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b=luKXKLwGpleiLQ52LNbjoP4QpHdqBNNGypV9NO+EfnUuKS+kTceiOevrPpOSjUt4X bEQC5ApRPmZwPKtU1w6BPgaUfQ9TeWFkuKXbC4UOhR8btejprAcdH4FHdUNGU66sgx sMLaDEjluZAxtEsn92d04maEm44fOej4LBFLWLJoWt/TsjATdQVioU99CtYv3mpvWt /meehLg1wApIWLtuqH40TaaD8uZ30kgcZWuRFPw0+62LaTOb7SyVJvbboAwJtSKSnw vd9HuyQGC9FHXYd3MYoKaAO8HAktLi4Q9Hglr8JOZ8OlUV7K1Vf5bZWks7ylbbpMG/ WBG2zN0Z5Ts4A== From: Mike Rapoport To: linux-mm@kvack.org, klourencodev@gmail.com Cc: Mike Rapoport Subject: Re: [PATCH v2] mm/memtest: add underflow detection for size calculation Date: Tue, 30 Dec 2025 15:36:44 +0200 Message-ID: <176710174243.4000193.7433666118508467327.b4-ty@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251229161321.9079-1-klourencodev@gmail.com> References: <20251229161321.9079-1-klourencodev@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam02 X-Stat-Signature: k3r1qyjemznix143t1xpk4o71s1j8hrp X-Rspam-User: X-Rspamd-Queue-Id: 1997820005 X-HE-Tag: 1767101816-812426 X-HE-Meta: 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 8l3cIfAN H59TqH8/PCnzsx4MW2cH6q9B6W458PGOxwn+4Wy57ExcA9WvBBHupDQy/0J70UWEreCTzZkhGKjbngdCd/8JhF3ctxCkrPXd02MAsw8MnuQlR5IdAUMYimiDtkWojGRzZrS34iNNSMXuQ9GUjFiGuGg8O2f8qOh2zXSuGKqh1FwINqtlxg5INs/m+qFKwVUntU0DYke0i6qldpT2b1ZtBZmAGFYVSlSRYj3OJL6nRYIkFwGPuFuJRwTRdAufh3Mv0yxXpUwnQuTCUtPU= 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, 29 Dec 2025 17:13:21 +0100, klourencodev@gmail.com wrote: > The computation: end = start + (size - (start_phys_aligned - start_phys)) / incr > could theoretically underflow if size < offset, leading to a massive > iteration. > > Add VM_WARN_ON_ONCE() to detect cases where the region size is smaller > than the alignment offset. While this should never happen in practice > due to memblock guarantees, the warning helps catch potential bugs in > early memory initialization code. > > [...] Applied to for-next branch of memblock.git tree, thanks! I massaged the changelog a bit and moved VM_WARN_ON_ONCE() down while applying. [1/1] mm/memtest: add underflow detection for size calculation commit: acd8aed2f2b6ce4bcc4f20e48ae88882b1b29fc3 tree: https://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock branch: for-next -- Sincerely yours, Mike.