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Date:   Wed, 9 Jun 2021 16:59:17 +0100
From:   Christoph Hellwig <hch@infradead.org>
To:     Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc:     linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
        linux-s390@vger.kernel.org, frankja@linux.ibm.com,
        borntraeger@de.ibm.com, cohuck@redhat.com, david@redhat.com,
        linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
        Nicholas Piggin <npiggin@gmail.com>,
        Uladzislau Rezki <urezki@gmail.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        David Rientjes <rientjes@google.com>
Subject: Re: [PATCH v2 1/2] mm/vmalloc: export __vmalloc_node_range
Message-ID: <YMDlVdB8m62AhbB7@infradead.org>
References: <20210608180618.477766-1-imbrenda@linux.ibm.com>
 <20210608180618.477766-2-imbrenda@linux.ibm.com>
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On Tue, Jun 08, 2021 at 08:06:17PM +0200, Claudio Imbrenda wrote:
> The recent patches to add support for hugepage vmalloc mappings added a
> flag for __vmalloc_node_range to allow to request small pages.
> This flag is not accessible when calling vmalloc, the only option is to
> call directly __vmalloc_node_range, which is not exported.
> 
> This means that a module can't vmalloc memory with small pages.
> 
> Case in point: KVM on s390x needs to vmalloc a large area, and it needs
> to be mapped with small pages, because of a hardware limitation.
> 
> This patch exports __vmalloc_node_range so it can be used in modules
> too.

No.  I spent a lot of effort to mak sure such a low-level API is
not exported.