Re: [PATCH v1 2/5] mm: memcg/percpu: account percpu memory to memory cgroups

Roman Gushchin
2020-06-05T22:44:47Z

On Fri, Jun 05, 2020 at 07:49:53PM +0000, Dennis Zhou wrote:
> On Thu, May 28, 2020 at 04:25:05PM -0700, Roman Gushchin wrote:
> > Percpu memory is becoming more and more widely used by various
> > subsystems, and the total amount of memory controlled by the percpu
> > allocator can make a good part of the total memory.
> >
> > As an example, bpf maps can consume a lot of percpu memory,
> > and they are created by a user. Also, some cgroup internals
> > (e.g. memory controller statistics) can be quite large.
> > On a machine with many CPUs and big number of cgroups they
> > can consume hundreds of megabytes.
> >
> > So the lack of memcg accounting is creating a breach in the memory
> > isolation. Similar to the slab memory, percpu memory should be
> > accounted by default.
> >
> > To implement the perpcu accounting it's possible to take the slab
> > memory accounting as a model to follow. Let's introduce two types of
> > percpu chunks: root and memcg. What makes memcg chunks different is
> > an additional space allocated to store memcg membership information.
> > If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be
> > used. If it's possible to charge the corresponding size to the target
> > memory cgroup, allocation is performed, and the memcg ownership data
> > is recorded. System-wide allocations are performed using root chunks,
> > so there is no additional memory overhead.
> >
> > To implement a fast reparenting of percpu memory on memcg removal,
> > we don't store mem_cgroup pointers directly: instead we use obj_cgroup
> > API, introduced for slab accounting.
> >
> > Signed-off-by: Roman Gushchin <guro@fb.com>
> > ---
> > mm/percpu-internal.h | 57 ++++++++++++-
> > mm/percpu-km.c | 5 +-
> > mm/percpu-stats.c | 36 +++++----
> > mm/percpu-vm.c | 5 +-
> > mm/percpu.c | 186 ++++++++++++++++++++++++++++++++++++++-----
> > 5 files changed, 248 insertions(+), 41 deletions(-)
> >
> > diff --git a/mm/percpu-internal.h b/mm/percpu-internal.h
> > index 0468ba500bd4..0cf36337eb47 100644
> > --- a/mm/percpu-internal.h
> > +++ b/mm/percpu-internal.h
> > @@ -5,6 +5,27 @@
> > #include <linux/types.h>
> > #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 do hold a reference at it.
> > + */
>
> nit: do you mind reflowing this to 80 characters and doing 2 spaces
> after each period to keep the formatting uniform.
>
> > +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.
> > @@ -54,6 +75,9 @@ struct pcpu_chunk {
> > int end_offset; /* additional area required to
> > have the region end page
> > aligned */
> > +#ifdef CONFIG_MEMCG_KMEM
> > + struct obj_cgroup **obj_cgroups; /* vector of object cgroups */
> > +#endif
> >
> > int nr_pages; /* # of pages served by this chunk */
> > int nr_populated; /* # of populated pages */
> > @@ -63,7 +87,7 @@ struct pcpu_chunk {
> >
> > extern spinlock_t pcpu_lock;
> >
> > -extern struct list_head *pcpu_slot;
> > +extern struct list_head *pcpu_chunk_lists;
> > extern int pcpu_nr_slots;
> > extern int pcpu_nr_empty_pop_pages;
> >
> > @@ -106,6 +130,37 @@ 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 enum pcpu_chunk_type pcpu_chunk_type(struct pcpu_chunk *chunk)
> > +{
> > + if (chunk->obj_cgroups)
> > + return PCPU_CHUNK_MEMCG;
> > + return PCPU_CHUNK_ROOT;
> > +}
> > +
> > +static bool pcpu_is_memcg_chunk(enum pcpu_chunk_type chunk_type)
> > +{
> > + return chunk_type == PCPU_CHUNK_MEMCG;
