kernel-packages team mailing list archive

[Nelson Elhage <nelhage@xxxxxxxxxxx>]

Hi @ddstreet, thanks for the update.

We unfortunately weren't able to reproduce this on your test kernel, and
have since moved to a newer kernel version for other reasons.

However, I can confirm that on the affected machine types, and only the
affected machine type, we see a memory range in `/proc/iomem` that ends
off of a multiple of 2M. Again, we do not see this on any other
machines.

I've attached `/proc/iomem` and `/proc/zoneinfo` from an affected machine (currently running an LTS backport kernel:
Linux [redacted] 3.19.0-33-generic #38~14.04.1-Ubuntu SMP Fri Nov 6 18:17:28 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
)

I'm pretty sure they show the kind of mismatch you're talking about;
iomem shows

100000000-f0fffefff : System RAM
f0ffff000-f0fffffff : RAM buffer
f10000000-f17ffffff : System RAM


But the “Node 0 Normal” zone, judging from (start_pfn, start_pfn+spanned) spans 100000000-f18000000. The machine in question is a c4.8xlarge in EC2.
 


** Attachment added: "iomem.txt"
   https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1497428/+attachment/4529726/+files/iomem.txt

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https://bugs.launchpad.net/bugs/1497428

Title:
  kernel BUG at /build/buildd/linux-3.13.0/mm/page_alloc.c:968

Status in linux package in Ubuntu:
  In Progress
Status in linux source package in Trusty:
  In Progress

Bug description:
  The kernel triggers a BUG when it finds it is in move_freepages() but
  the start and end pfns for the move are in different zones.

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