On Sat, Jul 12, 2014 at 02:03:57PM -0400, Sasha Levin wrote:
> On 06/20/2014 11:40 AM, Paul E. McKenney wrote:
> > rcu: Export debug_init_rcu_head() and and debug_init_rcu_head()
> >
> > Currently, call_rcu() relies on implicit allocation and initialization
> > for the debug-objects handling of RCU callbacks. If you hammer the
> > kernel hard enough with Sasha's modified version of trinity, you can end
> > up with the sl*b allocators recursing into themselves via this implicit
> > call_rcu() allocation.
> >
> > This commit therefore exports the debug_init_rcu_head() and
> > debug_rcu_head_free() functions, which permits the allocators to allocated
> > and pre-initialize the debug-objects information, so that there no longer
> > any need for call_rcu() to do that initialization, which in turn prevents
> > the recursion into the memory allocators.
> >
> > Reported-by: Sasha Levin <sasha.le...@oracle.com>
> > Suggested-by: Thomas Gleixner <t...@linutronix.de>
> > Signed-off-by: Paul E. McKenney <paul...@linux.vnet.ibm.com>
> > Acked-by: Thomas Gleixner <t...@linutronix.de>
>
> Hi Paul,
>
> Oddly enough, I still see the issue in -next (I made sure that this patch
> was in the tree):
Hello, Sasha,
This commit is only part of the solution. The allocators need to change
to make use of it.
Thanx, Paul
> [ 393.810123] =============================================
> [ 393.810123] [ INFO: possible recursive locking detected ]
> [ 393.810123] 3.16.0-rc4-next-20140711-sasha-00046-g07d3099-dirty #813 Not
> tainted
> [ 393.810123] ---------------------------------------------
> [ 393.810123] trinity-c32/9762 is trying to acquire lock:
> [ 393.810123] (&(&n->list_lock)->rlock){-.-...}, at:
> get_partial_node.isra.39 (mm/slub.c:1628)
> [ 393.810123]
> [ 393.810123] but task is already holding lock:
> [ 393.810123] (&(&n->list_lock)->rlock){-.-...}, at: __kmem_cache_shutdown
> (mm/slub.c:3210 mm/slub.c:3233 mm/slub.c:3244)
> [ 393.810123]
> [ 393.810123] other info that might help us debug this:
> [ 393.810123] Possible unsafe locking scenario:
> [ 393.810123]
> [ 393.810123] CPU0
> [ 393.810123] ----
> [ 393.810123] lock(&(&n->list_lock)->rlock);
> [ 393.810123] lock(&(&n->list_lock)->rlock);
> [ 393.810123]
> [ 393.810123] *** DEADLOCK ***
> [ 393.810123]
> [ 393.810123] May be due to missing lock nesting notation
> [ 393.810123]
> [ 393.810123] 5 locks held by trinity-c32/9762:
> [ 393.810123] #0: (net_mutex){+.+.+.}, at: copy_net_ns
> (net/core/net_namespace.c:254)
> [ 393.810123] #1: (cpu_hotplug.lock){++++++}, at: get_online_cpus
> (kernel/cpu.c:90)
> [ 393.810123] #2: (mem_hotplug.lock){.+.+.+}, at: get_online_mems
> (mm/memory_hotplug.c:83)
> [ 393.810123] #3: (slab_mutex){+.+.+.}, at: kmem_cache_destroy
> (mm/slab_common.c:344)
> [ 393.810123] #4: (&(&n->list_lock)->rlock){-.-...}, at:
> __kmem_cache_shutdown (mm/slub.c:3210 mm/slub.c:3233 mm/slub.c:3244)
> [ 393.810123]
> [ 393.810123] stack backtrace:
> [ 393.810123] CPU: 32 PID: 9762 Comm: trinity-c32 Not tainted
> 3.16.0-rc4-next-20140711-sasha-00046-g07d3099-dirty #813
> [ 393.843284] ffff880bc26730e0 0000000000000000 ffffffffb4ae7ff0
> ffff880bc26a3848
> [ 393.843284] ffffffffb0e47068 ffffffffb4ae7ff0 ffff880bc26a38f0
> ffffffffac258586
> [ 393.843284] ffff880bc2673e30 000000050000000a ffffffffb444dee0
