On Tue, 2021-08-31 at 11:47 +0300, Mike Rapoport wrote: > On Mon, Aug 30, 2021 at 04:59:18PM -0700, Rick Edgecombe wrote: > > fill_pte(), set_pte_vaddr(), etc allocate page tables with > > spp_getpage(). Use alloc_table() for these allocations in order to > > get > > tables from the cache of protected pages when needed. > > > I can't say I tracked all the users of set_pte_vaddr(), but I don't > see a > fundamental reason why spp_getpage() would need GFP_ATOMIC. Yea, I couldn't find why it was done that way in the first place, and there were almost too many callers to audit. I guess I could roll up my sleeves an audit it all, but its not foolproof. Or put a warn for atomic context and pull all of the GFP_ATOMIC code if it doesn't get triggered after awhile. Also seems weird that it just panics here if the allocation fails. > Even if there > is a caller of set_pte_vaddr() that cannot sleep, it seems that page > tables > can be prepopulated so that set_pte_vaddr() will not need to allocate > anything. Hmm, could work for the fixmap callers I guess (maybe already happening in practice). Xen and a few other things seems to use this for non- fixmap things, but it's during init and easier to audit.
