mkswap fails to use more than 2GiB and doesn't recognize LVM

mkswap fails to use more than 2GiB and doesn't recognize LVM

[Florian Pritz]

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Hi,

I'm running util-linux 2.19.1 with a x86_64 linux 3.0.1 on Arch Linux.

mkswap displays the following output when trying to create swap on a
8GiB logical volume.
> # mkswap /dev/mapper/vg_brynhild-swap
> mkswap: warning: truncating swap area to 2097144 KiB
> mkswap: /dev/mapper/vg_brynhild-swap: warning: don't erase bootbits sectors
>         on whole disk. Use -f to force.
> Setting up swapspace version 1, size = 2097140 KiB
> no label, UUID=5eae2d8b-f664-46f5-983c-bdcd4301fa66

I tried adding -p 8589934592 to force 8GiB, but that doesn't change
anything.

It also fails to see that we are using LVM so this is not a real device
and we won't overwrite any boot sectors.

busybox mkswap crates the expected 8GiB swap, so I think this is a bug.

-- 
Florian Pritz


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Re: mkswap fails to use more than 2GiB and doesn't recognize LVM

[Karel Zak]

On Thu, Aug 11, 2011 at 05:32:57PM +0200, Florian Pritz wrote:
> mkswap displays the following output when trying to create swap on a
> 8GiB logical volume.
> > # mkswap /dev/mapper/vg_brynhild-swap
> > mkswap: warning: truncating swap area to 2097144 KiB

 It seems correct. The swap header does not allow to address more than
 UINT_MAX pages. You have to create more swap areas or use system with
 bigger pages.

> > mkswap: /dev/mapper/vg_brynhild-swap: warning: don't erase bootbits sectors
> >         on whole disk. Use -f to force.
> > Setting up swapspace version 1, size = 2097140 KiB
> > no label, UUID=5eae2d8b-f664-46f5-983c-bdcd4301fa66
> 
> I tried adding -p 8589934592 to force 8GiB, but that doesn't change
> anything.

 :-)

> busybox mkswap crates the expected 8GiB swap, so I think this is a bug.

 Do you see see 8GiB swap area in /proc/swaps after swapon? I don't
 think so...

    Karel

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com

Re: mkswap fails to use more than 2GiB and doesn't recognize LVM

[Florian Pritz]

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On 11.08.2011 20:14, Karel Zak wrote:
>> busybox mkswap crates the expected 8GiB swap, so I think this is a bug.
> 
>  Do you see see 8GiB swap area in /proc/swaps after swapon? I don't
>  think so...

> cat /proc/swaps
Filename                                Type            Size    Used
Priority
/dev/dm-4                               partition       8388604 0       -1

-- 
Florian Pritz


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Re: mkswap fails to use more than 2GiB and doesn't recognize LVM

[Karel Zak]

On Thu, Aug 11, 2011 at 08:14:54PM +0200, Karel Zak wrote:
> On Thu, Aug 11, 2011 at 05:32:57PM +0200, Florian Pritz wrote:
> > mkswap displays the following output when trying to create swap on a
> > 8GiB logical volume.
> > > # mkswap /dev/mapper/vg_brynhild-swap
> > > mkswap: warning: truncating swap area to 2097144 KiB
> 
>  It seems correct.

 Ah... sorry, I didn't read your e-mail too carefully.

>  The swap header does not allow to address more than
>  UINT_MAX pages. You have to create more swap areas or use system with
>  bigger pages.

 Right, so if you have 4096 page size, then 4096 * 4294967295 is the
 max size...

 I think the problem is kernel version string -- "3.0". The mkswap
 code uses the version string to set the limit.

 The problem should be fixed in 2.20-rc1, commit
 fa7e0d6d442de9f5940f99fd93f4522602439131.

    Karel

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com