On Fri, Nov 11, 2011 at 11:04:31AM +0800, Shaohua Li wrote:
> On Fri, 2011-11-11 at 07:35 +0800, Julie Sullivan wrote:
> > (was '3.2-rc1: INFO: possible recursive locking detect')
> >
> > On Wednesday 09 November 2011 09:05:57 Yong Zhang wrote:
> > >
> > >Hi,
> > >Just get below waring when doing:
> > >for i in `seq 1 10`; do ./perf bench -f simple sched messaging -g 40; done
> >
> > >And kernel config is attached.
>
> Looks this could be a real dead lock. we hold a lock to free a object,
> but the free need allocate a new object. if the new object and the freed
> object are from the same slab, there is a deadlock.
>
> discard_slab() doesn't need hold the lock if the slab is already removed
> from partial list. how about below patch, only compile tested.
It work on my side.
Thanks,
Yong
>
> diff --git a/mm/slub.c b/mm/slub.c
> index 7d2a996..9375668 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -1858,7 +1858,7 @@ redo:
> }
>
> /* Unfreeze all the cpu partial slabs */
> -static void unfreeze_partials(struct kmem_cache *s)
> +static void unfreeze_partials(struct kmem_cache *s, struct page **discard_page)
> {
> struct kmem_cache_node *n = NULL;
> struct kmem_cache_cpu *c = this_cpu_ptr(s->cpu_slab);
> @@ -1915,14 +1915,28 @@ static void unfreeze_partials(struct kmem_cache *s)
> "unfreezing slab"));
>
> if (m == M_FREE) {
> - stat(s, DEACTIVATE_EMPTY);
> - discard_slab(s, page);
> - stat(s, FREE_SLAB);
> + page->next = *discard_page;
> + *discard_page = page;
> }
> }
>
> if (n)
> spin_unlock(&n->list_lock);
> +
> +}
> +
> +static void discard_page_list(struct kmem_cache *s, struct page *discard_page)
> +{
> + struct page *page;
> +
> + while (discard_page) {
> + page = discard_page;
> + discard_page = discard_page->next;
> +
> + stat(s, DEACTIVATE_EMPTY);
> + discard_slab(s, page);
> + stat(s, FREE_SLAB);
> + }
> }
>
> /*
> @@ -1950,13 +1964,15 @@ int put_cpu_partial(struct kmem_cache *s, struct page *page, int drain)
> pages = oldpage->pages;
> if (drain && pobjects > s->cpu_partial) {
> unsigned long flags;
> + struct page *discard_page = NULL;
> /*
> * partial array is full. Move the existing
> * set to the per node partial list.
> */
> local_irq_save(flags);
> - unfreeze_partials(s);
> + unfreeze_partials(s, &discard_page);
> local_irq_restore(flags);
> + discard_page_list(s, discard_page);
> pobjects = 0;
> pages = 0;
> }
> @@ -1988,12 +2004,14 @@ static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c)
> static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu)
> {
> struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu);
> + struct page *discard_page = NULL;
>
> if (likely(c)) {
> if (c->page)
> flush_slab(s, c);
>
> - unfreeze_partials(s);
> + unfreeze_partials(s, &discard_page);
> + discard_page_list(s, discard_page);
> }
> }
>
>
>
> > >---
> > >[ 350.148020] =============================================
> > [ 350.148020] [ INFO: possible recursive locking detected ]
> > [ 350.148020] 3.2.0-rc1-10791-g76a4b59-dirty #2
> > [ 350.148020] ---------------------------------------------
> > [ 350.148020] perf/9439 is trying to acquire lock:
> > [ 350.148020] (&(&n->list_lock)->rlock){-.-...}, at: [<ffffffff8113847f>] get_partial_node+0x5f/0x360
