mm: migration: allow migration to operate asynchronously and avoid synchronous compaction in the faster path
Migration synchronously waits for writeback if the initial passes fails.
Callers of memory compaction do not necessarily want this behaviour if the
caller is latency sensitive or expects that synchronous migration is not
going to have a significantly better success rate.
This patch adds a sync parameter to migrate_pages() allowing the caller to
indicate if wait_on_page_writeback() is allowed within migration or not.
For reclaim/compaction, try_to_compact_pages() is first called
asynchronously, direct reclaim runs and then try_to_compact_pages() is
called synchronously as there is a greater expectation that it'll succeed.
[akpm@linux-foundation.org: build/merge fix]
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/compaction.h b/include/linux/compaction.h
index 2592883..72cba40 100644
--- a/include/linux/compaction.h
+++ b/include/linux/compaction.h
@@ -21,10 +21,11 @@
extern int fragmentation_index(struct zone *zone, unsigned int order);
extern unsigned long try_to_compact_pages(struct zonelist *zonelist,
- int order, gfp_t gfp_mask, nodemask_t *mask);
+ int order, gfp_t gfp_mask, nodemask_t *mask,
+ bool sync);
extern unsigned long compaction_suitable(struct zone *zone, int order);
extern unsigned long compact_zone_order(struct zone *zone, int order,
- gfp_t gfp_mask);
+ gfp_t gfp_mask, bool sync);
/* Do not skip compaction more than 64 times */
#define COMPACT_MAX_DEFER_SHIFT 6
@@ -57,7 +58,8 @@
#else
static inline unsigned long try_to_compact_pages(struct zonelist *zonelist,
- int order, gfp_t gfp_mask, nodemask_t *nodemask)
+ int order, gfp_t gfp_mask, nodemask_t *nodemask,
+ bool sync)
{
return COMPACT_CONTINUE;
}
@@ -68,7 +70,7 @@
}
static inline unsigned long compact_zone_order(struct zone *zone, int order,
- gfp_t gfp_mask)
+ gfp_t gfp_mask, bool sync)
{
return 0;
}
diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 085527f..fa31902 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -13,9 +13,11 @@
extern int migrate_page(struct address_space *,
struct page *, struct page *);
extern int migrate_pages(struct list_head *l, new_page_t x,
- unsigned long private, int offlining);
+ unsigned long private, int offlining,
+ bool sync);
extern int migrate_huge_pages(struct list_head *l, new_page_t x,
- unsigned long private, int offlining);
+ unsigned long private, int offlining,
+ bool sync);
extern int fail_migrate_page(struct address_space *,
struct page *, struct page *);
@@ -33,9 +35,11 @@
static inline void putback_lru_pages(struct list_head *l) {}
static inline int migrate_pages(struct list_head *l, new_page_t x,
- unsigned long private, int offlining) { return -ENOSYS; }
+ unsigned long private, int offlining,
+ bool sync) { return -ENOSYS; }
static inline int migrate_huge_pages(struct list_head *l, new_page_t x,
- unsigned long private, int offlining) { return -ENOSYS; }
+ unsigned long private, int offlining,
+ bool sync) { return -ENOSYS; }
static inline int migrate_prep(void) { return -ENOSYS; }
static inline int migrate_prep_local(void) { return -ENOSYS; }
diff --git a/mm/compaction.c b/mm/compaction.c
index 8fe917e..47fca10 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -33,6 +33,7 @@
unsigned long nr_migratepages; /* Number of pages to migrate */
unsigned long free_pfn; /* isolate_freepages search base */
unsigned long migrate_pfn; /* isolate_migratepages search base */
+ bool sync; /* Synchronous migration */
/* Account for isolated anon and file pages */
unsigned long nr_anon;
@@ -455,7 +456,8 @@
nr_migrate = cc->nr_migratepages;
migrate_pages(&cc->migratepages, compaction_alloc,
- (unsigned long)cc, 0);
+ (unsigned long)cc, 0,
+ cc->sync);
update_nr_listpages(cc);
nr_remaining = cc->nr_migratepages;
@@ -482,7 +484,8 @@
}
unsigned long compact_zone_order(struct zone *zone,
- int order, gfp_t gfp_mask)
+ int order, gfp_t gfp_mask,
+ bool sync)
{
struct compact_control cc = {
.nr_freepages = 0,
@@ -490,6 +493,7 @@
.order = order,
.migratetype = allocflags_to_migratetype(gfp_mask),
.zone = zone,
+ .sync = sync,
};
INIT_LIST_HEAD(&cc.freepages);
INIT_LIST_HEAD(&cc.migratepages);
@@ -505,11 +509,13 @@
* @order: The order of the current allocation
* @gfp_mask: The GFP mask of the current allocation
* @nodemask: The allowed nodes to allocate from
+ * @sync: Whether migration is synchronous or not
*
* This is the main entry point for direct page compaction.
