Re: [PATCH v2 02/13] mm/vma: update do_mmap() to use vma_flags_t

On 7/11/26 20:44, Lorenzo Stoakes wrote:

The core do_mmap() function accepts a vm_flags_t parameter which it then
manipulates before passing to mmap_region() to do the heavy lifting of the
memory mapping.

Update do_mmap() to instead accept a vma_flags_t parameter, and adjust all
the logic within do_mmap() to manipulate this instead.

This is as part of the ongoing effort to convert VMA flags from a system
word size to a bitmap type which allows us to unrestrict the number of VMA
flags, as well as gain control over how VMA flag manipulation occurs.

We do not cascade these changes to all functions which accept vm_flags_t,
but rather use vma_flags_to_legacy() where necessary, specifically
deferring converting calc_vm_prot_bits(), calc_vm_flag_bits() and
__get_unmapped_area() to vma_flags_t.

Also utilise the new vma_flags_can_grow() predicate which correctly handles
the case of architectures without upward growing stacks.

As part of this change, introduce VMA_SHADOW_STACK so we can correctly
handle the case of the shadow stack not being defined.

No functional change intended.

Reviewed-by: Lance Yang <lance.yang@linux.dev>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Signed-off-by: Lorenzo Stoakes <ljs@kernel.org>

Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>