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authorLinus Torvalds <torvalds@linux-foundation.org>2021-07-01 17:17:24 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-07-01 17:17:24 -0700
commite267992f9ef0bf717d70a9ee18049782f77e4b3a (patch)
tree6caf3664452672f41e8039f6af4279e2df709d66 /mm
parent19b438592238b3b40c3f945bb5f9c4ca971c0c45 (diff)
parente4d777003a43feab2e000749163e531f6c48c385 (diff)
Merge branch 'for-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu
Pull percpu updates from Dennis Zhou: - percpu chunk depopulation - depopulate backing pages for chunks with empty pages when we exceed a global threshold without those pages. This lets us reclaim a portion of memory that would previously be lost until the full chunk would be freed (possibly never). - memcg accounting cleanup - previously separate chunks were managed for normal allocations and __GFP_ACCOUNT allocations. These are now consolidated which cleans up the code quite a bit. - a few misc clean ups for clang warnings * 'for-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu: percpu: optimize locking in pcpu_balance_workfn() percpu: initialize best_upa variable percpu: rework memcg accounting mm, memcg: introduce mem_cgroup_kmem_disabled() mm, memcg: mark cgroup_memory_nosocket, nokmem and noswap as __ro_after_init percpu: make symbol 'pcpu_free_slot' static percpu: implement partial chunk depopulation percpu: use pcpu_free_slot instead of pcpu_nr_slots - 1 percpu: factor out pcpu_check_block_hint() percpu: split __pcpu_balance_workfn() percpu: fix a comment about the chunks ordering
Diffstat (limited to 'mm')
-rw-r--r--mm/memcontrol.c11
-rw-r--r--mm/percpu-internal.h56
-rw-r--r--mm/percpu-km.c10
-rw-r--r--mm/percpu-stats.c44
-rw-r--r--mm/percpu-vm.c35
-rw-r--r--mm/percpu.c368
6 files changed, 338 insertions, 186 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 4ee243ce6135..b80aae448a49 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -81,14 +81,14 @@ DEFINE_PER_CPU(struct mem_cgroup *, int_active_memcg);
EXPORT_PER_CPU_SYMBOL_GPL(int_active_memcg);
/* Socket memory accounting disabled? */
-static bool cgroup_memory_nosocket;
+static bool cgroup_memory_nosocket __ro_after_init;
/* Kernel memory accounting disabled? */
-bool cgroup_memory_nokmem;
+bool cgroup_memory_nokmem __ro_after_init;
/* Whether the swap controller is active */
#ifdef CONFIG_MEMCG_SWAP
-bool cgroup_memory_noswap __read_mostly;
+bool cgroup_memory_noswap __ro_after_init;
#else
#define cgroup_memory_noswap 1
#endif
@@ -256,6 +256,11 @@ struct cgroup_subsys_state *vmpressure_to_css(struct vmpressure *vmpr)
#ifdef CONFIG_MEMCG_KMEM
extern spinlock_t css_set_lock;
+bool mem_cgroup_kmem_disabled(void)
+{
+ return cgroup_memory_nokmem;
+}
+
static void obj_cgroup_uncharge_pages(struct obj_cgroup *objcg,
unsigned int nr_pages);
diff --git a/mm/percpu-internal.h b/mm/percpu-internal.h
index ae26b118e246..639662c20c82 100644
--- a/mm/percpu-internal.h
+++ b/mm/percpu-internal.h
@@ -6,25 +6,6 @@
#include <linux/percpu.h>
/*
- * There are two chunk types: root and memcg-aware.
- * Chunks of each type have separate slots list.
- *
- * Memcg-aware chunks have an attached vector of obj_cgroup pointers, which is
- * used to store memcg membership data of a percpu object. Obj_cgroups are
- * ref-counted pointers to a memory cgroup with an ability to switch dynamically
- * to the parent memory cgroup. This allows to reclaim a deleted memory cgroup
- * without reclaiming of all outstanding objects, which hold a reference at it.
- */
-enum pcpu_chunk_type {
- PCPU_CHUNK_ROOT,
-#ifdef CONFIG_MEMCG_KMEM
- PCPU_CHUNK_MEMCG,
-#endif
- PCPU_NR_CHUNK_TYPES,
- PCPU_FAIL_ALLOC = PCPU_NR_CHUNK_TYPES
-};
-
-/*
* pcpu_block_md is the metadata block struct.
* Each chunk's bitmap is split into a number of full blocks.
* All units are in terms of bits.