*/
unsigned long try_to_compact_pages(struct zonelist *zonelist,
- int order, gfp_t gfp_mask, nodemask_t *nodemask)
+ int order, gfp_t gfp_mask, nodemask_t *nodemask,
+ bool sync)
{
enum zone_type high_zoneidx = gfp_zone(gfp_mask);
int may_enter_fs = gfp_mask & __GFP_FS;
@@ -533,7 +539,7 @@
nodemask) {
int status;
- status = compact_zone_order(zone, order, gfp_mask);
+ status = compact_zone_order(zone, order, gfp_mask, sync);
rc = max(status, rc);
/* If a normal allocation would succeed, stop compacting */
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 46ab2c0..2323a80 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1290,9 +1290,10 @@
/* Keep page count to indicate a given hugepage is isolated. */
list_add(&hpage->lru, &pagelist);
- ret = migrate_huge_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL, 0);
+ ret = migrate_huge_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL, 0,
+ true);
if (ret) {
- putback_lru_pages(&pagelist);
+ putback_lru_pages(&pagelist);
pr_debug("soft offline: %#lx: migration failed %d, type %lx\n",
pfn, ret, page->flags);
if (ret > 0)
@@ -1413,7 +1414,8 @@
LIST_HEAD(pagelist);
list_add(&page->lru, &pagelist);
- ret = migrate_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL, 0);
+ ret = migrate_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL,
+ 0, true);
if (ret) {
pr_info("soft offline: %#lx: migration failed %d, type %lx\n",
pfn, ret, page->flags);
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 2c6523a..584fc55 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -733,7 +733,8 @@
goto out;
}
/* this function returns # of failed pages */
- ret = migrate_pages(&source, hotremove_migrate_alloc, 0, 1);
+ ret = migrate_pages(&source, hotremove_migrate_alloc, 0,
+ 1, true);
if (ret)
putback_lru_pages(&source);
}
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 11ff260..9db2745 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -935,7 +935,7 @@
return PTR_ERR(vma);
if (!list_empty(&pagelist)) {
- err = migrate_pages(&pagelist, new_node_page, dest, 0);
+ err = migrate_pages(&pagelist, new_node_page, dest, 0, true);
if (err)
putback_lru_pages(&pagelist);
}
@@ -1155,7 +1155,7 @@
if (!list_empty(&pagelist)) {
nr_failed = migrate_pages(&pagelist, new_vma_page,
- (unsigned long)vma, 0);
+ (unsigned long)vma, 0, true);
if (nr_failed)
putback_lru_pages(&pagelist);
}
diff --git a/mm/migrate.c b/mm/migrate.c
index 94875b2..dc47f6c 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -614,7 +614,7 @@
* to the newly allocated page in newpage.
*/
static int unmap_and_move(new_page_t get_new_page, unsigned long private,
- struct page *page, int force, int offlining)
+ struct page *page, int force, int offlining, bool sync)
{
int rc = 0;
int *result = NULL;
@@ -682,7 +682,7 @@
BUG_ON(charge);
if (PageWriteback(page)) {
- if (!force)
+ if (!force || !sync)
goto uncharge;
wait_on_page_writeback(page);
}
@@ -827,7 +827,7 @@
*/
static int unmap_and_move_huge_page(new_page_t get_new_page,
unsigned long private, struct page *hpage,
- int force, int offlining)
+ int force, int offlining, bool sync)
{
int rc = 0;
int *result = NULL;
@@ -841,7 +841,7 @@
rc = -EAGAIN;
if (!trylock_page(hpage)) {
- if (!force)
+ if (!force || !sync)
goto out;
lock_page(hpage);
}
@@ -909,7 +909,8 @@
* Return: Number of pages not migrated or error code.
