On Wed, 21 Dec 2016, Linus Torvalds wrote: > On Wed, Dec 21, 2016 at 9:13 PM, Dave Chinner <da...@fromorbit.com> wrote: > > > > There may be deeper issues. I just started running scalability tests > > (e.g. 16-way fsmark create tests) and about a minute in I got a > > directory corruption reported - something I hadn't seen in the dev > > cycle at all. > > By "in the dev cycle", do you mean your XFS changes, or have you been > tracking the merge cycle at least for some testing? > > > I unmounted the fs, mkfs'd it again, ran the > > workload again and about a minute in this fired: > > > > [628867.607417] ------------[ cut here ]------------ > > [628867.608603] WARNING: CPU: 2 PID: 16925 at mm/workingset.c:461 > > shadow_lru_isolate+0x171/0x220 > > Well, part of the changes during the merge window were the shadow > entry tracking changes that came in through Andrew's tree. Adding > Johannes Weiner to the participants. > > > Now, this workload does not touch the page cache at all - it's > > entirely an XFS metadata workload, so it should not really be > > affecting the working set code. > > Well, I suspect that anything that creates memory pressure will end up > triggering the working set code, so .. > > That said, obviously memory corruption could be involved and result in > random issues too, but I wouldn't really expect that in this code. > > It would probably be really useful to get more data points - is the > problem reliably in this area, or is it going to be random and all > over the place.
Data point: kswapd got WARNING on mm/workingset.c:457 in shadow_lru_isolate, soon followed by NULL pointer deref in list_lru_isolate, one time when I tried out Sunday's git tree. Not seen since, I haven't had time to investigate, just set it aside as something to worry about if it happens again. But it looks like shadow_lru_isolate() has issues beyond Dave's case (I've no XFS and no iscsi), suspect unrelated to his other problems. Hugh > > That said: > > > And worse, on that last error, the /host/ is now going into meltdown > > (running 4.7.5) with 32 CPUs all burning down in ACPI code: > > The obvious question here is how much you trust the environment if the > host ends up also showing problems. Maybe you do end up having hw > issues pop up too. > > The primary suspect would presumably be the development kernel you're > testing triggering something, but it has to be asked.. > > Linus
