On Tue, Aug 22, 2017 at 11:37:03AM +0200, Peter Zijlstra wrote: > On Tue, Aug 22, 2017 at 06:22:36PM +0900, Byungchul Park wrote: > > On Tue, Aug 22, 2017 at 11:06:03AM +0200, Peter Zijlstra wrote: > > > So I did the below little hack, which basically wipes the entire lock > > > history when we start a work and thereby disregards/looses the > > > dependency on the work 'lock'. > > > > > > It makes my test box able to boot and build a kernel on XFS, so while I > > > see what you're saying (I think), it doesn't appear to instantly show. > > > > > > Should I run xfstests or something to further verify things are OK? Does > > > that need a scratch partition (I keep forgetting how to run that stuff > > > :/). > > > > > > --- > > > diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c > > > index 66011c9f5df3..de91cdce9460 100644 > > > --- a/kernel/locking/lockdep.c > > > +++ b/kernel/locking/lockdep.c > > > @@ -4756,10 +4756,14 @@ void crossrelease_hist_start(enum > > > xhlock_context_t c) > > > { > > > struct task_struct *cur = current; > > > > > > - if (cur->xhlocks) { > > > - cur->xhlock_idx_hist[c] = cur->xhlock_idx; > > > - cur->hist_id_save[c] = cur->hist_id; > > > - } > > > + if (!cur->xhlocks) > > > + return; > > > + > > > + if (c == XHLOCK_PROC) > > > + invalidate_xhlock(&xhlock(cur->xhlock_idx)); > > > > We have to detect dependecies if it exists, even in the following case: > > > > oooooooiiiiiiiiiiiiiiiiiii......... > > |<- range for commit ->| > > > > where > > o: acquisition outside of each work, > > i: acquisition inside of each work, > > > > With yours, we can never detect dependecies wrt 'o'. > > There really shouldn't be any o's when you call
There can be any o's. > crossrelease_hist_start(XHLOCK_PROC), it should denote the bottom of a No, I don't think so. It can be either the bottom or not. hist_start() and hist_end() is only for special contexts which need roll back on exit e.g. irq, work and so on. Normal kernel context should work well w/o hist_start() or hist_end(). > context, see: > > > https://lkml.kernel.org/r/20170301104328.gd6...@twins.programming.kicks-ass.net Actually, I don't agree with that. > And in that respect you placed the calls wrongly in process_one_work(), Why is it wrong? It's intended. Could you tell me why?