> > +}
> > +
> > +#else
> > +static enum pcpu_chunk_type pcpu_chunk_type(struct pcpu_chunk *chunk)
> > +{
> > + return PCPU_CHUNK_ROOT;
> > +}
> > +
> > +static bool pcpu_is_memcg_chunk(enum pcpu_chunk_type chunk_type)
> > +{
> > + return false;
> > +}
> > +#endif
> > +
> > +static 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 20d2b69a13b0..35c9941077ee 100644
> > --- a/mm/percpu-km.c
> > +++ b/mm/percpu-km.c
> > @@ -44,7 +44,8 @@ static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk,
> > /* nada */
> > }
> >
> > -static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp)
> > +static struct pcpu_chunk *pcpu_create_chunk(enum pcpu_chunk_type type,
> > + gfp_t gfp)
> > {
> > const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT;
> > struct pcpu_chunk *chunk;
> > @@ -52,7 +53,7 @@ static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp)
> > unsigned long flags;
> > int i;
> >
> > - chunk = pcpu_alloc_chunk(gfp);
> > + chunk = pcpu_alloc_chunk(type, gfp);
> > if (!chunk)
> > return NULL;
> >
> > diff --git a/mm/percpu-stats.c b/mm/percpu-stats.c
> > index 32558063c3f9..c8400a2adbc2 100644
> > --- a/mm/percpu-stats.c
> > +++ b/mm/percpu-stats.c
> > @@ -34,11 +34,15 @@ 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 (slot = 0; slot < pcpu_nr_slots; slot++)
> > - list_for_each_entry(chunk, &pcpu_slot[slot], list)
> > - max_nr_alloc = max(max_nr_alloc, chunk->nr_alloc);
> > + 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);
> >
> > return max_nr_alloc;
> > }
> > @@ -129,6 +133,9 @@ 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');
> > }
> >
> > @@ -137,6 +144,7 @@ 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;
> >
> > alloc_buffer:
> > spin_lock_irq(&pcpu_lock);
> > @@ -202,18 +210,18 @@ static int percpu_stats_show(struct seq_file *m, void *v)
> > chunk_map_stats(m, pcpu_reserved_chunk, buffer);
> > }
> >
> > - for (slot = 0; slot < pcpu_nr_slots; slot++) {
> > - list_for_each_entry(chunk, &pcpu_slot[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 (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);
> > + }
> > }
> > -
> > }
> > }
> >
> > diff --git a/mm/percpu-vm.c b/mm/percpu-vm.c
> > index a2b395acef89..e46f7a6917f9 100644
> > --- a/mm/percpu-vm.c
> > +++ b/mm/percpu-vm.c
> > @@ -328,12 +328,13 @@ 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(gfp_t gfp)
> > +static struct pcpu_chunk *pcpu_create_chunk(enum pcpu_chunk_type type,
> > + gfp_t gfp)
> > {
> > struct pcpu_chunk *chunk;
> > struct vm_struct **vms;
> >
> > - chunk = pcpu_alloc_chunk(gfp);
> > + chunk = pcpu_alloc_chunk(type, gfp);
> > if (!chunk)
> > return NULL;
> >
> > diff --git a/mm/percpu.c b/mm/percpu.c
> > index aa36b78d45a6..85f5755c9114 100644
> > --- a/mm/percpu.c
> > +++ b/mm/percpu.c
> > @@ -37,9 +37,14 @@
> > * takes care of normal allocations.
> > *
> > * The allocator organizes chunks into lists according to free size and
> > - * tries to allocate from the fullest chunk first. Each chunk is managed
> > - * by a bitmap with metadata blocks. The allocation map is updated on
> > - * every allocation and free to reflect the current state while the boundary
> > + * memcg-awareness. To make a percpu allocation memcg-aware the __GFP_ACCOUNT
> > + * flag should be passed. All memcg-aware allocations are sharing one set
> > + * of chunks and all unaccounted allocations and allocations performed
> > + * by processes belonging to the root memory cgroup are using the second set.
