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From: Mel Gorman <mgorman@techsingularity.net>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@kernel.org>, Vlastimil Babka <vbabka@suse.cz>,
	Hugh Dickins <hughd@google.com>, Linux-MM <linux-mm@kvack.org>,
	Linux-RT-Users <linux-rt-users@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Mel Gorman <mgorman@techsingularity.net>
Subject: [PATCH 0/1 v2] Protect vmstats on PREEMPT_RT
Date: Thu,  5 Aug 2021 17:00:18 +0100	[thread overview]
Message-ID: <20210805160019.1137-1-mgorman@techsingularity.net> (raw)

Changelog since v1
o Remove preempt_[en|dis]able_rt helper

When adding local_lock support to mm/page_alloc.c and reducing the overhead
of vmstats in general, I wondered how vmstats could be safe on PREEMPT_RT
as it partially relies on interrupts being disabled for the stats that
must be accurate for correctness. As it turns out, the preempt-rt tree
already encountered the same problem.

This series protects just the accurate counters. As Thomas expressed
concern that the preempt_enable_rt() helper could be abused, this
version open-codes the preemption with a comment explaining why it
is necessary.

This is specific to PREEMPT_RT which cannot be enabled on mainline yet
and should have no impact on !PREEMPT_RT kernels.

This patch replaces the following mmotm patches

o preempt-provide-preempt__nort-variants.patch
o mm-vmstat-protect-per-cpu-variables-with-preempt-disable-on-rt.patch

-- 
2.31.1


             reply	other threads:[~2021-08-05 16:00 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-05 16:00 Mel Gorman [this message]
2021-08-05 16:00 ` [PATCH 1/1] mm/vmstat: Protect per cpu variables with preempt disable on RT Mel Gorman
2021-08-05 23:22   ` Andrew Morton
2021-08-06  7:50     ` Vlastimil Babka
2021-08-06  8:44     ` Mel Gorman
2021-08-06 12:38   ` Vlastimil Babka
2021-08-31 16:45   ` Sebastian Andrzej Siewior
2021-09-02 20:07     ` Andrew Morton
2021-09-06 13:48     ` Mel Gorman
2021-09-06 14:03       ` Sebastian Andrzej Siewior

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