@@ -67,6 +48,8 @@ struct pcpu_chunk {
void *data; /* chunk data */
bool immutable; /* no [de]population allowed */
+ bool isolated; /* isolated from active chunk
+ slots */
int start_offset; /* the overlap with the previous
region to have a page aligned
base_addr */
@@ -87,7 +70,9 @@ extern spinlock_t pcpu_lock;
extern struct list_head *pcpu_chunk_lists;
extern int pcpu_nr_slots;
-extern int pcpu_nr_empty_pop_pages[];
+extern int pcpu_sidelined_slot;
+extern int pcpu_to_depopulate_slot;
+extern int pcpu_nr_empty_pop_pages;
extern struct pcpu_chunk *pcpu_first_chunk;
extern struct pcpu_chunk *pcpu_reserved_chunk;
@@ -128,37 +113,6 @@ static inline int pcpu_chunk_map_bits(struct pcpu_chunk *chunk)
return pcpu_nr_pages_to_map_bits(chunk->nr_pages);
}
-#ifdef CONFIG_MEMCG_KMEM
-static inline enum pcpu_chunk_type pcpu_chunk_type(struct pcpu_chunk *chunk)
-{
- if (chunk->obj_cgroups)
- return PCPU_CHUNK_MEMCG;
- return PCPU_CHUNK_ROOT;
-}
-
-static inline bool pcpu_is_memcg_chunk(enum pcpu_chunk_type chunk_type)
-{
- return chunk_type == PCPU_CHUNK_MEMCG;
-}
-
-#else
-static inline enum pcpu_chunk_type pcpu_chunk_type(struct pcpu_chunk *chunk)
-{
- return PCPU_CHUNK_ROOT;
-}
-
-static inline bool pcpu_is_memcg_chunk(enum pcpu_chunk_type chunk_type)
-{
- return false;
-}
-#endif
-
-static inline struct list_head *pcpu_chunk_list(enum pcpu_chunk_type chunk_type)
-{
- return &pcpu_chunk_lists[pcpu_nr_slots *
- pcpu_is_memcg_chunk(chunk_type)];
-}
-
#ifdef CONFIG_PERCPU_STATS
#include <linux/spinlock.h>
diff --git a/mm/percpu-km.c b/mm/percpu-km.c
index 35c9941077ee..c9d529dc7651 100644
--- a/mm/percpu-km.c
+++ b/mm/percpu-km.c
@@ -44,8 +44,7 @@ static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk,
/* nada */
}
-static struct pcpu_chunk *pcpu_create_chunk(enum pcpu_chunk_type type,
- gfp_t gfp)
+static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp)
{
const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT;
struct pcpu_chunk *chunk;
@@ -53,7 +52,7 @@ static struct pcpu_chunk *pcpu_create_chunk(enum pcpu_chunk_type type,
unsigned long flags;
int i;
- chunk = pcpu_alloc_chunk(type, gfp);
+ chunk = pcpu_alloc_chunk(gfp);
if (!chunk)
return NULL;
@@ -118,3 +117,8 @@ static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai)
return 0;
}
+
+static bool pcpu_should_reclaim_chunk(struct pcpu_chunk *chunk)
+{
+ return false;
+}
diff --git a/mm/percpu-stats.c b/mm/percpu-stats.c
index f6026dbcdf6b..c6bd092ff7a3 100644
--- a/mm/percpu-stats.c
+++ b/mm/percpu-stats.c
@@ -34,15 +34,11 @@ static int find_max_nr_alloc(void)
{
struct pcpu_chunk *chunk;
int slot, max_nr_alloc;
- enum pcpu_chunk_type type;
max_nr_alloc = 0;
- for (type = 0; type < PCPU_NR_CHUNK_TYPES; type++)
- for (slot = 0; slot < pcpu_nr_slots; slot++)
- list_for_each_entry(chunk, &pcpu_chunk_list(type)[slot],
- list)
- max_nr_alloc = max(max_nr_alloc,
- chunk->nr_alloc);
+ for (slot = 0; slot < pcpu_nr_slots; slot++)
+ list_for_each_entry(chunk, &pcpu_chunk_lists[slot], list)
+ max_nr_alloc = max(max_nr_alloc, chunk->nr_alloc);
return max_nr_alloc;
}
@@ -133,9 +129,6 @@ static void chunk_map_stats(struct seq_file *m, struct pcpu_chunk *chunk,
P("cur_min_alloc", cur_min_alloc);
P("cur_med_alloc", cur_med_alloc);
P("cur_max_alloc", cur_max_alloc);
-#ifdef CONFIG_MEMCG_KMEM
- P("memcg_aware", pcpu_is_memcg_chunk(pcpu_chunk_type(chunk)));
-#endif
seq_putc(m, '\n');
}
@@ -144,8 +137,6 @@ static int percpu_stats_show(struct seq_file *m, void *v)
struct pcpu_chunk *chunk;
int slot, max_nr_alloc;
int *buffer;
- enum pcpu_chunk_type type;
- int nr_empty_pop_pages;
alloc_buffer:
spin_lock_irq(&pcpu_lock);
@@ -166,10 +157,6 @@ alloc_buffer:
goto alloc_buffer;
}
- nr_empty_pop_pages = 0;
- for (type = 0; type < PCPU_NR_CHUNK_TYPES; type++)
- nr_empty_pop_pages += pcpu_nr_empty_pop_pages[type];
-
#define PL(X) \
seq_printf(m, " %-20s: %12lld\n", #X, (long long int)pcpu_stats_ai.X)
@@ -201,7 +188,7 @@ alloc_buffer:
PU(nr_max_chunks);
PU(min_alloc_size);
PU(max_alloc_size);
- P("empty_pop_pages", nr_empty_pop_pages);
+ P("empty_pop_pages", pcpu_nr_empty_pop_pages);
seq_putc(m, '\n');
#undef PU
@@ -215,18 +202,17 @@ alloc_buffer:
chunk_map_stats(m, pcpu_reserved_chunk, buffer);
}
- for (type = 0; type < PCPU_NR_CHUNK_TYPES; type++) {
- for (slot = 0; slot < pcpu_nr_slots; slot++) {
- list_for_each_entry(chunk, &pcpu_chunk_list(type)[slot],
- list) {
- if (chunk == pcpu_first_chunk) {
- seq_puts(m, "Chunk: <- First Chunk\n");
- chunk_map_stats(m, chunk, buffer);
- } else {
- seq_puts(m, "Chunk:\n");
