On Fri, Nov 23, 2018 at 12:15:57PM +0100, Michal Hocko wrote: > On Thu 22-11-18 17:51:04, Daniel Vetter wrote: > > Just a bit of paranoia, since if we start pushing this deep into > > callchains it's hard to spot all places where an mmu notifier > > implementation might fail when it's not allowed to. > > What does WARN give you more than the existing pr_info? Is really > backtrace that interesting?
Automated tools have to ignore everything at info level (there's too much of that). I guess I could do something like if (blockable) pr_warn(...) else pr_info(...) WARN() is simply my goto tool for getting something at warning level dumped into dmesg. But I think the pr_warn with the callback function should be enough indeed. If you wonder where all the info level stuff happens that we have to ignore: suspend/resume is a primary culprit (fairly important for gfx/desktops), but there's a bunch of other places. Even if we ignore everything at info and below we still need filters because some drivers are a bit too trigger-happy (i915 definitely included I guess, so everyone contributes to this problem). Cheers, Daniel > > > Cc: Andrew Morton <a...@linux-foundation.org> > > Cc: Michal Hocko <mho...@suse.com> > > Cc: "Christian König" <christian.koe...@amd.com> > > Cc: David Rientjes <rient...@google.com> > > Cc: Daniel Vetter <daniel.vet...@ffwll.ch> > > Cc: "Jérôme Glisse" <jgli...@redhat.com> > > Cc: linux...@kvack.org > > Cc: Paolo Bonzini <pbonz...@redhat.com> > > Signed-off-by: Daniel Vetter <daniel.vet...@intel.com> > > --- > > mm/mmu_notifier.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c > > index 5119ff846769..59e102589a25 100644 > > --- a/mm/mmu_notifier.c > > +++ b/mm/mmu_notifier.c > > @@ -190,6 +190,8 @@ int __mmu_notifier_invalidate_range_start(struct > > mm_struct *mm, > > pr_info("%pS callback failed with %d in > > %sblockable context.\n", > > > > mn->ops->invalidate_range_start, _ret, > > !blockable ? "non-" : ""); > > + WARN(blockable,"%pS callback failure not > > allowed\n", > > + mn->ops->invalidate_range_start); > > ret = _ret; > > } > > } > > -- > > 2.19.1 > > > > -- > Michal Hocko > SUSE Labs -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel