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Mon, 30 Mar 2026 10:41:35 -0400 (EDT) Date: Mon, 30 Mar 2026 15:41:34 +0100 From: Kiryl Shutsemau To: Usama Arif Cc: Andrew Morton , david@kernel.org, Lorenzo Stoakes , willy@infradead.org, linux-mm@kvack.org, fvdl@google.com, hannes@cmpxchg.org, riel@surriel.com, shakeel.butt@linux.dev, baohua@kernel.org, dev.jain@arm.com, baolin.wang@linux.alibaba.com, npache@redhat.com, Liam.Howlett@oracle.com, ryan.roberts@arm.com, Vlastimil Babka , lance.yang@linux.dev, linux-kernel@vger.kernel.org, kernel-team@meta.com, maddy@linux.ibm.com, mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, linux-s390@vger.kernel.org Subject: Re: [v3 16/24] mm: huge_mm: Make sure all split_huge_pmd calls are checked Message-ID: References: <20260327021403.214713-1-usama.arif@linux.dev> <20260327021403.214713-17-usama.arif@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260327021403.214713-17-usama.arif@linux.dev> X-Stat-Signature: qy1tgbkj9mcw7hdhot6t8m5rknqn51me X-Rspamd-Queue-Id: 924361C0016 X-Rspam-User: X-Rspamd-Server: rspam03 X-HE-Tag: 1774881698-128596 X-HE-Meta: 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 iNkB5oxd m85NRmyuB1YKxtJwUfsKDmsfHomXKHGvC/sTceikvN7vJ5IBKA+ClYhxmYtyU2n3gZKSuwyXcyjADkBbhSgI+rG6IDzefkB+6KnSw6HzGdjT7KOJzlFTu0ACQ3tEkrlsF4UjHsDi2q/Uiz/+qmxmbhUFPsIyf7oUngL58BufIutd8KZXDAFfll7IQRRSh26NytLlJNa2et92+2//T1OLw8nZ2VTqDWs3c/Qk4WUBqki3SAuSnNR9TN+NyWDF3nDZKrWnoj0UibhrnbHCRo9qxfLfdxnClQZhmeBH4vMNG8NH86QRir+1Quu2xFSjwlN6FiY2VEWdC2aik/BQ68vG6dt92S6DY5EMnuaUI Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Mar 26, 2026 at 07:08:58PM -0700, Usama Arif wrote: > Mark __split_huge_pmd(), split_huge_pmd() and split_huge_pmd_address() > with __must_check so the compiler warns if any caller ignores the return > value. Not checking return value and operating on the basis that the pmd > is split could result in a kernel bug. The possibility of an order-0 > allocation failing for page table allocation is very low, but it should > be handled correctly. I think we want the same __must_check annotation on stubs for CONFIG_THP=n. -- Kiryl Shutsemau / Kirill A. Shutemov