linux-kernel - Re: [PATCH 1/2] mm/damon: simplify the parameter passing for 'check

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Message-ID: <CAGjdHumMbS_jzt_HbTbmwrxOuY5yOC5U8Dq+A5AY_w78CBOHGw@mail.gmail.com>
Date:   Sat, 27 Aug 2022 04:32:47 +0800
From:   Kaixu Xia <xiakaixu1987@...il.com>
To:     SeongJae Park <sj@...nel.org>
Cc:     akpm@...ux-foundation.org, damon@...ts.linux.dev,
        linux-mm@...ck.org, LKML <linux-kernel@...r.kernel.org>,
        Kaixu Xia <kaixuxia@...cent.com>
Subject: Re: [PATCH 1/2] mm/damon: simplify the parameter passing for 'check_accesses'

On Sat, Aug 27, 2022 at 1:08 AM SeongJae Park <sj@...nel.org> wrote:
>
> Hi Kaixu,
>
> On Fri, 26 Aug 2022 16:31:17 +0800 xiakaixu1987@...il.com wrote:
>
> > From: Kaixu Xia <kaixuxia@...cent.com>
> >
> > The parameter 'struct damon_ctx *ctx' is unnecessary in damon
> > 'check_accesses' callback operation, so we can remove it.
>
> Thank you for the finding, but this wording is not 100% perfect, strictly
> speaking.  The callback operations indeed use the parameter, but the internal
> functions called by the callbacks (__damon_{p,v}a_check_access()) aren't.
>
> Could you please update the message?

Thanks for your comments. I will update it in the next version.
>
> >
> > Signed-off-by: Kaixu Xia <kaixuxia@...cent.com>
> > ---
> >  mm/damon/paddr.c | 5 ++---
> >  mm/damon/vaddr.c | 5 ++---
> >  2 files changed, 4 insertions(+), 6 deletions(-)
> >
> > diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
> > index dc131c6a5403..6b0d9e6aa677 100644
> > --- a/mm/damon/paddr.c
> > +++ b/mm/damon/paddr.c
> > @@ -166,8 +166,7 @@ static bool damon_pa_young(unsigned long paddr, unsigned long *page_sz)
> >       return result.accessed;
> >  }
> >
> > -static void __damon_pa_check_access(struct damon_ctx *ctx,
> > -                                 struct damon_region *r)
> > +static void __damon_pa_check_access(struct damon_region *r)
> >  {
> >       static unsigned long last_addr;
> >       static unsigned long last_page_sz = PAGE_SIZE;
> > @@ -196,7 +195,7 @@ static unsigned int damon_pa_check_accesses(struct damon_ctx *ctx)
> >
> >       damon_for_each_target(t, ctx) {
> >               damon_for_each_region(r, t) {
> > -                     __damon_pa_check_access(ctx, r);
> > +                     __damon_pa_check_access(r);
> >                       max_nr_accesses = max(r->nr_accesses, max_nr_accesses);
> >               }
> >       }
> > diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c
> > index 3c7b9d6dca95..c8c2f306bb6d 100644
> > --- a/mm/damon/vaddr.c
> > +++ b/mm/damon/vaddr.c
> > @@ -532,8 +532,7 @@ static bool damon_va_young(struct mm_struct *mm, unsigned long addr,
> >   * mm        'mm_struct' for the given virtual address space
> >   * r the region to be checked
> >   */
> > -static void __damon_va_check_access(struct damon_ctx *ctx,
> > -                            struct mm_struct *mm, struct damon_region *r)
> > +static void __damon_va_check_access(struct mm_struct *mm, struct damon_region *r)
>
> I still prefer 80 columns rule[1].  Could you please break this line?
>
>
> [1] https://docs.kernel.org/process/coding-style.html#breaking-long-lines-and-strings

Sorry, I missed the warning in the new 100 characters rules :)  Will fix it.
>
> >  {
> >       static struct mm_struct *last_mm;
> >       static unsigned long last_addr;
> > @@ -568,7 +567,7 @@ static unsigned int damon_va_check_accesses(struct damon_ctx *ctx)
> >               if (!mm)
> >                       continue;
> >               damon_for_each_region(r, t) {
> > -                     __damon_va_check_access(ctx, mm, r);
> > +                     __damon_va_check_access(mm, r);
> >                       max_nr_accesses = max(r->nr_accesses, max_nr_accesses);
> >               }
> >               mmput(mm);
> > --
> > 2.27.0
>
>
> Thanks,
> SJ