From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5F4B93043CF for ; Fri, 5 Dec 2025 07:05:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764918322; cv=none; b=uMZlPG0hx25omf0Pl1kp/APWIfnxBo0D27kWzU+mdzZlf8lmBkV/w9CzJlx9AfsynYuxMQKMQEEq3/4Hly5JliDungdxElTkb6t8cl/rK3qHjcBfRv/75o3h4eUKtpvCgvCecrE1VU5up/X5fbOtneXCrYhfFq5/DDS7VUxnY5Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764918322; c=relaxed/simple; bh=pLFYJRb6YhaKELyTkQIdNWJE3/HJjwoQZjQuRwUY00w=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=LVA7DB4C9fbRr92BwGee6qDOkgrY52+WFH246iBgf5tqVbbP+p3E4nNIS94lifIOSZFDiyvux+J2FLFapOKcYHHtNdA8DM2bP6lnCOmGel3FFiHqwF7NSm2ZO+cwqkgOfa10aNcl26I5uUBDck3kvrhk+rvI5owTAL3mHN2CIuc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=K3EFtiCP; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="K3EFtiCP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5E6D7C4CEF1; Fri, 5 Dec 2025 07:05:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764918321; bh=pLFYJRb6YhaKELyTkQIdNWJE3/HJjwoQZjQuRwUY00w=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; 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 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 >> 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