With this patch, the ShmemHugePages and ShmemFreeHoles lines of
/proc/meminfo are shown correctly; but ShmemPmdMapped remains 0.
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
---
include/linux/migrate.h | 3
include/linux/mm_types.h | 1
include/linux/shmem_fs.h | 3
include/trace/events/migrate.h | 3
mm/shmem.c | 439 ++++++++++++++++++++++++++++++-
5 files changed, 436 insertions(+), 13 deletions(-)
--- thpfs.orig/include/linux/migrate.h 2015-02-08 18:54:22.000000000 -0800
+++ thpfs/include/linux/migrate.h 2015-02-20 19:34:16.135982083 -0800
@@ -23,7 +23,8 @@ enum migrate_reason {
MR_SYSCALL, /* also applies to cpusets */
MR_MEMPOLICY_MBIND,
MR_NUMA_MISPLACED,
- MR_CMA
+ MR_CMA,
+ MR_SHMEM_HUGEHOLE,
};
#ifdef CONFIG_MIGRATION
--- thpfs.orig/include/linux/mm_types.h 2015-02-08 18:54:22.000000000 -0800
+++ thpfs/include/linux/mm_types.h 2015-02-20 19:34:16.135982083 -0800
@@ -165,6 +165,7 @@ struct page {
#endif
struct kmem_cache *slab_cache; /* SL[AU]B: Pointer to slab */
struct page *first_page; /* Compound tail pages */
+ atomic_long_t team_usage; /* In shmem's PageTeam page */
};
#ifdef CONFIG_MEMCG
--- thpfs.orig/include/linux/shmem_fs.h 2015-02-20 19:34:01.464015631 -0800
+++ thpfs/include/linux/shmem_fs.h 2015-02-20 19:34:16.135982083 -0800
@@ -19,8 +19,9 @@ struct shmem_inode_info {
unsigned long swapped; /* subtotal assigned to swap */
char *symlink; /* unswappable short symlink */
};
- struct shared_policy policy; /* NUMA memory alloc policy */
+ struct list_head shrinklist; /* shrinkable hpage inodes */
struct list_head swaplist; /* chain of maybes on swap */
+ struct shared_policy policy; /* NUMA memory alloc policy */
struct simple_xattrs xattrs; /* list of xattrs */
struct inode vfs_inode;
};
--- thpfs.orig/include/trace/events/migrate.h 2014-10-05 12:23:04.000000000 -0700
+++ thpfs/include/trace/events/migrate.h 2015-02-20 19:34:16.135982083 -0800
@@ -18,7 +18,8 @@
{MR_SYSCALL, "syscall_or_cpuset"}, \
{MR_MEMPOLICY_MBIND, "mempolicy_mbind"}, \
{MR_NUMA_MISPLACED, "numa_misplaced"}, \
- {MR_CMA, "cma"}
+ {MR_CMA, "cma"}, \
+ {MR_SHMEM_HUGEHOLE, "shmem_hugehole"}
TRACE_EVENT(mm_migrate_pages,
--- thpfs.orig/mm/shmem.c 2015-02-20 19:34:06.224004747 -0800
+++ thpfs/mm/shmem.c 2015-02-20 19:34:16.139982074 -0800
@@ -58,6 +58,7 @@ static struct vfsmount *shm_mnt;
#include <linux/falloc.h>
#include <linux/splice.h>
#include <linux/security.h>
+#include <linux/shrinker.h>
#include <linux/sysctl.h>
#include <linux/swapops.h>
#include <linux/pageteam.h>
@@ -74,6 +75,7 @@ static struct vfsmount *shm_mnt;
#include <asm/uaccess.h>
#include <asm/pgtable.h>
+#include "internal.h"
#define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
#define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
@@ -306,6 +308,13 @@ static bool shmem_confirm_swap(struct ad
#define SHMEM_RETRY_HUGE_PAGE ((struct page *)3)
/* otherwise hugehint is the hugeteam page to be used */
+/* tag for shrinker to locate unfilled hugepages */
+#define SHMEM_TAG_HUGEHOLE PAGECACHE_TAG_DIRTY
+
+static LIST_HEAD(shmem_shrinklist);
+static unsigned long shmem_shrinklist_depth;
+static DEFINE_SPINLOCK(shmem_shrinklist_lock);
+
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
/* ifdef here to avoid bloating shmem.o when not necessary */
@@ -360,26 +369,104 @@ restart:
return page;
}
+static int shmem_freeholes(struct page *head)
+{
+ /*
+ * Note: team_usage will also be used to count huge mappings,
+ * so treat a negative value from shmem_freeholes() as none.
