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Howlett" , Vlastimil Babka , Jann Horn , Pedro Falcato , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jonathan Corbet , Greg Kroah-Hartman , Dennis Dalessandro , Jason Gunthorpe , Leon Romanovsky , Paul Moore , Stephen Smalley , Jaroslav Kysela , Takashi Iwai , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Eduard Zingerman , Kumar Kartikeya Dwivedi , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Kiryl Shutsemau , Doug Gilbert , "James E.J. Bottomley" , "Martin K. Petersen" , Jaya Kumar , Simona Vetter , Helge Deller , Sebastian Reichel , John Hubbard , Peter Xu , Masami Hiramatsu , Oleg Nesterov , Peter Zijlstra , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Rik van Riel , Harry Yoo , Juri Lelli , Vincent Guittot , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Arnd Bergmann , Muchun Song , Oscar Salvador , "Matthew Wilcox (Oracle)" , Jan Kara , Marc Zyngier , Oliver Upton , Catalin Marinas , Madhavan Srinivasan , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , "David S. Miller" , Andreas Larsson , Alexander Viro , Christian Brauner , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Youngjun Park , Johannes Weiner , Qi Zheng , Shakeel Butt , Axel Rasmussen , Yuanchu Xie , Wei Xu , Chengming Zhou , Michal Hocko , Miklos Szeredi , Xu Xin Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-usb@vger.kernel.org, linux-rdma@vger.kernel.org, selinux@vger.kernel.org, linux-sound@vger.kernel.org, bpf@vger.kernel.org, linux-scsi@vger.kernel.org, linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-trace-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-arch@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, fuse-devel@lists.linux.dev References: <20260917-b4-mmap-prepare-vma-flag-sanify-v3-0-4583d8a23bca@kernel.org> <20260917-b4-mmap-prepare-vma-flag-sanify-v3-30-4583d8a23bca@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 9/17/26 18:22, Lorenzo Stoakes (ARM) wrote: > We currently disallow the installation of lightweight guard regions in VMAs > whose flags intersect VMA_SPECIAL_FLAGS or VMA_HUGETLB_BIT, or > VMA_LOCKED_BIT unless allow_locked is set. > > hugetlb VMAs set VMA_DONTEXPAND_BIT so this was already redundant, > VMA_SPECIAL_FLAGS already sufficed. > > However, now that VMA_IO_BIT is only set if VMA_PFNMAP or VMA_MIXEDMAP_BIT > is set, this check collapses to being the equivalent of > !vma_can_merge(). > > Update is_valid_guard_vma() to reflect this. > > No functional change intended. > > Signed-off-by: Lorenzo Stoakes (ARM) > --- > mm/madvise.c | 20 +++++++++++++------- > 1 file changed, 13 insertions(+), 7 deletions(-) > > diff --git a/mm/madvise.c b/mm/madvise.c > index 467601a8525b..0922d5f07a12 100644 > --- a/mm/madvise.c > +++ b/mm/madvise.c > @@ -1221,19 +1221,25 @@ static long madvise_remove(struct madvise_behavior *madv_behavior) > return error; > } > > -static bool is_valid_guard_vma(struct vm_area_struct *vma, bool allow_locked) > +static bool is_valid_guard_vma(const struct vm_area_struct *vma, > + bool allow_locked) > { > - vm_flags_t disallowed = VM_SPECIAL | VM_HUGETLB; > - > /* > - * A user could lock after setting a guard range but that's fine, as > + * A user could lock after setting a guard range but that's fine as > * they'd not be able to fault in. The issue arises when we try to zap > * existing locked VMAs. We don't want to do that. > */ > - if (!allow_locked) > - disallowed |= VM_LOCKED; > + if (!allow_locked && vma_test(vma, VMA_LOCKED_BIT)) > + return false; > + /* > + * Guard regions require a VMA whose page tables are managed solely by > + * the core, which is also what merging requires, so disallow any flags > + * that would prevent a merge. > + */ > + if (!vma_can_merge(vma)) > + return false; Acked-by: David Hildenbrand (Arm) -- Cheers, David