It makes no sense for a mapping whose contents the kernel does not own to specify that the range is MMIO.
Prior to this patch, all in-tree drivers which did so have been updated such that they are marked as kernel-owned. The check WARNs and fails the mmap for any out-of-tree driver that still sets VMA_IO_BIT without a kernel mapping. No functional change intended for in-tree code. Signed-off-by: Lorenzo Stoakes (ARM) <[email protected]> --- mm/vma.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/mm/vma.c b/mm/vma.c index c6ed04d27351..fa429771bea8 100644 --- a/mm/vma.c +++ b/mm/vma.c @@ -2787,6 +2787,12 @@ static int mmap_validate_vma_flags(const vma_flags_t *flags) return -EINVAL; #endif + if (!vma_flags_test_any(flags, VMA_PFNMAP_BIT, VMA_MIXEDMAP_BIT)) { + /* Only kernel-owned mappings may set VMA_IO_BIT. */ + if (WARN_ON_ONCE(vma_flags_test(flags, VMA_IO_BIT))) + return -EINVAL; + } + return 0; } -- 2.55.0