+ */
+ return HPAGE_PMD_NR - atomic_long_read(&head->team_usage);
+}
+
+static void shmem_clear_tag_hugehole(struct address_space *mapping,
+ pgoff_t index)
+{
+ struct page *page = NULL;
+
+ /*
+ * The tag was set on the first subpage to be inserted in cache.
+ * When written sequentially, or instantiated by a huge fault,
+ * it will be on the head page, but that's not always so. And
+ * radix_tree_tag_clear() succeeds when it finds a slot, whether
+ * tag was set on it or not. So first lookup and then clear.
+ */
+ radix_tree_gang_lookup_tag(&mapping->page_tree, (void **)&page,
+ index, 1, SHMEM_TAG_HUGEHOLE);
+ VM_BUG_ON(!page || page->index >= index + HPAGE_PMD_NR);
+ radix_tree_tag_clear(&mapping->page_tree, page->index,
+ SHMEM_TAG_HUGEHOLE);
+}
+
+static void shmem_added_to_hugeteam(struct page *page, struct zone *zone,
+ struct page *hugehint)
+{
+ struct address_space *mapping = page->mapping;
+ struct page *head = team_head(page);
+ int nr;
+
+ if (hugehint == SHMEM_ALLOC_HUGE_PAGE) {
+ atomic_long_set(&head->team_usage, 1);
+ radix_tree_tag_set(&mapping->page_tree, page->index,
+ SHMEM_TAG_HUGEHOLE);
+ __mod_zone_page_state(zone, NR_SHMEM_FREEHOLES, HPAGE_PMD_NR-1);
+ } else {
+ /* We do not need atomic ops until huge page gets mapped */
+ nr = atomic_long_read(&head->team_usage) + 1;
+ atomic_long_set(&head->team_usage, nr);
+ if (nr == HPAGE_PMD_NR) {
+ shmem_clear_tag_hugehole(mapping, head->index);
+ __inc_zone_state(zone, NR_SHMEM_HUGEPAGES);
+ }
+ __dec_zone_state(zone, NR_SHMEM_FREEHOLES);
+ }
+}
+
static int shmem_disband_hugehead(struct page *head)
{
struct address_space *mapping;
struct zone *zone;
int nr = -1;
- mapping = head->mapping;
- zone = page_zone(head);
+ /*
+ * Only in the shrinker migration case might head have been truncated.
+ * But although head->mapping may then be zeroed at any moment, mapping
+ * stays safe because shmem_evict_inode must take our shrinklist lock.
+ */
+ mapping = ACCESS_ONCE(head->mapping);
+ if (!mapping)
+ return nr;
+ zone = page_zone(head);
spin_lock_irq(&mapping->tree_lock);
+
if (PageTeam(head)) {
+ nr = atomic_long_read(&head->team_usage);
+ atomic_long_set(&head->team_usage, 0);
+ /*
+ * Disable additions to the team.
+ * Ensure head->private is written before PageTeam is
+ * cleared, so shmem_writepage() cannot write swap into
+ * head->private, then have it overwritten by that 0!
