linux-kernel - Re: [PATCH] mm: memcontrol: fix kernel stack account

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Message-ID: <CALvZod6Aqq_yCjfdbgKb1=Ocd04O=X_tNJ81kzyX77wHzBKBwA@mail.gmail.com>
Date:   Tue, 2 Mar 2021 06:02:14 -0800
From:   Shakeel Butt <shakeelb@...gle.com>
To:     Muchun Song <songmuchun@...edance.com>
Cc:     Roman Gushchin <guro@...com>, Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux MM <linux-mm@...ck.org>
Subject: Re: [PATCH] mm: memcontrol: fix kernel stack account

On Mon, Mar 1, 2021 at 11:52 PM Muchun Song <songmuchun@...edance.com> wrote:
>
> The alloc_thread_stack_node() cannot guarantee that allocated stack pages
> are in the same node when CONFIG_VMAP_STACK. Because we do not specify
> __GFP_THISNODE to __vmalloc_node_range().

Instead of __GFP_THISNODE, mention that the kernel_clone() passes
NUMA_NO_NODE which is being used for __vmalloc_node_range().

> Fix it by caling

calling

> mod_lruvec_page_state() for each page one by one.
>
> Fixes: 991e7673859e ("mm: memcontrol: account kernel stack per node")
> Signed-off-by: Muchun Song <songmuchun@...edance.com>

Please follow Michal's suggestion to update the commit message.

After that:

Reviewed-by: Shakeel Butt <shakeelb@...gle.com>

> ---
>  kernel/fork.c | 15 ++++++++++-----
>  1 file changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/kernel/fork.c b/kernel/fork.c
> index d66cd1014211..6e2201feb524 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -379,14 +379,19 @@ 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);
>
> +       if (vm) {
> +               int i;
>
> -       /* 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
> +               BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
> +
> +               for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
> +                       mod_lruvec_page_state(vm->pages[i], NR_KERNEL_STACK_KB,
> +                                             account * (PAGE_SIZE / 1024));
> +       } else {
> +               /* All stack pages are in the same node. */
>                 mod_lruvec_kmem_state(stack, NR_KERNEL_STACK_KB,
>                                       account * (THREAD_SIZE / 1024));
> +       }
>  }
>
>  static int memcg_charge_kernel_stack(struct task_struct *tsk)
> --
> 2.11.0
>