linux-kernel - Re: [PATCH v2] mm: cma: print cma name as well in cma

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Message-ID: <CAOuPNLi9zcLF_mpjxUR6fOjQ0q0BGoauaofpptuFi+mkkxXSKQ@mail.gmail.com>
Date:   Sat, 8 Jul 2023 12:22:06 +0530
From:   Pintu Agarwal <pintu.ping@...il.com>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Anshuman Khandual <anshuman.khandual@....com>,
        Pintu Kumar <quic_pintu@...cinc.com>,
        linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
        linux-mm@...ck.org
Subject: Re: [PATCH v2] mm: cma: print cma name as well in cma_alloc debug

On Fri, 7 Jul 2023 at 20:03, Pintu Agarwal <pintu.ping@...il.com> wrote:
>
> On Fri, 7 Jul 2023 at 19:52, Matthew Wilcox <willy@...radead.org> wrote:
> >
> > On Fri, Jul 07, 2023 at 07:46:31PM +0530, Pintu Agarwal wrote:
> > > On Fri, 7 Jul 2023 at 19:40, Matthew Wilcox <willy@...radead.org> wrote:
> > > > > One more question from here:
> > > > > pr_debug("%s(cma %p, name: %s, count %lu, align %d)\n", __func__,
> > > > >                 (void *)cma, cma->name, count, align);
> > > > >
> > > > > Do we really need this "cma %p" printing ?
> > > > > I hardly check it and simply rely on name and count.
> > > >
> > > > Printing pointers is almost always a bad idea.  Printing the base_pfn
> > > > might be a good idea to distinguish CMAs which happen to have the
> > > > same name?
> > > >
> > > No there is no name there, it's just a ptrval
> > > cma: cma_alloc(cma (ptrval), name: reserved, count 64, align 6)
> >
> > You misunderstand me.  I don't know how CMAs get their name.  Is it not
> > possible for two CMAs to have the same name as each other?
> >
> Oh yah that is possible, for example multiple players can use the same
> global cma region.

Yes, I think it's a good idea to include base_pfn instead of printing pointers.
Let's complete the cma->name inclusion first.
Later I will check about base_pfn and push in another patch.
Thanks