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Subject: Re: [PATCH v5 4/4] hugetlb: allow to free gigantic pages regardless
 of the configuration
To:     Alexandre Ghiti <alex@ghiti.fr>, Vlastimil Babka <vbabka@suse.cz>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Martin Schwidefsky <schwidefsky@de.ibm.com>,
        Heiko Carstens <heiko.carstens@de.ibm.com>,
        Yoshinori Sato <ysato@users.sourceforge.jp>,
        Rich Felker <dalias@libc.org>,
        "David S . Miller" <davem@davemloft.net>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H . Peter Anvin" <hpa@zytor.com>, x86@kernel.org,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Andy Lutomirski <luto@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org,
        linux-sh@vger.kernel.org, sparclinux@vger.kernel.org,
        linux-mm@kvack.org
References: <20190306190005.7036-1-alex@ghiti.fr>
 <20190306190005.7036-5-alex@ghiti.fr>
From:   Dave Hansen <dave.hansen@intel.com>
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Message-ID: <7c81abe0-5f9d-32f9-1e9a-70ab06d48f8e@intel.com>
Date:   Wed, 6 Mar 2019 11:16:44 -0800
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Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 3/6/19 11:00 AM, Alexandre Ghiti wrote:
> +static int set_max_huge_pages(struct hstate *h, unsigned long count,
> +			      nodemask_t *nodes_allowed)
>  {
>  	unsigned long min_count, ret;
>  
> -	if (hstate_is_gigantic(h) && !gigantic_page_supported())
> -		return h->max_huge_pages;
> +	/*
> +	 * Gigantic pages allocation depends on the capability for large page
> +	 * range allocation. If the system cannot provide alloc_contig_range,
> +	 * allow users to free gigantic pages.
> +	 */
> +	if (hstate_is_gigantic(h) && !IS_ENABLED(CONFIG_CONTIG_ALLOC)) {
> +		spin_lock(&hugetlb_lock);
> +		if (count > persistent_huge_pages(h)) {
> +			spin_unlock(&hugetlb_lock);
> +			return -EINVAL;
> +		}
> +		goto decrease_pool;
> +	}

We talked about it during the last round and I don't seen any mention of
it here in comments or the changelog: Why is this a goto?  Why don't we
just let the code fall through to the "decrease_pool" label?  Why is
this new block needed at all?  Can't we just remove the old check and
let it be?