On Tue, 26 Apr 2011 11:36:46 +0100 Mel Gorman <mgorman@xxxxxxx> wrote: > On Tue, Apr 26, 2011 at 07:49:47PM +1000, NeilBrown wrote: > > Maybe a > > WARN_ON((gfp_mask & __GFP_MEMALLOC) && (gfp_mask & __GFP_NOMEMALLOC)); > > might be wise? > > > > Both MEMALLOC and NOMEMALLOC are related to PFMEMALLOC reserves so > it's reasonable for them to have similar names. This warning will > also trigger because it's a combination of flags that does happen. > > Consider for example > > any interrupt > -> __netdev_alloc_skb (mask == GFP_ATOMIC) > -> __alloc_skb (mask == GFP_ATOMIC) > if (sk_memalloc_socks() && (flags & SKB_ALLOC_RX)) > gfp_mask |= __GFP_MEMALLOC; > (mask == GFP_ATOMIC|__GFP_NOMEMALLOC) > -> __kmalloc_reserve > First attempt tries to avoid reserves so adds __GFP_MEMALLOC > (mask == GFP_ATOMIC|__GFP_NOMEMALLOC|__GFP_MEMALLOC) > You have the "NO"s mixed up a bit which confused me for a while :-) But I see your point - I guess the WARN_ON isn't really needed. > You're right in that __GFP_NOMEMALLOC overrides __GFP_MEMALLOC so that > could do with a note. > Thanks, NeilBrown -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>