[CentOS] C 7: smpboot: CPU 16 is now offline, and slabs...

[m.roth at 5-cent.us]

m.roth at 5-cent.us wrote:
> Current kernel, and I just booted, and dmesg shows, of the 32 cores, 0, 2,
> 4 and 6 ok, and *all* other show "is now offline.
>
> What's happening here?
>
A followup: I also find a core in /var/spool/abrt, and "reason" is
 kernel BUG at mm/slub.c:3601!

In googling, I see threads about incorrect calculation of slabs. Following
one thread, I find
cat /sys/kernel/slab/:t-0000048/cpu_slabs

gives me

4 N0=4

Meanwhile, slabtop shows
 Active / Total Slabs (% used)      : 25927 / 25927 (100.0%)

Which changes, but just varying around that number, and st 100%.

So: should I increase the number of slabs, using the kernel parm of
swiotlb, and if so, for what I show above, should I set it to, say, 32000?

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