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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Frank van der Linden , linux-mm@kvack.org, linux-kernel@vger.kernel.org, muchun.song@linux.dev Subject: Re: [PATCH] mm/sparse: fix preinited section_mem_map clobbering on failure path Message-Id: <20260331131054.0164f3b3ab6f7868add37cd3@linux-foundation.org> In-Reply-To: <20260331113724.2080833-1-songmuchun@bytedance.com> References: <20260331113724.2080833-1-songmuchun@bytedance.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-Queue-Id: 551B9140005 X-Stat-Signature: gen7i3edih7r79qgywmuxuy5qroxsyxm X-Rspam-User: X-Rspamd-Server: rspam07 X-HE-Tag: 1774987856-206946 X-HE-Meta: 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 4yL9RB+p Wk6/TMb4mBTdtbInvJQvnfKuJ9nSvOzwkDUjq1q3eOUqHhRdB55Fgs8jSf0+2s7jsqfYvxUCBrDjkJ2RP2gDEK7uSS/Xnc5yXgj9jqv7rWNaLZCb6ksdu3bJL1nnXOM3lYhiNwB+s0Ee6dZe/o74Nk5JScUle0HSW3aqtkI7VV8lkbQhHOGlD0dh0jaZGt/kOLZjHfQFbQ9dOMIaAxlcDe/VWQcKsUKBrFBQ3jHtz6rKNVEh3PvZpzXb6ubTBcok3YMYt8ffvws5gZWiTEexw+TJzvkRThMos8XDmXxleHvKRhU7fsFwhHspQDhWhpRdI1helWJeIEoxY6yHOsTGbR+6eBnqH7RkKozMLDnLVqMhiDeCWLErJyow/00kvF59QXFu6 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, 31 Mar 2026 19:37:24 +0800 Muchun Song wrote: > 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: > > if (!preinited_vmemmap_section(ms)) > ms->section_mem_map = 0; > > A leftover line after that conditional block > > ms->section_mem_map = 0; > > 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. > > Drop the stray assignment so that preinited sections retain their > already valid state. Here I go again ;) Are there userspace impacts? AI review thinks it found a different bug: https://sashiko.dev/#/patchset/20260331113724.2080833-1-songmuchun@bytedance.com