Messages in this thread | | | Date | Mon, 8 Oct 2012 08:49:52 -0700 | From | Greg KH <> | Subject | Re: Patch Upstream: slab: fix the DEADLOCK issue on l3 alien lock |
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On Sun, Oct 07, 2012 at 10:39:44AM -0400, Gregs git-bot wrote: > commit: 947ca1856a7e60aa6d20536785e6a42dff25aa6e > From: Michael Wang <wangyun@linux.vnet.ibm.com> > Date: Wed, 5 Sep 2012 10:33:18 +0800 > Subject: slab: fix the DEADLOCK issue on l3 alien lock > > DEADLOCK will be report while running a kernel with NUMA and LOCKDEP enabled, > the process of this fake report is: > > kmem_cache_free() //free obj in cachep > -> cache_free_alien() //acquire cachep's l3 alien lock > -> __drain_alien_cache() > -> free_block() > -> slab_destroy() > -> kmem_cache_free() //free slab in cachep->slabp_cache > -> cache_free_alien() //acquire cachep->slabp_cache's l3 alien lock > > Since the cachep and cachep->slabp_cache's l3 alien are in the same lock class, > fake report generated. > > This should not happen since we already have init_lock_keys() which will > reassign the lock class for both l3 list and l3 alien. > > However, init_lock_keys() was invoked at a wrong position which is before we > invoke enable_cpucache() on each cache. > > Since until set slab_state to be FULL, we won't invoke enable_cpucache() > on caches to build their l3 alien while creating them, so although we invoked > init_lock_keys(), the l3 alien lock class won't change since we don't have > them until invoked enable_cpucache() later. > > This patch will invoke init_lock_keys() after we done enable_cpucache() > instead of before to avoid the fake DEADLOCK report. > > Michael traced the problem back to a commit in release 3.0.0: > > commit 30765b92ada267c5395fc788623cb15233276f5c > Author: Peter Zijlstra <peterz@infradead.org> > Date: Thu Jul 28 23:22:56 2011 +0200 > > slab, lockdep: Annotate the locks before using them > > Fernando found we hit the regular OFF_SLAB 'recursion' before we > annotate the locks, cure this. > > The relevant portion of the stack-trace: > > > [ 0.000000] [<c085e24f>] rt_spin_lock+0x50/0x56 > > [ 0.000000] [<c04fb406>] __cache_free+0x43/0xc3 > > [ 0.000000] [<c04fb23f>] kmem_cache_free+0x6c/0xdc > > [ 0.000000] [<c04fb2fe>] slab_destroy+0x4f/0x53 > > [ 0.000000] [<c04fb396>] free_block+0x94/0xc1 > > [ 0.000000] [<c04fc551>] do_tune_cpucache+0x10b/0x2bb > > [ 0.000000] [<c04fc8dc>] enable_cpucache+0x7b/0xa7 > > [ 0.000000] [<c0bd9d3c>] kmem_cache_init_late+0x1f/0x61 > > [ 0.000000] [<c0bba687>] start_kernel+0x24c/0x363 > > [ 0.000000] [<c0bba0ba>] i386_start_kernel+0xa9/0xaf > > Reported-by: Fernando Lopez-Lezcano <nando@ccrma.Stanford.EDU> > Acked-by: Pekka Enberg <penberg@kernel.org> > Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> > Link: http://lkml.kernel.org/r/1311888176.2617.379.camel@laptop > Signed-off-by: Ingo Molnar <mingo@elte.hu> > > The commit moved init_lock_keys() before we build up the alien, so we > failed to reclass it. > > Cc: <stable@vger.kernel.org> # 3.0+ > Acked-by: Christoph Lameter <cl@linux.com> > Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > Signed-off-by: Michael Wang <wangyun@linux.vnet.ibm.com> > Signed-off-by: Pekka Enberg <penberg@kernel.org>
The commit above shows up in 3.1, not 3.0, so this patch does not apply to the 3.0.y kernel from what I can tell. If this is incorrect, please let me know.
thanks,
greg k-h
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