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b=DnHvLCpSUmJ1NeZ/lqAsck/JGOrOhc99RsJ8vee97FxOXDShBzBieIEHn9D/AHByJ O5Pn7WgIrD4GVrsvG2b01PUBk7TQIeCksLVBVe9p+nAnyY7JyWLxPYAb3yPtOC6RD6 8R18iPoBEbQ9d0sQgTstl8BkrooE8OeWeQlyV2Vk= Date: Mon, 26 Jan 2026 11:05:50 -0800 From: Andrew Morton To: Ankur Arora Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org, david@kernel.org, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, mingo@redhat.com, mjguzik@gmail.com, luto@kernel.org, peterz@infradead.org, tglx@linutronix.de, willy@infradead.org, raghavendra.kt@amd.com, chleroy@kernel.org, ioworker0@gmail.com, lizhe.67@bytedance.com, boris.ostrovsky@oracle.com, konrad.wilk@oracle.com, kernel test robot Subject: Re: [PATCH] mm: folio_zero_user: open code range computation in folio_zero_user() Message-Id: <20260126110550.0df8f68ea232a745c187b2a6@linux-foundation.org> In-Reply-To: <20260126183212.2366596-1-ankur.a.arora@oracle.com> References: <20260107072009.1615991-9-ankur.a.arora@oracle.com> <20260126183212.2366596-1-ankur.a.arora@oracle.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 3DF371C0013 X-Stat-Signature: eu7iqyi5uihubsqrm5ww8hqexme9eaig X-Rspam-User: X-HE-Tag: 1769454353-506350 X-HE-Meta: U2FsdGVkX18kkgJ4PZ41W2gc8AaFXd6RsNgtOfa1rb3ggWO/QWZrAUI0KA1/JGFmWyHjig/+XyHICJ71FsDbwPy+zyPjw7LxYJDz742zsm5SGYozt1s2DrOuhRoo6gDbQLQFTPDdTf7P2QgWTdNFLtV54m8lisw0yv9xnMBhK/B0ry2DpAtT/Rv+/Xt3akGG+lN089BB2s9QeY3RVH+IZm8L+G758UJkkjfZ2AytkRkUDYArTKXjSEpsQuEfBRfOVMQzbmo9Ll1YAlSxV8OyQDNaA6wq/zEX1FM4f3YWEaBSiAr+CYn58S+vUMrDgGnrE6BqF+GmLtQaXV/JFh/yQg5CxH9SDtc0tXMzRPJlw0Rc2iW5HbgB0C9ADte6PC4Yp+7sTPcaQA8wFSZga9FLpAlknAbSeEzs5kMgjoMF/MQi+FGaFrqMAJAiDmkrWxFD/JG9YYYthbJKkzi6tSt0F1xU1n5n2j8HTgwDxmkb0eIB+hAf+HpvvCTsoiTCgp2AMA3H5pS3YwgKhN0zt8wNuCWnS060lYgEYtz6jCeZ2kN8YdPIhmKDEif1oe70qu6tSB2Xz/qkMRZjk+azIzaaPFe4uI7OZ/NKrioXjbd8hnB8I998OkwFSlYYHky3qo25tHvlT+0UFhfqKVN4CAXqLHtyMVR7lGlpF9pzwrsEp4AOpsF6qSUZYKuGWmg0CuVIOeJ8qYsgzDDEyAcd9+7QVReiDgjlb/1v5P8JK5YUNv6QHoVBH60uqkGjQitFe9JqxkDqsxfQoisGTB/RfGh/KqiWbIMdTX655014CUQCLX5qIA7CJRiRE0d5Iidi79i91Jj88BYSwoxZTqUZJYJ1AcSYHxbrfO2tjqKU3FfS1vNftoDY2Ay2afJ/kicIsCcqCj9DW/eU0Tu7ihaMxcGdqeZqIKDuxJbU3JCaV/M+MTdfyN1lkRmwWXVeJk3KuAUXq6ROeZJJzvkrBd+xNYM JpRAFPDv 6LiKRvOax++Uy3ZzRfj5DTTml3U9mvt8tdpAEtwW7nk/oeP/Y5XBfZ5jIriUDEwzD6a94kHpEOLX8AvkiRMudLGX0HDDTghgqsDe9nMmGmaGpo2ucAlOU/9xBbNq38F5Fg+Uq3aP1H3+GvqRYFnc4tmAoRUNUupA7kGXZO30h9DTavQVooU7BDi3kQse/pN0LaJtu9JvAhgYPxWNra1YV4PUpyxE4tWTcwPws5X0uUrlrOeJ7WYiUTVyv21qmYHrtW3bzp0gf7pIub8QrKjkJv2uDSaQY45Fewr5YVaiFq8r36TI8UyLQMX6GoU95VkFgC/JN 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, 26 Jan 2026 10:32:12 -0800 Ankur Arora wrote: > riscv64-gcc-linux-gnu (v8.5) reports a compile time assert in: > > r[2] = DEFINE_RANGE(clamp_t(s64, fault_idx - radius, pg.start, pg.end), > clamp_t(s64, fault_idx + radius, pg.start, pg.end)); > > where it decides that pg.start > pg.end in: > clamp_t(s64, fault_idx + radius, pg.start, pg.end)); > > where pg comes from: > const struct range pg = DEFINE_RANGE(0, folio_nr_pages(folio) - 1); > > That does not seem like it could be true. Even for pg.start == pg.end, > we would need folio_test_large() to evaluate to false at compile time: > > static inline unsigned long folio_nr_pages(const struct folio *folio) > { > if (!folio_test_large(folio)) > return 1; > return folio_large_nr_pages(folio); > } > > Workaround by open coding the range computation. Also, simplify the type > declarations for the relevant variables. Thanks. It's a shame. gcc-8.50 is five years old. Documentation/Changes says we support 8.1. > I'm not certain about linux-next rebasing protocol, but I'm guessing > this patch will be squashed in patch-8 ("mm: folio_zero_user: cache > neighbouring pages"). If the base patch was in mm-unstable then I'd squash. But it is now in the allegedly non-rebasing mm-stable so I'll queue this into mm-unstable->mm-stable as a separate thing, with Fixes: 93552c9a3350 ("mm: folio_zero_user: cache neighbouring pages") So there will be a bisection hole for riscv people who use an ancient compiler, shrug. > mm/memory.c | 23 +++++++++++------------ > 1 file changed, 11 insertions(+), 12 deletions(-) We could of course revert this when we're able to confirm that the currently-supported gcc versions all handle it OK.