On Thu 08-06-17 16:48:31, Michal Hocko wrote: > On Wed 07-06-17 13:56:01, David Rientjes wrote: > > On Wed, 7 Jun 2017, Vlastimil Babka wrote: > > > > > >> Hmm I'd expect such spin lock to be reported together with mmap_sem in > > > >> the debugging "locks held" message? > > > > > > > > My bisection of the problem is about half done. My latest good version > > > > is commit > > > > 7b8cd33 and the latest bad one is 2ea659a. Only about 7 steps to go. > > > > > > Hmm, your bisection will most likely just find commit 338a16ba15495 > > > which added the cond_resched() at mm/khugepaged.c:655. CCing David who > > > added it. > > > > > > > I agree it's probably going to bisect to 338a16ba15495 since it's the > > cond_resched() at the line number reported, but I think there must be > > something else going on. I think the list of locks held by khugepaged is > > correct because it matches with the implementation. The preempt_count(), > > as suggested by Andrew, does not. If this is reproducible, I'd like to > > know what preempt_count() is. > > collapse_huge_page > pte_offset_map > kmap_atomic > kmap_atomic_prot > preempt_disable > __collapse_huge_page_copy > pte_unmap > kunmap_atomic > __kunmap_atomic > preempt_enable > > I suspect, so cond_resched seems indeed inappropriate on 32b systems.
The code still seems to be in the mmotm tree. Are there any plans to fix this or drop the patch? -- Michal Hocko SUSE Labs
