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From:   Shakeel Butt <shakeelb@google.com>
Date:   Fri, 21 Aug 2020 13:23:20 -0700
Message-ID: <CALvZod7mfgOab_NSBegCcJ4jL6pb98CfckUhk7QgNCLsmiB4aQ@mail.gmail.com>
Subject: Re: [PATCH v6 0/4] Charge loop device i/o to issuing cgroup
To:     Roman Gushchin <guro@fb.com>
Cc:     Dan Schatzberg <schatzberg.dan@gmail.com>,
        Jens Axboe <axboe@kernel.dk>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Jan Kara <jack@suse.cz>, Amir Goldstein <amir73il@gmail.com>,
        Tejun Heo <tj@kernel.org>, Li Zefan <lizefan@huawei.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Michal Hocko <mhocko@kernel.org>,
        Vladimir Davydov <vdavydov.dev@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Hugh Dickins <hughd@google.com>,
        Chris Down <chris@chrisdown.name>,
        Yang Shi <yang.shi@linux.alibaba.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        "Peter Zijlstra (Intel)" <peterz@infradead.org>,
        Ingo Molnar <mingo@kernel.org>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Andrea Arcangeli <aarcange@redhat.com>,
        "open list:BLOCK LAYER" <linux-block@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>,
        "open list:FILESYSTEMS (VFS and infrastructure)" 
        <linux-fsdevel@vger.kernel.org>,
        "open list:CONTROL GROUP (CGROUP)" <cgroups@vger.kernel.org>,
        "open list:CONTROL GROUP - MEMORY RESOURCE CONTROLLER (MEMCG)" 
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On Fri, Aug 21, 2020 at 1:05 PM Roman Gushchin <guro@fb.com> wrote:
>
> On Fri, Aug 21, 2020 at 09:27:56AM -0700, Shakeel Butt wrote:
> > On Fri, Aug 21, 2020 at 9:02 AM Roman Gushchin <guro@fb.com> wrote:
> > >
> > > On Fri, Aug 21, 2020 at 11:04:05AM -0400, Dan Schatzberg wrote:
> > > > On Thu, Aug 20, 2020 at 10:06:44AM -0700, Shakeel Butt wrote:
> > > > > On Thu, May 28, 2020 at 6:55 AM Dan Schatzberg <schatzberg.dan@gmail.com> wrote:
> > > > > >
> > > > > > Much of the discussion about this has died down. There's been a
> > > > > > concern raised that we could generalize infrastructure across loop,
> > > > > > md, etc. This may be possible, in the future, but it isn't clear to me
> > > > > > how this would look like. I'm inclined to fix the existing issue with
> > > > > > loop devices now (this is a problem we hit at FB) and address
> > > > > > consolidation with other cases if and when those need to be addressed.
> > > > > >
> > > > >
> > > > > What's the status of this series?
> > > >
> > > > Thanks for reminding me about this. I haven't got any further
> > > > feedback. I'll bug Jens to take a look and see if he has any concerns
> > > > and if not send a rebased version.
> > >
> > > Just as a note, I stole a patch from this series called
> > > "mm: support nesting memalloc_use_memcg()" to use for the bpf memory accounting.
> > > I rewrote the commit log and rebased to the tot with some trivial changes.
> > >
> > > I just sent it upstream:
> > > https://lore.kernel.org/bpf/20200821150134.2581465-1-guro@fb.com/T/#md7edb6b5b940cee1c4d15e3cef17aa8b07328c2e
> > >
> > > It looks like we need it for two independent sub-systems, so I wonder
> > > if we want to route it first through the mm tree as a standalone patch?
> > >
> >
> > Another way is to push that patch to 5.9-rc2 linus tree, so both block
> > and mm branches for 5.10 will have it. (Not sure if that's ok.)
>
> Ok, it looks like the patch provides a generally useful API enhancement.
> And we do have at least two potential use cases for it.
> Let me send it as a standalone patch to linux-mm@.
>
> Btw, Shakeel, what do you think of s/memalloc_use_memcg()/set_active_memcg() ?
>

I am fine with it.