- chunk_map_stats(m, chunk, buffer);
- }
- }
+ for (slot = 0; slot < pcpu_nr_slots; slot++) {
+ list_for_each_entry(chunk, &pcpu_chunk_lists[slot], list) {
+ if (chunk == pcpu_first_chunk)
+ seq_puts(m, "Chunk: <- First Chunk\n");
+ else if (slot == pcpu_to_depopulate_slot)
+ seq_puts(m, "Chunk (to_depopulate)\n");
+ else if (slot == pcpu_sidelined_slot)
+ seq_puts(m, "Chunk (sidelined):\n");
+ else
+ seq_puts(m, "Chunk:\n");
+ chunk_map_stats(m, chunk, buffer);
}
}
diff --git a/mm/percpu-vm.c b/mm/percpu-vm.c
index 8d3844bc0c7c..ee5d89fcd66f 100644
--- a/mm/percpu-vm.c
+++ b/mm/percpu-vm.c
@@ -329,13 +329,12 @@ static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk,
pcpu_free_pages(chunk, pages, page_start, page_end);
}
-static struct pcpu_chunk *pcpu_create_chunk(enum pcpu_chunk_type type,
- gfp_t gfp)
+static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp)
{
struct pcpu_chunk *chunk;
struct vm_struct **vms;
- chunk = pcpu_alloc_chunk(type, gfp);
+ chunk = pcpu_alloc_chunk(gfp);
if (!chunk)
return NULL;
@@ -378,3 +377,33 @@ static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai)
/* no extra restriction */
return 0;
}
+
+/**
+ * pcpu_should_reclaim_chunk - determine if a chunk should go into reclaim
+ * @chunk: chunk of interest
+ *
+ * This is the entry point for percpu reclaim. If a chunk qualifies, it is then
+ * isolated and managed in separate lists at the back of pcpu_slot: sidelined
+ * and to_depopulate respectively. The to_depopulate list holds chunks slated
+ * for depopulation. They no longer contribute to pcpu_nr_empty_pop_pages once
+ * they are on this list. Once depopulated, they are moved onto the sidelined
+ * list which enables them to be pulled back in for allocation if no other chunk
+ * can suffice the allocation.
+ */
+static bool pcpu_should_reclaim_chunk(struct pcpu_chunk *chunk)
+{
+ /* do not reclaim either the first chunk or reserved chunk */
+ if (chunk == pcpu_first_chunk || chunk == pcpu_reserved_chunk)
+ return false;
+
+ /*
+ * If it is isolated, it may be on the sidelined list so move it back to
+ * the to_depopulate list. If we hit at least 1/4 pages empty pages AND
+ * there is no system-wide shortage of empty pages aside from this
+ * chunk, move it to the to_depopulate list.
+ */
+ return ((chunk->isolated && chunk->nr_empty_pop_pages) ||
+ (pcpu_nr_empty_pop_pages >
+ (PCPU_EMPTY_POP_PAGES_HIGH + chunk->nr_empty_pop_pages) &&
+ chunk->nr_empty_pop_pages >= chunk->nr_pages / 4));
+}
diff --git a/mm/percpu.c b/mm/percpu.c
index f99e9306b939..b4cebeca4c0c 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -99,7 +99,10 @@
#include "percpu-internal.h"
-/* the slots are sorted by free bytes left, 1-31 bytes share the same slot */
+/*
+ * The slots are sorted by the size of the biggest continuous free area.
+ * 1-31 bytes share the same slot.
+ */
#define PCPU_SLOT_BASE_SHIFT 5
/* chunks in slots below this are subject to being sidelined on failed alloc */
#define PCPU_SLOT_FAIL_THRESHOLD 3
@@ -132,6 +135,9 @@ static int pcpu_unit_size __ro_after_init;
static int pcpu_nr_units __ro_after_init;
static int pcpu_atom_size __ro_after_init;
int pcpu_nr_slots __ro_after_init;
+static int pcpu_free_slot __ro_after_init;
+int pcpu_sidelined_slot __ro_after_init;
+int pcpu_to_depopulate_slot __ro_after_init;
static size_t pcpu_chunk_struct_size __ro_after_init;
/* cpus with the lowest and highest unit addresses */
@@ -173,10 +179,10 @@ struct list_head *pcpu_chunk_lists __ro_after_init; /* chunk list slots */
static LIST_HEAD(pcpu_map_extend_chunks);
/*
- * The number of empty populated pages by chunk type, protected by pcpu_lock.
+ * The number of empty populated pages, protected by pcpu_lock.
* The reserved chunk doesn't contribute to the count.
*/
-int pcpu_nr_empty_pop_pages[PCPU_NR_CHUNK_TYPES];
+int pcpu_nr_empty_pop_pages;
/*
* The number of populated pages in use by the allocator, protected by
@@ -234,7 +240,7 @@ static int __pcpu_size_to_slot(int size)
static int pcpu_size_to_slot(int size)
{
if (size == pcpu_unit_size)
- return pcpu_nr_slots - 1;
+ return pcpu_free_slot;
return __pcpu_size_to_slot(size);
}
@@ -303,6 +309,25 @@ static unsigned long pcpu_block_off_to_off(int index, int off)
return index * PCPU_BITMAP_BLOCK_BITS + off;
}
+/**
+ * pcpu_check_block_hint - check against the contig hint
+ * @block: block of interest
+ * @bits: size of allocation
+ * @align: alignment of area (max PAGE_SIZE)
+ *
+ * Check to see if the allocation can fit in the block's contig hint.
