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authorVitaly Wool <vitalywool@gmail.com>2019-05-14 03:22:43 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2019-05-14 19:47:50 +0300
commit9050cce104c04982fb7b5dea9aee4f66f245d6d3 (patch)
treea1819d628e925c24512a17aea18c65190d348547
parent1c52e6d0681020e2272c0cbce270dd91a215e7d3 (diff)
downloadlinux-9050cce104c04982fb7b5dea9aee4f66f245d6d3.tar.xz
mm/z3fold.c: introduce helper functions
Patch series "z3fold: support page migration", v2. This patchset implements page migration support and slightly better buddy search. To implement page migration support, z3fold has to move away from the current scheme of handle encoding. i. e. stop encoding page address in handles. Instead, a small per-page structure is created which will contain actual addresses for z3fold objects, while pointers to fields of that structure will be used as handles. Thus, it will be possible to change the underlying addresses to reflect page migration. To support migration itself, 3 callbacks will be implemented: 1: isolation callback: z3fold_page_isolate(): try to isolate the page by removing it from all lists. Pages scheduled for some activity and mapped pages will not be isolated. Return true if isolation was successful or false otherwise 2: migration callback: z3fold_page_migrate(): re-check critical conditions and migrate page contents to the new page provided by the system. Returns 0 on success or negative error code otherwise 3: putback callback: z3fold_page_putback(): put back the page if z3fold_page_migrate() for it failed permanently (i. e. not with -EAGAIN code). To make sure an isolated page doesn't get freed, its kref is incremented in z3fold_page_isolate() and decremented during post-migration compaction, if migration was successful, or by z3fold_page_putback() in the other case. Since the new handle encoding scheme implies slight memory consumption increase, better buddy search (which decreases memory consumption) is included in this patchset. This patch (of 4): Introduce a separate helper function for object allocation, as well as 2 smaller helpers to add a buddy to the list and to get a pointer to the pool from the z3fold header. No functional changes here. Link: http://lkml.kernel.org/r/20190417103633.a4bb770b5bf0fb7e43ce1666@gmail.com Signed-off-by: Vitaly Wool <vitaly.vul@sony.com> Cc: Dan Streetman <ddstreet@ieee.org> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Cc: Krzysztof Kozlowski <k.kozlowski@samsung.com> Cc: Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com> Cc: Uladzislau Rezki <urezki@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/z3fold.c184
1 files changed, 100 insertions, 84 deletions
diff --git a/mm/z3fold.c b/mm/z3fold.c
index aee9b0b8d907..7a59875d880c 100644
--- a/mm/z3fold.c
+++ b/mm/z3fold.c
@@ -255,10 +255,15 @@ static enum buddy handle_to_buddy(unsigned long handle)
return (handle - zhdr->first_num) & BUDDY_MASK;
}
+static inline struct z3fold_pool *zhdr_to_pool(struct z3fold_header *zhdr)
+{
+ return zhdr->pool;
+}
+
static void __release_z3fold_page(struct z3fold_header *zhdr, bool locked)
{
struct page *page = virt_to_page(zhdr);
- struct z3fold_pool *pool = zhdr->pool;
+ struct z3fold_pool *pool = zhdr_to_pool(zhdr);
WARN_ON(!list_empty(&zhdr->buddy));
