Messages in this thread | | | Date | Tue, 2 Jun 2009 15:40:24 +0200 | From | Nick Piggin <> | Subject | Re: [PATCH] [13/16] HWPOISON: The high level memory error handler in the VM v3 |
| |
On Tue, Jun 02, 2009 at 03:41:26PM +0200, Andi Kleen wrote: > On Tue, Jun 02, 2009 at 03:24:41PM +0200, Nick Piggin wrote: > > On Tue, Jun 02, 2009 at 03:25:38PM +0200, Andi Kleen wrote: > > > The reason this code double checks is that someone could have > > > a reference (remember we can come in any time) we cannot kill immediately. > > > > Can't kill what? The page is gone from pagecache. It may remain > > other kernel references, but I don't see why this code will > > consider this as a failure (and not, for example, a raised error > > count). > > It's a failure because the page was still used and not successfully > isolated.
But you're predicating success on page_count, so there can be other users anyway. You do check page_count later and emit a different message in this case, but even that isn't enough to tell you if it has no more users.
I wouldn't have thought it's worth the complication, but there is nothing preventing you using my truncate function and also keeping this error check to test afterwards.
> > + * remove_from_page_cache assumes (mapping && !mapped) > > + */ > > + if (page_mapping(p) && !page_mapped(p)) { > > Ok you're right. That one is not needed. I will remove it. > > > > > > > User page tables was on the todo list, these are actually relatively > > > easy. The biggest issue is to detect them. > > > > > > Metadata would likely need file system callbacks, which I would like to > > > avoid at this point. > > > > So I just don't know why you argue the point that you have lots > > of large holes left. > > I didn't argue that. My point was just that I currently don't have > data what holes are the worst on given workloads. If I figure out at > some point that writeback pages are a significant part of some important > workload I would be interested in tackling them. > That said I think that's unlikely, but I'm not ruling it out.
Well, it sounds like maybe there is a sane way to do them with your IO interception... but anyway let's not worry about this right now ;)
| |