+ * Note, a chunk uses the same hints as a block so this can also check against
+ * the chunk's contig hint.
+ */
+static bool pcpu_check_block_hint(struct pcpu_block_md *block, int bits,
+ size_t align)
+{
+ int bit_off = ALIGN(block->contig_hint_start, align) -
+ block->contig_hint_start;
+
+ return bit_off + bits <= block->contig_hint;
+}
+
/*
* pcpu_next_hint - determine which hint to use
* @block: block of interest
@@ -507,13 +532,10 @@ static void __pcpu_chunk_move(struct pcpu_chunk *chunk, int slot,
bool move_front)
{
if (chunk != pcpu_reserved_chunk) {
- struct list_head *pcpu_slot;
-
- pcpu_slot = pcpu_chunk_list(pcpu_chunk_type(chunk));
if (move_front)
- list_move(&chunk->list, &pcpu_slot[slot]);
+ list_move(&chunk->list, &pcpu_chunk_lists[slot]);
else
- list_move_tail(&chunk->list, &pcpu_slot[slot]);
+ list_move_tail(&chunk->list, &pcpu_chunk_lists[slot]);
}
}
@@ -539,10 +561,36 @@ static void pcpu_chunk_relocate(struct pcpu_chunk *chunk, int oslot)
{
int nslot = pcpu_chunk_slot(chunk);
+ /* leave isolated chunks in-place */
+ if (chunk->isolated)
+ return;
+
if (oslot != nslot)
__pcpu_chunk_move(chunk, nslot, oslot < nslot);
}
+static void pcpu_isolate_chunk(struct pcpu_chunk *chunk)
+{
+ lockdep_assert_held(&pcpu_lock);
+
+ if (!chunk->isolated) {
+ chunk->isolated = true;
+ pcpu_nr_empty_pop_pages -= chunk->nr_empty_pop_pages;
+ }
+ list_move(&chunk->list, &pcpu_chunk_lists[pcpu_to_depopulate_slot]);
+}
+
+static void pcpu_reintegrate_chunk(struct pcpu_chunk *chunk)
+{
+ lockdep_assert_held(&pcpu_lock);
+
+ if (chunk->isolated) {
+ chunk->isolated = false;
+ pcpu_nr_empty_pop_pages += chunk->nr_empty_pop_pages;
+ pcpu_chunk_relocate(chunk, -1);
+ }
+}
+
/*
* pcpu_update_empty_pages - update empty page counters
* @chunk: chunk of interest
@@ -555,8 +603,8 @@ static void pcpu_chunk_relocate(struct pcpu_chunk *chunk, int oslot)
static inline void pcpu_update_empty_pages(struct pcpu_chunk *chunk, int nr)
{
chunk->nr_empty_pop_pages += nr;
- if (chunk != pcpu_reserved_chunk)
- pcpu_nr_empty_pop_pages[pcpu_chunk_type(chunk)] += nr;
+ if (chunk != pcpu_reserved_chunk && !chunk->isolated)
+ pcpu_nr_empty_pop_pages += nr;
}
/*
@@ -1063,14 +1111,11 @@ static int pcpu_find_block_fit(struct pcpu_chunk *chunk, int alloc_bits,
int bit_off, bits, next_off;
/*
- * Check to see if the allocation can fit in the chunk's contig hint.
- * This is an optimization to prevent scanning by assuming if it
- * cannot fit in the global hint, there is memory pressure and creating
- * a new chunk would happen soon.
+ * This is an optimization to prevent scanning by assuming if the
+ * allocation cannot fit in the global hint, there is memory pressure
+ * and creating a new chunk would happen soon.
*/
- bit_off = ALIGN(chunk_md->contig_hint_start, align) -
- chunk_md->contig_hint_start;
- if (bit_off + alloc_bits > chunk_md->contig_hint)
+ if (!pcpu_check_block_hint(chunk_md, alloc_bits, align))
return -1;
bit_off = pcpu_next_hint(chunk_md, alloc_bits);
@@ -1352,7 +1397,7 @@ static struct pcpu_chunk * __init pcpu_alloc_first_chunk(unsigned long tmp_addr,
alloc_size);
#ifdef CONFIG_MEMCG_KMEM
- /* first chunk isn't memcg-aware */
+ /* first chunk is free to use */
chunk->obj_cgroups = NULL;
#endif
pcpu_init_md_blocks(chunk);
@@ -1394,7 +1439,7 @@ static struct pcpu_chunk * __init pcpu_alloc_first_chunk(unsigned long tmp_addr,
return chunk;
}
-static struct pcpu_chunk *pcpu_alloc_chunk(enum pcpu_chunk_type type, gfp_t gfp)
+static struct pcpu_chunk *pcpu_alloc_chunk(gfp_t gfp)
{
struct pcpu_chunk *chunk;
int region_bits;
@@ -1423,7 +1468,7 @@ static struct pcpu_chunk *pcpu_alloc_chunk(enum pcpu_chunk_type type, gfp_t gfp)
goto md_blocks_fail;
#ifdef CONFIG_MEMCG_KMEM
- if (pcpu_is_memcg_chunk(type)) {
+ if (!mem_cgroup_kmem_disabled()) {
chunk->obj_cgroups =
pcpu_mem_zalloc(pcpu_chunk_map_bits(chunk) *
sizeof(struct obj_cgroup *), gfp);
@@ -1536,8 +1581,7 @@ static int pcpu_populate_chunk(struct pcpu_chunk *chunk,
int page_start, int page_end, gfp_t gfp);
static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk,
int page_start, int page_end);
-static struct pcpu_chunk *pcpu_create_chunk(enum pcpu_chunk_type type,
- gfp_t gfp);
+static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp);
static void pcpu_destroy_chunk(struct pcpu_chunk *chunk);
static struct page *pcpu_addr_to_page(void *addr);
static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai);
@@ -1580,25 +1624,25 @@ static struct pcpu_chunk *pcpu_chunk_addr_search(void *addr)
}
#ifdef CONFIG_MEMCG_KMEM
-static enum pcpu_chunk_type pcpu_memcg_pre_alloc_hook(size_t size, gfp_t gfp,
- struct obj_cgroup **objcgp)
+static bool pcpu_memcg_pre_alloc_hook(size_t size, gfp_t gfp,
+ struct obj_cgroup **objcgp)
{
struct obj_cgroup *objcg;
if (!memcg_kmem_enabled() || !(gfp & __GFP_ACCOUNT))
- return PCPU_CHUNK_ROOT;
+ return true;
objcg = get_obj_cgroup_from_current();
if (!objcg)
- return PCPU_CHUNK_ROOT;
+ return true;
if (obj_cgroup_charge(objcg, gfp, size * num_possible_cpus())) {
obj_cgroup_put(objcg);
- return PCPU_FAIL_ALLOC;
+ return false;
}
*objcgp = objcg;
- return PCPU_CHUNK_MEMCG;
+ return true;
}
static void pcpu_memcg_post_alloc_hook(struct obj_cgroup *objcg,
@@ -1608,7 +1652,7 @@ static void pcpu_memcg_post_alloc_hook(struct obj_cgroup *objcg,
if (!objcg)
return;
- if (chunk) {
+ if (likely(chunk && chunk->obj_cgroups)) {
chunk->obj_cgroups[off >> PCPU_MIN_ALLOC_SHIFT] = objcg;
rcu_read_lock();
@@ -1625,10 +1669,12 @@ static void pcpu_memcg_free_hook(struct pcpu_chunk *chunk, int off, size_t size)
{
struct obj_cgroup *objcg;
- if (!pcpu_is_memcg_chunk(pcpu_chunk_type(chunk)))
+ if (unlikely(!chunk->obj_cgroups))
return;
objcg = chunk->obj_cgroups[off >> PCPU_MIN_ALLOC_SHIFT];
+ if (!objcg)
+ return;
chunk->obj_cgroups[off >> PCPU_MIN_ALLOC_SHIFT] = NULL;
obj_cgroup_uncharge(objcg, size * num_possible_cpus());
@@ -1642,10 +1688,10 @@ static void pcpu_memcg_free_hook(struct pcpu_chunk *chunk, int off, size_t size)
}
#else /* CONFIG_MEMCG_KMEM */
-static enum pcpu_chunk_type
+static bool
pcpu_memcg_pre_alloc_hook(size_t size, gfp_t gfp, struct obj_cgroup **objcgp)
{
- return PCPU_CHUNK_ROOT;
+ return true;
}
static void pcpu_memcg_post_alloc_hook(struct obj_cgroup *objcg,
@@ -1680,8 +1726,6 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,
gfp_t pcpu_gfp;
bool is_atomic;
bool do_warn;
- enum pcpu_chunk_type type;
- struct list_head *pcpu_slot;
struct obj_cgroup *objcg = NULL;
static int warn_limit = 10;
struct pcpu_chunk *chunk, *next;
@@ -1717,10 +1761,8 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,
return NULL;
}
- type = pcpu_memcg_pre_alloc_hook(size, gfp, &objcg);
- if (unlikely(type == PCPU_FAIL_ALLOC))
+ if (unlikely(!pcpu_memcg_pre_alloc_hook(size, gfp, &objcg)))
return NULL;
- pcpu_slot = pcpu_chunk_list(type);
if (!is_atomic) {
/*
@@ -1758,8 +1800,9 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,
restart:
/* search through normal chunks */
- for (slot = pcpu_size_to_slot(size); slot < pcpu_nr_slots; slot++) {
- list_for_each_entry_safe(chunk, next, &pcpu_slot[slot], list) {
+ for (slot = pcpu_size_to_slot(size); slot <= pcpu_free_slot; slot++) {
+ list_for_each_entry_safe(chunk, next, &pcpu_chunk_lists[slot],
+ list) {
off = pcpu_find_block_fit(chunk, bits, bit_align,
is_atomic);
if (off < 0) {
@@ -1769,9 +1812,10 @@ restart:
}
off = pcpu_alloc_area(chunk, bits, bit_align, off);
- if (off >= 0)
+ if (off >= 0) {
+ pcpu_reintegrate_chunk(chunk);
goto area_found;
-
+ }
}
}
@@ -1787,8 +1831,8 @@ restart:
goto fail;
}
- if (list_empty(&pcpu_slot[pcpu_nr_slots - 1])) {
- chunk = pcpu_create_chunk(type, pcpu_gfp);
+ if (list_empty(&pcpu_chunk_lists[pcpu_free_slot])) {
+ chunk = pcpu_create_chunk(pcpu_gfp);
if (!chunk) {
err = "failed to allocate new chunk";
goto fail;
@@ -1832,7 +1876,7 @@ area_found:
mutex_unlock(&pcpu_alloc_mutex);
}
- if (pcpu_nr_empty_pop_pages[type] < PCPU_EMPTY_POP_PAGES_LOW)
+ if (pcpu_nr_empty_pop_pages < PCPU_EMPTY_POP_PAGES_LOW)
pcpu_schedule_balance_work();
/* clear the areas and return address relative to base address */
@@ -1930,33 +1974,28 @@ void __percpu *__alloc_reserved_percpu(size_t size, size_t align)
}
/**
- * __pcpu_balance_workfn - manage the amount of free chunks and populated pages
- * @type: chunk type
+ * pcpu_balance_free - manage the amount of free chunks
+ * @empty_only: free chunks only if there are no populated pages
*
- * Reclaim all fully free chunks except for the first one. This is also
- * responsible for maintaining the pool of empty populated pages. However,
- * it is possible that this is called when physical memory is scarce causing
- * OOM killer to be triggered. We should avoid doing so until an actual
- * allocation causes the failure as it is possible that requests can be
- * serviced from already backed regions.