> ffff880bc2673e48
> [ 393.843284] Call Trace:
> [ 393.843284] dump_stack (lib/dump_stack.c:52)
> [ 393.843284] __lock_acquire (kernel/locking/lockdep.c:1739
> kernel/locking/lockdep.c:1783 kernel/locking/lockdep.c:2115
> kernel/locking/lockdep.c:3182)
> [ 393.843284] lock_acquire (kernel/locking/lockdep.c:3602)
> [ 393.843284] ? get_partial_node.isra.39 (mm/slub.c:1628)
> [ 393.843284] _raw_spin_lock (include/linux/spinlock_api_smp.h:143
> kernel/locking/spinlock.c:151)
> [ 393.843284] ? get_partial_node.isra.39 (mm/slub.c:1628)
> [ 393.843284] get_partial_node.isra.39 (mm/slub.c:1628)
> [ 393.843284] ? check_irq_usage (kernel/locking/lockdep.c:1638)
> [ 393.843284] ? __slab_alloc (mm/slub.c:2307)
> [ 393.843284] ? __this_cpu_preempt_check (lib/smp_processor_id.c:63)
> [ 393.843284] __slab_alloc (mm/slub.c:1730 mm/slub.c:2208 mm/slub.c:2372)
> [ 393.843284] ? __debug_object_init (lib/debugobjects.c:100
> lib/debugobjects.c:312)
> [ 393.843284] ? kvm_clock_read (./arch/x86/include/asm/preempt.h:90
> arch/x86/kernel/kvmclock.c:86)
> [ 393.843284] ? sched_clock (./arch/x86/include/asm/paravirt.h:192
> arch/x86/kernel/tsc.c:304)
> [ 393.843284] kmem_cache_alloc (mm/slub.c:2445 mm/slub.c:2487 mm/slub.c:2492)
> [ 393.843284] ? debug_smp_processor_id (lib/smp_processor_id.c:57)
> [ 393.843284] ? __debug_object_init (lib/debugobjects.c:100
> lib/debugobjects.c:312)
> [ 393.843284] ? check_chain_key (kernel/locking/lockdep.c:2188)
> [ 393.843284] __debug_object_init (lib/debugobjects.c:100
> lib/debugobjects.c:312)
> [ 393.843284] ? _raw_spin_unlock_irqrestore
> (include/linux/spinlock_api_smp.h:160 kernel/locking/spinlock.c:191)
> [ 393.843284] ? __this_cpu_preempt_check (lib/smp_processor_id.c:63)
> [ 393.843284] debug_object_init (lib/debugobjects.c:365)
> [ 393.843284] rcuhead_fixup_activate (kernel/rcu/update.c:260)
> [ 393.843284] debug_object_activate (lib/debugobjects.c:280
> lib/debugobjects.c:439)
> [ 393.843284] ? preempt_count_sub (kernel/sched/core.c:2600)
> [ 393.843284] ? slab_cpuup_callback (mm/slub.c:1484)
> [ 393.843284] __call_rcu (kernel/rcu/rcu.h:76 (discriminator 8)
> kernel/rcu/tree.c:2665 (discriminator 8))
> [ 393.843284] ? __kmem_cache_shutdown (mm/slub.c:3210 mm/slub.c:3233
> mm/slub.c:3244)
> [ 393.843284] call_rcu (kernel/rcu/tree_plugin.h:679)
> [ 393.843284] discard_slab (mm/slub.c:1522)
> [ 393.843284] __kmem_cache_shutdown (mm/slub.c:3210 mm/slub.c:3233
> mm/slub.c:3244)
> [ 393.843284] kmem_cache_destroy (mm/slab_common.c:350)
> [ 393.843284] nf_conntrack_cleanup_net_list
> (net/netfilter/nf_conntrack_core.c:1569 (discriminator 3))
> [ 393.843284] nf_conntrack_pernet_exit
> (net/netfilter/nf_conntrack_standalone.c:558)
> [ 393.843284] ops_exit_list.isra.1 (net/core/net_namespace.c:135)
> [ 393.843284] setup_net (net/core/net_namespace.c:180 (discriminator 3))
> [ 393.843284] copy_net_ns (net/core/net_namespace.c:255)
> [ 393.843284] create_new_namespaces (kernel/nsproxy.c:95)
> [ 393.843284] unshare_nsproxy_namespaces (kernel/nsproxy.c:190
> (discriminator 4))
> [ 393.843284] SyS_unshare (kernel/fork.c:1865 kernel/fork.c:1814)
> [ 393.843284] tracesys (arch/x86/kernel/entry_64.S:542)
>
>
> Thanks,
> Sasha
>
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