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b=K3EFtiCPH/gJxujbU4Cm+y7/bAey3QI9Olbp9MYwWGqC7Nmv8R/IjCikrcpGvkR+W ahUS+ovOEboDaV6dvr6n+DYzDjqyq+goOcuPYIQPNztPcQ0qdsAPnc/EszXF/NRH1k BScJhY6UnO97T36Uv92hUXAXhZzyfiFIPORS9dEO7uqHQyKbKV/ZR4g9SGV30lCKqP qn/kmdHGZg3eIpG4Fa/IGcKA7LtGyxxdtF0K7sUXEOMvhfZ3fbnRcACcAWBBtxJMz7 0Znmvz69YxleWE8ugaLzl+EOQM+eebbFiMDO1OS3/2ni9BuY3eoU+QapHyPYLBKDk1 Ti0fvrzdzB2qg== Message-ID: Date: Fri, 5 Dec 2025 08:05:14 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] Revert "mm: fix MAX_FOLIO_ORDER on powerpc configs with hugetlb" To: Mike Rapoport , Andrew Morton Cc: Shuah Khan , maddy@linux.ibm.com, mpe@ellerman.id.au, npiggin@gmail.com, christophe.leroy@csgroup.eu, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, vbabka@suse.cz, surenb@google.com, mhocko@suse.com, masahiroy@kernel.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Linus Torvalds References: <20251204023358.54107-1-skhan@linuxfoundation.org> <20251204135746.6d291cc861b4507b1fe95aaa@linux-foundation.org> From: "David Hildenbrand (Red Hat)" Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: D016A1C0006 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: cgtbwmsarcshjco9afsdwzqt5jigh7jp X-HE-Tag: 1764918322-986092 X-HE-Meta: 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 nx2EMcm9 63Jy/OF2XLrkKGJNlABlT3Xc1D7z3mzySyeNIco1KFhl90hxEfor0iVh9qAZMqRkxcAoSNsx5YUgYoC0/YUsAR4uJx+e66eEr46PaePdKTrTi1LUWOoAv3dMEC1To+7jN5ZMsmaZa3R4WH21Yi7dWn1LKTs1w59Y4NFNbuSp5zZFyAzPPbksmX9epyE5m4XSTkmvpsfL/nGAIR1/FIliqTL9B7lUjEQ4Rz0LNRrWpnFVmFOhcs7SGsDHbahqCTVDej1eM4LsgRwImQ/OOa96cvc2ZtHHmsxck1s1DV+9dzpWWPGouBsYcYPdmuvPSJnFGzcDCrpHobrNS6it4oRMkkj3Xj09RKfygCxmSv2erGyJeAu4= 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: >> 39231e8d6ba7 simply shuffles ifdefs and Kconfig items, so I assume it >> exposed a pre-existing bug. >> >> Reverting 39231e8d6ba7 will re-hide that bug. > > Shuah confirmed that the bugs were on v6.18-rc6 and they were fixed in > 6.18 [1]. > > I verified that reverting 39231e8d6ba7 from v6.18-rc6 does not solve > anything, but applying 5bebe8de19264 does [2]. > Thanks! > So reverting 39231e8d6ba7 does not change anything and there is no bug it > hides. The bug was introduced by adfb6609c680 ("mm/huge_memory: initialise > the tags of the huge zero folio"), was fixed by 5bebe8de1926 > ("mm/huge_memory: Fix initialization of huge zero folio") ... > >> And that isn't a bad thing. If we re-hide the bug in 6.18.x and in >> mainline then that relieves the people who are hitting this and it >> takes the pressure off David, Mike and yourself to get the underlying >> bug fixed in a hurry. >> >> So I think I'll queue this as a hotfix, plan to send it Linuswards in a >> couple of days. >> >> Or Linus may choose to apply it directly or to do a local revert of >> 39231e8d6ba7. But I don't see how a local revert will get communicated >> to the 6.18.x maintainers. >> >> David, Linus, opinions please? >> >>> Signed-off-by: Shuah Khan >> >> Let's have a cc:stable here, just to be sure. > > ... and we can skip all this hassle. Yes. Thinking about reverting arbitrary commits after Shuah clearly tested something wrong is completely unreasonable. -- Cheers David