On 25.06.2014 01:44, David Rientjes wrote: > On Thu, 12 Jun 2014, Stefan Bader wrote: > >> doh, so you guys have been hit by that before. And I have missed the fact >> that >> single_open is special. Which makes the change for the upper limit do the >> wrong >> thing. While long-term it sounds like changing it to vmalloc or iterative >> reads >> sounds better, maybe the change from possible to online cpus might be >> something >> that is better acceptable as a quick fix... Not sure. At least this giving >> back >> a bit of attention to the matter and it is not only affecting zSeries. x86 >> starts to see hw that requires a similar high possible cpus... :) >> > > Heiko's patches that should fix this problem are now in -mm, so it would > be nice to know if there are any existing issues that haven't been > addressed yet with your bug report. See > http://www.ozlabs.org/~akpm/mmotm/ >
Heiko and I both had the same issue. Since some x86 hardware also reaches a lot of CPUs (hyperthreads included), we bumped the possible number of CPUs to 256 at least for the 64bit kernel. And that resulted in failed accesses to /proc/stat when memory became fragmented. So the first patch will avoid this on most systems. I have not seen this myself, but I would expect him to be happy with 1/2 already. For really excessive hardware 2/2 will close the gap. Since this is no critical bug, I am fine with 3.17, too. I have not done so, yet, but I could let our reporter try the patches (again, probably not verifying the second part). Just waited to do so to see whether the code settles down to these changes. -Stefan
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