set_bit(PAGE_STALE, &page->private);
@@ -295,9 +300,10 @@ static void release_z3fold_page_locked_list(struct kref *ref)
{
struct z3fold_header *zhdr = container_of(ref, struct z3fold_header,
refcount);
- spin_lock(&zhdr->pool->lock);
+ struct z3fold_pool *pool = zhdr_to_pool(zhdr);
+ spin_lock(&pool->lock);
list_del_init(&zhdr->buddy);
- spin_unlock(&zhdr->pool->lock);
+ spin_unlock(&pool->lock);
WARN_ON(z3fold_page_trylock(zhdr));
__release_z3fold_page(zhdr, true);
@@ -349,6 +355,23 @@ static int num_free_chunks(struct z3fold_header *zhdr)
return nfree;
}
+/* Add to the appropriate unbuddied list */
+static inline void add_to_unbuddied(struct z3fold_pool *pool,
+ struct z3fold_header *zhdr)
+{
+ if (zhdr->first_chunks == 0 || zhdr->last_chunks == 0 ||
+ zhdr->middle_chunks == 0) {
+ struct list_head *unbuddied = get_cpu_ptr(pool->unbuddied);
+
+ int freechunks = num_free_chunks(zhdr);
+ spin_lock(&pool->lock);
+ list_add(&zhdr->buddy, &unbuddied[freechunks]);
+ spin_unlock(&pool->lock);
+ zhdr->cpu = smp_processor_id();
+ put_cpu_ptr(pool->unbuddied);
+ }
+}
+
static inline void *mchunk_memmove(struct z3fold_header *zhdr,
unsigned short dst_chunk)
{
@@ -406,10 +429,8 @@ static int z3fold_compact_page(struct z3fold_header *zhdr)
static void do_compact_page(struct z3fold_header *zhdr, bool locked)
{
- struct z3fold_pool *pool = zhdr->pool;
+ struct z3fold_pool *pool = zhdr_to_pool(zhdr);
struct page *page;
- struct list_head *unbuddied;
- int fchunks;
page = virt_to_page(zhdr);
if (locked)
@@ -430,18 +451,7 @@ static void do_compact_page(struct z3fold_header *zhdr, bool locked)
}
z3fold_compact_page(zhdr);
- unbuddied = get_cpu_ptr(pool->unbuddied);
- fchunks = num_free_chunks(zhdr);
- if (fchunks < NCHUNKS &&
- (!zhdr->first_chunks || !zhdr->middle_chunks ||
- !zhdr->last_chunks)) {
- /* the page's not completely free and it's unbuddied */
- spin_lock(&pool->lock);
- list_add(&zhdr->buddy, &unbuddied[fchunks]);
- spin_unlock(&pool->lock);
- zhdr->cpu = smp_processor_id();
- }
- put_cpu_ptr(pool->unbuddied);
+ add_to_unbuddied(pool, zhdr);
z3fold_page_unlock(zhdr);
}
@@ -453,6 +463,67 @@ static void compact_page_work(struct work_struct *w)
do_compact_page(zhdr, false);
}
+/* returns _locked_ z3fold page header or NULL */
+static inline struct z3fold_header *__z3fold_alloc(struct z3fold_pool *pool,
+ size_t size, bool can_sleep)
+{
+ struct z3fold_header *zhdr = NULL;
+ struct page *page;
+ struct list_head *unbuddied;
+ int chunks = size_to_chunks(size), i;
+
+lookup:
+ /* First, try to find an unbuddied z3fold page. */
+ unbuddied = get_cpu_ptr(pool->unbuddied);
+ for_each_unbuddied_list(i, chunks) {
+ struct list_head *l = &unbuddied[i];
+
+ zhdr = list_first_entry_or_null(READ_ONCE(l),
+ struct z3fold_header, buddy);
+
+ if (!zhdr)
+ continue;
+
+ /* Re-check under lock. */
+ spin_lock(&pool->lock);
+ l = &unbuddied[i];
+ if (unlikely(zhdr != list_first_entry(READ_ONCE(l),
+ struct z3fold_header, buddy)) ||
+ !z3fold_page_trylock(zhdr)) {
+ spin_unlock(&pool->lock);
+ zhdr = NULL;
+ put_cpu_ptr(pool->unbuddied);
+ if (can_sleep)
+ cond_resched();
+ goto lookup;
+ }
+ list_del_init(&zhdr->buddy);
+ zhdr->cpu = -1;
+ spin_unlock(&pool->lock);
+
+ page = virt_to_page(zhdr);
+ if (test_bit(NEEDS_COMPACTING, &page->private)) {
+ z3fold_page_unlock(zhdr);
+ zhdr = NULL;
