From: Michal Hocko <mhocko@suse.com>
To: Qu Wenruo <wqu@suse.com>
Cc: linux-btrfs@vger.kernel.org, hannes@cmpxchg.org,
roman.gushchin@linux.dev, shakeel.butt@linux.dev,
muchun.song@linux.dev, cgroups@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: [PATCH v7 1/3] memcontrol: define root_mem_cgroup for CONFIG_MEMCG=n cases
Date: Fri, 19 Jul 2024 13:13:40 +0200 [thread overview]
Message-ID: <ZppKZJKMcPF4OGVc@tiehlicka> (raw)
In-Reply-To: <2050f8a1bc181a9aaf01e0866e230e23216000f4.1721384771.git.wqu@suse.com>
On Fri 19-07-24 19:58:39, Qu Wenruo wrote:
> There is an incoming btrfs patchset, which will use @root_mem_cgroup as
> the active cgroup to attach metadata folios to its internal btree
> inode, so that btrfs can skip the possibly costly charge for the
> internal inode which is only accessible by btrfs itself.
>
> However @root_mem_cgroup is not always defined (not defined for
> CONFIG_MEMCG=n case), thus all such callers need to do the extra
> handling for different CONFIG_MEMCG settings.
>
> So here we add a special macro definition of root_mem_cgroup, making it
> to always be NULL.
Isn't just a declaration sufficient? Nothing should really dereference
the pointer anyway.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2024-07-19 11:13 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-19 10:28 [PATCH v7 0/3] btrfs: try to allocate larger folios for metadata Qu Wenruo
2024-07-19 10:28 ` [PATCH v7 1/3] memcontrol: define root_mem_cgroup for CONFIG_MEMCG=n cases Qu Wenruo
2024-07-19 11:13 ` Michal Hocko [this message]
2024-07-19 21:58 ` Qu Wenruo
2024-07-22 7:32 ` Michal Hocko
2024-07-19 10:28 ` [PATCH v7 2/3] btrfs: always uses root memcgroup for filemap_add_folio() Qu Wenruo
2024-07-19 17:02 ` Johannes Weiner
2024-07-19 17:25 ` Roman Gushchin
2024-07-19 18:13 ` Michal Hocko
2024-07-19 22:11 ` Qu Wenruo
2024-07-22 7:34 ` Michal Hocko
2024-07-22 8:08 ` Qu Wenruo
2024-07-24 3:46 ` Qu Wenruo
2024-07-19 10:28 ` [PATCH v7 3/3] btrfs: prefer to allocate larger folio for metadata Qu Wenruo
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