From: Andrew Morton <akpm@linux-foundation.org>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>,
linux-mm@kvack.org, Thomas Gleixner <tglx@linutronix.de>,
Luis Chamberlain <mcgrof@kernel.org>,
Kees Cook <keescook@chromium.org>,
Iurii Zaikin <yzaikin@google.com>,
Mel Gorman <mgorman@techsingularity.net>,
Linux API <linux-api@vger.kernel.org>
Subject: Re: [PATCH 2/2 v3] mm/compaction: Disable compact_unevictable_allowed on RT
Date: Tue, 3 Mar 2020 15:56:35 -0800 [thread overview]
Message-ID: <20200303155635.1955cb90451abd3ef8bfba63@linux-foundation.org> (raw)
In-Reply-To: <20200303202225.nhqc3v5gwlb7x6et@linutronix.de>
On Tue, 3 Mar 2020 21:22:25 +0100 Sebastian Andrzej Siewior <bigeasy@linutronix.de> wrote:
> Since commit
> 5bbe3547aa3ba ("mm: allow compaction of unevictable pages")
>
> it is allowed to examine mlocked pages and compact them by default.
> On -RT even minor pagefaults are problematic because it may take a few
> 100us to resolve them and until then the task is blocked.
>
> Make compact_unevictable_allowed = 0 default and issue a warning on RT
> if it is changed.
Fair enough, I guess.
> @@ -2572,6 +2577,26 @@ int proc_dointvec(struct ctl_table *table, int write,
> return do_proc_dointvec(table, write, buffer, lenp, ppos, NULL, NULL);
> }
>
> +#ifdef CONFIG_COMPACTION
> +static int proc_dointvec_warn_RT_change(struct ctl_table *table, int write,
> + void __user *buffer, size_t *lenp,
> + loff_t *ppos)
> +{
> + int ret, old;
> +
> + if (!IS_ENABLED(CONFIG_PREEMPT_RT) || !write)
> + return proc_dointvec(table, write, buffer, lenp, ppos);
> +
> + old = *(int *)table->data;
> + ret = proc_dointvec(table, write, buffer, lenp, ppos);
> + if (ret)
> + return ret;
> + WARN_ONCE(old != *(int *)table->data, "sysctl attribute %s changed.",
> + table->procname);
The WARN will include a stack trace which just isn't interesting. A
pr_warn() would be better?
> + return ret;
> +}
> +#endif
next prev parent reply other threads:[~2020-03-03 23:56 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-15 16:10 [PATCH] mm/compaction: Disable compact_unevictable_allowed on RT Sebastian Andrzej Siewior
2020-01-15 22:04 ` Vlastimil Babka
2020-01-16 10:22 ` Sebastian Andrzej Siewior
2020-03-02 17:35 ` [PATCH v2] " Sebastian Andrzej Siewior
2020-03-02 21:25 ` Andrew Morton
2020-03-03 17:59 ` Sebastian Andrzej Siewior
2020-03-03 20:20 ` [PATCH 1/2] =?UTF-8?q?mm/compaction:=20Really=20limit=20compact?= =?UTF-8?q?=5Funevictable=5Fallowed=20to=200=E2=80=A61?= Sebastian Andrzej Siewior
2020-03-03 20:22 ` [PATCH 2/2 v3] mm/compaction: Disable compact_unevictable_allowed on RT Sebastian Andrzej Siewior
2020-03-03 23:56 ` Andrew Morton [this message]
2020-03-04 8:19 ` Vlastimil Babka
2020-03-04 9:27 ` Sebastian Andrzej Siewior
2020-03-19 16:39 ` [PATCH 2/2 v4] " Sebastian Andrzej Siewior
2020-03-19 16:49 ` Vlastimil Babka
2020-03-19 16:55 ` [PATCH 2/2 v5] " Sebastian Andrzej Siewior
2020-03-04 8:18 ` [PATCH 2/2 v3] " Vlastimil Babka
2020-03-04 9:25 ` Sebastian Andrzej Siewior
2020-03-04 9:11 ` Mel Gorman
2020-03-04 8:12 ` [PATCH 1/2] mm/compaction: Really limit compact_unevictable_allowed to 0…1 Vlastimil Babka
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