Re: [PATCH v2] mm: memcontrol: account kernel stack per node

From: Roman Gushchin
Date: Tue Jun 30 2020 - 14:36:24 EST

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In reply to: Shakeel Butt: "[PATCH v2] mm: memcontrol: account kernel stack per node"
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On Tue, Jun 30, 2020 at 09:15:39AM -0700, Shakeel Butt wrote:
> Currently the kernel stack is being accounted per-zone. There is no need
> to do that. In addition due to being per-zone, memcg has to keep a
> separate MEMCG_KERNEL_STACK_KB. Make the stat per-node and deprecate
> MEMCG_KERNEL_STACK_KB as memcg_stat_item is an extension of
> node_stat_item. In addition localize the kernel stack stats updates to
> account_kernel_stack().
>
> Signed-off-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
> ---
> Changes since v1:
> - Use lruvec based stat update functions based on Roman's suggestion.

Reviewed-by: Roman Gushchin <guro@xxxxxx>

I really like it, it makes this complicated code way simpler.

Thanks, Shakeel!

>
> drivers/base/node.c | 4 +--
> fs/proc/meminfo.c | 4 +--
> include/linux/memcontrol.h | 21 ++++++++++++++--
> include/linux/mmzone.h | 8 +++---
> kernel/fork.c | 51 +++++++++++---------------------------
> kernel/scs.c | 2 +-
> mm/memcontrol.c | 2 +-
> mm/page_alloc.c | 16 ++++++------
> mm/vmstat.c | 8 +++---
> 9 files changed, 55 insertions(+), 61 deletions(-)
>
> diff --git a/drivers/base/node.c b/drivers/base/node.c
> index 0cf13e31603c..508b80f6329b 100644
> --- a/drivers/base/node.c
> +++ b/drivers/base/node.c
> @@ -440,9 +440,9 @@ static ssize_t node_read_meminfo(struct device *dev,
> nid, K(node_page_state(pgdat, NR_FILE_MAPPED)),
> nid, K(node_page_state(pgdat, NR_ANON_MAPPED)),
> nid, K(i.sharedram),
> - nid, sum_zone_node_page_state(nid, NR_KERNEL_STACK_KB),
> + nid, node_page_state(pgdat, NR_KERNEL_STACK_KB),
> #ifdef CONFIG_SHADOW_CALL_STACK
> - nid, sum_zone_node_page_state(nid, NR_KERNEL_SCS_KB),
> + nid, node_page_state(pgdat, NR_KERNEL_SCS_KB),
> #endif
> nid, K(sum_zone_node_page_state(nid, NR_PAGETABLE)),
> nid, 0UL,
> diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c
> index f262bff3ca31..887a5532e449 100644
> --- a/fs/proc/meminfo.c
> +++ b/fs/proc/meminfo.c
> @@ -101,10 +101,10 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
> show_val_kb(m, "SReclaimable: ", sreclaimable);
> show_val_kb(m, "SUnreclaim: ", sunreclaim);
> seq_printf(m, "KernelStack: %8lu kB\n",
> - global_zone_page_state(NR_KERNEL_STACK_KB));
> + global_node_page_state(NR_KERNEL_STACK_KB));
> #ifdef CONFIG_SHADOW_CALL_STACK
> seq_printf(m, "ShadowCallStack:%8lu kB\n",
> - global_zone_page_state(NR_KERNEL_SCS_KB));
> + global_node_page_state(NR_KERNEL_SCS_KB));
> #endif
> show_val_kb(m, "PageTables: ",
> global_zone_page_state(NR_PAGETABLE));
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index ba1e42715ecf..b8f52a3fed90 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -33,8 +33,6 @@ enum memcg_stat_item {
> MEMCG_SWAP = NR_VM_NODE_STAT_ITEMS,
> MEMCG_SOCK,
> MEMCG_PERCPU_B,
> - /* XXX: why are these zone and not node counters? */
> - MEMCG_KERNEL_STACK_KB,
> MEMCG_NR_STAT,
> };
>
> @@ -737,8 +735,19 @@ void __mod_memcg_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx,
> void __mod_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx,
> int val);
> void __mod_lruvec_slab_state(void *p, enum node_stat_item idx, int val);
> +
> void mod_memcg_obj_state(void *p, int idx, int val);
>
> +static inline void mod_lruvec_slab_state(void *p, enum node_stat_item idx,
> + int val)
> +{
> + unsigned long flags;
> +
> + local_irq_save(flags);
> + __mod_lruvec_slab_state(p, idx, val);
> + local_irq_restore(flags);
> +}
> +
> static inline void mod_memcg_lruvec_state(struct lruvec *lruvec,
> enum node_stat_item idx, int val)
> {
