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From: Muchun Song In-Reply-To: <20260331131054.0164f3b3ab6f7868add37cd3@linux-foundation.org> Date: Wed, 1 Apr 2026 10:37:01 +0800 Cc: Muchun Song , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Frank van der Linden , linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Message-Id: <0D1D7025-7DF4-41DB-83A4-6AA800FBAAD6@linux.dev> References: <20260331113724.2080833-1-songmuchun@bytedance.com> <20260331131054.0164f3b3ab6f7868add37cd3@linux-foundation.org> To: Andrew Morton X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: EFEA414000A X-Stat-Signature: oh157553nbqub1cmypnp6pkaq535x6gc X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1775011067-438778 X-HE-Meta: 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 FT3D6ThX Y0pmFcEqMBqyBz8W765eFYFLOWwycFcnrWXQb6bfX+9Ks8yMe53RXFzMXKk+6FJr5iBViH38iYMx3gNQYQriYoUIzN07k2T3lUyrTC2Wmh2T0Vq+P2bukz9Fkgb1c/6Kpsd1+ZaiE9lZzLfdaM0v7lg8K5evv/ThX550tTV6sEHVWXHvtcC1w0wOgv9xuLTNRTy47/oKHbtdLVx/z4+0V7scF02k0NRCPKepHlDo2AWCstZKKmmS0L3qySZU11/GcVhAt8Fr69qqwBsfD++FAtTUjXiA7wBQ8gcbkJeXILX77TQ998Nz6/0mOmlTDHFQn4j3/rui/51WWxNe84B6wAuHcb7x2fvWwwK+TUIDnQs1q+oKrx3/uuius943rkAyNcD/qX5rk/pWIw22ztAyLWBzwIfnR9cSMHyxemo8zmlHP44U= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > On Apr 1, 2026, at 04:10, Andrew Morton = wrote: >=20 > On Tue, 31 Mar 2026 19:37:24 +0800 Muchun Song = wrote: >=20 >> sparse_init_nid() is careful to leave alone every section whose = vmemmap >> has already been set up by sparse_vmemmap_init_nid_early(); it only >> clears section_mem_map for the rest: >>=20 >> if (!preinited_vmemmap_section(ms)) >> ms->section_mem_map =3D 0; >>=20 >> A leftover line after that conditional block >>=20 >> ms->section_mem_map =3D 0; >>=20 >> was supposed to be deleted but was missed in the failure path, = causing the >> field to be overwritten for all sections when memory allocation = fails, >> effectively destroying the pre-initialization check. >>=20 >> Drop the stray assignment so that preinited sections retain their >> already valid state. >=20 > Here I go again ;) Are there userspace impacts? Those pre-inited sections (HugeTLB pages) are not activated. However, = such failures are extremely rare, so I don't see any major issues. >=20 > AI review thinks it found a different bug: > = https://sashiko.dev/#/patchset/20260331113724.2080833-1-songmuchun@bytedan= ce.com I don't think the issue reported by AI is a real problem, because the allocation of sparse_usagebuf has already taken these hugetlb sections into account. Thanks.