Re: [PATCH v5 14/38] mm/vma: add vma[_flags]_is_mm_managed() predicates

Rather than referring to VMA flags with uncertain meaning, add a new
predicate that explicitly describes what absence of the VMA_PFNMAP_BIT and
VMA_MIXEDMAP_BIT flags means, and then refer to that function for
determining VMA mergeability.

If neither of these flags are set, that means the contents of the mapping
are managed by core mm.

Otherwise they are instead owned by some other kernel component, usually a
driver: the memory may be MMIO, kernel-allocated pages or even ordinary
pages the driver maps itself, but core mm must not populate, reclaim,
migrate, copy-on-write or merge the range itself.

We initially also treat VMA_IO_BIT as implying a mapping is not mm-managed,
as by implication it cannot be. (mlock() also sets VMA_IO_BIT transiently
[ ... ]
No functional change intended.

Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
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/20261009-b4-mmap-prepare-vma-flag-sanify-v5-0-923b70125b1e@kernel.org?part=14