+ */
+ smp_mb__before_atomic();
ClearPageTeam(head);
- __dec_zone_state(zone, NR_SHMEM_HUGEPAGES);
- nr = 1;
+
+ if (nr >= HPAGE_PMD_NR) {
+ __dec_zone_state(zone, NR_SHMEM_HUGEPAGES);
+ VM_BUG_ON(nr != HPAGE_PMD_NR);
+ } else if (nr) {
+ shmem_clear_tag_hugehole(mapping, head->index);
+ __mod_zone_page_state(zone, NR_SHMEM_FREEHOLES,
+ nr - HPAGE_PMD_NR);
+ } /* else shmem_getpage_gfp disbanding a failed alloced_huge */
}
+
spin_unlock_irq(&mapping->tree_lock);
return nr;
}
-static void shmem_disband_hugetails(struct page *head)
+static void shmem_disband_hugetails(struct page *head,
+ struct list_head *list, int nr)
{
struct page *page;
struct page *endpage;
@@ -387,7 +474,7 @@ static void shmem_disband_hugetails(stru
page = head;
endpage = head + HPAGE_PMD_NR;
- /* Condition follows in next commit */ {
+ if (!nr) {
/*
* The usual case: disbanding team and freeing holes as cold
* (cold being more likely to preserve high-order extents).
@@ -403,7 +490,52 @@ static void shmem_disband_hugetails(stru
else if (put_page_testzero(page))
free_hot_cold_page(page, 1);
}
+ } else if (nr < 0) {
+ struct zone *zone = page_zone(page);
+ int orig_nr = nr;
+ /*
+ * Shrinker wants to migrate cache pages from this team.
+ */
+ if (!PageSwapBacked(page)) { /* head was not in cache */
+ page->mapping = NULL;
+ if (put_page_testzero(page))
+ free_hot_cold_page(page, 1);
+ } else if (isolate_lru_page(page) == 0) {
+ list_add_tail(&page->lru, list);
+ nr++;
+ }
+ while (++page < endpage) {
+ if (PageTeam(page)) {
+ if (isolate_lru_page(page) == 0) {
+ list_add_tail(&page->lru, list);
+ nr++;
+ }
+ ClearPageTeam(page);
+ } else if (put_page_testzero(page))
+ free_hot_cold_page(page, 1);
+ }
+ /* Yes, shmem counts in NR_ISOLATED_ANON but NR_FILE_PAGES */
+ mod_zone_page_state(zone, NR_ISOLATED_ANON, nr - orig_nr);
+ } else {
+ /*
+ * Shrinker wants free pages from this team to migrate into.
+ */
+ if (!PageSwapBacked(page)) { /* head was not in cache */
+ page->mapping = NULL;
+ list_add_tail(&page->lru, list);
+ nr--;
+ }
+ while (++page < endpage) {
+ if (PageTeam(page))
+ ClearPageTeam(page);
+ else if (nr) {
+ list_add_tail(&page->lru, list);
+ nr--;
+ } else if (put_page_testzero(page))
+ free_hot_cold_page(page, 1);
+ }
}
+ VM_BUG_ON(nr > 0); /* maybe a few were not isolated */
}
static void shmem_disband_hugeteam(struct page *page)
@@ -445,12 +577,252 @@ static void shmem_disband_hugeteam(struc
if (head != page)
unlock_page(head);
if (nr_used >= 0)
- shmem_disband_hugetails(head);
+ shmem_disband_hugetails(head, NULL, 0);
if (head != page)
page_cache_release(head);
preempt_enable();
}
+static struct page *shmem_get_hugehole(struct address_space *mapping,
+ unsigned long *index)
+{
+ struct page *page;
+ struct page *head;
+
+ rcu_read_lock();
+ while (radix_tree_gang_lookup_tag(&mapping->page_tree, (void **)&page,
+ *index, 1, SHMEM_TAG_HUGEHOLE)) {