> > + *
> > + * The allocator tries to allocate from the fullest chunk first. Each chunk
> > + * is managed by a bitmap with metadata blocks. The allocation map is updated
> > + * on every allocation and free to reflect the current state while the boundary
> > * map is only updated on allocation. Each metadata block contains
> > * information to help mitigate the need to iterate over large portions
> > * of the bitmap. The reverse mapping from page to chunk is stored in
> > @@ -81,6 +86,7 @@
> > #include <linux/kmemleak.h>
> > #include <linux/sched.h>
> > #include <linux/sched/mm.h>
> > +#include <linux/memcontrol.h>
> >
> > #include <asm/cacheflush.h>
> > #include <asm/sections.h>
> > @@ -160,7 +166,7 @@ struct pcpu_chunk *pcpu_reserved_chunk __ro_after_init;
> > DEFINE_SPINLOCK(pcpu_lock); /* all internal data structures */
> > static DEFINE_MUTEX(pcpu_alloc_mutex); /* chunk create/destroy, [de]pop, map ext */
> >
> > -struct list_head *pcpu_slot __ro_after_init; /* chunk list slots */
> > +struct list_head *pcpu_chunk_lists __ro_after_init; /* chunk list slots */
> >
> > /* chunks which need their map areas extended, protected by pcpu_lock */
> > static LIST_HEAD(pcpu_map_extend_chunks);
> > @@ -500,6 +506,9 @@ 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]);
> > else
> > @@ -1341,6 +1350,10 @@ static struct pcpu_chunk * __init pcpu_alloc_first_chunk(unsigned long tmp_addr,
> > panic("%s: Failed to allocate %zu bytes\n", __func__,
> > alloc_size);
> >
> > +#ifdef CONFIG_MEMCG_KMEM
> > + /* first chunk isn't memcg-aware */
> > + chunk->obj_cgroups = NULL;
> > +#endif
> > pcpu_init_md_blocks(chunk);
> >
> > /* manage populated page bitmap */
> > @@ -1380,7 +1393,7 @@ static struct pcpu_chunk * __init pcpu_alloc_first_chunk(unsigned long tmp_addr,
> > return chunk;
> > }
> >
> > -static struct pcpu_chunk *pcpu_alloc_chunk(gfp_t gfp)
> > +static struct pcpu_chunk *pcpu_alloc_chunk(enum pcpu_chunk_type type, gfp_t gfp)
> > {
> > struct pcpu_chunk *chunk;
> > int region_bits;
> > @@ -1408,6 +1421,16 @@ static struct pcpu_chunk *pcpu_alloc_chunk(gfp_t gfp)
> > if (!chunk->md_blocks)
> > goto md_blocks_fail;
> >
> > +#ifdef CONFIG_MEMCG_KMEM
> > + if (pcpu_is_memcg_chunk(type)) {
> > + chunk->obj_cgroups =
> > + pcpu_mem_zalloc(pcpu_chunk_map_bits(chunk) *
> > + sizeof(struct obj_cgroup *), gfp);
> > + if (!chunk->obj_cgroups)
> > + goto objcg_fail;
> > + }
> > +#endif
> > +
> > pcpu_init_md_blocks(chunk);
> >
> > /* init metadata */
> > @@ -1415,6 +1438,8 @@ static struct pcpu_chunk *pcpu_alloc_chunk(gfp_t gfp)
> >
> > return chunk;
> >
> > +objcg_fail:
> > + pcpu_mem_free(chunk->md_blocks);
> > md_blocks_fail:
> > pcpu_mem_free(chunk->bound_map);
> > bound_map_fail:
> > @@ -1429,6 +1454,9 @@ static void pcpu_free_chunk(struct pcpu_chunk *chunk)
> > {
> > if (!chunk)
> > return;
> > +#ifdef CONFIG_MEMCG_KMEM
> > + pcpu_mem_free(chunk->obj_cgroups);
> > +#endif
> > pcpu_mem_free(chunk->md_blocks);
> > pcpu_mem_free(chunk->bound_map);
> > pcpu_mem_free(chunk->alloc_map);
> > @@ -1505,7 +1533,8 @@ 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(gfp_t gfp);
> > +static struct pcpu_chunk *pcpu_create_chunk(enum pcpu_chunk_type type,
> > + 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);
> > @@ -1547,6 +1576,77 @@ static struct pcpu_chunk *pcpu_chunk_addr_search(void *addr)
> > return pcpu_get_page_chunk(pcpu_addr_to_page(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)
> > +{
> > + struct obj_cgroup *objcg;
> > +
> > + if (!memcg_kmem_enabled() || !(gfp & __GFP_ACCOUNT) ||
> > + memcg_kmem_bypass())
> > + return PCPU_CHUNK_ROOT;
> > +
> > + objcg = get_obj_cgroup_from_current();
> > + if (!objcg)
> > + return PCPU_CHUNK_ROOT;
> > +
> > + if (obj_cgroup_charge(objcg, gfp, size * num_possible_cpus())) {
> > + obj_cgroup_put(objcg);
> > + return PCPU_FAIL_ALLOC;
> > + }
> > +
> > + *objcgp = objcg;
> > + return PCPU_CHUNK_MEMCG;
> > +}
> > +