> @@ -1159,6 +1168,14 @@ static inline void __mod_lruvec_slab_state(void *p, enum node_stat_item idx,
> __mod_node_page_state(page_pgdat(page), idx, val);
> }
>
> +static inline void mod_lruvec_slab_state(void *p, enum node_stat_item idx,
> + int val)
> +{
> + struct page *page = virt_to_head_page(p);
> +
> + mod_node_page_state(page_pgdat(page), idx, val);
> +}
> +
> static inline void mod_memcg_obj_state(void *p, int idx, int val)
> {
> }
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index 8e859444927a..b79f73ce8b57 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -153,10 +153,6 @@ enum zone_stat_item {
> NR_ZONE_WRITE_PENDING, /* Count of dirty, writeback and unstable pages */
> NR_MLOCK, /* mlock()ed pages found and moved off LRU */
> NR_PAGETABLE, /* used for pagetables */
> - NR_KERNEL_STACK_KB, /* measured in KiB */
> -#if IS_ENABLED(CONFIG_SHADOW_CALL_STACK)
> - NR_KERNEL_SCS_KB, /* measured in KiB */
> -#endif
> /* Second 128 byte cacheline */
> NR_BOUNCE,
> #if IS_ENABLED(CONFIG_ZSMALLOC)
> @@ -201,6 +197,10 @@ enum node_stat_item {
> NR_KERNEL_MISC_RECLAIMABLE, /* reclaimable non-slab kernel pages */
> NR_FOLL_PIN_ACQUIRED, /* via: pin_user_page(), gup flag: FOLL_PIN */
> NR_FOLL_PIN_RELEASED, /* pages returned via unpin_user_page() */
> + NR_KERNEL_STACK_KB, /* measured in KiB */
> +#if IS_ENABLED(CONFIG_SHADOW_CALL_STACK)
> + NR_KERNEL_SCS_KB, /* measured in KiB */
> +#endif
> NR_VM_NODE_STAT_ITEMS
> };
>
> diff --git a/kernel/fork.c b/kernel/fork.c
> index 73fdfa9674b5..f00c7a4913e1 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -276,13 +276,8 @@ static inline void free_thread_stack(struct task_struct *tsk)
> if (vm) {
> int i;
>
> - for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
> - mod_memcg_page_state(vm->pages[i],
> - MEMCG_KERNEL_STACK_KB,
> - -(int)(PAGE_SIZE / 1024));
> -
> + for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
> memcg_kmem_uncharge_page(vm->pages[i], 0);
> - }
>
> for (i = 0; i < NR_CACHED_STACKS; i++) {
> if (this_cpu_cmpxchg(cached_stacks[i],
> @@ -382,31 +377,14 @@ static void account_kernel_stack(struct task_struct *tsk, int account)
> void *stack = task_stack_page(tsk);
> struct vm_struct *vm = task_stack_vm_area(tsk);
>
> - BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK) && PAGE_SIZE % 1024 != 0);
> -
> - if (vm) {
> - int i;
> -
> - BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
>
> - for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
> - mod_zone_page_state(page_zone(vm->pages[i]),
> - NR_KERNEL_STACK_KB,
> - PAGE_SIZE / 1024 * account);
> - }
> - } else {
> - /*
> - * All stack pages are in the same zone and belong to the
> - * same memcg.
> - */
> - struct page *first_page = virt_to_page(stack);
> -
> - mod_zone_page_state(page_zone(first_page), NR_KERNEL_STACK_KB,
> - THREAD_SIZE / 1024 * account);
> -
> - mod_memcg_obj_state(stack, MEMCG_KERNEL_STACK_KB,
> - account * (THREAD_SIZE / 1024));
> - }
> + /* All stack pages are in the same node. */
> + if (vm)
> + mod_lruvec_page_state(vm->pages[0], NR_KERNEL_STACK_KB,
> + account * (THREAD_SIZE / 1024));
> + else
> + mod_lruvec_slab_state(stack, NR_KERNEL_STACK_KB,
> + account * (THREAD_SIZE / 1024));
> }
>
> static int memcg_charge_kernel_stack(struct task_struct *tsk)
> @@ -415,24 +393,23 @@ static int memcg_charge_kernel_stack(struct task_struct *tsk)
> struct vm_struct *vm = task_stack_vm_area(tsk);
> int ret;
>
> + BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK) && PAGE_SIZE % 1024 != 0);
> +
> if (vm) {
> int i;
>
> + BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
> +
> for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
> /*
> * If memcg_kmem_charge_page() fails, page->mem_cgroup
> - * pointer is NULL, and both memcg_kmem_uncharge_page()
> - * and mod_memcg_page_state() in free_thread_stack()
