linux-kernel - Re: [rfc/patch] mm/slub: restore/expand unfreeze

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Message-ID: <b41fa4f2-8368-f33a-10c2-68554b16eb1e@suse.cz>
Date:   Sun, 25 Jul 2021 21:34:14 +0200
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Mike Galbraith <efault@....de>,
        Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>
Cc:     linux-rt-users@...r.kernel.org,
        Mel Gorman <mgorman@...hsingularity.net>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: Re: [rfc/patch] mm/slub: restore/expand unfreeze_partials() local
 exclusion scope

On 7/25/21 9:12 PM, Vlastimil Babka wrote:
> +	/*
> +	 * On !RT we just want to disable preemption, on RT we need the lock
> +	 * for real. This happens to match local_lock() semantics.
> +	 */
> +	local_lock(&s->cpu_slab->lock);

OK I realized (and tglx confirmed) that this will blow up on !RT +
lockdep if interrupted by ___slab_alloc() that will do
local_lock_irqsave(). So back to #ifdefs it is. But should work as-is
for RT testing.