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Date:   Thu, 18 May 2023 11:43:02 +0800
From:   Baoquan He <bhe@redhat.com>
To:     Christoph Hellwig <hch@infradead.org>
Cc:     linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
        linux-mm@kvack.org, arnd@arndb.de, christophe.leroy@csgroup.eu,
        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 06/17] mm/ioremap: add slab availability
 checking in ioremap_prot
Message-ID: <ZGWext9KmmH+Dbtu@MiWiFi-R3L-srv>
References: <20230515090848.833045-1-bhe@redhat.com>
 <20230515090848.833045-7-bhe@redhat.com>
 <ZGR0mLozn5OQzAEN@infradead.org>
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On 05/16/23 at 11:30pm, Christoph Hellwig wrote:
> On Mon, May 15, 2023 at 05:08:37PM +0800, Baoquan He wrote:
> > Several architectures has done checking if slab if available in
> > ioremap_prot(). In fact it should be done in generic ioremap_prot()
> > since on any architecutre, slab allocator must be available before
> > get_vm_area_caller() and vunmap() are used.
> > 
> > Add the checking into generic_ioremap_prot().
> 
> Should we add a WARN_ON/WARN_ON_ONCE to aid debugging?

Sounds like a great idea, will add WARN_ON_ONCE as below. Thanks.

	if (WARN_ON_ONCE(!slab_is_available()))
		return NULL;