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Date: Mon, 27 Sep 2010 11:17:19 +0900 (JST) From: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com> To: Eric Dumazet <eric.dumazet@...il.com> Cc: kosaki.motohiro@...fujitsu.com, Andrew Morton <akpm@...ux-foundation.org>, Rik van Riel <riel@...hat.com>, linux-mm@...ck.org, linux-kernel@...r.kernel.org, netdev@...r.kernel.org Subject: Re: [PATCH] mm: do not print backtraces on GFP_ATOMIC failures > > > @@ -72,7 +72,7 @@ struct vm_area_struct; > > > /* This equals 0, but use constants in case they ever change */ > > > #define GFP_NOWAIT (GFP_ATOMIC & ~__GFP_HIGH) > > > /* GFP_ATOMIC means both !wait (__GFP_WAIT not set) and use emergency pool */ > > > -#define GFP_ATOMIC (__GFP_HIGH) > > > +#define GFP_ATOMIC (__GFP_HIGH | __GFP_NOWARN) > > > #define GFP_NOIO (__GFP_WAIT) > > > #define GFP_NOFS (__GFP_WAIT | __GFP_IO) > > > #define GFP_KERNEL (__GFP_WAIT | __GFP_IO | __GFP_FS) > > > > A much finer-tuned implementation would be to add __GFP_NOWARN just to > > the networking call sites. I asked about this in June and it got > > nixed: > > > > http://www.spinics.net/lists/netdev/msg131965.html > > -- > > Yes, I remember this particular report was useful to find and correct a > bug. > > I dont know what to say. > > Being silent or verbose, it really depends on the context ? At least, MM developers don't want to track network allocation failure issue. We don't have enough knowledge in this area. To be honest, We are unhappy current bad S/N bug report rate ;) Traditionally, We hoped this warnings help to debug VM issue. but It haven't happen. We haven't detect VM issue from this allocation failure report. Instead, We've received a lot of network allocation failure report. Recently, The S/N ratio became more bad. If the network device enable jumbo frame feature, order-2 GFP_ATOMIC allocation is called frequently. Anybody don't have to assume order-2 allocation can success anytime. I'm not against accurate warning at all. but I cant tolerate this semi-random warning steal our time. If anyone will not make accurate warning, I hope to remove this one completely instead. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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