linux-kernel - Re: [PATCH 5/5] mm/page_alloc: improve memmap_pages and dma

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Date:   Tue, 25 May 2021 16:39:45 +0800
From:   Dong Aisheng <dongas86@...il.com>
To:     David Hildenbrand <david@...hat.com>
Cc:     Dong Aisheng <aisheng.dong@....com>, linux-mm@...ck.org,
        open list <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 5/5] mm/page_alloc: improve memmap_pages and dma_reserve
 dbg msg

On Tue, May 25, 2021 at 4:01 PM David Hildenbrand <david@...hat.com> wrote:
>
> On 17.05.21 13:20, Dong Aisheng wrote:
> > Make debug message more accurately.
> >
> > Cc: Andrew Morton <akpm@...ux-foundation.org>
> > Signed-off-by: Dong Aisheng <aisheng.dong@....com>
> > ---
> >   mm/page_alloc.c | 5 +++--
> >   1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> > index 3100fcb08500..16f494352f58 100644
> > --- a/mm/page_alloc.c
> > +++ b/mm/page_alloc.c
> > @@ -7263,14 +7263,15 @@ static void __init free_area_init_core(struct pglist_data *pgdat)
> >                                       pr_debug("  %s zone: %lu pages used for memmap\n",
> >                                                zone_names[j], memmap_pages);
> >                       } else
> > -                             pr_warn("  %s zone: %lu pages exceeds freesize %lu\n",
> > +                             pr_warn("  %s zone: %lu memmap pages exceeds freesize %lu\n",
> >                                       zone_names[j], memmap_pages, freesize);
> >               }
> >
> >               /* Account for reserved pages */
> >               if (j == 0 && freesize > dma_reserve) {
> >                       freesize -= dma_reserve;
> > -                     pr_debug("  %s zone: %lu pages reserved\n", zone_names[0], dma_reserve);
> > +                     pr_debug("  %s zone: %lu pages reserved for dma\n",
> > +                              zone_names[0], dma_reserve);
>
> ... which is not really correct I think. See the comment above
> set_dma_reserve(). It's called dma_reserve because it involves the first
> zone -- where many unfreeable allocations like the kernel image end up.
>
> Memory is not reserved for dma purposes ... and the zone name should be
> sufficient.

You're right. I will drop this line of change.
Thanks

Regards
Aisheng

>
> --
> Thanks,
>
> David / dhildenb
>
>