linux-kernel - Re: __vmalloc() vs. GFP_NOIO/GFP

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Message-ID: <20160103203514.GN9938@ZenIV.linux.org.uk>
Date:	Sun, 3 Jan 2016 20:35:14 +0000
From:	Al Viro <viro@...IV.linux.org.uk>
To:	Dave Chinner <david@...morbit.com>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, Ming Lei <ming.lei@...onical.com>
Subject: Re: __vmalloc() vs. GFP_NOIO/GFP_NOFS

On Mon, Jan 04, 2016 at 07:12:33AM +1100, Dave Chinner wrote:

> That'd be a nice start, though it doesn't address callers of
> vm_map_ram() which also has hard-coded GFP_KERNEL allocation masks
> for various allocations.

... all 3 of them, that is - XFS, android/ion/ion_heap.c and
v4l2-core.  5 call sites total.  Adding a gfp_t argument to those
shouldn't be an issue...

BTW, far scarier one is not GFP_NOFS or GFP_IO - there's a weird
caller passing GFP_ATOMIC to __vmalloc(), for no reason I can guess.

_That_ really couldn't be handled without passing gfp_t to page allocation
primitives, but I very much doubt that it's needed there at all; it's in
alloc_large_system_hash() and I really cannot imagine a situation when
it would be used in e.g. a nonblocking context.

Folks, what is that one for?
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