hi,

> The interaction of the new metadata cache and the page cache seems to lead
> to significant kernel memory fragmentation.  Because most requests from
> the metadata cache are small, larger regions of free memory are split up;
> when the metadata cache returns memory, it does so one buffer at a time
> (typically just one or two pages) and this means that even when we have
> quite a bit of memory free, very little of it may be contiguous.  This
> causes problems for drivers like the USB drivers and the drivers for
> various cardbus cards.

are you talking about kva fragmentation?
it isn't related to umass allocation failures.

YAMAMOTO Takashi