From: Johannes Weiner <hannes@cmpxchg.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Rik van Riel <riel@surriel.com>,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, Dave Chinner <david@fromorbit.com>,
Yafang Shao <laoar.shao@gmail.com>,
Michal Hocko <mhocko@suse.com>, Roman Gushchin <guro@fb.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Al Viro <viro@zeniv.linux.org.uk>,
kernel-team@fb.com
Subject: Re: [PATCH] vfs: keep inodes with page cache off the inode shrinker LRU
Date: Wed, 12 Feb 2020 13:52:09 -0500 [thread overview]
Message-ID: <20200212185209.GA206066@cmpxchg.org> (raw)
In-Reply-To: <20200212102645.7b2e5b228048b6d22331e47d@linux-foundation.org>
On Wed, Feb 12, 2020 at 10:26:45AM -0800, Andrew Morton wrote:
> On Wed, 12 Feb 2020 11:35:40 -0500 Johannes Weiner <hannes@cmpxchg.org> wrote:
>
> > Since the cache purging code was written for highmem scenarios, how
> > about making it specific to CONFIG_HIGHMEM at least?
>
> Why do I have memories of suggesting this a couple of weeks ago ;)
Sorry, you did. I went back and found your email now. It completely
slipped my mind after that thread went off into another direction.
> > That way we improve the situation for the more common setups, without
> > regressing highmem configurations. And if somebody wanted to improve
> > the CONFIG_HIGHMEM behavior as well, they could still do so.
> >
> > Somethig like the below delta on top of my patch?
>
> Does it need to be that complicated? What's wrong with
>
> --- a/fs/inode.c~a
> +++ a/fs/inode.c
> @@ -761,6 +761,10 @@ static enum lru_status inode_lru_isolate
> return LRU_ROTATE;
> }
>
> +#ifdef CONFIG_HIGHMEM
> + /*
> + * lengthy blah
> + */
> if (inode_has_buffers(inode) || inode->i_data.nrpages) {
> __iget(inode);
> spin_unlock(&inode->i_lock);
> @@ -779,6 +783,7 @@ static enum lru_status inode_lru_isolate
> spin_lock(lru_lock);
> return LRU_RETRY;
> }
> +#endif
Pages can show up here even under !CONFIG_HIGHMEM. Because of the lock
order to maintain LRU state (i_lock -> xa_lock), when the page cache
inserts new pages it doesn't unlink the inode from the LRU atomically,
and the shrinker might get here before inode_pages_set(). In that case
we need the shrinker to punt the inode off the LRU (the #else branch).
> WARN_ON(inode->i_state & I_NEW);
> inode->i_state |= I_FREEING;
> _
>
> Whatever we do will need plenty of testing. It wouldn't surprise me
> if there are people who unknowingly benefit from this code on
> 64-bit machines.
If we agree this is the way to go, I can put the patch into our tree
and gather data from the Facebook fleet before we merge it.
next prev parent reply other threads:[~2020-02-12 18:52 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-11 17:55 [PATCH] vfs: keep inodes with page cache off the inode shrinker LRU Johannes Weiner
2020-02-11 18:20 ` Johannes Weiner
2020-02-11 19:05 ` Rik van Riel
2020-02-11 19:31 ` Johannes Weiner
2020-02-11 23:44 ` Andrew Morton
2020-02-12 0:28 ` Linus Torvalds
2020-02-12 0:47 ` Andrew Morton
2020-02-12 1:03 ` Linus Torvalds
2020-02-12 8:50 ` Russell King - ARM Linux admin
2020-02-13 9:50 ` Lucas Stach
2020-02-13 16:52 ` Arnd Bergmann
2020-02-15 11:25 ` Geert Uytterhoeven
2020-02-15 16:59 ` Arnd Bergmann
2020-02-16 9:44 ` Geert Uytterhoeven
2020-02-16 19:54 ` Chris Paterson
2020-02-16 20:38 ` Arnd Bergmann
2020-02-20 14:35 ` Chris Paterson
2020-02-26 18:04 ` santosh.shilimkar
2020-02-26 21:01 ` Arnd Bergmann
2020-02-26 21:11 ` santosh.shilimkar
2020-03-06 20:34 ` Nishanth Menon
2020-03-07 1:08 ` santosh.shilimkar
2020-03-08 10:58 ` Arnd Bergmann
2020-03-08 14:19 ` Russell King - ARM Linux admin
2020-03-09 13:33 ` Arnd Bergmann
2020-03-09 14:04 ` Russell King - ARM Linux admin
2020-03-09 15:04 ` Arnd Bergmann
2020-03-10 9:16 ` Michal Hocko
2020-03-09 15:59 ` Catalin Marinas
2020-03-09 16:09 ` Russell King - ARM Linux admin
2020-03-09 16:57 ` Catalin Marinas
2020-03-09 19:46 ` Arnd Bergmann
2020-03-11 14:29 ` Catalin Marinas
2020-03-11 16:59 ` Arnd Bergmann
2020-03-11 17:26 ` Catalin Marinas
2020-03-11 22:21 ` Arnd Bergmann
2020-02-12 3:58 ` Matthew Wilcox
2020-02-12 8:09 ` Michal Hocko
2020-02-17 13:31 ` Pavel Machek
2020-02-12 16:35 ` Johannes Weiner
2020-02-12 18:26 ` Andrew Morton
2020-02-12 18:52 ` Johannes Weiner [this message]
2020-02-12 12:25 ` Yafang Shao
2020-02-12 16:42 ` Johannes Weiner
2020-02-13 1:47 ` Yafang Shao
2020-02-13 13:46 ` Johannes Weiner
2020-02-14 2:02 ` Yafang Shao
2020-02-13 18:34 ` [PATCH v2] " Johannes Weiner
2020-02-14 16:53 ` [PATCH] " kbuild test robot
2020-02-14 21:30 ` kbuild test robot
2020-02-14 21:30 ` [PATCH] vfs: fix boolreturn.cocci warnings kbuild test robot
2020-05-12 21:29 ` [PATCH] vfs: keep inodes with page cache off the inode shrinker LRU Johannes Weiner
2020-05-13 1:32 ` Yafang Shao
2020-05-13 13:00 ` Johannes Weiner
2020-05-13 21:15 ` Andrew Morton
2020-05-14 11:27 ` Johannes Weiner
2020-05-14 2:24 ` Andrew Morton
2020-05-14 10:37 ` Johannes Weiner
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