Re: btrfs-rmw-2: page allocation failure: order:1, mode:0x8020

[Marc MERLIN <marc@merlins.org>]

On Wed, Mar 19, 2014 at 12:20:08PM -0400, Chris Mason wrote:
> On 03/19/2014 11:45 AM, Marc MERLIN wrote:
> >My server died last night during a btrfs send/receive to a btrfs radi5 
> >array
> >
> >Here are the logs. Is this anything known or with a possible workaround?
> >
> >Thanks,
> >Marc
> >
> >btrfs-rmw-2: page allocation failure: order:1, mode:0x8020
> 
> This is an order 1 atomic allocation from the mvs driver, we really 
> should not be depending on that to get IO done.  A quick search and it 
> looks like we're allocating MVS_SLOT_BUF_SZ (8192) bytes.
> 
> You could try bumping the lowmem reserves.

Thanks for the info.

So for now, I have
CONFIG_X86_RESERVE_LOW=64

This is the option we're talking about, right?

Should I double it?

For now, I have the copy running again, and it's been going for 8 hours
without failure on the old kernel but of course that doesn't mean my 2TB
copy will complete without hitting the bug again.

Thanks,
Marc
-- 
"A mouse is a device used to point at the xterm you want to type in" - A.S.R.
Microsoft is to operating systems ....
                                      .... what McDonalds is to gourmet cooking
Home page: http://marc.merlins.org/