> > [ 350.148020]
> > [ 350.148020] but task is already holding lock:
> > [ 350.148020] (&(&n->list_lock)->rlock){-.-...}, at: [<ffffffff811380c9>] unfreeze_partials+0x199/0x3c0
> > [ 350.148020]
> > [ 350.148020] other info that might help us debug this:
> > [ 350.148020] Possible unsafe locking scenario:
> > [ 350.148020]
> > [ 350.148020] CPU0
> > [ 350.148020] ----
> > [ 350.148020] lock(&(&n->list_lock)->rlock);
> > [ 350.148020] lock(&(&n->list_lock)->rlock);
> > [ 350.148020]
> > [ 350.148020] *** DEADLOCK ***
> > [ 350.148020]
> > [ 350.148020] May be due to missing lock nesting notation
> > [ 350.148020]
> > [ 350.148020] 2 locks held by perf/9439:
> > [ 350.148020] #0: (tasklist_lock){.+.+..}, at: [<ffffffff810552ee>] release_task+0x9e/0x500
> > >[ 350.148020] #1: (&(&n->list_lock)->rlock){-.-...}, at: [<ffffffff811380c9>] unfreeze_partials+0x199/0x3c0
> >
> >
> > Hi Yong
> >
> > I've been getting a similar report not when using perf though, just in my dmesg at startup:
> > (if people want my .config please ask, I'm not including it else in case it's just unhelpful noise)
> >
> > Cheers
> > Julie
> >
> > [ 34.545934] =============================================
> > [ 34.545936] [ INFO: possible recursive locking detected ]
> > [ 34.545939] 3.2.0-rc1 #103
> > [ 34.545940] ---------------------------------------------
> > [ 34.545943] kdeinit4/2559 is trying to acquire lock:
> > [ 34.545945] (&(&n->list_lock)->rlock){-.-...}, at: [<ffffffff8110aaa4>] get_partial_node+0x3f/0x17a
> > [ 34.545954]
> > [ 34.545955] but task is already holding lock:
> > [ 34.545957] (&(&n->list_lock)->rlock){-.-...}, at: [<ffffffff81109efe>] unfreeze_partials+0xc4/0x193
> > [ 34.545963]
> > [ 34.545964] other info that might help us debug this:
> > [ 34.545966] Possible unsafe locking scenario:
> > [ 34.545966]
> > [ 34.545968] CPU0
> > [ 34.545969] ----
> > [ 34.545971] lock(&(&n->list_lock)->rlock);
> > [ 34.545974] lock(&(&n->list_lock)->rlock);
> > [ 34.545977]
> > [ 34.545978] *** DEADLOCK ***
> > [ 34.545978]
> > [ 34.545980] May be due to missing lock nesting notation
> > [ 34.545981]
> > [ 34.545983] 1 lock held by kdeinit4/2559:
> > [ 34.545985] #0: (&(&n->list_lock)->rlock){-.-...}, at: [<ffffffff81109efe>] unfreeze_partials+0xc4/0x193
> > [ 34.545992]
> > [ 34.545992] stack backtrace:
> > [ 34.545995] Pid: 2559, comm: kdeinit4 Not tainted 3.2.0-rc1 #103
> > [ 34.545997] Call Trace:
> > [ 34.546003] [<ffffffff81076548>] __lock_acquire+0x9d8/0xdf7
> > [ 34.546008] [<ffffffff8105fdf5>] ? __kernel_text_address+0x26/0x4c
> > [ 34.546010] [<ffffffff81004c57>] ? print_context_stack+0x9c/0xb2
> > [ 34.546010] [<ffffffff8110aaa4>] ? get_partial_node+0x3f/0x17a
> > [ 34.546010] [<ffffffff81076e4a>] lock_acquire+0xd8/0xfe
> > [ 34.546010] [<ffffffff8110aaa4>] ? get_partial_node+0x3f/0x17a
> > [ 34.546010] [<ffffffff8107e092>] ? __module_text_address+0x12/0x5f
> > [ 34.546010] [<ffffffff815af2d3>] _raw_spin_lock+0x45/0x7a
> > [ 34.546010] [<ffffffff8110aaa4>] ? get_partial_node+0x3f/0x17a
> > [ 34.546010] [<ffffffff8110aaa4>] get_partial_node+0x3f/0x17a
> > [ 34.546010] [<ffffffff810733fb>] ? look_up_lock_class+0x5f/0xbe
> > [ 34.546010] [<ffffffff8107e092>] ? __module_text_address+0x12/0x5f
