On 19.08.24 12:19, Michal Hocko wrote:
On Mon 19-08-24 11:44:39, David Hildenbrand wrote:
[...]
if (gfp_mask & __GFP_NOFAIL) {
/*
- * All existing users of the __GFP_NOFAIL are blockable, so warn
- * of any new users that actually require GFP_NOWAIT
+ * All existing users of the __GFP_NOFAIL are blockable
+ * otherwise we introduce a busy loop with inside the page
+ * allocator from non-sleepable contexts
*/
- if (WARN_ON_ONCE_GFP(!can_direct_reclaim, gfp_mask))
- goto fail;
+ BUG_ON(!can_direct_reclaim);
No new BUG_ON(), WARN_ON_ONCE() is good enough for something that should be
found during ordinary testing.
Do you mean
if (WARN_ON_ONCE_GFP(...))
goto retry?
Not really ...
but now I read the description more carefully and I am not sure why we
are so into throwing around BUG_ONs here, for something that is simply
not allowed and doesn't make sense.
If __GFP_NOFAIL is documented to
"
+ * It _must_ be blockable and used together with __GFP_DIRECT_RECLAIM.
+ * It should _never_ be used in non-sleepable contexts.
"
Why not document
"__GFP_NOFAIL always implies __GFP_DIRECT_RECLAIM" and do exactly that?
--
Cheers,
David / dhildenb
