Re: [PATCH v5 20/38] mm/gup: error out early on !VMA_MAYREAD_BIT VMAs
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From: "David Hildenbrand (Arm)" <david@kernel.org>
Date: 2026-10-12 18:16:03
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On 10/9/26 20:04, 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. Acked-by: Zi Yan <ziy@nvidia.com> Reviewed-by: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org> ---
Acked-by: David Hildenbrand (Arm) <david@kernel.org> -- Cheers, David