* [PATCH] watchdog: Fix lockdep warning @ 2023-08-11 17:11 Helge Deller 2023-08-15 11:54 ` Petr Mladek 0 siblings, 1 reply; 3+ messages in thread From: Helge Deller @ 2023-08-11 17:11 UTC (permalink / raw) To: Andrew Morton, linux-kernel, Petr Mladek; +Cc: linux-parisc Fully initialize detector_work work struct to avoid this kernel warning when lockdep is enabled: ===================================== WARNING: bad unlock balance detected! 6.5.0-rc5+ #687 Not tainted ------------------------------------- swapper/0/1 is trying to release lock (detector_work) at: [<000000004037e554>] __flush_work+0x60/0x658 but there are no more locks to release! other info that might help us debug this: no locks held by swapper/0/1. stack backtrace: CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.5.0-rc5+ #687 Hardware name: 9000/785/C3700 Backtrace: [<0000000041455d5c>] print_unlock_imbalance_bug.part.0+0x20c/0x230 [<000000004040d5e8>] lock_release+0x2e8/0x3f8 [<000000004037e5cc>] __flush_work+0xd8/0x658 [<000000004037eb7c>] flush_work+0x30/0x60 [<000000004011f140>] lockup_detector_check+0x54/0x128 [<0000000040306430>] do_one_initcall+0x9c/0x408 [<0000000040102d44>] kernel_init_freeable+0x688/0x7f0 [<000000004146df68>] kernel_init+0x64/0x3a8 [<0000000040302020>] ret_from_kernel_thread+0x20/0x28 Signed-off-by: Helge Deller <deller@gmx.de> --- diff --git a/kernel/watchdog.c b/kernel/watchdog.c index be38276a365f..eab0dfcfa3f9 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -1022,5 +1022,6 @@ void __init lockup_detector_init(void) else allow_lockup_detector_init_retry = true; + INIT_WORK(&detector_work, lockup_detector_delay_init); lockup_detector_setup(); } ^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] watchdog: Fix lockdep warning 2023-08-11 17:11 [PATCH] watchdog: Fix lockdep warning Helge Deller @ 2023-08-15 11:54 ` Petr Mladek 2023-08-15 12:44 ` Helge Deller 0 siblings, 1 reply; 3+ messages in thread From: Petr Mladek @ 2023-08-15 11:54 UTC (permalink / raw) To: Helge Deller Cc: Andrew Morton, linux-kernel, linux-parisc, Peter Zijlstra, Ingo Molnar, Will Deacon, Waiman Long, Boqun Feng, Tejun Heo, Lai Jiangshan Adding workqueue and lockdep people into Cc. On Fri 2023-08-11 19:11:46, Helge Deller wrote: > Fully initialize detector_work work struct to avoid this kernel warning > when lockdep is enabled: > > ===================================== > WARNING: bad unlock balance detected! > 6.5.0-rc5+ #687 Not tainted > ------------------------------------- > swapper/0/1 is trying to release lock (detector_work) at: > [<000000004037e554>] __flush_work+0x60/0x658 > but there are no more locks to release! > > other info that might help us debug this: > no locks held by swapper/0/1. > > stack backtrace: > CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.5.0-rc5+ #687 > Hardware name: 9000/785/C3700 > Backtrace: > [<0000000041455d5c>] print_unlock_imbalance_bug.part.0+0x20c/0x230 > [<000000004040d5e8>] lock_release+0x2e8/0x3f8 > [<000000004037e5cc>] __flush_work+0xd8/0x658 > [<000000004037eb7c>] flush_work+0x30/0x60 > [<000000004011f140>] lockup_detector_check+0x54/0x128 > [<0000000040306430>] do_one_initcall+0x9c/0x408 > [<0000000040102d44>] kernel_init_freeable+0x688/0x7f0 > [<000000004146df68>] kernel_init+0x64/0x3a8 > [<0000000040302020>] ret_from_kernel_thread+0x20/0x28 > > Signed-off-by: Helge Deller <deller@gmx.de> > > --- > > diff --git a/kernel/watchdog.c b/kernel/watchdog.c > index