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Date: Tue, 12 Mar 2024 13:36:54 -0700
From: Roman Gushchin <roman.gushchin@linux.dev>
To: Matthew Wilcox <willy@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Josh Poimboeuf <jpoimboe@kernel.org>,
	Jeff Layton <jlayton@kernel.org>,
	Chuck Lever <chuck.lever@oracle.com>, Kees Cook <kees@kernel.org>,
	Christoph Lameter <cl@linux.com>, Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Hyeonggon Yoo <42.hyeyoo@gmail.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Michal Hocko <mhocko@kernel.org>,
	Shakeel Butt <shakeelb@google.com>,
	Muchun Song <muchun.song@linux.dev>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Christian Brauner <brauner@kernel.org>, Jan Kara <jack@suse.cz>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	cgroups@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH RFC 2/4] mm, slab: move slab_memcg hooks to
 mm/memcontrol.c
Message-ID: <ZfC85o4ed4IAZ-4h@P9FQF9L96D>
References: <20240301-slab-memcg-v1-0-359328a46596@suse.cz>
 <20240301-slab-memcg-v1-2-359328a46596@suse.cz>
 <ZfClX_CJBYRW-cCc@P9FQF9L96D>
 <ZfCt6TKEENN_Rq_C@casper.infradead.org>
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In-Reply-To: <ZfCt6TKEENN_Rq_C@casper.infradead.org>

On Tue, Mar 12, 2024 at 07:32:57PM +0000, Matthew Wilcox wrote:
> On Tue, Mar 12, 2024 at 11:56:31AM -0700, Roman Gushchin wrote:
> > On Fri, Mar 01, 2024 at 06:07:09PM +0100, Vlastimil Babka wrote:
> > > The hooks make multiple calls to functions in mm/memcontrol.c, including
> > > to th current_obj_cgroup() marked __always_inline. It might be faster to
> > > make a single call to the hook in mm/memcontrol.c instead. The hooks
> > > also don't use almost anything from mm/slub.c. obj_full_size() can move
> > > with the hooks and cache_vmstat_idx() to the internal mm/slab.h
> > > 
> > > Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
> > > ---
> > >  mm/memcontrol.c |  90 ++++++++++++++++++++++++++++++++++++++++++++++++++
> > >  mm/slab.h       |  10 ++++++
> > >  mm/slub.c       | 100 --------------------------------------------------------
> > >  3 files changed, 100 insertions(+), 100 deletions(-)
> > 
> > Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
> > 
> > Btw, even before your change:
> > $ cat mm/memcontrol.c | wc -l
> > 8318
> > so I wonder if soon we might want to split it into some smaller parts.
> 
> If we are going to split it, perhaps a mm/memcg-v1.c would make sense,
> because I certainly don't have a good idea about what's v1 and what's
> v2.  And maybe we could even conditionally compile the v1 file ;-)

Good call.
We already have cgroup/cgroup-v1.c and cgroup/legacy_freezer.c.

Thanks!