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Subject: Re: [PATCH] mm, soft-offline: convert parameter to pfn
To:     Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc:     "linux-mm@kvack.org" <linux-mm@kvack.org>,
        Michal Hocko <mhocko@kernel.org>,
        Oscar Salvador <osalvador@suse.de>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>
References: <20191016070924.GA10178@hori.linux.bs1.fc.nec.co.jp>
 <e931b14b-da27-2720-5344-b5c0b08b38ad@redhat.com>
 <20191016082735.GB13770@hori.linux.bs1.fc.nec.co.jp>
From:   David Hildenbrand <david@redhat.com>
Organization: Red Hat GmbH
Message-ID: <c78962ba-ffa1-90e2-0116-6c94d082de2f@redhat.com>
Date:   Wed, 16 Oct 2019 10:34:52 +0200
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On 16.10.19 10:27, Naoya Horiguchi wrote:
> On Wed, Oct 16, 2019 at 09:56:19AM +0200, David Hildenbrand wrote:
>> On 16.10.19 09:09, Naoya Horiguchi wrote:
>>> Hi,
>>>
>>> I wrote a simple cleanup for parameter of soft_offline_page(),
>>> based on thread https://lkml.org/lkml/2019/10/11/57.
>>>
>>> I know that we need more cleanup on hwpoison-inject, but I think
>>> that will be mentioned in re-write patchset Oscar is preparing now.
>>> So let me shared only this part as a separate one now.
> ...
>>
>> I think you should rebase that patch on linux-next (where the
>> pfn_to_online_page() check is in place). I assume you'll want to move the
>> pfn_to_online_page() check into soft_offline_page() then as well?
> 
> I rebased to next-20191016. And yes, we will move pfn_to_online_page()
> into soft offline code.  It seems that we can also move pfn_valid(),
> but is simply moving like below good enough for you?

At least I can't am the patch to current next/master (due to  
pfn_to_online_page()).

> 
>    @@ -1877,11 +1877,17 @@ static int soft_offline_free_page(struct page *page)
>      * This is not a 100% solution for all memory, but tries to be
>      * ``good enough'' for the majority of memory.
>      */
>    -int soft_offline_page(struct page *page, int flags)
>    +int soft_offline_page(unsigned long pfn, int flags)
>     {
>     	int ret;
>    -	unsigned long pfn = page_to_pfn(page);
>    +	struct page *page;
>     
>    +	if (!pfn_valid(pfn))
>    +		return -ENXIO;
>    +	/* Only online pages can be soft-offlined (esp., not ZONE_DEVICE). */
>    +	if (!pfn_to_online_page(pfn))
>    +		return -EIO;
>    +	page = pfn_to_page(pfn);
>     	if (is_zone_device_page(page)) {
>     		pr_debug_ratelimited("soft_offline: %#lx page is device page\n",
>     				pfn);
>    --
> 
> Or we might have an option to do as memory_failure() does like below:

In contrast to soft offlining, memory failure can deal with devmem. So I  
think the above makes sense.

-- 

Thanks,

David / dhildenb