Re: [PATCH v8 0/4] introduce memory hinting API for external process

From: Minchan Kim <minchan@kernel.org>
To: Oleksandr Natalenko <oleksandr@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Christian Brauner <christian.brauner@ubuntu.com>,
	linux-mm <linux-mm@kvack.org>,
	linux-api@vger.kernel.org, Suren Baghdasaryan <surenb@google.com>,
	Tim Murray <timmurray@google.com>,
	Sandeep Patil <sspatil@google.com>,
	Sonny Rao <sonnyrao@google.com>,
	Brian Geffon <bgeffon@google.com>, Michal Hocko <mhocko@suse.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Shakeel Butt <shakeelb@google.com>,
	John Dias <joaodias@google.com>,
	Joel Fernandes <joel@joelfernandes.org>,
	Jann Horn <jannh@google.com>,
	alexander.h.duyck@linux.intel.com, sj38.park@gmail.com,
	David Rientjes <rientjes@google.com>,
	Arjun Roy <arjunroy@google.com>
Subject: Re: [PATCH v8 0/4]  introduce memory hinting API for external process
Date: Tue, 23 Jun 2020 18:31:22 -0700	[thread overview]
Message-ID: <20200624013122.GA9502@google.com> (raw)
In-Reply-To: <20200623090721.5owt4cxjji6isqe3@butterfly.localdomain>

Hi Oleksandr,

On Tue, Jun 23, 2020 at 11:07:21AM +0200, Oleksandr Natalenko wrote:
> On Mon, Jun 22, 2020 at 12:28:56PM -0700, Minchan Kim wrote:
> > Now, we have MADV_PAGEOUT and MADV_COLD as madvise hinting API. With that,
> > application could give hints to kernel what memory range are preferred to be
> > reclaimed. However, in some platform(e.g., Android), the information
> > required to make the hinting decision is not known to the app.
> > Instead, it is known to a centralized userspace daemon(e.g., ActivityManagerService),
> > and that daemon must be able to initiate reclaim on its own without any app
> > involvement.
> > 
> > To solve the concern, this patch introduces new syscall - process_madvise(2).
> > Bascially, it's same with madvise(2) syscall but it has some differences.
> > 
> > 1. It needs pidfd of target process to provide the hint
> > 2. It supports only MADV_{COLD|PAGEOUT} at this moment.
> >    Other hints in madvise will be opened when there are explicit requests from
> >    community to prevent unexpected bugs we couldn't support.
> > 3. Only privileged processes can do something for other process's address
> >    space.
> > 
> > For more detail of the new API, please see "mm: introduce external memory hinting API"
> > description in this patchset.
> > 
> > * from v7 -  http://lore.kernel.org/r/20200302193630.68771-1-minchan@kernel.org
> >   * dropping pid support from new syscall and fold releated patches into syscall patch
> >   * dropping KSM patch by discussion - Oleksandr, I lost the discussion.
> >     Please resend the single patch against of the patchset if you resolves the discussion.
> >     https://lore.kernel.org/linux-api/20200302193630.68771-8-minchan@kernel.org/
> 
> What "next" tag this (v8) submission is based on please?

It's against on v5.8-rc1-mmots-2020-06-20-21-44 from mmotm - https://github.com/hnaz/linux-mm.git