Messages in this thread | | | Date | Tue, 22 Aug 2017 11:37:03 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v3 1/3] lockdep: Make LOCKDEP_CROSSRELEASE configs all part of PROVE_LOCKING |
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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 crossrelease_hist_start(XHLOCK_PROC), it should denote the bottom of a context, see:
https://lkml.kernel.org/r/20170301104328.GD6515@twins.programming.kicks-ass.net
And in that respect you placed the calls wrongly in process_one_work(), except it now works out nicely to disregard these fake locks.
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