linux-kernel - Re: [PATCH v2 4/5] mm: add largest_zero

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Message-ID: <47277451-4220-436a-a2ef-b0a58d556c4f@suse.de>
Date: Mon, 18 Aug 2025 14:04:21 +0200
From: Hannes Reinecke <hare@...e.de>
To: "Pankaj Raghav (Samsung)" <kernel@...kajraghav.com>,
 Suren Baghdasaryan <surenb@...gle.com>, Ryan Roberts <ryan.roberts@....com>,
 Baolin Wang <baolin.wang@...ux.alibaba.com>, Vlastimil Babka
 <vbabka@...e.cz>, Zi Yan <ziy@...dia.com>, Mike Rapoport <rppt@...nel.org>,
 Dave Hansen <dave.hansen@...ux.intel.com>, Michal Hocko <mhocko@...e.com>,
 David Hildenbrand <david@...hat.com>,
 Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 Thomas Gleixner <tglx@...utronix.de>, Nico Pache <npache@...hat.com>,
 Dev Jain <dev.jain@....com>, "Liam R . Howlett" <Liam.Howlett@...cle.com>,
 Jens Axboe <axboe@...nel.dk>
Cc: linux-kernel@...r.kernel.org, willy@...radead.org, linux-mm@...ck.org,
 Ritesh Harjani <ritesh.list@...il.com>, linux-block@...r.kernel.org,
 linux-fsdevel@...r.kernel.org, "Darrick J . Wong" <djwong@...nel.org>,
 mcgrof@...nel.org, gost.dev@...sung.com, hch@....de,
 Pankaj Raghav <p.raghav@...sung.com>
Subject: Re: [PATCH v2 4/5] mm: add largest_zero_folio() routine

On 8/8/25 14:11, Pankaj Raghav (Samsung) wrote:
> From: Pankaj Raghav <p.raghav@...sung.com>
> 
> The callers of mm_get_huge_zero_folio() have access to a mm struct and
> the lifetime of the huge_zero_folio is tied to the lifetime of the mm
> struct.
> 
> largest_zero_folio() will give access to huge_zero_folio when
> PERSISTENT_HUGE_ZERO_FOLIO config option is enabled for callers that do not
> want to tie the lifetime to a mm struct. This is very useful for
> filesystem and block layers where the request completions can be async
> and there is no guarantee on the mm struct lifetime.
> 
> This function will return a ZERO_PAGE folio if PERSISTENT_HUGE_ZERO_FOLIO
> is disabled or if we failed to allocate a huge_zero_folio during early
> init.
> 
> Co-developed-by: David Hildenbrand <david@...hat.com>
> Signed-off-by: David Hildenbrand <david@...hat.com>
> Signed-off-by: Pankaj Raghav <p.raghav@...sung.com>
> ---
>   include/linux/huge_mm.h | 22 ++++++++++++++++++++++
>   1 file changed, 22 insertions(+)
> 
Reviewed-by: Hannes Reinecke <hare@...e.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                  Kernel Storage Architect
hare@...e.de                                +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
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