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Date: Thu, 17 Dec 2020 13:52:38 -0500
From: Pavel Tatashin <pasha.tatashin@...een.com>
To: pasha.tatashin@...een.com, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, akpm@...ux-foundation.org, vbabka@...e.cz,
mhocko@...e.com, david@...hat.com, osalvador@...e.de,
dan.j.williams@...el.com, sashal@...nel.org,
tyhicks@...ux.microsoft.com, iamjoonsoo.kim@....com,
mike.kravetz@...cle.com, rostedt@...dmis.org, mingo@...hat.com,
jgg@...pe.ca, peterz@...radead.org, mgorman@...e.de,
willy@...radead.org, rientjes@...gle.com, jhubbard@...dia.com,
linux-doc@...r.kernel.org, ira.weiny@...el.com,
linux-kselftest@...r.kernel.org
Subject: [PATCH v4 05/10] mm/gup: migrate pinned pages out of movable zone
We should not pin pages in ZONE_MOVABLE. Currently, we do not pin only
movable CMA pages. Generalize the function that migrates CMA pages to
migrate all movable pages. Use is_pinnable_page() to check which
pages need to be migrated
Signed-off-by: Pavel Tatashin <pasha.tatashin@...een.com>
Reviewed-by: John Hubbard <jhubbard@...dia.com>
---
include/linux/migrate.h | 1 +
include/linux/mmzone.h | 11 ++++--
include/trace/events/migrate.h | 3 +-
mm/gup.c | 68 ++++++++++++++--------------------
4 files changed, 39 insertions(+), 44 deletions(-)
diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 4594838a0f7c..aae5ef0b3ba1 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -27,6 +27,7 @@ enum migrate_reason {
MR_MEMPOLICY_MBIND,
MR_NUMA_MISPLACED,
MR_CONTIG_RANGE,
+ MR_LONGTERM_PIN,
MR_TYPES
};
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index b593316bff3d..25c0c13ba4b1 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -386,9 +386,14 @@ enum zone_type {
* likely to succeed, and to locally limit unmovable allocations - e.g.,
* to increase the number of THP/huge pages. Notable special cases are:
*
- * 1. Pinned pages: (long-term) pinning of movable pages might
- * essentially turn such pages unmovable. Memory offlining might
- * retry a long time.
+ * 1. Pinned pages: (long-term) pinning of movable pages is avoided
+ * when pages are pinned and faulted, but it is still possible that
+ * address space already has pages in ZONE_MOVABLE at the time when
+ * pages are pinned (i.e. user has touches that memory before
+ * pinning). In such case we try to migrate them to a different zone,
+ * but if migration fails the pages can still end-up pinned in
+ * ZONE_MOVABLE. In such case, memory offlining might retry a long
+ * time and will only succeed once user application unpins pages.
* 2. memblock allocations: kernelcore/movablecore setups might create
* situations where ZONE_MOVABLE contains unmovable allocations
* after boot. Memory offlining and allocations fail early.
diff --git a/include/trace/events/migrate.h b/include/trace/events/migrate.h
index 4d434398d64d..363b54ce104c 100644
--- a/include/trace/events/migrate.h
+++ b/include/trace/events/migrate.h
@@ -20,7 +20,8 @@
EM( MR_SYSCALL, "syscall_or_cpuset") \
EM( MR_MEMPOLICY_MBIND, "mempolicy_mbind") \
EM( MR_NUMA_MISPLACED, "numa_misplaced") \
- EMe(MR_CONTIG_RANGE, "contig_range")
+ EM( MR_CONTIG_RANGE, "contig_range") \
+ EMe(MR_LONGTERM_PIN, "longterm_pin")
/*
* First define the enums in the above macros to be exported to userspace
diff --git a/mm/gup.c b/mm/gup.c
index 04602e94856b..591d8e2dfc70 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -89,11 +89,12 @@ static __maybe_unused struct page *try_grab_compound_head(struct page *page,
int orig_refs = refs;
/*
- * Can't do FOLL_LONGTERM + FOLL_PIN with CMA in the gup fast
- * path, so fail and let the caller fall back to the slow path.
+ * Can't do FOLL_LONGTERM + FOLL_PIN gup fast path if not in a
+ * right zone, so fail and let the caller fall back to the slow
+ * path.
