On Thu, Jan 25, 2024 at 8:43 AM Alexandru Elisei <alexandru.elisei@xxxxxxx> wrote: > > arm64 uses VM_HIGH_ARCH_0 and VM_HIGH_ARCH_1 for enabling MTE for a VMA. > When VM_HIGH_ARCH_0, which arm64 renames to VM_MTE, is set for a VMA, and > the gfp flag __GFP_ZERO is present, the __GFP_ZEROTAGS gfp flag also gets > set in vma_alloc_zeroed_movable_folio(). > > Expand this to be more generic by adding an arch hook that modifes the gfp > flags for an allocation when the VMA is known. > > Note that __GFP_ZEROTAGS is ignored by the page allocator unless __GFP_ZERO > is also set; from that point of view, the current behaviour is unchanged, > even though the arm64 flag is set in more places. When arm64 will have > support to reuse the tag storage for data allocation, the uses of the > __GFP_ZEROTAGS flag will be expanded to instruct the page allocator to try > to reserve the corresponding tag storage for the pages being allocated. > > The flags returned by arch_calc_vma_gfp() are or'ed with the flags set by > the caller; this has been done to keep an architecture from modifying the > flags already set by the core memory management code; this is similar to > how do_mmap() -> calc_vm_flag_bits() -> arch_calc_vm_flag_bits() has been > implemented. This can be revisited in the future if there's a need to do > so. > > Signed-off-by: Alexandru Elisei <alexandru.elisei@xxxxxxx> This patch also needs to update the non-CONFIG_NUMA definition of vma_alloc_folio in include/linux/gfp.h to call arch_calc_vma_gfp. See: https://r.android.com/2849146 Peter
