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From: Muchun Song In-Reply-To: <20260128135500.22121-10-kas@kernel.org> Date: Thu, 29 Jan 2026 11:00:07 +0800 Cc: Andrew Morton , David Hildenbrand , Matthew Wilcox , Usama Arif , Frank van der Linden , Oscar Salvador , Mike Rapoport , Vlastimil Babka , Lorenzo Stoakes , Zi Yan , Baoquan He , Michal Hocko , Johannes Weiner , Jonathan Corbet , Huacai Chen , WANG Xuerui , Palmer Dabbelt , Paul Walmsley , Albert Ou , Alexandre Ghiti , kernel-team@meta.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, loongarch@lists.linux.dev, linux-riscv@lists.infradead.org Content-Transfer-Encoding: quoted-printable Message-Id: References: <20260128135500.22121-1-kas@kernel.org> <20260128135500.22121-10-kas@kernel.org> To: Kiryl Shutsemau X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Queue-Id: DF6A440010 X-Rspamd-Server: rspam07 X-Stat-Signature: e81bmitxznojdmi3xh57pfr94jjtzu3t X-HE-Tag: 1769655652-498835 X-HE-Meta: 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 w/F7cuUY CcWKI1rJiEGtFzfwBgMfT7Hgnh5b0xsZtTSMR077A+8ihNq83yzwuuKbBQusSeBAVb5MJTXMFiZsxsHQ7wNCMJj21Iyv3cAeHgLOfcY+W4qp7Ub9NL3XsLcWBGHIaBMaPCD1efV2QUnhyCAhhUgkiJQUZNaZ1Kg0iUdBLuL9gQQ2fuy2Qf1Mz2SXGJouAhtQHXt6Q3GvBcXEbOPtqkBzvuVpJRA2z4TwXpq9qBYdJ9RWMifMNqWCKb5BLb14cYwChxLwOhn2v9m1mvv+5czD6EuJg96NXCRAweUWWFubpvatjo7RTbpm4h7efxKeU4X3s7CKM5P1ArljjX2Q= 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 Jan 28, 2026, at 21:54, Kiryl Shutsemau wrote: >=20 > If page->compound_info encodes a mask, it is expected that vmemmap to = be > naturally aligned to the maximum folio size. >=20 > Trigger a BUG() for CONFIG_DEBUG_VM=3Dy or WARN() otherwise. >=20 > Signed-off-by: Kiryl Shutsemau > Acked-by: Zi Yan > --- > mm/sparse.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) >=20 > diff --git a/mm/sparse.c b/mm/sparse.c > index b5b2b6f7041b..9c0f4015778c 100644 > --- a/mm/sparse.c > +++ b/mm/sparse.c > @@ -600,6 +600,19 @@ void __init sparse_init(void) > BUILD_BUG_ON(!is_power_of_2(sizeof(struct mem_section))); > memblocks_present(); >=20 > + if (compound_info_has_mask()) { > + unsigned long alignment; > + bool aligned; > + > + alignment =3D MAX_FOLIO_NR_PAGES * sizeof(struct page); > + aligned =3D IS_ALIGNED((unsigned long) pfn_to_page(0), = alignment); > + > + if (IS_ENABLED(CONFIG_DEBUG_VM)) > + BUG_ON(!aligned); > + else > + WARN_ON(!aligned); Since you=E2=80=99ve fixed all the problematic architectures, I don=E2=80=99= t believe we=E2=80=99ll ever hit the WARN or BUG here anymore. I think we can now simplify the code further and just use VM_BUG_ON: if any architecture changes in the future, the misalignment will be caught during testing, so we won=E2=80=99t need to worry about it at = run-time. > + } > + > pnum_begin =3D first_present_section_nr(); > nid_begin =3D sparse_early_nid(__nr_to_section(pnum_begin)); >=20 > --=20 > 2.51.2 >=20