*/
- if (unlikely(flags & FOLL_LONGTERM) &&
- is_migrate_cma_page(page))
+ if (unlikely((flags & FOLL_LONGTERM) &&
+ !is_pinnable_page(page)))
return NULL;
/*
@@ -1549,19 +1550,18 @@ struct page *get_dump_page(unsigned long addr)
}
#endif /* CONFIG_ELF_CORE */
-#ifdef CONFIG_CMA
-static long check_and_migrate_cma_pages(struct mm_struct *mm,
- unsigned long start,
- unsigned long nr_pages,
- struct page **pages,
- struct vm_area_struct **vmas,
- unsigned int gup_flags)
+static long check_and_migrate_movable_pages(struct mm_struct *mm,
+ unsigned long start,
+ unsigned long nr_pages,
+ struct page **pages,
+ struct vm_area_struct **vmas,
+ unsigned int gup_flags)
{
unsigned long i;
unsigned long step;
bool drain_allow = true;
bool migrate_allow = true;
- LIST_HEAD(cma_page_list);
+ LIST_HEAD(movable_page_list);
long ret = nr_pages;
struct migration_target_control mtc = {
.nid = NUMA_NO_NODE,
@@ -1579,13 +1579,12 @@ static long check_and_migrate_cma_pages(struct mm_struct *mm,
*/
step = compound_nr(head) - (pages[i] - head);
/*
- * If we get a page from the CMA zone, since we are going to
- * be pinning these entries, we might as well move them out
- * of the CMA zone if possible.
+ * If we get a movable page, since we are going to be pinning
+ * these entries, try to move them out if possible.
*/
- if (is_migrate_cma_page(head)) {
+ if (!is_pinnable_page(head)) {
if (PageHuge(head))
- isolate_huge_page(head, &cma_page_list);
+ isolate_huge_page(head, &movable_page_list);
else {
if (!PageLRU(head) && drain_allow) {
lru_add_drain_all();
@@ -1593,7 +1592,7 @@ static long check_and_migrate_cma_pages(struct mm_struct *mm,
}
if (!isolate_lru_page(head)) {
- list_add_tail(&head->lru, &cma_page_list);
+ list_add_tail(&head->lru, &movable_page_list);
mod_node_page_state(page_pgdat(head),
NR_ISOLATED_ANON +
page_is_file_lru(head),
@@ -1605,7 +1604,7 @@ static long check_and_migrate_cma_pages(struct mm_struct *mm,
i += step;
}
- if (!list_empty(&cma_page_list)) {
+ if (!list_empty(&movable_page_list)) {
/*
* drop the above get_user_pages reference.
*/
@@ -1615,25 +1614,24 @@ static long check_and_migrate_cma_pages(struct mm_struct *mm,
for (i = 0; i < nr_pages; i++)
put_page(pages[i]);
- if (migrate_pages(&cma_page_list, alloc_migration_target, NULL,
- (unsigned long)&mtc, MIGRATE_SYNC, MR_CONTIG_RANGE)) {
+ if (migrate_pages(&movable_page_list, alloc_migration_target, NULL,
+ (unsigned long)&mtc, MIGRATE_SYNC, MR_LONGTERM_PIN)) {
/*
* some of the pages failed migration. Do get_user_pages
* without migration.
*/
migrate_allow = false;
- if (!list_empty(&cma_page_list))
- putback_movable_pages(&cma_page_list);
+ if (!list_empty(&movable_page_list))
+ putback_movable_pages(&movable_page_list);
}
/*
* We did migrate all the pages, Try to get the page references
- * again migrating any new CMA pages which we failed to isolate
- * earlier.
+ * again migrating any pages which we failed to isolate earlier.
*/
ret = __get_user_pages_locked(mm, start, nr_pages,
- pages, vmas, NULL,
- gup_flags);
+ pages, vmas, NULL,
+ gup_flags);
if ((ret > 0) && migrate_allow) {
nr_pages = ret;
@@ -1644,17 +1642,6 @@ static long check_and_migrate_cma_pages(struct mm_struct *mm,
return ret;
}
-#else
-static long check_and_migrate_cma_pages(struct mm_struct *mm,
- unsigned long start,
- unsigned long nr_pages,
- struct page **pages,
- struct vm_area_struct **vmas,
- unsigned int gup_flags)
-{
- return nr_pages;
-}
-#endif /* CONFIG_CMA */
/*
* __gup_longterm_locked() is a wrapper for __get_user_pages_locked which
@@ -1678,8 +1665,9 @@ static long __gup_longterm_locked(struct mm_struct *mm,
if (gup_flags & FOLL_LONGTERM) {
if (rc > 0)
- rc = check_and_migrate_cma_pages(mm, start, rc, pages,
- vmas, gup_flags);
+ rc = check_and_migrate_movable_pages(mm, start, rc,
+ pages, vmas,
+ gup_flags);
memalloc_pin_restore(flags);
}
return rc;
--
2.25.1
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