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Message-ID: <CALvZod6BMBuJrw2SnaUR8gWUzoX1NYnTC0=XbMYM+B_F4O5sUQ@mail.gmail.com>
Date: Tue, 30 Jun 2020 07:34:13 -0700
From: Shakeel Butt <shakeelb@...gle.com>
To: Roman Gushchin <guro@...com>
Cc: Johannes Weiner <hannes@...xchg.org>,
Michal Hocko <mhocko@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Linux MM <linux-mm@...ck.org>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm: memcontrol: account kernel stack per node
On Mon, Jun 29, 2020 at 8:24 PM Roman Gushchin <guro@...com> wrote:
>
> On Mon, Jun 29, 2020 at 05:44:13PM -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.
> >
> > Signed-off-by: Shakeel Butt <shakeelb@...gle.com>
> > ---
> > drivers/base/node.c | 4 ++--
> > fs/proc/meminfo.c | 4 ++--
> > include/linux/memcontrol.h | 2 --
> > include/linux/mmzone.h | 8 ++++----
> > kernel/fork.c | 29 ++++++++++-------------------
> > kernel/scs.c | 2 +-
> > mm/memcontrol.c | 2 +-
> > mm/page_alloc.c | 16 ++++++++--------
> > mm/vmstat.c | 8 ++++----
> > 9 files changed, 32 insertions(+), 43 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..a3ddb236898e 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,
> > };
> >
> > 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..ee5393350ef7 100644
> > --- a/kernel/fork.c
> > +++ b/kernel/fork.c
> > @@ -278,7 +278,7 @@ static inline void free_thread_stack(struct task_struct *tsk)
> >
> > for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
> > mod_memcg_page_state(vm->pages[i],
> > - MEMCG_KERNEL_STACK_KB,
> > + NR_KERNEL_STACK_KB,
> > -(int)(PAGE_SIZE / 1024));
>
> Hello, Shakeel!
>
> Thank you for the cleanup, it makes total sense to me.
>
> However I have some concerns: mod_memcg_page_state() does change only memcg's counters,
> but not lruvec counters. So to make it per-node per-memcg (aka lruvec)
> we need to use mod_lruvec_state(), otherwise we won't have global per-node values.
>
> >
> > memcg_kmem_uncharge_page(vm->pages[i], 0);
> > @@ -381,32 +381,23 @@ 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);
> > + struct page *page;
> >
> > 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);
> > + page = vm->pages[0];
> >
> > - 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,
> > + page = virt_to_page(stack);
> > + mod_memcg_obj_state(stack, NR_KERNEL_STACK_KB,
> > account * (THREAD_SIZE / 1024));
> > }
> > +
> > + /* All stack pages are in the same node. */
> > + mod_node_page_state(page_pgdat(page), NR_KERNEL_STACK_KB,
> > + THREAD_SIZE / 1024 * account);
> > }
>
> And then we probably don't need a separate change for memcg- and per-node counters.
>
Yes, I thought about combining memcg and per-node counters but got
worried that the cached stacks for CONFIG_VMAP_STACK would not be
accounted for in the per-node global counters but I see that we
already don't account for them in both counters. I will further
simplify these. Thanks for the suggestion.
Shakeel
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