..7613c4718d24 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1052,7 +1052,7 @@ static struct page *dequeue_huge_page_node_exact(struct hstate *h, int nid)
bool pin = !!(current->flags & PF_MEMALLOC_PIN);

list_for_each_entry(page, &h->hugepage_freelists[nid], lru) {
- if (pin && is_migrate_cma_page(page))
+ if (pin && !is_pinnable_page(page))
continue;

if (PageHWPoison(page))
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index de9bcd08d002..4dcee3bfd2fe 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3805,16 +3805,13 @@ alloc_flags_nofragment(struct zone *zone, gfp_t gfp_mask)
return alloc_flags;
}

-static inline unsigned int current_alloc_flags(gfp_t gfp_mask,
- unsigned int alloc_flags)
+/* Must be called after current_gfp_context() which can change gfp_mask */
+static inline unsigned int gpf_to_alloc_flags(gfp_t gfp_mask,
+ unsigned int alloc_flags)
{
#ifdef CONFIG_CMA
- unsigned int pflags = current->flags;
-
- if (!(pflags & PF_MEMALLOC_PIN) &&
- gfp_migratetype(gfp_mask) == MIGRATE_MOVABLE)
+ if (gfp_migratetype(gfp_mask) == MIGRATE_MOVABLE)
alloc_flags |= ALLOC_CMA;
-
#endif
return alloc_flags;
}
@@ -4470,7 +4467,7 @@ gfp_to_alloc_flags(gfp_t gfp_mask)
} else if (unlikely(rt_task(current)) && !in_interrupt())
alloc_flags |= ALLOC_HARDER;

- alloc_flags = current_alloc_flags(gfp_mask, alloc_flags);
+ alloc_flags = gpf_to_alloc_flags(gfp_mask, alloc_flags);

return alloc_flags;
}
@@ -4772,7 +4769,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,

reserve_flags = __gfp_pfmemalloc_flags(gfp_mask);
if (reserve_flags)
- alloc_flags = current_alloc_flags(gfp_mask, reserve_flags);
+ alloc_flags = gpf_to_alloc_flags(gfp_mask, reserve_flags);

/*
* Reset the nodemask and zonelist iterators if memory policies can be
@@ -4941,7 +4938,7 @@ static inline bool prepare_alloc_pages(gfp_t gfp_mask, unsigned int order,
if (should_fail_alloc_page(gfp_mask, order))
return false;

- *alloc_flags = current_alloc_flags(gfp_mask, *alloc_flags);
+ *alloc_flags = gpf_to_alloc_flags(gfp_mask, *alloc_flags);

/* Dirty zone balancing only done in the fast path */
ac->spread_dirty_pages = (gfp_mask & __GFP_WRITE);
@@ -4983,7 +4980,8 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, int preferred_nid,
* Apply scoped allocation constraints. This is mainly about GFP_NOFS
* resp. GFP_NOIO which has to be inherited for all allocation requests
* from a particular context which has been marked by
- * memalloc_no{fs,io}_{save,restore}.
+ * memalloc_no{fs,io}_{save,restore}. And PF_MEMALLOC_PIN which ensures
+ * movable zones are not used during allocation.
*/
gfp_mask = current_gfp_context(gfp_mask);
alloc_mask = gfp_mask;
--
2.25.1