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From:   Alexander Duyck <alexander.duyck@gmail.com>
Date:   Thu, 13 Aug 2020 07:32:46 -0700
Message-ID: <CAKgT0UcRFqXUOJ+QjgtjdQE6A7EMgAc_v9b7+mXy-ZJLvG2AgQ@mail.gmail.com>
Subject: Re: [RFC PATCH 1/3] mm: Drop locked from isolate_migratepages_block
To:     Alex Shi <alex.shi@linux.alibaba.com>
Cc:     Yang Shi <yang.shi@linux.alibaba.com>,
        kbuild test robot <lkp@intel.com>,
        Rong Chen <rong.a.chen@intel.com>,
        Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
        "Kirill A. Shutemov" <kirill@shutemov.name>,
        Hugh Dickins <hughd@google.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Daniel Jordan <daniel.m.jordan@oracle.com>,
        linux-mm <linux-mm@kvack.org>,
        Shakeel Butt <shakeelb@google.com>,
        Matthew Wilcox <willy@infradead.org>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Tejun Heo <tj@kernel.org>, cgroups@vger.kernel.org,
        Andrew Morton <akpm@linux-foundation.org>,
        Wei Yang <richard.weiyang@gmail.com>,
        Mel Gorman <mgorman@techsingularity.net>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>
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On Wed, Aug 12, 2020 at 11:57 PM Alex Shi <alex.shi@linux.alibaba.com> wrot=
e:
>
>
>
> =E5=9C=A8 2020/8/13 =E4=B8=8B=E5=8D=8812:02, Alexander Duyck =E5=86=99=E9=
=81=93:
> > From: Alexander Duyck <alexander.h.duyck@linux.intel.com>
> >
> > We can drop the need for the locked variable by making use of the
> > lruvec_holds_page_lru_lock function. By doing this we can avoid some rc=
u
> > locking ugliness for the case where the lruvec is still holding the LRU
> > lock associated with the page. Instead we can just use the lruvec and i=
f it
> > is NULL we assume the lock was released.
> >
> > Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
> > ---
> >  mm/compaction.c |   45 ++++++++++++++++++++-------------------------
> >  1 file changed, 20 insertions(+), 25 deletions(-)
>
> Thanks a lot!
> Don't know if community is ok if we keep the patch following whole patchs=
et alone?

I am fine with you squashing it with another patch if you want. In
theory this could probably be squashed in with the earlier patch I
submitted that introduced lruvec_holds_page_lru_lock or some other
patch. It is mostly just a cleanup anyway as it gets us away from
needing to hold the RCU read lock in the case that we already have the
correct lruvec.