On Mon, Aug 26, 2024 at 08:41:42PM GMT, Matthew Wilcox wrote:

On Mon, Aug 26, 2024 at 03:39:47PM -0400, Kent Overstreet wrote:

quoted

Given the amount of plumbing required here, it's clear that passing gfp
flags is the less safe way of doing it, and this really does belong in
the allocation context.

Failure to pass gfp flags correctly (which we know is something that
happens today, e.g. vmalloc -> pte allocation) means you're introducing
a deadlock.

The problem with vmalloc is that the page table allocation _doesn't_
take a GFP parameter.

yeah, I know. I posted patches to plumb it through, which were nacked by
Linus.

And we're trying to get away from passing gfp flags directly, are we
not? I just don't buy the GFP_NOFAIL unsafety argument.