linux-ext4 - Re: [PATCH v6 02/13] mm: remove extra ZONE

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Date:   Mon, 16 Aug 2021 14:56:40 -0400
From:   Felix Kuehling <felix.kuehling@....com>
To:     John Hubbard <jhubbard@...dia.com>, Christoph Hellwig <hch@....de>,
        Alex Sierra <alex.sierra@....com>
Cc:     akpm@...ux-foundation.org, linux-mm@...ck.org,
        rcampbell@...dia.com, linux-ext4@...r.kernel.org,
        linux-xfs@...r.kernel.org, amd-gfx@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org, jgg@...dia.com, jglisse@...hat.com
Subject: Re: [PATCH v6 02/13] mm: remove extra ZONE_DEVICE struct page
 refcount

Am 2021-08-15 um 4:40 p.m. schrieb John Hubbard:
> On 8/15/21 8:37 AM, Christoph Hellwig wrote:
>>> diff --git a/include/linux/mm.h b/include/linux/mm.h
>>> index 8ae31622deef..d48a1f0889d1 100644
>>> --- a/include/linux/mm.h
>>> +++ b/include/linux/mm.h
>>> @@ -1218,7 +1218,7 @@ __maybe_unused struct page
>>> *try_grab_compound_head(struct page *page, int refs,
>>>   static inline __must_check bool try_get_page(struct page *page)
>>>   {
>>>       page = compound_head(page);
>>> -    if (WARN_ON_ONCE(page_ref_count(page) <= 0))
>>> +    if (WARN_ON_ONCE(page_ref_count(page) <
>>> (int)!is_zone_device_page(page)))
>>
>> Please avoid the overly long line.  In fact I'd be tempted to just not
>> bother here and keep the old, more lose check.  Especially given that
>> John has a patch ready that removes try_get_page entirely.
>>
>
> Yes. Andrew has accepted it into mmotm.
>
> Ralph's patch here was written well before my cleanup that removed
> try_grab_page() [1]. But now that we're here, if you drop this hunk then
> it will make merging easier, I think.
>
>
> [1]
> https://lore.kernel.org/r/20210813044133.1536842-4-jhubbard@nvidia.com

Hi John,

Thanks for the pointer. We'll drop this hunk and add a statement to our
patch description to highlight the dependency on your patch.

Regards,
  Felix


>
> thanks,
> -- 
> John Hubbard
> NVIDIA
>