+ put_cpu_ptr(pool->unbuddied);
+ if (can_sleep)
+ cond_resched();
+ goto lookup;
+ }
+
+ /*
+ * this page could not be removed from its unbuddied
+ * list while pool lock was held, and then we've taken
+ * page lock so kref_put could not be called before
+ * we got here, so it's safe to just call kref_get()
+ */
+ kref_get(&zhdr->refcount);
+ break;
+ }
+ put_cpu_ptr(pool->unbuddied);
+
+ return zhdr;
+}
/*
* API Functions
@@ -546,7 +617,7 @@ static void z3fold_destroy_pool(struct z3fold_pool *pool)
static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp,
unsigned long *handle)
{
- int chunks = 0, i, freechunks;
+ int chunks = size_to_chunks(size);
struct z3fold_header *zhdr = NULL;
struct page *page = NULL;
enum buddy bud;
@@ -561,56 +632,8 @@ static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp,
if (size > PAGE_SIZE - ZHDR_SIZE_ALIGNED - CHUNK_SIZE)
bud = HEADLESS;
else {
- struct list_head *unbuddied;
- chunks = size_to_chunks(size);
-
-lookup:
- /* First, try to find an unbuddied z3fold page. */
- unbuddied = get_cpu_ptr(pool->unbuddied);
- for_each_unbuddied_list(i, chunks) {
- struct list_head *l = &unbuddied[i];
-
- zhdr = list_first_entry_or_null(READ_ONCE(l),
- struct z3fold_header, buddy);
-
- if (!zhdr)
- continue;
-
- /* Re-check under lock. */
- spin_lock(&pool->lock);
- l = &unbuddied[i];
- if (unlikely(zhdr != list_first_entry(READ_ONCE(l),
- struct z3fold_header, buddy)) ||
- !z3fold_page_trylock(zhdr)) {
- spin_unlock(&pool->lock);
- put_cpu_ptr(pool->unbuddied);
- goto lookup;
- }
- list_del_init(&zhdr->buddy);
- zhdr->cpu = -1;
- spin_unlock(&pool->lock);
-
- page = virt_to_page(zhdr);
- if (test_bit(NEEDS_COMPACTING, &page->private)) {
- z3fold_page_unlock(zhdr);
- zhdr = NULL;
- put_cpu_ptr(pool->unbuddied);
- if (can_sleep)
- cond_resched();
- goto lookup;
- }
-
- /*
- * this page could not be removed from its unbuddied
- * list while pool lock was held, and then we've taken
- * page lock so kref_put could not be called before
- * we got here, so it's safe to just call kref_get()
- */
- kref_get(&zhdr->refcount);
- break;
- }
- put_cpu_ptr(pool->unbuddied);
-
+retry:
+ zhdr = __z3fold_alloc(pool, size, can_sleep);
if (zhdr) {
if (zhdr->first_chunks == 0) {
if (zhdr->middle_chunks != 0 &&
@@ -630,8 +653,9 @@ lookup:
z3fold_page_unlock(zhdr);
pr_err("No free chunks in unbuddied\n");
WARN_ON(1);
- goto lookup;
+ goto retry;
}
+ page = virt_to_page(zhdr);
goto found;
}
bud = FIRST;
@@ -662,8 +686,12 @@ lookup:
if (!page)
return -ENOMEM;
- atomic64_inc(&pool->pages_nr);
zhdr = init_z3fold_page(page, pool);
+ if (!zhdr) {
+ __free_page(page);
+ return -ENOMEM;
+ }
+ atomic64_inc(&pool->pages_nr);
if (bud == HEADLESS) {
set_bit(PAGE_HEADLESS, &page->private);
@@ -680,19 +708,7 @@ found:
zhdr->middle_chunks = chunks;
zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS;
}
-
- if (zhdr->first_chunks == 0 || zhdr->last_chunks == 0 ||
- zhdr->middle_chunks == 0) {
- struct list_head *unbuddied = get_cpu_ptr(pool->unbuddied);
-
- /* Add to unbuddied list */
- freechunks = num_free_chunks(zhdr);
- spin_lock(&pool->lock);
- list_add(&zhdr->buddy, &unbuddied[freechunks]);
- spin_unlock(&pool->lock);
- zhdr->cpu = smp_processor_id();
- put_cpu_ptr(pool->unbuddied);
- }
+ add_to_unbuddied(pool, zhdr);
headless:
spin_lock(&pool->lock);