> > +static void pcpu_memcg_post_alloc_hook(struct obj_cgroup *objcg,
> > + struct pcpu_chunk *chunk, int off,
> > + size_t size)
> > +{
> > + if (!objcg)
> > + return;
> > +
> > + if (chunk) {
> > + chunk->obj_cgroups[off >> PCPU_MIN_ALLOC_SHIFT] = objcg;
> > + } else {
> > + obj_cgroup_uncharge(objcg, size * num_possible_cpus());
> > + obj_cgroup_put(objcg);
> > + }
> > +}
> > +
> > +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)))
> > + return;
> > +
> > + objcg = chunk->obj_cgroups[off >> PCPU_MIN_ALLOC_SHIFT];
> > + chunk->obj_cgroups[off >> PCPU_MIN_ALLOC_SHIFT] = NULL;
> > +
> > + obj_cgroup_uncharge(objcg, size * num_possible_cpus());
> > +
> > + obj_cgroup_put(objcg);
> > +}
> > +
> > +#else /* CONFIG_MEMCG_KMEM */
> > +static enum pcpu_chunk_type pcpu_memcg_pre_alloc_hook(size_t size, gfp_t gfp,
> > + struct mem_cgroup **memcgp)
> > +{
> > + return PCPU_CHUNK_ROOT;
> > +}
> > +
> > +static void pcpu_memcg_post_alloc_hook(struct mem_cgroup *memcg,
> > + struct pcpu_chunk *chunk, int off,
> > + size_t size)
> > +{
> > +}
> > +
> > +static void pcpu_memcg_free_hook(struct pcpu_chunk *chunk, int off, size_t size)
> > +{
> > +}
> > +#endif /* CONFIG_MEMCG_KMEM */
> > +
> > /**
> > * pcpu_alloc - the percpu allocator
> > * @size: size of area to allocate in bytes
> > @@ -1568,6 +1668,9 @@ 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;
> > const char *err;
> > @@ -1602,16 +1705,23 @@ 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))
> > + return NULL;
> > + pcpu_slot = pcpu_chunk_list(type);
> > +
> > if (!is_atomic) {
> > /*
> > * pcpu_balance_workfn() allocates memory under this mutex,
> > * and it may wait for memory reclaim. Allow current task
> > * to become OOM victim, in case of memory pressure.
> > */
> > - if (gfp & __GFP_NOFAIL)
> > + if (gfp & __GFP_NOFAIL) {
> > mutex_lock(&pcpu_alloc_mutex);
> > - else if (mutex_lock_killable(&pcpu_alloc_mutex))
> > + } else if (mutex_lock_killable(&pcpu_alloc_mutex)) {
> > + pcpu_memcg_post_alloc_hook(objcg, NULL, 0, size);
> > return NULL;
> > + }
> > }
> >
> > spin_lock_irqsave(&pcpu_lock, flags);
> > @@ -1637,7 +1747,8 @@ 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) {
> > + list_for_each_entry_safe(chunk, next, &pcpu_slot[slot],
> > + list) {
>
> nit: this line change doesn't do anything. Can you please remove it.
>
> > off = pcpu_find_block_fit(chunk, bits, bit_align,
> > is_atomic);
> > if (off < 0) {
> > @@ -1666,7 +1777,7 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,
> > }
> >
> > if (list_empty(&pcpu_slot[pcpu_nr_slots - 1])) {
> > - chunk = pcpu_create_chunk(pcpu_gfp);
> > + chunk = pcpu_create_chunk(type, pcpu_gfp);
> > if (!chunk) {
> > err = "failed to allocate new chunk";
> > goto fail;
> > @@ -1723,6 +1834,8 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,
> > trace_percpu_alloc_percpu(reserved, is_atomic, size, align,
> > chunk->base_addr, off, ptr);
> >
> > + pcpu_memcg_post_alloc_hook(objcg, chunk, off, size);
> > +
> > return ptr;
> >
> > fail_unlock:
> > @@ -1744,6 +1857,9 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,
> > } else {
> > mutex_unlock(&pcpu_alloc_mutex);
> > }
> > +
> > + pcpu_memcg_post_alloc_hook(objcg, NULL, 0, size);
> > +
> > return NULL;
> > }
> >
> > @@ -1803,8 +1919,8 @@ void __percpu *__alloc_reserved_percpu(size_t size, size_t align)
> > }
> >
> > /**
> > - * pcpu_balance_workfn - manage the amount of free chunks and populated pages
> > - * @work: unused
> > + * __pcpu_balance_workfn - manage the amount of free chunks and populated pages
> > + * @type: chunk type
> > *
> > * Reclaim all fully free chunks except for the first one. This is also
> > * responsible for maintaining the pool of empty populated pages. However,
> > @@ -1813,11 +1929,12 @@ void __percpu *__alloc_reserved_percpu(size_t size, size_t align)
> > * allocation causes the failure as it is possible that requests can be
> > * serviced from already backed regions.
