Re: [PATCH v4 25/38] mm: remove VMA_IO_BIT check in vma[_flags]_is_mm_managed()

We have now made it such that every driver which sets VMA_IO_BIT marks it
as not mm-managed.

However, vma_flags_is_mm_managed() currently treats VMA_IO_BIT as
disqualifying. This was a product of drivers previously marking a range as
not mm-managed by
setting VMA_IO_BIT alone.

Fix this by removing the VMA_IO_BIT check in vma_flags_is_mm_managed(),
and update mmap_validate_vma_flags() to use vma_flags_is_mm_managed()
rather than open-coding the VMA_PFNMAP_BIT, VMA_MIXEDMAP_BIT check.

This change means that vma[_flags]_can_merge() doesn't check VMA_IO_BIT any
longer (which is now redundant) as it calls vma_flags_is_mm_managed().

[ ... ]
Finally, update the VMA userland merge 'special' flag tests to no longer
assert that VMA_IO_BIT prevents merge as VMA_PFNMAP_BIT, VMA_MIXEDMAP_BIT
now suffices.

Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261003-b4-mmap-prepare-vma-flag-sanify-v4-0-a1f052500fd7@kernel.org?part=25