Hi Roman, On Tue, Dec 04, 2018 at 12:50:58PM +0100, Roman Penyaev wrote: > On 2018-12-03 18:34, Linus Torvalds wrote: > > This also ends up making the memory ordering of "xchg()" very very > > important. Yes, we've documented it as being an ordering op, but I'm > > not sure we've relied on it this directly before. > > Seems exit_mm() does exactly the same, the following chunk: > > up_read(&mm->mmap_sem); > > self.task = current; > self.next = xchg(&core_state->dumper.next, &self); > > > At least code pattern looks similar. Maybe add a comment on top of (your) xchg() to note/justify these memory ordering requirements? As Paul said: "if there are races, this would help force them to happen" (and simplify the review, this/future). Andrea
