From: Matthew Wilcox <willy@infradead.org>
To: Boris Burkov <boris@bur.io>
Cc: akpm@linux-foundation.org, linux-btrfs@vger.kernel.org,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
kernel-team@fb.com, shakeel.butt@linux.dev, wqu@suse.com,
mhocko@kernel.org, muchun.song@linux.dev,
roman.gushchin@linux.dev, hannes@cmpxchg.org
Subject: Re: [PATCH v3 2/4] mm: add vmstat for cgroup uncharged pages
Date: Tue, 19 Aug 2025 03:50:49 +0100 [thread overview]
Message-ID: <aKPmiWAwDPNdNBUA@casper.infradead.org> (raw)
In-Reply-To: <04b3a5c9944d79072d752c85dac1294ca9bee183.1755562487.git.boris@bur.io>
On Mon, Aug 18, 2025 at 05:36:54PM -0700, Boris Burkov wrote:
> Uncharged pages are tricky to track by their essential "uncharged"
> nature. To maintain good accounting, introduce a vmstat counter tracking
> all uncharged pages. Since this is only meaningful when cgroups are
> configured, only expose the counter when CONFIG_MEMCG is set.
I don't understand why this is needed. Maybe Shakeel had better
reasoning that wasn't captured in the commit message.
If they're unaccounted, then you can get a good estimate of them
just by subtracting the number of accounted pages from the number of
file pages. Sure there's a small race between the two numbers being
updated, so you migth be off by a bit.
next prev parent reply other threads:[~2025-08-19 2:50 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-19 0:36 [PATCH v3 0/4] introduce uncharged file mapped folios Boris Burkov
2025-08-19 0:36 ` [PATCH v3 1/4] mm/filemap: add AS_UNCHARGED Boris Burkov
2025-08-19 2:46 ` Matthew Wilcox
2025-08-19 3:57 ` Boris Burkov
2025-08-20 22:06 ` Klara Modin
2025-08-20 22:22 ` Shakeel Butt
2025-08-20 22:52 ` Boris Burkov
2025-08-20 23:15 ` Klara Modin
2025-08-20 23:53 ` Shakeel Butt
2025-08-21 19:37 ` Shakeel Butt
2025-08-19 0:36 ` [PATCH v3 2/4] mm: add vmstat for cgroup uncharged pages Boris Burkov
2025-08-19 2:50 ` Matthew Wilcox [this message]
2025-08-19 4:05 ` Boris Burkov
2025-08-19 15:53 ` Shakeel Butt
2025-08-19 23:46 ` Matthew Wilcox
2025-08-20 1:25 ` Shakeel Butt
2025-08-20 13:19 ` Matthew Wilcox
2025-08-20 16:21 ` Shakeel Butt
2025-08-19 0:36 ` [PATCH v3 3/4] btrfs: set AS_UNCHARGED on the btree_inode Boris Burkov
2025-08-19 0:36 ` [PATCH v3 4/4] memcg: remove warning from folio_lruvec Boris Burkov
2025-08-19 2:41 ` Matthew Wilcox
2025-08-19 5:20 ` Andrew Morton
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