+ if (radix_tree_exception(page))
+ continue;
+ if (!page_cache_get_speculative(page))
+ continue;
+ if (!PageTeam(page) || page->mapping != mapping)
+ goto release;
+ head = team_head(page);
+ if (head != page) {
+ if (!page_cache_get_speculative(head))
+ goto release;
+ page_cache_release(page);
+ page = head;
+ if (!PageTeam(page) || page->mapping != mapping)
+ goto release;
+ }
+ if (shmem_freeholes(head) > 0) {
+ rcu_read_unlock();
+ *index = head->index + HPAGE_PMD_NR;
+ return head;
+ }
+release:
+ page_cache_release(page);
+ }
+ rcu_read_unlock();
+ return NULL;
+}
+
+static unsigned long shmem_choose_hugehole(struct list_head *fromlist,
+ struct list_head *tolist)
+{
+ unsigned long freed = 0;
+ unsigned long double_depth;
+ struct list_head *this, *next;
+ struct shmem_inode_info *info;
+ struct address_space *mapping;
+ struct page *frompage = NULL;
+ struct page *topage = NULL;
+ struct page *page;
+ pgoff_t index;
+ int fromused;
+ int toused;
+ int nid;
+
+ double_depth = 0;
+ spin_lock(&shmem_shrinklist_lock);
+ list_for_each_safe(this, next, &shmem_shrinklist) {
+ info = list_entry(this, struct shmem_inode_info, shrinklist);
+ mapping = info->vfs_inode.i_mapping;
+ if (!radix_tree_tagged(&mapping->page_tree,
+ SHMEM_TAG_HUGEHOLE)) {
+ list_del_init(&info->shrinklist);
+ shmem_shrinklist_depth--;
+ continue;
+ }
+ index = 0;
+ while ((page = shmem_get_hugehole(mapping, &index))) {
+ /* Choose to migrate from page with least in use */
+ if (!frompage ||
+ shmem_freeholes(page) > shmem_freeholes(frompage)) {
+ if (frompage)
+ page_cache_release(frompage);
+ frompage = page;
+ if (shmem_freeholes(page) == HPAGE_PMD_NR-1) {
+ /* No point searching further */
+ double_depth = -3;
+ break;
+ }
+ } else
+ page_cache_release(page);
+ }
+
+ /* Only reclaim from the older half of the shrinklist */
+ double_depth += 2;
+ if (double_depth >= min(shmem_shrinklist_depth, 2000UL))
+ break;
+ }
+
+ if (!frompage)
+ goto unlock;
+ preempt_disable();
+ fromused = shmem_disband_hugehead(frompage);
+ spin_unlock(&shmem_shrinklist_lock);
+ if (fromused > 0)
+ shmem_disband_hugetails(frompage, fromlist, -fromused);
+ preempt_enable();
+ nid = page_to_nid(frompage);
+ page_cache_release(frompage);
+
+ if (fromused <= 0)
+ return 0;
+ freed = HPAGE_PMD_NR - fromused;
+ if (fromused > HPAGE_PMD_NR/2)
+ return freed;
+
+ double_depth = 0;
+ spin_lock(&shmem_shrinklist_lock);
+ list_for_each_safe(this, next, &shmem_shrinklist) {
+ info = list_entry(this, struct shmem_inode_info, shrinklist);
+ mapping = info->vfs_inode.i_mapping;
+ if (!radix_tree_tagged(&mapping->page_tree,
+ SHMEM_TAG_HUGEHOLE)) {
+ list_del_init(&info->shrinklist);
+ shmem_shrinklist_depth--;
+ continue;
+ }
+ index = 0;
+ while ((page = shmem_get_hugehole(mapping, &index))) {
+ /* Choose to migrate to page with just enough free */
+ if (shmem_freeholes(page) >= fromused &&
