Messages in this thread Patch in this message |  | | Subject | Re: [PATCH -next] lockdep: skip debugobjects for lock_classes[] init | From | Bart Van Assche <> | Date | Sun, 3 Mar 2019 10:19:01 -0800 |
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On 3/2/19 8:02 PM, Qian Cai wrote: > The linux-next commit a0b0fd53e1e6 ("locking/lockdep: Free lock classes > that are no longer in use") let init_data_structures_once() call > init_rcu_head(). As the result, smp_setup_processor_id() calls > debug_object_init() before debug_objects_early_init() triggering errors > below on arm64 and ppc64le. Since debug_objects_early_init() depends on > smp_setup_processor_id(), so it is not straightforward to move the > former earlier in start_kernel(). Hence, just skip all debugobjects > creations in init_data_structures_once() as a good trade-off by losing > track of some RCU list heads debugging. > > BUG: spinlock bad magic on CPU#0, swapper/0 > lock: obj_hash+0xc3048/0x100000, .magic: 00000000, .owner: <none>/-1, > .owner_cpu: 0 > CPU: 0 PID: 0 Comm: swapper Not tainted 5.0.0-rc8-next-20190301+ #1 > Call trace: > dump_backtrace+0x0/0x450 > show_stack+0x20/0x2c > dump_stack+0xe0/0x16c > spin_bug+0x200/0x224 > do_raw_spin_lock+0x1bc/0x23c > _raw_spin_lock_irqsave+0xac/0xd0 > __debug_object_init+0xf0/0x19dc > debug_object_init+0x54/0x6c > init_rcu_head+0x24/0x30 > init_data_structures_once+0xb0/0x41c > register_lock_class+0x70c/0x1454 > __lock_acquire+0xc4/0x235c > lock_acquire+0x508/0x668 > _raw_spin_lock+0x88/0xac > vprintk_emit+0x33c/0x53c > vprintk_default+0x54/0x7c > vprintk_func+0x320/0x40c > printk+0x64/0x8c > smp_setup_processor_id+0x6c/0x84 > start_kernel+0x38/0x8f8 > ODEBUG: Out of memory. ODEBUG disabled > > Signed-off-by: Qian Cai <cai@lca.pw> > --- > kernel/locking/lockdep.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c > index 21cb81fe6359..1309a6fe88ee 100644 > --- a/kernel/locking/lockdep.c > +++ b/kernel/locking/lockdep.c > @@ -988,7 +988,6 @@ static void init_data_structures_once(void) > > initialization_happened = true; > > - init_rcu_head(&delayed_free.rcu_head); > INIT_LIST_HEAD(&delayed_free.pf[0].zapped); > INIT_LIST_HEAD(&delayed_free.pf[1].zapped);
Hi Qian,
Thanks for having reported this issue. Had you considered to follow an approach similar to the patch below?
Thanks,
Bart.
[PATCH] locking/lockdep: Only call init_rcu_head() after RCU has been initialized
init_data_structures_once() is called for the first time before RCU has been initialized. Make sure that init_rcu_head() is called before the RCU head is used and after RCU has been initialized.
Signed-off-by: Bart Van Assche <bvanassche@acm.org> --- kernel/locking/lockdep.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 21cb81fe6359..c8c83e1e2664 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -980,15 +980,22 @@ static inline void check_data_structures(void) { } */ static void init_data_structures_once(void) { - static bool initialization_happened; + static bool ds_initialized, rcu_head_initialized; int i;
- if (likely(initialization_happened)) + if (likely(rcu_head_initialized)) return;
- initialization_happened = true; + if (system_state >= SYSTEM_SCHEDULING) { + init_rcu_head(&delayed_free.rcu_head); + rcu_head_initialized = true; + } + + if (ds_initialized) + return; + + ds_initialized = true;
- init_rcu_head(&delayed_free.rcu_head); INIT_LIST_HEAD(&delayed_free.pf[0].zapped); INIT_LIST_HEAD(&delayed_free.pf[1].zapped);
-- 2.20.1
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