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authorAnshuman Khandual <anshuman.khandual@arm.com>2019-03-05 15:43:44 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2019-03-05 21:07:15 -0800
commit7ed2c31dabdeb3ee6abe8ff5aac7287821a50cba (patch)
treecfffb48c12e040b52e9fd56993f47091156073a7
parent6b7e5cad651a2b1031a4c69a98f87e3532dd4cef (diff)
downloadlinux-7ed2c31dabdeb3ee6abe8ff5aac7287821a50cba.tar.bz2
mm/hugetlb: distinguish between migratability and movability
Patch series "arm64/mm: Enable HugeTLB migration", v4. This patch series enables HugeTLB migration support for all supported huge page sizes at all levels including contiguous bit implementation. Following HugeTLB migration support matrix has been enabled with this patch series. All permutations have been tested except for the 16GB. CONT PTE PMD CONT PMD PUD -------- --- -------- --- 4K: 64K 2M 32M 1G 16K: 2M 32M 1G 64K: 2M 512M 16G First the series adds migration support for PUD based huge pages. It then adds a platform specific hook to query an architecture if a given huge page size is supported for migration while also providing a default fallback option preserving the existing semantics which just checks for (PMD|PUD|PGDIR)_SHIFT macros. The last two patches enables HugeTLB migration on arm64 and subscribe to this new platform specific hook by defining an override. The second patch differentiates between movability and migratability aspects of huge pages and implements hugepage_movable_supported() which can then be used during allocation to decide whether to place the huge page in movable zone or not. This patch (of 5): During huge page allocation it's migratability is checked to determine if it should be placed under movable zones with GFP_HIGHUSER_MOVABLE. But the movability aspect of the huge page could depend on other factors than just migratability. Movability in itself is a distinct property which should not be tied with migratability alone. This differentiates these two and implements an enhanced movability check which also considers huge page size to determine if it is feasible to be placed under a movable zone. At present it just checks for gigantic pages but going forward it can incorporate other enhanced checks. Link: http://lkml.kernel.org/r/1545121450-1663-2-git-send-email-anshuman.khandual@arm.com Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> Reviewed-by: Steve Capper <steve.capper@arm.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Suggested-by: Michal Hocko <mhocko@kernel.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/hugetlb.h30
-rw-r--r--mm/hugetlb.c2
-rw-r--r--mm/migrate.c2
3 files changed, 32 insertions, 2 deletions
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 087fd5f48c91..1b858d795731 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -506,6 +506,31 @@ static inline bool hugepage_migration_supported(struct hstate *h)
#endif
}
+/*
+ * Movability check is different as compared to migration check.
+ * It determines whether or not a huge page should be placed on
+ * movable zone or not. Movability of any huge page should be
+ * required only if huge page size is supported for migration.
+ * There wont be any reason for the huge page to be movable if
+ * it is not migratable to start with. Also the size of the huge
+ * page should be large enough to be placed under a movable zone
+ * and still feasible enough to be migratable. Just the presence
+ * in movable zone does not make the migration feasible.
+ *
+ * So even though large huge page sizes like the gigantic ones
+ * are migratable they should not be movable because its not
+ * feasible to migrate them from movable zone.
+ */
+static inline bool hugepage_movable_supported(struct hstate *h)
+{
+ if (!hugepage_migration_supported(h))
+ return false;
+
+ if (hstate_is_gigantic(h))
+ return false;
+ return true;
+}
+
static inline spinlock_t *huge_pte_lockptr(struct hstate *h,
struct mm_struct *mm, pte_t *pte)
{
@@ -602,6 +627,11 @@ static inline bool hugepage_migration_supported(struct hstate *h)
return false;
}
+static inline bool hugepage_movable_supported(struct hstate *h)
+{
+ return false;
+}
+
static inline spinlock_t *huge_pte_lockptr(struct hstate *h,
struct mm_struct *mm, pte_t *pte)
{
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 3c504fa6b460..2fb3062a3595 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -920,7 +920,7 @@ retry_cpuset:
/* Movability of hugepages depends on migration support. */
static inline gfp_t htlb_alloc_mask(struct hstate *h)
{
- if (hugepage_migration_supported(h))
+ if (hugepage_movable_supported(h))
return GFP_HIGHUSER_MOVABLE;
else
return GFP_HIGHUSER;
diff --git a/mm/migrate.c b/mm/migrate.c
index 181f5d2718a9..0413596fc523 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1287,7 +1287,7 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
struct anon_vma *anon_vma = NULL;
/*
- * Movability of hugepages depends on architectures and hugepage size.
+ * Migratability of hugepages depends on architectures and their size.
* This check is necessary because some callers of hugepage migration
* like soft offline and memory hotremove don't walk through page
* tables or check whether the hugepage is pmd-based or not before