> > [ 34.546010] [<ffffffff8110ad4e>] __slab_alloc+0x16f/0x3ae
> > [ 34.546010] [<ffffffff81008529>] ? native_sched_clock+0x3b/0x3d
> > [ 34.546010] [<ffffffff81112d46>] ? create_object+0x39/0x283
> > [ 34.546010] [<ffffffff81008529>] ? native_sched_clock+0x3b/0x3d
> > [ 34.546010] [<ffffffff81072655>] ? arch_local_irq_save+0x9/0xc
> > [ 34.546010] [<ffffffff81112d46>] ? create_object+0x39/0x283
> > [ 34.546010] [<ffffffff8110c54c>] kmem_cache_alloc+0x5b/0x12b
> > [ 34.546010] [<ffffffff81112d46>] create_object+0x39/0x283
> > [ 34.546010] [<ffffffff8159655c>] kmemleak_alloc+0x73/0x98
> > [ 34.546010] [<ffffffff81250c3c>] ? __debug_object_init+0x43/0x2e7
> > [ 34.546010] [<ffffffff8110c5b4>] kmem_cache_alloc+0xc3/0x12b
> > [ 34.546010] [<ffffffff810679c7>] ? sched_clock_local+0x12/0x75
> > [ 34.546010] [<ffffffff81250c3c>] __debug_object_init+0x43/0x2e7
> > [ 34.546010] [<ffffffff81067b92>] ? local_clock+0x2b/0x3c
> > [ 34.546010] [<ffffffff81073b06>] ? lock_release_holdtime+0x59/0x60
> > [ 34.546010] [<ffffffff81250ef4>] debug_object_init+0x14/0x16
> > [ 34.546010] [<ffffffff8105fc57>] rcuhead_fixup_activate+0x27/0x5f
> > [ 34.546010] [<ffffffff81250943>] debug_object_fixup+0x1e/0x2b
> > [ 34.546010] [<ffffffff81250fdb>] debug_object_activate+0xcc/0xd9
> > [ 34.546010] [<ffffffff8110939f>] ? discard_slab+0x4e/0x4e
> > [ 34.546010] [<ffffffff810a8b77>] __call_rcu+0x4f/0x18e
> > [ 34.546010] [<ffffffff810a8ce2>] call_rcu_sched+0x15/0x17
> > [ 34.546010] [<ffffffff81109396>] discard_slab+0x45/0x4e
> > [ 34.546010] [<ffffffff81109fa4>] unfreeze_partials+0x16a/0x193
> > [ 34.546010] [<ffffffff81073b06>] ? lock_release_holdtime+0x59/0x60
> > [ 34.546010] [<ffffffff815afd87>] ? _raw_spin_unlock_irqrestore+0x3f/0x55
> > [ 34.546010] [<ffffffff8110a020>] put_cpu_partial+0x53/0xbd
> > [ 34.546010] [<ffffffff8110a197>] __slab_free+0x10d/0x229
> > [ 34.546010] [<ffffffff810f5e08>] ? anon_vma_free+0x3d/0x41
> > [ 34.546010] [<ffffffff810f5e08>] ? anon_vma_free+0x3d/0x41
> > [ 34.546010] [<ffffffff8110a44b>] kmem_cache_free+0x7d/0xc4
> > [ 34.546010] [<ffffffff810f5e08>] anon_vma_free+0x3d/0x41
> > [ 34.546010] [<ffffffff810f6d9e>] __put_anon_vma+0x38/0x3d
> > [ 34.546010] [<ffffffff810f6dcc>] put_anon_vma+0x29/0x2d
> > [ 34.546010] [<ffffffff810f6f28>] unlink_anon_vmas+0xf5/0x14c
> > [ 34.546010] [<ffffffff815ae4c4>] ? mutex_unlock+0xe/0x10
> > [ 34.546010] [<ffffffff810ed096>] free_pgtables+0x73/0xd0
> > [ 34.546010] [<ffffffff810f30ad>] exit_mmap+0xac/0xe5
> > [ 34.546010] [<ffffffff81043d05>] mmput+0x60/0x108
> > [ 34.546010] [<ffffffff81048323>] exit_mm+0x119/0x126
> > [ 34.546010] [<ffffffff815afd34>] ? _raw_spin_unlock_irq+0x30/0x44
> > [ 34.546010] [<ffffffff81049a59>] do_exit+0x233/0x80f
> > [ 34.546010] [<ffffffff81073330>] ? trace_hardirqs_off_caller+0x33/0x90
> > [ 34.546010] [<ffffffff815affca>] ? retint_swapgs+0xe/0x13
> > [ 34.546010] [<ffffffff8104a2dd>] do_group_exit+0x88/0xb6
> > [ 34.546010] [<ffffffff8104a322>] sys_exit_group+0x17/0x1b
> > [ 34.546010] [<ffffffff815b662b>] system_call_fastpath+0x16/0x1b
> >
> >
> >
> >
> > --
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>
>
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