+ page_to_nid(page) == nid) {
+ if (!topage || shmem_freeholes(page) <
+ shmem_freeholes(topage)) {
+ if (topage)
+ page_cache_release(topage);
+ topage = page;
+ if (shmem_freeholes(page) == fromused) {
+ /* No point searching further */
+ double_depth = -3;
+ break;
+ }
+ } else
+ page_cache_release(page);
+ } else
+ page_cache_release(page);
+ }
+
+ /* Only reclaim from the older half of the shrinklist */
+ double_depth += 2;
+ if (double_depth >= min(shmem_shrinklist_depth, 2000UL))
+ break;
+ }
+
+ if (!topage)
+ goto unlock;
+ preempt_disable();
+ toused = shmem_disband_hugehead(topage);
+ spin_unlock(&shmem_shrinklist_lock);
+ if (toused > 0) {
+ if (HPAGE_PMD_NR - toused >= fromused)
+ shmem_disband_hugetails(topage, tolist, fromused);
+ else
+ shmem_disband_hugetails(topage, NULL, 0);
+ freed += HPAGE_PMD_NR - toused;
+ }
+ preempt_enable();
+ page_cache_release(topage);
+ return freed;
+unlock:
+ spin_unlock(&shmem_shrinklist_lock);
+ return freed;
+}
+
+static struct page *shmem_get_migrate_page(struct page *frompage,
+ unsigned long private, int **result)
+{
+ struct list_head *tolist = (struct list_head *)private;
+ struct page *topage;
+
+ VM_BUG_ON(list_empty(tolist));
+ topage = list_first_entry(tolist, struct page, lru);
+ list_del(&topage->lru);
+ return topage;
+}
+
+static void shmem_put_migrate_page(struct page *topage, unsigned long private)
+{
+ struct list_head *tolist = (struct list_head *)private;
+
+ list_add(&topage->lru, tolist);
+}
+
+static void shmem_putback_migrate_pages(struct list_head *tolist)
+{
+ struct page *topage;
+ struct page *next;
+
+ /*
+ * The tolist pages were not counted in NR_ISOLATED, so stats
+ * would go wrong if putback_movable_pages() were used on them.
+ * Indeed, even putback_lru_page() is wrong for these pages.
+ */
+ list_for_each_entry_safe(topage, next, tolist, lru) {
+ list_del(&topage->lru);
+ if (put_page_testzero(topage))
+ free_hot_cold_page(topage, 1);
+ }
+}
+
+static unsigned long shmem_shrink_hugehole(struct shrinker *shrink,
+ struct shrink_control *sc)
+{
+ unsigned long freed;
+ LIST_HEAD(fromlist);
+ LIST_HEAD(tolist);
+
+ freed = shmem_choose_hugehole(&fromlist, &tolist);
+ if (list_empty(&fromlist))
+ return SHRINK_STOP;
+ if (!list_empty(&tolist)) {
+ migrate_pages(&fromlist, shmem_get_migrate_page,
+ shmem_put_migrate_page, (unsigned long)&tolist,
+ MIGRATE_SYNC, MR_SHMEM_HUGEHOLE);
+ preempt_disable();
+ drain_local_pages(NULL); /* try to preserve huge freed page */
+ preempt_enable();
+ shmem_putback_migrate_pages(&tolist);
+ }
+ putback_movable_pages(&fromlist); /* if any were left behind */
+ return freed;
+}
+
+static unsigned long shmem_count_hugehole(struct shrinker *shrink,
+ struct shrink_control *sc)
+{
+ /*
+ * Huge hole space is not charged to any memcg:
+ * only shrink it for global reclaim.
+ * But at present we're only called for global reclaim anyway.
