Re: [RFC 2/5] memcontrol: add boot option to enable memsw account on dfl

[jingxiang zeng <jingxiangzeng.cas@gmail.com>]

On Thu, 20 Mar 2025 at 03:34, Shakeel Butt <shakeel.butt@linux.dev> wrote:
>
> On Wed, Mar 19, 2025 at 02:41:45PM +0800, Jingxiang Zeng wrote:
> > From: Zeng Jingxiang <linuszeng@tencent.com>
> >
> > Added cgroup.memsw_account_on_dfl startup parameter, which
> > is off by default. When enabled in cgroupv2 mode, the memory
> > accounting mode of swap will be reverted to cgroupv1 mode.
> >
> > Signed-off-by: Zeng Jingxiang <linuszeng@tencent.com>
> > ---
> >  include/linux/memcontrol.h |  4 +++-
> >  mm/memcontrol.c            | 11 +++++++++++
> >  2 files changed, 14 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> > index dcb087ee6e8d..96f2fad1c351 100644
> > --- a/include/linux/memcontrol.h
> > +++ b/include/linux/memcontrol.h
> > @@ -62,10 +62,12 @@ struct mem_cgroup_reclaim_cookie {
> >
> >  #ifdef CONFIG_MEMCG
> >
> > +DECLARE_STATIC_KEY_FALSE(memsw_account_on_dfl);
> >  /* Whether enable memory+swap account in cgroupv2 */
> >  static inline bool do_memsw_account_on_dfl(void)
> >  {
> > -     return IS_ENABLED(CONFIG_MEMSW_ACCOUNT_ON_DFL);
> > +     return IS_ENABLED(CONFIG_MEMSW_ACCOUNT_ON_DFL)
> > +                             || static_branch_unlikely(&memsw_account_on_dfl);
>
> Why || in above condition? Shouldn't it be && ?

It seems that changing it to && is better, Thanks.
>
> >  }
> >
> >  #define MEM_CGROUP_ID_SHIFT  16
> > diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> > index 768d6b15dbfa..c1171fb2bfd6 100644
> > --- a/mm/memcontrol.c
> > +++ b/mm/memcontrol.c
> > @@ -5478,3 +5478,14 @@ static int __init mem_cgroup_swap_init(void)
> >  subsys_initcall(mem_cgroup_swap_init);
> >
> >  #endif /* CONFIG_SWAP */
> > +
> > +DEFINE_STATIC_KEY_FALSE(memsw_account_on_dfl);
> > +static int __init memsw_account_on_dfl_setup(char *s)
> > +{
> > +     if (!strcmp(s, "1"))
> > +             static_branch_enable(&memsw_account_on_dfl);
> > +     else if (!strcmp(s, "0"))
> > +             static_branch_disable(&memsw_account_on_dfl);
> > +     return 1;
> > +}
> > +__setup("cgroup.memsw_account_on_dfl=", memsw_account_on_dfl_setup);
>
> Please keep the above in memcontrol-v1.c
>
> > +
> > \ No newline at end of file
> > --
> > 2.41.1
> >
>