Re: [PATCH v3 1/5] mm: Define VM_DROPPABLE for powerpc/32

Christophe Leroy christophe.leroy@csgroup.eu writes:

Commit 9651fcedf7b9 ("mm: add MAP_DROPPABLE for designating always lazily freeable mappings") only adds VM_DROPPABLE for 64 bits architectures.

In order to also use the getrandom vDSO implementation on powerpc/32, use VM_ARCH_1 for VM_DROPPABLE on powerpc/32. This is possible because VM_ARCH_1 is used for VM_SAO on powerpc and VM_SAO is only for powerpc/64.

Also, there can't be any existing users of VM_SAO on 32-bit, because PROT_SAO (which maps to VM_SAO) is only accepted on CPUs that support SAO, and those CPUs are all 64-bit.

cheers