> - * will ignore this page. So it's safe.
> + * pointer is NULL, and memcg_kmem_uncharge_page() in
> + * free_thread_stack() will ignore this page.
> */
> ret = memcg_kmem_charge_page(vm->pages[i], GFP_KERNEL,
> 0);
> if (ret)
> return ret;
> -
> - mod_memcg_page_state(vm->pages[i],
> - MEMCG_KERNEL_STACK_KB,
> - PAGE_SIZE / 1024);
> }
> }
> #endif
> diff --git a/kernel/scs.c b/kernel/scs.c
> index 5d4d9bbdec36..4ff4a7ba0094 100644
> --- a/kernel/scs.c
> +++ b/kernel/scs.c
> @@ -17,7 +17,7 @@ static void __scs_account(void *s, int account)
> {
> struct page *scs_page = virt_to_page(s);
>
> - mod_zone_page_state(page_zone(scs_page), NR_KERNEL_SCS_KB,
> + mod_node_page_state(page_pgdat(scs_page), NR_KERNEL_SCS_KB,
> account * (SCS_SIZE / SZ_1K));
> }
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index b1a644224383..06de63901f81 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -1485,7 +1485,7 @@ static char *memory_stat_format(struct mem_cgroup *memcg)
> (u64)memcg_page_state(memcg, NR_FILE_PAGES) *
> PAGE_SIZE);
> seq_buf_printf(&s, "kernel_stack %llu\n",
> - (u64)memcg_page_state(memcg, MEMCG_KERNEL_STACK_KB) *
> + (u64)memcg_page_state(memcg, NR_KERNEL_STACK_KB) *
> 1024);
> seq_buf_printf(&s, "slab %llu\n",
> (u64)(memcg_page_state(memcg, NR_SLAB_RECLAIMABLE_B) +
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 174c849ba9f2..0568b126f719 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5402,6 +5402,10 @@ void show_free_areas(unsigned int filter, nodemask_t *nodemask)
> " anon_thp: %lukB"
> #endif
> " writeback_tmp:%lukB"
> + " kernel_stack:%lukB"
> +#ifdef CONFIG_SHADOW_CALL_STACK
> + " shadow_call_stack:%lukB"
> +#endif
> " all_unreclaimable? %s"
> "\n",
> pgdat->node_id,
> @@ -5423,6 +5427,10 @@ void show_free_areas(unsigned int filter, nodemask_t *nodemask)
> K(node_page_state(pgdat, NR_ANON_THPS) * HPAGE_PMD_NR),
> #endif
> K(node_page_state(pgdat, NR_WRITEBACK_TEMP)),
> + node_page_state(pgdat, NR_KERNEL_STACK_KB),
> +#ifdef CONFIG_SHADOW_CALL_STACK
> + node_page_state(pgdat, NR_KERNEL_SCS_KB),
> +#endif
> pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES ?
> "yes" : "no");
> }
> @@ -5454,10 +5462,6 @@ void show_free_areas(unsigned int filter, nodemask_t *nodemask)
> " present:%lukB"
> " managed:%lukB"
> " mlocked:%lukB"
> - " kernel_stack:%lukB"
> -#ifdef CONFIG_SHADOW_CALL_STACK
> - " shadow_call_stack:%lukB"
> -#endif
> " pagetables:%lukB"
> " bounce:%lukB"
> " free_pcp:%lukB"
> @@ -5479,10 +5483,6 @@ void show_free_areas(unsigned int filter, nodemask_t *nodemask)
> K(zone->present_pages),
> K(zone_managed_pages(zone)),
> K(zone_page_state(zone, NR_MLOCK)),
> - zone_page_state(zone, NR_KERNEL_STACK_KB),
> -#ifdef CONFIG_SHADOW_CALL_STACK
> - zone_page_state(zone, NR_KERNEL_SCS_KB),
> -#endif
> K(zone_page_state(zone, NR_PAGETABLE)),
> K(zone_page_state(zone, NR_BOUNCE)),
> K(free_pcp),
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index 2c5a96694490..96bf8bfffd1d 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -1158,10 +1158,6 @@ const char * const vmstat_text[] = {
> "nr_zone_write_pending",
> "nr_mlock",
> "nr_page_table_pages",
> - "nr_kernel_stack",
> -#if IS_ENABLED(CONFIG_SHADOW_CALL_STACK)
> - "nr_shadow_call_stack",
> -#endif
> "nr_bounce",
> #if IS_ENABLED(CONFIG_ZSMALLOC)
> "nr_zspages",
> @@ -1212,6 +1208,10 @@ const char * const vmstat_text[] = {
> "nr_kernel_misc_reclaimable",
> "nr_foll_pin_acquired",
> "nr_foll_pin_released",
> + "nr_kernel_stack",
> +#if IS_ENABLED(CONFIG_SHADOW_CALL_STACK)
> + "nr_shadow_call_stack",
> +#endif
>
> /* enum writeback_stat_item counters */
> "nr_dirty_threshold",
> --
> 2.27.0.212.ge8ba1cc988-goog
>

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In reply to: Shakeel Butt: "[PATCH v2] mm: memcontrol: account kernel stack per node"
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