> On Tuesday 19 January 2010, Benjamin Herrenschmidt wrote: > > On Tue, 2010-01-19 at 10:19 +0900, KOSAKI Motohiro wrote: > > > I think the race happen itself is bad. memory and I/O subsystem can't solve such race > > > elegantly. These doesn't know enough suspend state knowlege. I think the practical > > > solution is that higher level design prevent the race happen. > > > > > > > > > > My patch attempts to avoid these two problems as well as the problem with > > > > drivers using GFP_KERNEL allocations during suspend which I admit might be > > > > solved by reworking the drivers. > > > > > > Agreed. In this case, only drivers change can solve the issue. > > > > As I explained earlier, this is near to impossible since the allocations > > are too often burried deep down the call stack or simply because the > > driver doesn't know that we started suspending -another- driver... > > > > I don't think trying to solve those problems at the driver level is > > realistic to be honest. This is one of those things where we really just > > need to make allocators 'just work' from a driver perspective. > > > > It can't be perfect of course, as mentioned earlier, there will be a > > problem if too little free memory is really available due to lots of > > dirty pages around, but most of this can be somewhat alleviated in > > practice, for example by pushing things out a bit at suspend time, > > making some more memory free etc... But yeah, nothing replaces proper > > error handling in drivers for allocation failures even with > > GFP_KERNEL :-) > > Agreed. > > Moreover, I didn't try to do anything about that before, because memory > allocation problems during suspend/resume just didn't happen. We kind of knew > they were possible, but since they didn't show up, it wasn't immediately > necessary to address them. > > Now, however, people started to see these problems in testing and I'm quite > confident that this is a result of recent changes in the mm subsystem. Namely, > if you read the Maxim's report carefully, you'll notice that in his test case > the mm subsystem apparently attempted to use I/O even though there was free > memory available in the system. This is the case I want to prevent from > happening in the first place. Hi Rafael, Do you mean this is the unrelated issue of nVidia bug? Probably I haven't catch your point. I don't find Maxim's original bug report. Can we share the test-case and your analysis detail? _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
