On Fri, 2011-10-14 at 01:21 +0200, Peter Zijlstra wrote: > On Thu, 2011-10-13 at 16:03 -0700, David Rientjes wrote: > > > Ok, I think this may be related to what Sitsofe reported in the "lockdep > > recursive locking detected" thread on LKML (see > > http://marc.info/?l=linux-kernel&m=131805699106560). > > > > Peter and Christoph hypothesized that 056c62418cc6 ("slab: fix lockdep > > warnings") may not have had full coverage when setting lockdep classes for > > kmem_list3 locks that may be called inside of each other because of > > off-slab metadata. > > > > I think it's safe to say there is no deadlock possibility here or we would > > have seen it since 2006 and this is just a matter of lockdep annotation > > that needs to be done. So don't worry too much about the warning even > > though I know it's annoying and it suppresses future lockdep output (even > > more annoying!). > > > > I'm not sure if there's a patch to address that yet, I think one was in > > the works. If not, I'll take a look at rewriting that lockdep annotation. > > Urgh, I so totally forgot about that.. :-/ So no, no patch yet. --- Subject: slab, lockdep: Fix silly bug From: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> Date: Mon Nov 28 21:12:40 CET 2011 Commit 30765b92 ("slab, lockdep: Annotate the locks before using them") moves the init_lock_keys() call from after g_cpucache_up = FULL, to before it. And overlooks the fact that init_node_lock_keys() tests for it and ignores everything !FULL. Introduce a LATE stage and change the lockdep test to be <LATE. Cc: stable@xxxxxxxxxx Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> Link: http://lkml.kernel.org/n/tip-gadqbdfxorhia1w5ewmoiodd@xxxxxxxxxxxxxx --- Index: linux-2.6/mm/slab.c =================================================================== --- linux-2.6.orig/mm/slab.c +++ linux-2.6/mm/slab.c @@ -595,6 +595,7 @@ static enum { PARTIAL_AC, PARTIAL_L3, EARLY, + LATE, FULL } g_cpucache_up; @@ -671,7 +672,7 @@ static void init_node_lock_keys(int q) { struct cache_sizes *s = malloc_sizes; - if (g_cpucache_up != FULL) + if (g_cpucache_up < LATE) return; for (s = malloc_sizes; s->cs_size != ULONG_MAX; s++) { @@ -1666,6 +1667,8 @@ void __init kmem_cache_init_late(void) { struct kmem_cache *cachep; + g_cpucache_up = LATE; + /* Annotate slab for lockdep -- annotate the malloc caches */ init_lock_keys(); -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. 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