Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20211001205657.815551-1-surenb@google.com> <5358242.RVGM2oBbkg@devpool47>
 <CAJuCfpF57Wppc_Si98wEo5cASBgEdS7J=Lt9Ont9+TsVr=KM_w@mail.gmail.com> <20211005210003.v3zgqhefn5j65gig@revolver>
In-Reply-To: <20211005210003.v3zgqhefn5j65gig@revolver>
From:   Suren Baghdasaryan <surenb@google.com>
Date:   Tue, 5 Oct 2021 14:30:48 -0700
Message-ID: <CAJuCfpGaxhpePj8KN3S=Q7jMUjaeWZfoBTAHqjodhoH5MV-9yQ@mail.gmail.com>
Subject: Re: [PATCH v10 1/3] mm: rearrange madvise code to allow for reuse
To:     Liam Howlett <liam.howlett@oracle.com>
Cc:     Rolf Eike Beer <eb@emlix.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Colin Cross <ccross@google.com>,
        Sumit Semwal <sumit.semwal@linaro.org>,
        Michal Hocko <mhocko@suse.com>,
        Dave Hansen <dave.hansen@intel.com>,
        Kees Cook <keescook@chromium.org>,
        Matthew Wilcox <willy@infradead.org>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Randy Dunlap <rdunlap@infradead.org>,
        Kalesh Singh <kaleshsingh@google.com>,
        Peter Xu <peterx@redhat.com>,
        "rppt@kernel.org" <rppt@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        "vincenzo.frascino@arm.com" <vincenzo.frascino@arm.com>,
        =?UTF-8?B?Q2hpbndlbiBDaGFuZyAo5by16Yym5paHKQ==?= 
        <chinwen.chang@mediatek.com>,
        Axel Rasmussen <axelrasmussen@google.com>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Jann Horn <jannh@google.com>,
        "apopple@nvidia.com" <apopple@nvidia.com>,
        John Hubbard <jhubbard@nvidia.com>,
        Yu Zhao <yuzhao@google.com>, Will Deacon <will@kernel.org>,
        "fenghua.yu@intel.com" <fenghua.yu@intel.com>,
        "thunder.leizhen@huawei.com" <thunder.leizhen@huawei.com>,
        Hugh Dickins <hughd@google.com>,
        "feng.tang@intel.com" <feng.tang@intel.com>,
        Jason Gunthorpe <jgg@ziepe.ca>, Roman Gushchin <guro@fb.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        "krisman@collabora.com" <krisman@collabora.com>,
        Chris Hyser <chris.hyser@oracle.com>,
        Peter Collingbourne <pcc@google.com>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        Jens Axboe <axboe@kernel.dk>,
        "legion@kernel.org" <legion@kernel.org>,
        Cyrill Gorcunov <gorcunov@gmail.com>,
        Pavel Machek <pavel@ucw.cz>,
        Muchun Song <songmuchun@bytedance.com>,
        Viresh Kumar <viresh.kumar@linaro.org>,
        Thomas Cedeno <thomascedeno@google.com>,
        "sashal@kernel.org" <sashal@kernel.org>,
        "cxfcosmos@gmail.com" <cxfcosmos@gmail.com>,
        LKML <linux-kernel@vger.kernel.org>,
        "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
        "linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
        linux-mm <linux-mm@kvack.org>,
        kernel-team <kernel-team@android.com>,
        Pekka Enberg <penberg@kernel.org>,
        Ingo Molnar <mingo@kernel.org>,
        Oleg Nesterov <oleg@redhat.com>,
        Jan Glauber <jan.glauber@gmail.com>,
        John Stultz <john.stultz@linaro.org>,
        Rob Landley <rob@landley.net>,
        Cyrill Gorcunov <gorcunov@openvz.org>,
        "Serge E. Hallyn" <serge.hallyn@ubuntu.com>,
        David Rientjes <rientjes@google.com>,
        Mel Gorman <mgorman@suse.de>, Shaohua Li <shli@fusionio.com>,
        Minchan Kim <minchan@kernel.org>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

On Tue, Oct 5, 2021 at 2:00 PM Liam Howlett <liam.howlett@oracle.com> wrote=
:
>
> * Suren Baghdasaryan <surenb@google.com> [211004 12:18]:
> > On Mon, Oct 4, 2021 at 12:03 AM Rolf Eike Beer <eb@emlix.com> wrote:
> > >
> > > > --- a/mm/madvise.c
> > > > +++ b/mm/madvise.c
> > > > @@ -63,76 +63,20 @@ static int madvise_need_mmap_write(int behavior=
)
> > > >  }
> > > >
> > > >  /*
> > > > - * We can potentially split a vm area into separate
> > > > - * areas, each area with its own behavior.
> > > > + * Update the vm_flags on regiion of a vma, splitting it or mergin=
g it as
> > >                                 ^^
> >
> > Thanks! Will fix in the next version.
>
> Since you'll be respinning for this comment, can you please point out
> that the split will keep the VMA as [vma->vm_start, new_end)?  That is,
> __split_vma() is passed 0 for new_below.  It might prove useful since
> the code is being reused.

Hmm. There are two cases here:

        if (start !=3D vma->vm_start) {
                ...
                error =3D __split_vma(mm, vma, start, 1);
        }

and

        if (end !=3D vma->vm_end) {
                ...
                error =3D __split_vma(mm, vma, end, 0);
        }

so, I don't think such a comment would be completely correct, no?

>
> Thanks,
> Liam
>
> >
> > >
> > > Eike
> > > --
> > > Rolf Eike Beer, emlix GmbH, http://www.emlix.com
> > > Fon +49 551 30664-0, Fax +49 551 30664-11
> > > Gothaer Platz 3, 37083 G=C3=B6ttingen, Germany
> > > Sitz der Gesellschaft: G=C3=B6ttingen, Amtsgericht G=C3=B6ttingen HR =
B 3160
> > > Gesch=C3=A4ftsf=C3=BChrung: Heike Jordan, Dr. Uwe Kracke =E2=80=93 Us=
t-IdNr.: DE 205 198 055
> > >
> > > emlix - smart embedded open source
> > >
> > > --
> > > To unsubscribe from this group and stop receiving emails from it, sen=
d an email to kernel-team+unsubscribe@android.com.
> >