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Howlett" , Jann Horn , Pedro Falcato , Mike Rapoport , Suren Baghdasaryan , Kees Cook , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Vineet Gupta , Russell King , Catalin Marinas , Will Deacon , Brian Cain , Huacai Chen , WANG Xuerui , Thomas Bogendoerfer , Dinh Nguyen , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H . Peter Anvin" , Richard Weinberger , Anton Ivanov , Johannes Berg , Alexander Viro , Christian Brauner , Jan Kara , Xu Xin , Chengming Zhou , Michal Hocko , Paul Moore , Stephen Smalley , Ondrej Mosnacek , linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-hexagon@vger.kernel.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-um@lists.infradead.org, linux-fsdevel@vger.kernel.org, selinux@vger.kernel.org References: <02a6b26542ab70d60175e0125cff5fd00073c7ae.1773846935.git.ljs@kernel.org> From: "Vlastimil Babka (SUSE)" In-Reply-To: <02a6b26542ab70d60175e0125cff5fd00073c7ae.1773846935.git.ljs@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 3/18/26 16:50, Lorenzo Stoakes (Oracle) wrote: > vma_flags_count() determines how many bits are set in VMA flags, using > bitmap_weight(). > > vma_flags_test_single_mask() determines if a vma_flags_t set of flags > contains a single flag specified as another vma_flags_t value, or if the > sought flag mask is empty, it is defined to return false. > > This is useful when we want to declare a VMA flag as optionally a single > flag in a mask or empty depending on kernel configuration. > > This allows us to have VM_NONE-like semantics when checking whether the > flag is set. > > In a subsequent patch, we introduce the use of VMA_DROPPABLE of type > vma_flags_t using precisely these semantics. > > It would be actively confusing to use vma_flags_test_any_single_mask() for > this (and vma_flags_test_all_mask() is not correct to use here, as it > trivially returns true when tested against an empty vma flags mask). > > We introduce vma_flags_count() to be able to assert that the compared flag > mask is singular or empty, checked when CONFIG_DEBUG_VM is enabled. > > Also update the VMA tests as part of this change. > > Signed-off-by: Lorenzo Stoakes (Oracle) Acked-by: Vlastimil Babka (SUSE)