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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Pankaj Raghav , Hannes Reinecke , Hugh Dickins , Yang Shi , Kiryl Shutsemau , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Hengbin Zhang Subject: Re: [PATCH mm-hotfixes v2 2/2] mm/huge_memory: separate out CONFIG_PERSISTENT_HUGE_ZERO_FOLIO logic Message-ID: References: <20260730-fix-refcounted-huge-zero-v2-0-c5d8a41b317f@kernel.org> <20260730-fix-refcounted-huge-zero-v2-2-c5d8a41b317f@kernel.org> <011609c5-deea-43f2-a2c2-90f64053eb3a@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <011609c5-deea-43f2-a2c2-90f64053eb3a@kernel.org> X-Rspam-User: X-Stat-Signature: jgpjbbbdob64k45ubmg987xghzcp9xu5 X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: A4A931C0006 X-HE-Tag: 1786527428-669107 X-HE-Meta: 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 V1qfiu6U QKNV+bULBT1I08FJ5I8O0Nw5L/Wm3O00S5ifE18g9THbP793HwoC7PsU0pqv6+aeBU5LkbmyEbdYqGvKuRMw2x6JbpqdUZuLOMhaGL19hKuOnxrk/udLAOPUuzTBkE1QuTk3xe77V9ti7XkWM3koQxbOGZxODPnrPQmLySIa39KyHZgmUl84OnZNFMB5lINToEWjTCn0FuccObRTVD/G/N10bWFL/BE1zS7e6A7M9fbZaI7tnAuMAHduNhLMqZr7VrorsttSShq8QbRC4IDUTT4T1sNK9tHV/LxweK9YCcGQCbnbvxsD4SsTP0U47WkDbbnmX Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Aug 12, 2026 at 10:05:55AM +0200, David Hildenbrand (Arm) wrote: > On 7/30/26 12:55, Lorenzo Stoakes (ARM) wrote: > > Rather than mixing the refcounted and non-refcounted > > CONFIG_PERSISTENT_HUGE_ZERO_FOLIO logic, separate the two out cleanly > > so it is clear what happens when this configuration option is set and what > > happens when it is not. > > > > Introduce HUGE_ZERO_UNSET_PFN to abstract the ~0UL assignment, only > > introduce the refcount, lock and shrinker if > > !CONFIG_PERSISTENT_HUGE_ZERO_FOLIO, abstract initialisation and teardown, > > abstract the huge zero folio allocation from refcounting. > > > > Also change a BUG_ON() to WARN_ON_ONCE() while we're at it. > > > > No functional change intended. > > Ugh. Why is this patch already upsteam with > > Fixes: 3b77e8c8cde5 ("mm/thp: make is_huge_zero_pmd() safe and quicker") > Cc: Yeah these tags weren't part of it + it was intended as a separate thing but I guess it got lost in translation. I should probably have just sent it entirely separately after the fix landed so my bad on that part. > > It's absolutely not a fix. It's a cleanup that should have been reviewed properly. > > I really wanted to review this. > > Making David grumpy in the morning, good job everyone. Sorry about that :) At least it's not schlop? ;)) > > -- > Cheers, > > David -- Cheers, Lorenzo