On Sun, 23 Aug 2015, Tetsuo Handa wrote:
> >From 08a638e04351386ab03cd1223988ac7940d4d3aa Mon Sep 17 00:00:00 2001
> From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
> Date: Sat, 1 Aug 2015 22:46:12 +0900
> Subject: [PATCH 2/2] mm: Fix potentially scheduling in GFP_ATOMIC
> allocations.
>
> Currently, if somebody does GFP_ATOMIC | __GFP_NOFAIL allocation,
> wait_iff_congested() might be called via __alloc_pages_high_priority()
> before reaching
>
> if (!wait) {
> WARN_ON_ONCE(gfp_mask & __GFP_NOFAIL);
> goto nopage;
> }
>
> because gfp_to_alloc_flags() includes ALLOC_NO_WATERMARKS if TIF_MEMDIE
> was set.
>
> We need to check for __GFP_WAIT flag at __alloc_pages_high_priority()
> in order to make sure that we won't schedule.
>
I've brought the GFP_ATOMIC | __GFP_NOFAIL combination up before, which
resulted in the WARN_ON_ONCE() that you cited. We don't support such a
combination. Fixing up the documentation in any places you feel it is
deficient would be the best.
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