Re: [PATCH] [Request for inclusion] Filesystem in Userspace

Miklos Szeredi
2004-11-18T19:31:30Z

> The GFP_IO and GFP_FS pages are the _real_ protectors. They don't dip into
> the (very limited) set of pages, they say "we can still free 90% of
> memory, we just have to ignore that dangerous 10%".

I don't see how this makes more problems to userspace filesystems.
When you clear GFP_IO or GFP_FS for an allocation you are limiting
yourself from freeing some sort of memory. But that will not make it
easier to actually _get_ that memory.

With FUSE the allocation is NOT limited. Deadlock will not happen
since page writeback is non-blocking, so while more FUSE backed pages
can't be written, other filesystem's pages can be written back. The
situation is better not worse.

What am I missing?

Thanks,
Miklos