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 not being mm-managed. 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. Reviewed-by: Zi Yan <[email protected]> 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 df2efdfa3805..43d32c3b8f6b 100644 --- a/mm/vma.c +++ b/mm/vma.c @@ -2793,6 +2793,12 @@ 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)) { + /* mm-managed mappings may not set VMA_IO_BIT. */ + if (WARN_ON_ONCE(vma_flags_test(flags, VMA_IO_BIT))) + return -EINVAL; + } + return 0; } -- 2.55.0
