Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Fri, 2 Jul 2021 14:17:49 +0200
From:   Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To:     Vlastimil Babka <vbabka@suse.cz>
Cc:     linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Christoph Lameter <cl@linux.com>,
        David Rientjes <rientjes@google.com>,
        Pekka Enberg <penberg@kernel.org>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Mel Gorman <mgorman@techsingularity.net>,
        Jesper Dangaard Brouer <brouer@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Jann Horn <jannh@google.com>
Subject: Re: [RFC v2 31/34] mm, slub: optionally save/restore irqs in
 slab_[un]lock()/
Message-ID: <20210702121749.edrkrwf6uaxwoiyp@linutronix.de>
References: <20210609113903.1421-1-vbabka@suse.cz>
 <20210609113903.1421-32-vbabka@suse.cz>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <20210609113903.1421-32-vbabka@suse.cz>
Precedence: bulk

On 2021-06-09 13:39:00 [+0200], Vlastimil Babka wrote:
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -353,18 +353,35 @@ static inline unsigned int oo_objects(struct kmem_cache_order_objects x)
>  /*
>   * Per slab locking using the pagelock
>   */
> -static __always_inline void slab_lock(struct page *page)
> +static __always_inline void
> +__slab_lock(struct page *page, unsigned long *flags, bool disable_irqs)
>  {
>  	VM_BUG_ON_PAGE(PageTail(page), page);
> +	if (disable_irqs)
> +		local_irq_save(*flags);
>  	bit_spin_lock(PG_locked, &page->flags);
>  }
>  
> -static __always_inline void slab_unlock(struct page *page)
> +static __always_inline void
> +__slab_unlock(struct page *page, unsigned long *flags, bool disable_irqs)
>  {
>  	VM_BUG_ON_PAGE(PageTail(page), page);
> +	if (disable_irqs)
> +		local_irq_restore(*flags);
>  	__bit_spin_unlock(PG_locked, &page->flags);
>  }

You should first unlock then enable IRQs.

Sebastian