linux-kernel - Re: [PATCH 00/13] mm: clean up some lru related pieces

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Date:   Fri, 18 Sep 2020 14:19:02 -0700 (PDT)
From:   Hugh Dickins <hughd@...gle.com>
To:     Yu Zhao <yuzhao@...gle.com>
cc:     Hugh Dickins <hughd@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...nel.org>,
        Alex Shi <alex.shi@...ux.alibaba.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Roman Gushchin <guro@...com>,
        Shakeel Butt <shakeelb@...gle.com>,
        Chris Down <chris@...isdown.name>,
        Yafang Shao <laoar.shao@...il.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Huang Ying <ying.huang@...el.com>,
        Pankaj Gupta <pankaj.gupta.linux@...il.com>,
        Matthew Wilcox <willy@...radead.org>,
        Konstantin Khlebnikov <koct9i@...il.com>,
        Minchan Kim <minchan@...nel.org>,
        Jaewon Kim <jaewon31.kim@...sung.com>, cgroups@...r.kernel.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 00/13] mm: clean up some lru related pieces

On Fri, 18 Sep 2020, Yu Zhao wrote:
> On Fri, Sep 18, 2020 at 01:46:59PM -0700, Hugh Dickins wrote:
> > On Thu, 17 Sep 2020, Yu Zhao wrote:
> > 
> > > Hi Andrew,
> > > 
> > > I see you have taken this:
> > >   mm: use add_page_to_lru_list()/page_lru()/page_off_lru()
> > > Do you mind dropping it?
> > > 
> > > Michal asked to do a bit of additional work. So I thought I probably
> > > should create a series to do more cleanups I've been meaning to.
> > > 
> > > This series contains the change in the patch above and goes a few
> > > more steps farther. It's intended to improve readability and should
> > > not have any performance impacts. There are minor behavior changes in
> > > terms of debugging and error reporting, which I have all highlighted
> > > in the individual patches. All patches were properly tested on 5.8
> > > running Chrome OS, with various debug options turned on.
> > > 
> > > Michal,
> > > 
> > > Do you mind taking a looking at the entire series?
> > > 
> > > Thank you.
> > > 
> > > Yu Zhao (13):
> > >   mm: use add_page_to_lru_list()
> > >   mm: use page_off_lru()
> > >   mm: move __ClearPageLRU() into page_off_lru()
> > >   mm: shuffle lru list addition and deletion functions
> > >   mm: don't pass enum lru_list to lru list addition functions
> > >   mm: don't pass enum lru_list to trace_mm_lru_insertion()
> > >   mm: don't pass enum lru_list to del_page_from_lru_list()
> > >   mm: rename page_off_lru() to __clear_page_lru_flags()
> > >   mm: inline page_lru_base_type()
> > >   mm: VM_BUG_ON lru page flags
> > >   mm: inline __update_lru_size()
> > >   mm: make lruvec_lru_size() static
> > >   mm: enlarge the int parameter of update_lru_size()
> > > 
> > >  include/linux/memcontrol.h     |  14 ++--
> > >  include/linux/mm_inline.h      | 115 ++++++++++++++-------------------
> > >  include/linux/mmzone.h         |   2 -
> > >  include/linux/vmstat.h         |   2 +-
> > >  include/trace/events/pagemap.h |  11 ++--
> > >  mm/compaction.c                |   2 +-
> > >  mm/memcontrol.c                |  10 +--
> > >  mm/mlock.c                     |   2 +-
> > >  mm/swap.c                      |  53 ++++++---------
> > >  mm/vmscan.c                    |  28 +++-----
> > >  10 files changed, 95 insertions(+), 144 deletions(-)
> > > 
> > > -- 
> > > 2.28.0.681.g6f77f65b4e-goog
> > 
> > Sorry, Yu, I may be out-of-line in sending this: but as you know,
> > Alex Shi has a long per-memcg lru_lock series playing in much the
> > same area (particularly conflicting in mm/swap.c and mm/vmscan.c):
> > a patchset that makes useful changes, that I'm very keen to help
> > into mmotm a.s.a.p (but not before I've completed diligence).
> > 
> > We've put a lot of effort into its testing, I'm currently reviewing
> > it patch by patch (my general silence indicating that I'm busy on that,
> > but slow as ever): so I'm a bit discouraged to have its stability
> > potentially undermined by conflicting cleanups at this stage.
> > 
> > If there's general agreement that your cleanups are safe and welcome
> > (Michal's initial reaction sheds some doubt on that), great: I hope
> > that Andrew can fast-track them into mmotm, then Alex rebase on top
> > of them, and I then re-test and re-review.
> > 
> > But if that quick agreement is not forthcoming, may I ask you please
> > to hold back, and resend based on top of Alex's next posting?
> 
> The per-memcg lru lock series seems a high priority, and I have
> absolutely no problem accommodate your request.

Many thanks!

> 
> In return, may I ask you or Alex to review this series after you
> have finished with per-memcg lru lock (to make sure that I resolve
> all the conflicts correctly at least)?

Fair enough: I promise to do so.

And your rebasing will necessarily lead you to review some parts
of Alex's patchset, which will help us all too.

Andrew, Yu asked at the start:
> > > I see you have taken this:
> > >   mm: use add_page_to_lru_list()/page_lru()/page_off_lru()
> > > Do you mind dropping it?
Dropping that for now will help too.

Thanks,
Hugh