Re: [PATCH v3 21/40] mm/gup: error out early on !VMA_MAYREAD_BIT VMAs
From: "Zi Yan" <ziy@nvidia.com>
Date: 2026-09-26 02:30:26
Also in:
bpf, dri-devel, fuse-devel, kvm, kvm-riscv, kvmarm, linux-arch, linux-doc, linux-fbdev, linux-fsdevel, linux-mm, linux-perf-users, linux-rdma, linux-riscv, linux-s390, linux-scsi, linux-sound, linux-trace-kernel, linux-usb, lkml, selinux, sparclinux
On Thu Sep 17, 2026 at 12:22 PM EDT, Lorenzo Stoakes (ARM) wrote:
When populating a VMA range via the aptly named populate_vma_page_range() an unreadable VMA will always eventually fail with -EFAULT. That a VMA is accessible is always checked, however VMA_MAYREAD_BIT is not. All user mappings always have VMA_MAYREAD_BIT set, so this check only impacts kernel mappings. It is implemented specifically to disallow population of uprobes XOL mappings which are exec-only. A nasty interaction with these mappings may occur if they are mlocked, so actively disallow this early. This allows a subsequent commit to remove the VM_IO check in __mm_populate() which otherwise requires non-MMIO mappings to be wrongly flagged simply as a workaround. Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org> --- mm/gup.c | 4 ++++ 1 file changed, 4 insertions(+)
Acked-by: Zi Yan <ziy@nvidia.com> -- Best Regards, Yan, Zi