+ * If empty_only is %false, reclaim all fully free chunks regardless of the
+ * number of populated pages. Otherwise, only reclaim chunks that have no
+ * populated pages.
+ *
+ * CONTEXT:
+ * pcpu_lock (can be dropped temporarily)
*/
-static void __pcpu_balance_workfn(enum pcpu_chunk_type type)
+static void pcpu_balance_free(bool empty_only)
{
- /* gfp flags passed to underlying allocators */
- const gfp_t gfp = GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN;
LIST_HEAD(to_free);
- struct list_head *pcpu_slot = pcpu_chunk_list(type);
- struct list_head *free_head = &pcpu_slot[pcpu_nr_slots - 1];
+ struct list_head *free_head = &pcpu_chunk_lists[pcpu_free_slot];
struct pcpu_chunk *chunk, *next;
- int slot, nr_to_pop, ret;
+
+ lockdep_assert_held(&pcpu_lock);
/*
* There's no reason to keep around multiple unused chunks and VM
* areas can be scarce. Destroy all free chunks except for one.
*/
- mutex_lock(&pcpu_alloc_mutex);
- spin_lock_irq(&pcpu_lock);
-
list_for_each_entry_safe(chunk, next, free_head, list) {
WARN_ON(chunk->immutable);
@@ -1964,11 +2003,14 @@ static void __pcpu_balance_workfn(enum pcpu_chunk_type type)
if (chunk == list_first_entry(free_head, struct pcpu_chunk, list))
continue;
- list_move(&chunk->list, &to_free);
+ if (!empty_only || chunk->nr_empty_pop_pages == 0)
+ list_move(&chunk->list, &to_free);
}
- spin_unlock_irq(&pcpu_lock);
+ if (list_empty(&to_free))
+ return;
+ spin_unlock_irq(&pcpu_lock);
list_for_each_entry_safe(chunk, next, &to_free, list) {
unsigned int rs, re;
@@ -1982,6 +2024,29 @@ static void __pcpu_balance_workfn(enum pcpu_chunk_type type)
pcpu_destroy_chunk(chunk);
cond_resched();
}
+ spin_lock_irq(&pcpu_lock);
+}
+
+/**
+ * pcpu_balance_populated - manage the amount of populated pages
+ *
+ * Maintain a certain amount of populated pages to satisfy atomic allocations.
+ * It is possible that this is called when physical memory is scarce causing
+ * OOM killer to be triggered. We should avoid doing so until an actual
+ * allocation causes the failure as it is possible that requests can be
+ * serviced from already backed regions.