*/
int migrate_pages(struct list_head *from,
- new_page_t get_new_page, unsigned long private, int offlining)
+ new_page_t get_new_page, unsigned long private, int offlining,
+ bool sync)
{
int retry = 1;
int nr_failed = 0;
@@ -929,7 +930,8 @@
cond_resched();
rc = unmap_and_move(get_new_page, private,
- page, pass > 2, offlining);
+ page, pass > 2, offlining,
+ sync);
switch(rc) {
case -ENOMEM:
@@ -958,7 +960,8 @@
}
int migrate_huge_pages(struct list_head *from,
- new_page_t get_new_page, unsigned long private, int offlining)
+ new_page_t get_new_page, unsigned long private, int offlining,
+ bool sync)
{
int retry = 1;
int nr_failed = 0;
@@ -974,7 +977,8 @@
cond_resched();
rc = unmap_and_move_huge_page(get_new_page,
- private, page, pass > 2, offlining);
+ private, page, pass > 2, offlining,
+ sync);
switch(rc) {
case -ENOMEM:
@@ -1107,7 +1111,7 @@
err = 0;
if (!list_empty(&pagelist)) {
err = migrate_pages(&pagelist, new_page_node,
- (unsigned long)pm, 0);
+ (unsigned long)pm, 0, true);
if (err)
putback_lru_pages(&pagelist);
}
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 03a66a3..0fd4864 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1812,7 +1812,8 @@
__alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
struct zonelist *zonelist, enum zone_type high_zoneidx,
nodemask_t *nodemask, int alloc_flags, struct zone *preferred_zone,
- int migratetype, unsigned long *did_some_progress)
+ int migratetype, unsigned long *did_some_progress,
+ bool sync_migration)
{
struct page *page;
struct task_struct *tsk = current;
@@ -1822,7 +1823,7 @@
tsk->flags |= PF_MEMALLOC;
*did_some_progress = try_to_compact_pages(zonelist, order, gfp_mask,
- nodemask);
+ nodemask, sync_migration);
tsk->flags &= ~PF_MEMALLOC;
if (*did_some_progress != COMPACT_SKIPPED) {
@@ -1859,7 +1860,8 @@
__alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
struct zonelist *zonelist, enum zone_type high_zoneidx,
nodemask_t *nodemask, int alloc_flags, struct zone *preferred_zone,
- int migratetype, unsigned long *did_some_progress)
+ int migratetype, unsigned long *did_some_progress,
+ bool sync_migration)
{
return NULL;
}
@@ -2001,6 +2003,7 @@
unsigned long pages_reclaimed = 0;
unsigned long did_some_progress;
struct task_struct *p = current;
+ bool sync_migration = false;
/*
* In the slowpath, we sanity check order to avoid ever trying to
@@ -2063,14 +2066,19 @@
if (test_thread_flag(TIF_MEMDIE) && !(gfp_mask & __GFP_NOFAIL))
goto nopage;
- /* Try direct compaction */
+ /*
+ * Try direct compaction. The first pass is asynchronous. Subsequent
+ * attempts after direct reclaim are synchronous
+ */
page = __alloc_pages_direct_compact(gfp_mask, order,
zonelist, high_zoneidx,
nodemask,
alloc_flags, preferred_zone,
- migratetype, &did_some_progress);
+ migratetype, &did_some_progress,
+ sync_migration);
if (page)
goto got_pg;
+ sync_migration = true;
/* Try direct reclaim and then allocating */
page = __alloc_pages_direct_reclaim(gfp_mask, order,
@@ -2134,7 +2142,8 @@
zonelist, high_zoneidx,
nodemask,
alloc_flags, preferred_zone,
- migratetype, &did_some_progress);
+ migratetype, &did_some_progress,
+ sync_migration);
if (page)
goto got_pg;
}
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 10ebd74..8320d11 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2377,7 +2377,8 @@
* would ordinarily call try_to_compact_pages()
*/
if (sc.order > PAGE_ALLOC_COSTLY_ORDER)
- compact_zone_order(zone, sc.order, sc.gfp_mask);
+ compact_zone_order(zone, sc.order, sc.gfp_mask,
+ false);
if (!zone_watermark_ok_safe(zone, order,
high_wmark_pages(zone), end_zone, 0)) {