+ */
+ if (list_empty(&shmem_shrinklist))
+ return 0;
+ return global_page_state(NR_SHMEM_FREEHOLES);
+}
+
+static struct shrinker shmem_hugehole_shrinker = {
+ .count_objects = shmem_count_hugehole,
+ .scan_objects = shmem_shrink_hugehole,
+ .seeks = DEFAULT_SEEKS, /* would another value work better? */
+ .batch = HPAGE_PMD_NR, /* would another value work better? */
+};
+
#else /* !CONFIG_TRANSPARENT_HUGEPAGE */
#define shmem_huge SHMEM_HUGE_DENY
@@ -466,6 +838,17 @@ static inline void shmem_disband_hugetea
{
BUILD_BUG();
}
+
+static inline void shmem_added_to_hugeteam(struct page *page,
+ struct zone *zone, struct page *hugehint)
+{
+}
+
+static inline unsigned long shmem_shrink_hugehole(struct shrinker *shrink,
+ struct shrink_control *sc)
+{
+ return 0;
+}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
/*
@@ -508,10 +891,10 @@ shmem_add_to_page_cache(struct page *pag
goto errout;
}
- if (!PageTeam(page))
+ if (PageTeam(page))
+ shmem_added_to_hugeteam(page, zone, hugehint);
+ else
page_cache_get(page);
- else if (hugehint == SHMEM_ALLOC_HUGE_PAGE)
- __inc_zone_state(zone, NR_SHMEM_HUGEPAGES);
mapping->nrpages++;
__inc_zone_state(zone, NR_FILE_PAGES);
@@ -839,6 +1222,14 @@ static void shmem_evict_inode(struct ino
shmem_unacct_size(info->flags, inode->i_size);
inode->i_size = 0;
shmem_truncate_range(inode, 0, (loff_t)-1);
+ if (!list_empty(&info->shrinklist)) {
+ spin_lock(&shmem_shrinklist_lock);
+ if (!list_empty(&info->shrinklist)) {
+ list_del_init(&info->shrinklist);
+ shmem_shrinklist_depth--;
+ }
+ spin_unlock(&shmem_shrinklist_lock);
+ }
if (!list_empty(&info->swaplist)) {
mutex_lock(&shmem_swaplist_mutex);
list_del_init(&info->swaplist);
@@ -1189,10 +1580,18 @@ static struct page *shmem_alloc_page(gfp
if (*hugehint == SHMEM_ALLOC_HUGE_PAGE) {
head = alloc_pages_vma(gfp|__GFP_NORETRY|__GFP_NOWARN,
HPAGE_PMD_ORDER, &pvma, 0, numa_node_id());
+ if (!head) {
+ shmem_shrink_hugehole(NULL, NULL);
+ head = alloc_pages_vma(
+ gfp|__GFP_NORETRY|__GFP_NOWARN,
+ HPAGE_PMD_ORDER, &pvma, 0,
+ numa_node_id());
+ }
if (head) {
split_page(head, HPAGE_PMD_ORDER);
/* Prepare head page for add_to_page_cache */
+ atomic_long_set(&head->team_usage, 0);
__SetPageTeam(head);
head->mapping = mapping;
head->index = round_down(index, HPAGE_PMD_NR);
@@ -1504,6 +1903,21 @@ repeat:
if (sgp == SGP_WRITE)
__SetPageReferenced(page);
/*
+ * Might we see !list_empty a moment before the shrinker
+ * removes this inode from its list? Unlikely, since we
+ * already set a tag in the tree. Some barrier required?
+ */
+ if (alloced_huge && list_empty(&info->shrinklist)) {
+ spin_lock(&shmem_shrinklist_lock);
+ if (list_empty(&info->shrinklist)) {
+ list_add_tail(&info->shrinklist,
+ &shmem_shrinklist);
+ shmem_shrinklist_depth++;
+ }
+ spin_unlock(&shmem_shrinklist_lock);
+ }
+
+ /*
* Let SGP_FALLOC use the SGP_WRITE optimization on a new page.
*/
if (sgp == SGP_FALLOC)
@@ -1724,6 +2138,7 @@ static struct inode *shmem_get_inode(str
spin_lock_init(&info->lock);
info->seals = F_SEAL_SEAL;
info->flags = flags & VM_NORESERVE;
+ INIT_LIST_HEAD(&info->shrinklist);
INIT_LIST_HEAD(&info->swaplist);
simple_xattrs_init(&info->xattrs);
cache_no_acl(inode);
@@ -3564,6 +3979,10 @@ int __init shmem_init(void)
printk(KERN_ERR "Could not kern_mount tmpfs\n");
goto out1;
}
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+ register_shrinker(&shmem_hugehole_shrinker);
+#endif
return 0;
out1:
--
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