+ *
+ * CONTEXT:
+ * pcpu_lock (can be dropped temporarily)
+ */
+static void pcpu_balance_populated(void)
+{
+ /* gfp flags passed to underlying allocators */
+ const gfp_t gfp = GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN;
+ struct pcpu_chunk *chunk;
+ int slot, nr_to_pop, ret;
+
+ lockdep_assert_held(&pcpu_lock);
/*
* Ensure there are certain number of free populated pages for
@@ -2000,23 +2065,21 @@ retry_pop:
pcpu_atomic_alloc_failed = false;
} else {
nr_to_pop = clamp(PCPU_EMPTY_POP_PAGES_HIGH -
- pcpu_nr_empty_pop_pages[type],
+ pcpu_nr_empty_pop_pages,
0, PCPU_EMPTY_POP_PAGES_HIGH);
}
- for (slot = pcpu_size_to_slot(PAGE_SIZE); slot < pcpu_nr_slots; slot++) {
+ for (slot = pcpu_size_to_slot(PAGE_SIZE); slot <= pcpu_free_slot; slot++) {
unsigned int nr_unpop = 0, rs, re;
if (!nr_to_pop)
break;
- spin_lock_irq(&pcpu_lock);
- list_for_each_entry(chunk, &pcpu_slot[slot], list) {
+ list_for_each_entry(chunk, &pcpu_chunk_lists[slot], list) {
nr_unpop = chunk->nr_pages - chunk->nr_populated;
if (nr_unpop)
break;
}
- spin_unlock_irq(&pcpu_lock);
if (!nr_unpop)
continue;
@@ -2026,12 +2089,13 @@ retry_pop:
chunk->nr_pages) {
int nr = min_t(int, re - rs, nr_to_pop);
+ spin_unlock_irq(&pcpu_lock);
ret = pcpu_populate_chunk(chunk, rs, rs + nr, gfp);
+ cond_resched();
+ spin_lock_irq(&pcpu_lock);
if (!ret) {
nr_to_pop -= nr;
- spin_lock_irq(&pcpu_lock);
pcpu_chunk_populated(chunk, rs, rs + nr);
- spin_unlock_irq(&pcpu_lock);
} else {
nr_to_pop = 0;
}
@@ -2043,30 +2107,133 @@ retry_pop:
if (nr_to_pop) {
/* ran out of chunks to populate, create a new one and retry */
- chunk = pcpu_create_chunk(type, gfp);
+ spin_unlock_irq(&pcpu_lock);
+ chunk = pcpu_create_chunk(gfp);
+ cond_resched();
+ spin_lock_irq(&pcpu_lock);
if (chunk) {
- spin_lock_irq(&pcpu_lock);
pcpu_chunk_relocate(chunk, -1);
- spin_unlock_irq(&pcpu_lock);
goto retry_pop;
}
}
+}
- mutex_unlock(&pcpu_alloc_mutex);
+/**
+ * pcpu_reclaim_populated - scan over to_depopulate chunks and free empty pages
+ *
+ * Scan over chunks in the depopulate list and try to release unused populated
+ * pages back to the system. Depopulated chunks are sidelined to prevent
+ * repopulating these pages unless required. Fully free chunks are reintegrated
+ * and freed accordingly (1 is kept around). If we drop below the empty
+ * populated pages threshold, reintegrate the chunk if it has empty free pages.
+ * Each chunk is scanned in the reverse order to keep populated pages close to
+ * the beginning of the chunk.
+ *
+ * CONTEXT:
+ * pcpu_lock (can be dropped temporarily)
+ *
+ */
+static void pcpu_reclaim_populated(void)
+{
+ struct pcpu_chunk *chunk;
+ struct pcpu_block_md *block;
+ int i, end;
+
+ lockdep_assert_held(&pcpu_lock);
+
+restart:
+ /*
+ * Once a chunk is isolated to the to_depopulate list, the chunk is no
+ * longer discoverable to allocations whom may populate pages. The only
+ * other accessor is the free path which only returns area back to the
+ * allocator not touching the populated bitmap.
+ */
+ while (!list_empty(&pcpu_chunk_lists[pcpu_to_depopulate_slot])) {
+ chunk = list_first_entry(&pcpu_chunk_lists[pcpu_to_depopulate_slot],
+ struct pcpu_chunk, list);
+ WARN_ON(chunk->immutable);
+
+ /*
+ * Scan chunk's pages in the reverse order to keep populated
+ * pages close to the beginning of the chunk.
+ */
+ for (i = chunk->nr_pages - 1, end = -1; i >= 0; i--) {
+ /* no more work to do */
+ if (chunk->nr_empty_pop_pages == 0)
+ break;
+
+ /* reintegrate chunk to prevent atomic alloc failures */
+ if (pcpu_nr_empty_pop_pages < PCPU_EMPTY_POP_PAGES_HIGH) {
+ pcpu_reintegrate_chunk(chunk);
+ goto restart;
+ }
+
+ /*
+ * If the page is empty and populated, start or
+ * extend the (i, end) range. If i == 0, decrease
+ * i and perform the depopulation to cover the last
+ * (first) page in the chunk.
+ */
+ block = chunk->md_blocks + i;
+ if (block->contig_hint == PCPU_BITMAP_BLOCK_BITS &&
+ test_bit(i, chunk->populated)) {
+ if (end == -1)
+ end = i;
+ if (i > 0)
+ continue;
+ i--;
+ }
+
+ /* depopulate if there is an active range */
+ if (end == -1)
+ continue;
+
+ spin_unlock_irq(&pcpu_lock);
+ pcpu_depopulate_chunk(chunk, i + 1, end + 1);
+ cond_resched();
+ spin_lock_irq(&pcpu_lock);
+
+ pcpu_chunk_depopulated(chunk, i + 1, end + 1);
+
+ /* reset the range and continue */
+ end = -1;
+ }
+
+ if (chunk->free_bytes == pcpu_unit_size)
+ pcpu_reintegrate_chunk(chunk);
+ else
+ list_move(&chunk->list,
+ &pcpu_chunk_lists[pcpu_sidelined_slot]);
+ }
}
/**
* pcpu_balance_workfn - manage the amount of free chunks and populated pages
* @work: unused
*
- * Call __pcpu_balance_workfn() for each chunk type.
+ * For each chunk type, manage the number of fully free chunks and the number of
+ * populated pages. An important thing to consider is when pages are freed and
+ * how they contribute to the global counts.
*/
static void pcpu_balance_workfn(struct work_struct *work)
{
- enum pcpu_chunk_type type;
+ /*
+ * pcpu_balance_free() is called twice because the first time we may
+ * trim pages in the active pcpu_nr_empty_pop_pages which may cause us
+ * to grow other chunks. This then gives pcpu_reclaim_populated() time
+ * to move fully free chunks to the active list to be freed if
+ * appropriate.
