On Tue Aug 6, 2024 at 5:48 AM AEST, Linus Torvalds wrote: > On Mon, 5 Aug 2024 at 12:38, Jeff Xu <jeffxu@xxxxxxxxxx> wrote: > > > > I'm curious, why does ppc need to unmap vdso ? ( other archs don't > > have unmap logic.) > > I have no idea. There are comments about 'perf' getting confused about > mmap counts when 'context.vdso' isn't set up. > > But x86 has the same context.vdso logic, and does *not* set the > pointer before installing the vma, for example. Also does not zero it > out on munmap(), although it does have the mremap logic. > > For all I know it may all be entirely unnecessary, and could be > removed entirely. I don't know much about vdso code, it predated my involvedment in ppc. Commit 83d3f0e90c6c8 says CRIU (checkpoint restore in userspace) is moving it around. Why CRIU wants to do that, I don't know. Can userspace on other archs not unmap their vdsos? Thanks, Nick
