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Howlett" , Linus Torvalds , linux-arm-kernel@axis.com, linux-arm-kernel@lists.infradead.org, linux-crypto@vger.kernel.org, linux-ide@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mips@vger.kernel.org, linux-mmc@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-scsi@vger.kernel.org, Lorenzo Stoakes , Marco Elver , Marek Szyprowski , Michal Hocko , Muchun Song , netdev@vger.kernel.org, Oscar Salvador , Peter Xu , Robin Murphy , Suren Baghdasaryan , Tejun Heo , virtualization@lists.linux.dev, Vlastimil Babka , wireguard@lists.zx2c4.com, x86@kernel.org, Zi Yan Subject: Re: [PATCH RFC 10/35] mm/hugetlb: cleanup hugetlb_folio_init_tail_vmemmap() Message-ID: References: <20250821200701.1329277-1-david@redhat.com> <20250821200701.1329277-11-david@redhat.com> <9156d191-9ec4-4422-bae9-2e8ce66f9d5e@redhat.com> <7077e09f-6ce9-43ba-8f87-47a290680141@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 6F26D20007 X-Stat-Signature: tmx9xwqno6e3e7d47cg46i3aupbdpzpw X-Rspam-User: X-HE-Tag: 1756132362-423653 X-HE-Meta: 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 S4UbS3FX jab5yTyewERqSteF2AV70K1V2nUBZrIgRXFkaNB+9Kauq2+g9tCQMl8G1/4TEMBJphyC9Slo+BK4ic/TIjQu8ZBN1vvhk18oXbNzGVYR6EnsfXnArDvz+PnLPdWms8ayWDBMMjr0AWYzJ1W3vsUtTchkWWr3mtafc7bYG1XVOe9joYU9DjVTNnfDT1bIVuNVfeisJqADAfh1kuAQ7OguOXfcQ7jONBDgKYIayFgVH2EfM60boAq7HNT2VSstoxSGQpDN1uONu/Ihuj661OnxCfd9PoMprMSHraeiuCcSM67qQmb+P3Dw2Id7KH+6sfK+P7Wg+MGgfNrp0728= 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 25, 2025 at 02:48:58PM +0200, David Hildenbrand wrote: > On 23.08.25 10:59, Mike Rapoport wrote: > > On Fri, Aug 22, 2025 at 08:24:31AM +0200, David Hildenbrand wrote: > > > On 22.08.25 06:09, Mika Penttilä wrote: > > > > > > > > On 8/21/25 23:06, David Hildenbrand wrote: > > > > > > > > > All pages were already initialized and set to PageReserved() with a > > > > > refcount of 1 by MM init code. > > > > > > > > Just to be sure, how is this working with MEMBLOCK_RSRV_NOINIT, where MM is supposed not to > > > > initialize struct pages? > > > > > > Excellent point, I did not know about that one. > > > > > > Spotting that we don't do the same for the head page made me assume that > > > it's just a misuse of __init_single_page(). > > > > > > But the nasty thing is that we use memblock_reserved_mark_noinit() to only > > > mark the tail pages ... > > > > And even nastier thing is that when CONFIG_DEFERRED_STRUCT_PAGE_INIT is > > disabled struct pages are initialized regardless of > > memblock_reserved_mark_noinit(). > > > > I think this patch should go in before your updates: > > Shouldn't we fix this in memblock code? > > Hacking around that in the memblock_reserved_mark_noinit() user sound wrong > -- and nothing in the doc of memblock_reserved_mark_noinit() spells that > behavior out. We can surely update the docs, but unfortunately I don't see how to avoid hacking around it in hugetlb. Since it's used to optimise HVO even further to the point hugetlb open codes memmap initialization, I think it's fair that it should deal with all possible configurations. > -- > Cheers > > David / dhildenb > > -- Sincerely yours, Mike.