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Subject: Re: [PATCH v1 2/3] kernel/resource: make walk_mem_res() find all busy
 IORESOURCE_MEM resources
To:     Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc:     linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        Andrew Morton <akpm@linux-foundation.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Dan Williams <dan.j.williams@intel.com>,
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        Mauro Carvalho Chehab <mchehab+huawei@kernel.org>,
        Dave Young <dyoung@redhat.com>, Baoquan He <bhe@redhat.com>,
        Vivek Goyal <vgoyal@redhat.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Keith Busch <keith.busch@intel.com>,
        Michal Hocko <mhocko@suse.com>, Qian Cai <cai@lca.pw>,
        Oscar Salvador <osalvador@suse.de>,
        Eric Biederman <ebiederm@xmission.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        Brijesh Singh <brijesh.singh@amd.com>, x86@kernel.org,
        kexec@lists.infradead.org
References: <20210322160200.19633-1-david@redhat.com>
 <20210322160200.19633-3-david@redhat.com>
 <YFnMOK6VuIBsoKWr@smile.fi.intel.com>
From:   David Hildenbrand <david@redhat.com>
Organization: Red Hat GmbH
Message-ID: <16bfac8e-cee1-c8ce-14f1-70e697e4f2f1@redhat.com>
Date:   Tue, 23 Mar 2021 12:26:27 +0100
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On 23.03.21 12:08, Andy Shevchenko wrote:
> On Mon, Mar 22, 2021 at 05:01:59PM +0100, David Hildenbrand wrote:
>> It used to be true that we can have system RAM only on the first level
>> in the resourc tree. However, this is no longer holds for driver-managed
>> system RAM (i.e., dax/kmem and virtio-mem).
>>
>> The function walk_mem_res() only consideres the first level and is
>> used in arch/x86/mm/ioremap.c:__ioremap_check_mem() only. We currently
>> fail to identify System RAM added by dax/kmem and virtio-mem as
>> "IORES_MAP_SYSTEM_RAM", for example, allowing for remapping of such
>> "normal RAM" in __ioremap_caller().
> 
> Here I dunno, but consider to add Fixes tag if it fixes known bad behaviour.

Haven't observed it in the wild. We can add the same fixes tags as to 
patch #1.

-- 
Thanks,

David / dhildenb