> On Mar 30, 2022, at 5:04 PM, Edgecombe, Rick P <rick.p.edgecombe@xxxxxxxxx> wrote: > > On Wed, 2022-03-30 at 15:56 -0700, Song Liu wrote: >> [1] >> https://lore.kernel.org/lkml/5bd16e2c06a2df357400556c6ae01bb5d3c5c32a.camel@xxxxxxxxx/ > > The issues I brought up around VM_FLUSH_RESET_PERMS are not fixed in > this series. And I think the solution I proposed is kind of wonky with > respect to hibernate. So I think maybe hibernate should be fixed to not > impose restrictions on the direct map, so the wonkiness is not needed. > But then this "fixes" series becomes quite extensive. > > I wonder, why not just push the patch 1 here, then re-enable this thing > when it is all properly fixed up. It looked like your code could handle > the allocation not actually getting large pages. Only shipping patch 1 should eliminate the issues. But that will also reduce the benefit in iTLB efficiency (I don't know by how much yet.) > > Another solution that would keep large pages but still need fixing up > later: Just don't use VM_FLUSH_RESET_PERMS for now. Call > set_memory_nx() and then set_memory_rw() on the module space address > before vfree(). This will clean up everything that's needed with > respect to direct map permissions. Have vmalloc warn if is sees > VM_FLUSH_RESET_PERMS and huge pages together. Do you mean we should remove set_vm_flush_reset_perms() from alloc_new_pack() and do set_memory_nx() and set_memory_rw() before we call vfree() in bpf_prog_pack_free()? If this works, I would prefer we go with this way. Thanks, Song
