linux-kernel - Re: [PATCH 2/2] kho: fix restoring of contiguous ranges of order-0 pages

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Message-ID: <86ms42mj44.fsf@kernel.org>
Date: Mon, 01 Dec 2025 14:23:07 +0100
From: Pratyush Yadav <pratyush@...nel.org>
To: Mike Rapoport <rppt@...nel.org>
Cc: Pratyush Yadav <pratyush@...nel.org>,  Andrew Morton
 <akpm@...ux-foundation.org>,  Alexander Graf <graf@...zon.com>,  Pasha
 Tatashin <pasha.tatashin@...een.com>,  kexec@...ts.infradead.org,
  linux-mm@...ck.org,  linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] kho: fix restoring of contiguous ranges of order-0
 pages

On Mon, Dec 01 2025, Mike Rapoport wrote:

> Hi Pratyush,
>
> On Tue, Nov 25, 2025 at 02:45:59PM +0100, Pratyush Yadav wrote:
>> On Tue, Nov 25 2025, Mike Rapoport wrote:
>
> ...
>
>> > @@ -243,11 +243,16 @@ static struct page *kho_restore_page(phys_addr_t phys)
>> >  	/* Head page gets refcount of 1. */
>> >  	set_page_count(page, 1);
>> >  
>> > -	/* For higher order folios, tail pages get a page count of zero. */
>> > +	/*
>> > +	 * For higher order folios, tail pages get a page count of zero.
>> > +	 * For physically contiguous order-0 pages every pages gets a page
>> > +	 * count of 1
>> > +	 */
>> > +	ref_cnt = is_folio ? 0 : 1;
>> >  	for (unsigned int i = 1; i < nr_pages; i++)
>> > -		set_page_count(page + i, 0);
>> > +		set_page_count(page + i, ref_cnt);
>> >  
>> > -	if (info.order > 0)
>> > +	if (is_folio && info.order)
>> 
>> This is getting a bit difficult to parse. Let's separate out folio and
>> page initialization to separate helpers:
>  
> Sorry, I've missed this earlier and now the patches are in akpm's -stable
> branch.
> Let's postpone these changes for the next cycle, maybe along with support
> for deferred initialization of struct page.

Sure, no problem.

[...]

-- 
Regards,
Pratyush Yadav