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Peter Anvin" , Vlastimil Babka , Zi Yan , Mike Rapoport , Dave Hansen , Michal Hocko , David Hildenbrand , Andrew Morton , Thomas Gleixner , Nico Pache , Dev Jain , "Liam R . Howlett" , Jens Axboe , linux-kernel@vger.kernel.org, linux-mm@kvack.org, willy@infradead.org, x86@kernel.org, linux-block@vger.kernel.org, Ritesh Harjani , linux-fsdevel@vger.kernel.org, "Darrick J . Wong" , mcgrof@kernel.org, gost.dev@samsung.com, hch@lst.de, Pankaj Raghav Subject: Re: [PATCH 4/5] mm: add largest_zero_folio() routine Message-ID: References: <20250804121356.572917-1-kernel@pankajraghav.com> <20250804121356.572917-5-kernel@pankajraghav.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: A06C9C0002 X-Stat-Signature: o8kujmze99dfm6w6abcgkz4josj43q8c X-HE-Tag: 1754393112-130345 X-HE-Meta: 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 KQ8W1+aW 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Aug 04, 2025 at 05:50:46PM +0100, Lorenzo Stoakes wrote: > On Mon, Aug 04, 2025 at 02:13:55PM +0200, Pankaj Raghav (Samsung) wrote: > > From: Pankaj Raghav > > > > Add largest_zero_folio() routine so that huge_zero_folio can be > > used directly when CONFIG_STATIC_HUGE_ZERO_FOLIO is enabled. This will > > return ZERO_PAGE folio if CONFIG_STATIC_HUGE_ZERO_FOLIO is disabled or > > if we failed to allocate a huge_zero_folio. > > > > Co-developed-by: David Hildenbrand > > Signed-off-by: David Hildenbrand > > Signed-off-by: Pankaj Raghav > > This looks good to me minus nit + comment below, so: > > Reviewed-by: Lorenzo Stoakes > Thanks. > > --- > > include/linux/huge_mm.h | 17 +++++++++++++++++ > > 1 file changed, 17 insertions(+) > > > > diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h > > index 78ebceb61d0e..c44a6736704b 100644 > > --- a/include/linux/huge_mm.h > > +++ b/include/linux/huge_mm.h > > @@ -716,4 +716,21 @@ static inline int split_folio_to_order(struct folio *folio, int new_order) > > return split_folio_to_list_to_order(folio, NULL, new_order); > > } > > > > +/* > > Maybe let's make this a kernel doc comment? Yes, I will change it in the next version :) > > > + * largest_zero_folio - Get the largest zero size folio available > > + * > > + * This function will return huge_zero_folio if CONFIG_STATIC_HUGE_ZERO_FOLIO > > + * is enabled. Otherwise, a ZERO_PAGE folio is returned. > > + * > > + * Deduce the size of the folio with folio_size instead of assuming the > > + * folio size. > > + */ > > +static inline struct folio *largest_zero_folio(void) > > +{ > > + struct folio *folio = get_static_huge_zero_folio(); > > + > > + if (folio) > > + return folio; > > + return page_folio(ZERO_PAGE(0)); > > Feels like we should have this in a wrapper function somewhere. Then again it > seems people generally always open-code 'ZERO_PAGE(0)' anyway so maybe this is > sort of the 'way things are done'? :P > > > +} > > #endif /* _LINUX_HUGE_MM_H */ > > -- > > 2.49.0 > >