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b=IAzw1OUHYgUWBP5mdicRgkXgo68l062ZNu3AOYLPZXPFoAEtFD1fhoIwy2uRycPZY 96wUtdi8CnoG3eZUHlVW37tSpWW6YJl6D8dn2jqFgwB+4tDZ9jzkbADts5LgJ94LKX 9u5T6aFzJsO61OIQXrXQfZqjRX+qVBy1/I2z7Vxe1H/OExo7dhtAtfnEkgg69CRkGk 4VGCkxc6Zf/JDHGdwrUYFCpVp6pb3dBU9b5LZBoBse7FvyGmKojZRmzdvvgpvpiMpb mF5For1ffogsUFSD6jGYvu7hFZWxq0+HwB5Y85vSctNh9hlsn5Ox6Mku0zKBmni9Mb F1Twn2KYLcVzg== Message-ID: Date: Thu, 4 Dec 2025 23:12:06 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] Revert "mm: fix MAX_FOLIO_ORDER on powerpc configs with hugetlb" To: Andrew Morton , Shuah Khan Cc: 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, rppt@kernel.org, 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: <20251204135746.6d291cc861b4507b1fe95aaa@linux-foundation.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 9A6DE40006 X-Stat-Signature: jcbik68boqszmymcct68xcrbiim3juim X-Rspam-User: X-HE-Tag: 1764886335-438420 X-HE-Meta: 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 B3XxqB0O J7DFx1N4H+uViODgqz6WMIIKIA8N7PvtZfCl8GitlDf1qkSjj/loDQN3Y4XSS4I4wzipEhIVonz3Y1JG8uxfpg1O47cEGs6Ar5h7OxXGRTCcGrIwS8OXASE6UeTxOz79ZPg400xriuQL+4C//BuuciFglUrCt1oDSeC8g0CgkaFi0poPbd876JaW9hka/uQ1PC6X3kfqYY37ERQPx/DN4l6JjBntyIitLlOT00CGGxZ7djkX97R6rQqZyT6Gzt71LNjvCndB7NuLvpd371DWXXlgAa1+nsBo2ffrxn9rKENZvhFCa5Atk2IHzuzS5ovGPGHalWBH4oLh5vgawG/ToFXo4LvovLc6wb7QrctoSBkWxmMUJ3uPvhCg5kmaHiZpnlp0GbmWeeqQwppM= 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 12/4/25 22:57, Andrew Morton wrote: > On Wed, 3 Dec 2025 19:33:56 -0700 Shuah Khan wrote: > >> This reverts commit 39231e8d6ba7f794b566fd91ebd88c0834a23b98. >> >> Enabling HAVE_GIGANTIC_FOLIOS broke kernel build and git clone on two >> systems. git fetch-pack fails when cloning large repos and make hangs >> or errors out of Makefile.build with Error: 139. These failures are >> random with git clone failing after fetching 1% of the objects, and >> make hangs while compiling random files. >> >> The blow is is one of the git clone failures: >> >> git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git linux_6.19 >> Cloning into 'linux_6.19'... >> remote: Enumerating objects: 11173575, done. >> remote: Counting objects: 100% (785/785), done. >> remote: Compressing objects: 100% (373/373), done. >> remote: Total 11173575 (delta 534), reused 505 (delta 411), pack-reused 11172790 (from 1) >> Receiving objects: 100% (11173575/11173575), 3.00 GiB | 7.08 MiB/s, done. >> Resolving deltas: 100% (9195212/9195212), done. >> fatal: did not receive expected object 0002003e951b5057c16de5a39140abcbf6e44e50 >> fatal: fetch-pack: invalid index-pack output > > 39231e8d6ba7 simply shuffles ifdefs and Kconfig items, so I assume it > exposed a pre-existing bug. > > Reverting 39231e8d6ba7 will re-hide that bug. > > 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? I have so far no indication that this patch here would change anything relevant to the problem we are seeing, all it does is changing MAX_FOLIO_ORDER that does not affect any logic we would really care about here (safety checks and snapshot_page()). Can we please wait a bit so we have confirmation that it's not a leftover from the huge-zero-folio thingy or something different? As Mike reports, he found ways to reproduce something similar even with 39231e8d6ba7 reverted. -- Cheers David