From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 6 Jun 2007 13:11:21 -0700 From: Andrew Morton Subject: Re: SLUB: Use ilog2 instead of series of constant comparisons. Message-Id: <20070606131121.a8f7be78.akpm@linux-foundation.org> In-Reply-To: References: <20070606100817.7af24b74.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: linux-mm@kvack.org, Pekka Enberg , Andy Whitcroft , Martin Bligh List-ID: On Wed, 6 Jun 2007 11:36:07 -0700 (PDT) Christoph Lameter wrote: > On Wed, 6 Jun 2007, Andrew Morton wrote: > > > This caused test.kernel.org's power4 build to blow up: > > > > http://test.kernel.org/abat/93315/debug/test.log.0 > > > > fs/built-in.o(.text+0x148420): In function `.CalcNTLMv2_partial_mac_key': > > : undefined reference to `.____ilog2_NaN' > > Hmmm... Weird message that does not allow too much analysis. > The __ilog2_NaN comes about if 0 or a negative number is passed to ilog. > There is no way for that to happen since we check for KMALLOC_MIN_SIZE > and KMALLOC_MAX_SIZE in kmalloc_index() and an unsigned value is used. > > There is also nothing special in CalcNTLMv2_partial_mac_key(). Two > kmallocs of 33 bytes and 132 bytes each. Yes, the code all looks OK. I suspect this is another case of the compiler failing to remove unreachable stuff. > Buggy compiler (too much stress on constant folding)? Or hardware? Can we > rerun the test? It happened multiple times: http://test.kernel.org/functional/pSeries-101_2.html I'm sure there's a way of extracting the compiler version out of test.kernel.org but I can't see it there. Andy, maybe we should toss a gcc --version in there or something? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org