> > */
> > -static void pcpu_balance_workfn(struct work_struct *work)
> > +static void __pcpu_balance_workfn(enum pcpu_chunk_type type)
> > {
> > /* 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 pcpu_chunk *chunk, *next;
> > int slot, nr_to_pop, ret;
> > @@ -1915,7 +2032,7 @@ static void pcpu_balance_workfn(struct work_struct *work)
> >
> > if (nr_to_pop) {
> > /* ran out of chunks to populate, create a new one and retry */
> > - chunk = pcpu_create_chunk(gfp);
> > + chunk = pcpu_create_chunk(type, gfp);
> > if (chunk) {
> > spin_lock_irq(&pcpu_lock);
> > pcpu_chunk_relocate(chunk, -1);
> > @@ -1927,6 +2044,20 @@ static void pcpu_balance_workfn(struct work_struct *work)
> > mutex_unlock(&pcpu_alloc_mutex);
> > }
> >
> > +/**
> > + * pcpu_balance_workfn - manage the amount of free chunks and populated pages
> > + * @work: unused
> > + *
> > + * Call __pcpu_balance_workfn() for each chunk type.
> > + */
> > +static void pcpu_balance_workfn(struct work_struct *work)
> > +{
> > + enum pcpu_chunk_type type;
> > +
> > + for (type = 0; type < PCPU_NR_CHUNK_TYPES; type++)
> > + __pcpu_balance_workfn(type);
> > +}
> > +
> > /**
> > * free_percpu - free percpu area
> > * @ptr: pointer to area to free
> > @@ -1941,8 +2072,9 @@ void free_percpu(void __percpu *ptr)
> > void *addr;
> > struct pcpu_chunk *chunk;
> > unsigned long flags;
> > - int off;
> > + int size, off;
> > bool need_balance = false;
> > + struct list_head *pcpu_slot;
> >
> > if (!ptr)
> > return;
> > @@ -1956,7 +2088,11 @@ void free_percpu(void __percpu *ptr)
> > chunk = pcpu_chunk_addr_search(addr);
> > off = addr - chunk->base_addr;
> >
> > - pcpu_free_area(chunk, off);
> > + 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) {
> > @@ -2267,6 +2403,7 @@ 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)) { \
> > @@ -2384,13 +2521,18 @@ void __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
> > * empty chunks.
> > */
> > pcpu_nr_slots = __pcpu_size_to_slot(pcpu_unit_size) + 2;
> > - pcpu_slot = memblock_alloc(pcpu_nr_slots * sizeof(pcpu_slot[0]),
> > - SMP_CACHE_BYTES);
> > - if (!pcpu_slot)
> > + pcpu_chunk_lists = memblock_alloc(pcpu_nr_slots *
> > + sizeof(pcpu_chunk_lists[0]) *
> > + PCPU_NR_CHUNK_TYPES,
> > + SMP_CACHE_BYTES);
> > + if (!pcpu_chunk_lists)
> > panic("%s: Failed to allocate %zu bytes\n", __func__,
> > - pcpu_nr_slots * sizeof(pcpu_slot[0]));
> > - for (i = 0; i < pcpu_nr_slots; i++)
> > - INIT_LIST_HEAD(&pcpu_slot[i]);
> > + pcpu_nr_slots * sizeof(pcpu_chunk_lists[0]) *
> > + PCPU_NR_CHUNK_TYPES);
> > +
> > + 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]);
> >
> > /*
> > * The end of the static region needs to be aligned with the
> > --
> > 2.25.4
> >
>
> There were just 2 minor nits. Do you mind resending with them fixed as
> I'm not sure I'll be carrying these patches or not.

Sure, will send v2 based on the slab controller v6 early next week.

>
> Acked-by: Dennis Zhou <dennis@kernel.org>

Thank you!