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Date:   Tue, 16 May 2023 23:41:26 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     Baoquan He <bhe@redhat.com>
Cc:     linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
        linux-mm@kvack.org, arnd@arndb.de, christophe.leroy@csgroup.eu,
        hch@infradead.org, agordeev@linux.ibm.com,
        wangkefeng.wang@huawei.com, schnelle@linux.ibm.com,
        David.Laight@aculab.com, shorne@gmail.com, willy@infradead.org,
        deller@gmx.de
Subject: Re: [PATCH v5 RESEND 14/17] mm/ioremap: Consider IOREMAP space in
 generic ioremap
Message-ID: <ZGR3Ft27kdgXKKfp@infradead.org>
References: <20230515090848.833045-1-bhe@redhat.com>
 <20230515090848.833045-15-bhe@redhat.com>
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On Mon, May 15, 2023 at 05:08:45PM +0800, Baoquan He wrote:
> @@ -35,8 +35,13 @@ void __iomem *generic_ioremap_prot(phys_addr_t phys_addr, size_t size,
>  	if (!ioremap_allowed(phys_addr, size, pgprot_val(prot)))
>  		return NULL;
>  
> +#ifdef IOREMAP_START
> +	area = __get_vm_area_caller(size, VM_IOREMAP, IOREMAP_START,
> +				    IOREMAP_END, __builtin_return_address(0));
> +#else
>  	area = get_vm_area_caller(size, VM_IOREMAP,
>  			__builtin_return_address(0));
> +#endif

I think this would be cleaner if we'd just always use
__get_vm_area_caller and at the top of the file add a:

#ifndef IOREMAP_START
#define IOREMAP_START	VMALLOC_START
#define IOREMAP_END	VMALLOC_END
#endif

Together with a little comment that ioremap often, but not always
uses the generic vmalloc area.