On 09/09/2016 06:03 AM, Li Zhong wrote:
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index a2214c6..d624ff3 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3448,6 +3448,12 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, if (page) goto got_pg; + if (ac->nodemask && nodes_empty(*ac->nodemask)) { + pr_warn("nodemask is empty\n"); + gfp_mask &= ~__GFP_NOWARN; + goto nopage; + } +Wouldn't it be better to do if (WARN_ON(ac->nodemask && nodes_empty(*ac->nodemask)) { ... so we can identify the misbehaving call site?I think with __GFP_NOWARN cleared, we could know the call site from warn_alloc_failed(). And the message “nodemask is empty” makes the error obvious without going to the source.
Yes, that was my suggestion. It uses the generic warn_alloc_failed() this way. With a WARN_ON we would either have to "return NULL" (and get only the WARN_ON without the extra warn_alloc_failed() stuff) or "goto nopage" and thus get two backtraces. But this should be really rare occurence, so I don't have a particularly strong preference.
Anyway, since I suggested it in the first place: Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Thanks, Zhong
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