+ */
+ mutex_lock(&pcpu_alloc_mutex);
+ spin_lock_irq(&pcpu_lock);
+
+ pcpu_balance_free(false);
+ pcpu_reclaim_populated();
+ pcpu_balance_populated();
+ pcpu_balance_free(true);
- for (type = 0; type < PCPU_NR_CHUNK_TYPES; type++)
- __pcpu_balance_workfn(type);
+ spin_unlock_irq(&pcpu_lock);
+ mutex_unlock(&pcpu_alloc_mutex);
}
/**
@@ -2085,7 +2252,6 @@ void free_percpu(void __percpu *ptr)
unsigned long flags;
int size, off;
bool need_balance = false;
- struct list_head *pcpu_slot;
if (!ptr)
return;
@@ -2101,19 +2267,24 @@ void free_percpu(void __percpu *ptr)
size = pcpu_free_area(chunk, off);
- pcpu_slot = pcpu_chunk_list(pcpu_chunk_type(chunk));
-
pcpu_memcg_free_hook(chunk, off, size);
- /* if there are more than one fully free chunks, wake up grim reaper */
- if (chunk->free_bytes == pcpu_unit_size) {
+ /*
+ * If there are more than one fully free chunks, wake up grim reaper.
+ * If the chunk is isolated, it may be in the process of being
+ * reclaimed. Let reclaim manage cleaning up of that chunk.
+ */
+ if (!chunk->isolated && chunk->free_bytes == pcpu_unit_size) {
struct pcpu_chunk *pos;
- list_for_each_entry(pos, &pcpu_slot[pcpu_nr_slots - 1], list)
+ list_for_each_entry(pos, &pcpu_chunk_lists[pcpu_free_slot], list)
if (pos != chunk) {
need_balance = true;
break;
}
+ } else if (pcpu_should_reclaim_chunk(chunk)) {
+ pcpu_isolate_chunk(chunk);
+ need_balance = true;
}
trace_percpu_free_percpu(chunk->base_addr, off, ptr);
@@ -2414,7 +2585,6 @@ void __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
int map_size;
unsigned long tmp_addr;
size_t alloc_size;
- enum pcpu_chunk_type type;
#define PCPU_SETUP_BUG_ON(cond) do { \
if (unlikely(cond)) { \
@@ -2528,22 +2698,24 @@ void __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
pcpu_stats_save_ai(ai);
/*
- * Allocate chunk slots. The additional last slot is for
- * empty chunks.
+ * Allocate chunk slots. The slots after the active slots are:
+ * sidelined_slot - isolated, depopulated chunks
+ * free_slot - fully free chunks
+ * to_depopulate_slot - isolated, chunks to depopulate
*/
- pcpu_nr_slots = __pcpu_size_to_slot(pcpu_unit_size) + 2;
+ pcpu_sidelined_slot = __pcpu_size_to_slot(pcpu_unit_size) + 1;
+ pcpu_free_slot = pcpu_sidelined_slot + 1;
+ pcpu_to_depopulate_slot = pcpu_free_slot + 1;
+ pcpu_nr_slots = pcpu_to_depopulate_slot + 1;
pcpu_chunk_lists = memblock_alloc(pcpu_nr_slots *
- sizeof(pcpu_chunk_lists[0]) *
- PCPU_NR_CHUNK_TYPES,
+ sizeof(pcpu_chunk_lists[0]),
SMP_CACHE_BYTES);
if (!pcpu_chunk_lists)
panic("%s: Failed to allocate %zu bytes\n", __func__,
- pcpu_nr_slots * sizeof(pcpu_chunk_lists[0]) *
- PCPU_NR_CHUNK_TYPES);
+ pcpu_nr_slots * sizeof(pcpu_chunk_lists[0]));
- for (type = 0; type < PCPU_NR_CHUNK_TYPES; type++)
- for (i = 0; i < pcpu_nr_slots; i++)
- INIT_LIST_HEAD(&pcpu_chunk_list(type)[i]);
+ for (i = 0; i < pcpu_nr_slots; i++)
+ INIT_LIST_HEAD(&pcpu_chunk_lists[i]);
/*
* The end of the static region needs to be aligned with the
@@ -2580,7 +2752,7 @@ void __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
/* link the first chunk in */
pcpu_first_chunk = chunk;
- pcpu_nr_empty_pop_pages[PCPU_CHUNK_ROOT] = pcpu_first_chunk->nr_empty_pop_pages;
+ pcpu_nr_empty_pop_pages = pcpu_first_chunk->nr_empty_pop_pages;
pcpu_chunk_relocate(pcpu_first_chunk, -1);
/* include all regions of the first chunk */
@@ -2733,6 +2905,7 @@ static struct pcpu_alloc_info * __init __flatten pcpu_build_alloc_info(
* Related to atom_size, which could be much larger than the unit_size.
*/
last_allocs = INT_MAX;
+ best_upa = 0;
for (upa = max_upa; upa; upa--) {
int allocs = 0, wasted = 0;
@@ -2759,6 +2932,7 @@ static struct pcpu_alloc_info * __init __flatten pcpu_build_alloc_info(
last_allocs = allocs;
best_upa = upa;
}
+ BUG_ON(!best_upa);
upa = best_upa;
/* allocate and fill alloc_info */