Messages in this thread | | | Date | Fri, 15 Dec 2006 23:26:33 -0700 | From | Matthew Wilcox <> | Subject | Doubled stack dumps during locking testsuite |
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Hi Ingo,
I built a parisc kernel with CONFIG_DEBUG_LOCKING_API_SELFTESTS enabled recently, and got some interesting results:
double unlock: ok | ok |failed|WARNING at /home/willy/merge-2.6/kernel/mutex-debug.c:83 debug_mutex_unlock() Backtrace: [<0000000040144b38>] printk+0x40/0x50 [<000000004028d5f4>] init_class_Z+0xa4/0xc0 [<0000000040144b38>] printk+0x40/0x50 [<0000000040171fbc>] register_cpu_notifier+0x5c/0x78 [<0000000040340212>] lpfc_sli_issue_mbox_wait+0x138/0x1c8 [<0000000040204d01>] sg_grt_trans+0x150/0x168 [<0000000040285700>] kobject_uevent+0x8/0x20 [<0000000040304d65>] scsi_error_handler+0x9f4/0xa48 [<0000000040207450>] dump_write+0x40/0x58 [<000000004044c67c>] packet_getsockopt+0x144/0x150 [<000000004044b05c>] packet_ioctl+0x1a4/0x1b0 [<00000000404466d4>] unix_ioctl+0x154/0x168 [<000000004042d5dc>] ipv4_sysctl_forward_strategy+0x12c/0x138 [<000000004042d558>] ipv4_sysctl_forward_strategy+0xa8/0x138 [<000000004042c1d4>] ip_mc_msfget+0x16c/0x1d0 [<00000000404230a8>] ipv4_doint_and_flush_strategy+0x110/0x138
WARNING at /home/willy/merge-2.6/kernel/mutex-debug.c:86 debug_mutex_unlock() Backtrace: [<0000000040144b38>] printk+0x40/0x50 [<000000004028d5f4>] init_class_Z+0xa4/0xc0 [<0000000040144b38>] printk+0x40/0x50 [<0000000040171fbc>] register_cpu_notifier+0x5c/0x78 [<0000000040340212>] lpfc_sli_issue_mbox_wait+0x138/0x1c8 [<0000000040204d01>] sg_grt_trans+0x150/0x168 [<0000000040285700>] kobject_uevent+0x8/0x20 [<0000000040304d65>] scsi_error_handler+0x9f4/0xa48 [<0000000040207450>] dump_write+0x40/0x58 [<000000004044c67c>] packet_getsockopt+0x144/0x150 [<000000004044b05c>] packet_ioctl+0x1a4/0x1b0 [<00000000404466d4>] unix_ioctl+0x154/0x168 [<000000004042d5dc>] ipv4_sysctl_forward_strategy+0x12c/0x138 [<000000004042d558>] ipv4_sysctl_forward_strategy+0xa8/0x138 [<000000004042c1d4>] ip_mc_msfget+0x16c/0x1d0 [<00000000404230a8>] ipv4_doint_and_flush_strategy+0x110/0x138
failed|failed|failed|
Now, lines 83 to 86 of mutex-debug.c are:
DEBUG_LOCKS_WARN_ON(lock->owner != current_thread_info()); DEBUG_LOCKS_WARN_ON(lock->magic != lock); DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next); DEBUG_LOCKS_WARN_ON(lock->owner != current_thread_info());
Do we really need to test the same thing twice and produce the same stack dump?
Moreover, do we want to get stack dumps while running the locking testsuite in the first place? From various comments, it looks like it's supposed to be turned off, but it looks like the sense of debug_locks_silent is inverted in the definition of DEBUG_LOCKS_WARN_ON:
if (unlikely(c)) { \ if (debug_locks_silent || debug_locks_off()) \ WARN_ON(1); \
Surely that should be:
if (!debug_locks_silent && debug_locks_off()) WARN_ON(1);
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