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Re: [Qemu-devel] problems with 1G hugepages and linux 3.12-rc3
From: |
Gleb Natapov |
Subject: |
Re: [Qemu-devel] problems with 1G hugepages and linux 3.12-rc3 |
Date: |
Tue, 8 Oct 2013 15:23:24 +0300 |
Copying Andrea,
On Sun, Oct 06, 2013 at 02:47:41AM +0200, andy123 wrote:
> Hi,
>
> as the subject states, I have some problems with 1G hugepages with
> qemu(-vfio-git) on Linux 3.12-rc3.
>
> I start qemu like this, for example:
> "/usr/bin/qemu-system-x86_64 -enable-kvm -m 1024 -mem-path /dev/hugepages
> -drive file=/files/vm/arch.img,if=virtio,media=disk -monitor stdio"
> where /dev/hugepages is "hugetlbfs on /dev/hugepages type hugetlbfs
> (rw,relatime,mode=1770,gid=78,pagesize=1G,pagesize=1G)"
> and the kernel is booted with "hugepagesz=1G hugepages=4".
> This result in lots of error message in dmesg, as seen here:
> https://gist.github.com/ajs124/6842823 (starting at 18:04:28)
>
> After starting and stopping multiple virtual machines, the hugepages seem to
> "fill up" and qemu outputs
> "file_ram_alloc: can't mmap RAM pages: Cannot allocate memory", but works
> anyways.
> With fill up, I mean that I can start qemu 2 time with "-m 2048" and 4 times
> with "-m 1024", before it fails to mmap.
>
I can reproduce huge page leak, but not oops, but they can be related.
Can you revert 11feeb498086a3a5907b8148bdf1786a9b18fc55 and retry?
> This works without any problems in 3.11.x and also with 2M hugepages (umount
> /dev/hugepages && mount -t hugetlbfs -o pagesize=2048k /dev/hugepages).
>
> I'm running this in arch linux and there has already been some discussion on
> the arch forums
> (https://bbs.archlinux.org/viewtopic.php?pid=1333469#p1333469) but I tried to
> add everything I wrote over there in this mail.
>
> In case I missed something or you need more information, I'll happily supply
> it in order to get this resolved.
>
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--
Gleb.