Re: xfsdump stuck in io_schedule

[Andrew Morton <akpm@xxxxxxxxx>]

Zlatko Calusic wrote:
> 
> Let's recapitulate:
> 
> I'm dumping (or tarring) xfs filesystem (/usr) which consists of lots
> of files from a faster (7200rpm, plate speed up to 37MB/sec) IDE disk
> to a (big = 2 - 3GB) file on a xfs partition on a slower (5400rpm,
> plate speed up to 23MB/sec) IDE disk and I'm getting page allocation
> failures during that exercise. Kernel is virgin 2.5.47, preempt is
> off, number of processors doesn't make a difference.
> 
> Now, more than ever, this looks like a VM bug, not really xfs
> specific. Andrew, what would you like me to try to clarify it further?

Well, not really a "bug".  Mode zero allocations will always fail, and
the caller needs to handle that.  For some reason kswapd is not keeping
up here.  It would be interesting to put a dump_stack() alongside that
page allocation failure printk in mm/page_alloc.c.

How much memory do you have?