On Thursday 06 July 2006 16:19, David Brownell wrote: > > > > > > I have seen that before: Atomic snapshot used fpu copy in some wrong > > > > > variants. Symptom was exactly that -- elevated preempt count -- > > > > > because fpu copy routine elevated it, then copied the task struct. > > > > > > > > > > But I thought we solved that problem...? > > > > > > > > We did. We don't use memcpy for precisely that reason. 3DNOW memcpy was one > > > > of the problem children. This would be a different creature though, > > > > wouldn't it? > > > > > > Hmm. Aparently we had a parting of ways on this at some point. Memcpy is being > > > used by swsusp, and it has been used since before 2.6.12-rc1. (This is when > > > doing the atomic copy, not resuming). > > And it could well be that's when this bug appeared. It's on an Athlon, > so that theory checks out as well as possible short of a patch. > > > > Do you mean the one in copy_data_pages()? Indeed, that may be a problem if > > the MMU-based memcpy is used. > > > > Pavel, should we fix this? > > Of course it needs fixing ... it's a bug, also a regression. > > My question is where to fix... swsusp_arch_resume() seems most > correct, albeit messy. There's unfortunately no exact parallel > on the resume side to where the bug was inserted. Those of us > who avoid hacking asm code might prefer restore_processor_state(). Well, I meant replacing the memcpy() in copy_data_pages with an open coded copying loop. That should be enough to fix the problem. Rafael
