lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Thu, 26 Jun 2008 17:06:24 -0400 From: Dave Jones <davej@...hat.com> To: Evgeniy Polyakov <johnpol@....mipt.ru> Cc: Andrew Morton <akpm@...ux-foundation.org>, Nick Piggin <nickpiggin@...oo.com.au>, Chris Snook <csnook@...hat.com>, Dave Jones <davej@...emonkey.org.uk>, Linux Kernel <linux-kernel@...r.kernel.org>, netdev@...r.kernel.org, Peter Zijlstra <peterz@...radead.org> Subject: Re: GFP_ATOMIC page allocation failures. This thread seemed to die out with no resolution.. On Thu, Apr 03, 2008 at 12:59:22PM +0400, Evgeniy Polyakov wrote: > On Wed, Apr 02, 2008 at 10:32:54PM -0700, Andrew Morton (akpm@...ux-foundation.org) wrote: > > > > It also tells us when we mucked up the net driver - I doubt if we (or at > > > > least, I) would have discovered that e1000 does a 32k allocation for a > > > > 5k(?) frame if this warning wasn't coming out. > > > > > > Is that right? If it is allocating for 9K MTU, then the slab allocator > > > (slub in this case) will bump that up to the 16K kmalloc slab. If it is > > > a 5K frame, then it would get the 8K kmalloc slab I think. > > > > > > Oh, but SLUB's default MIN_OBJECTS is 4, so 4*8 is 32 indeed. So slub > > > is probably deciding to round the kmalloc-8192 allocations up to order-3. > > > I think. How did you know it was a 5k frame? :) > > > > urgh, it was a while ago, and I don't know if e1000e retains the behaviour. > > > > iirc the issue was with some errant versions of the hardware needing > > exorbitant alignment and additional padding at the end because of > > occasional DMA overruns. Something like that. > > e1000 hardware does require power-of-two alignment, network stack adds > additional structure at the end, so with e1000 it ends up with two > rounds to the higher power of two. > 5k ends up with 16k allocations, 9k - to 32k. > > This problem is known for years already and number of fixes was > proposed, but the really good one is to rewrite e1000 allocation path to > use fragments, which I believe was done in the new e1000 driver. So this morning, we got a fresh report from this in 2.6.25.6's e1000 driver https://bugzilla.redhat.com/show_bug.cgi?id=453010 Pages and pages of spew, which make users freak out. This stuff might be 'nice to know', but if it isn't getting fixed, I can see why some distros have been shipping the 'silence GFP_ATOMIC failures' patches for some time. Dave > And as a side note: shuting allocation failures is a very bad step, > since it hides allocation problems for drivers. if people do care about > it add __GFP_SMALL_WARN flag which will just print that allocation > failed, its order and function where it happend. -- http://www.codemonkey.org.uk -- 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/
Powered by blists - more mailing lists