be38276a365f..eab0dfcfa3f9 100644 > --- a/kernel/watchdog.c > +++ b/kernel/watchdog.c > @@ -1022,5 +1022,6 @@ void __init lockup_detector_init(void) > else > allow_lockup_detector_init_retry = true; > > + INIT_WORK(&detector_work, lockup_detector_delay_init); > lockup_detector_setup(); > } Strange. The work is initialized when declared: static struct work_struct detector_work __initdata = __WORK_INITIALIZER(detector_work, lockup_detector_delay_init); , which should initialize the lockdep map as well. I would expect this is enough. And I do not see this on x86_64 with CONFIG_PROVE_LOCKING=y on today's Linus' tree. And the flush_work() is always called from the lockup_detector_check() late init call. IMHO, it must be a bug somewhere else. Otherwise, many other users of DECLARE_WORK() or __WORK_INITIALIZER() would have the same problem. Or do I miss something? Best Regards, Petr ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] watchdog: Fix lockdep warning 2023-08-15 11:54 ` Petr Mladek @ 2023-08-15 12:44 ` Helge Deller 0 siblings, 0 replies; 3+ messages in thread From: Helge Deller @ 2023-08-15 12:44 UTC (permalink / raw) To: Petr Mladek Cc: Andrew Morton, linux-kernel, linux-parisc, Peter Zijlstra, Ingo Molnar, Will Deacon, Waiman Long, Boqun Feng, Tejun Heo, Lai Jiangshan On 8/15/23 13:54, Petr Mladek wrote: > Adding workqueue and lockdep people into Cc. > > On Fri 2023-08-11 19:11:46, Helge Deller wrote: >> Fully initialize detector_work work struct to avoid this kernel warning >> when lockdep is enabled: >> >> ===================================== >> WARNING: bad unlock balance detected! >> 6.5.0-rc5+ #687 Not tainted >> ------------------------------------- >> swapper/0/1 is trying to release lock (detector_work) at: >> [<000000004037e554>] __flush_work+0x60/0x658 >> but there are no more locks to release! >> >> other info that might help us debug this: >> no locks held by swapper/0/1. >> >> stack backtrace: >> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.5.0-rc5+ #687 >> Hardware name: 9000/785/C3700 >> Backtrace: >> [<0000000041455d5c>] print_unlock_imbalance_bug.part.0+0x20c/0x230 >> [<000000004040d5e8>] lock_release+0x2e8/0x3f8 >> [<000000004037e5cc>] __flush_work+0xd8/0x658 >> [<000000004037eb7c>] flush_work+0x30/0x60 >> [<000000004011f140>] lockup_detector_check+0x54/0x128 >> [<0000000040306430>] do_one_initcall+0x9c/0x408 >> [<0000000040102d44>] kernel_init_freeable+0x688/0x7f0 >> [<000000004146df68>] kernel_init+0x64/0x3a8 >> [<0000000040302020>] ret_from_kernel_thread+0x20/0x28 >> >> Signed-off-by: Helge Deller <deller@gmx.de> >> >> --- >> >> diff --git a/kernel/watchdog.c b/kernel/watchdog.c >> index be38276a365f..eab0dfcfa3f9 100644 >> --- a/kernel/watchdog.c >> +++ b/kernel/watchdog.c >> @@ -1022,5 +1022,6 @@ void __init lockup_detector_init(void) >> else >> allow_lockup_detector_init_retry = true; >> >> + INIT_WORK(&detector_work, lockup_detector_delay_init); >> lockup_detector_setup(); >> } > > Strange. The work is initialized when declared: > > static struct work_struct detector_work __initdata = > __WORK_INITIALIZER(detector_work, lockup_detector_delay_init); > > , which should initialize the lockdep map as well. I would expect > this is enough. Right. It's enough... > And I do not see this on x86_64 with CONFIG_PROVE_LOCKING=y > on today's Linus' tree. And the flush_work() is always called > from the lockup_detector_check() late init call. > > IMHO, it must be a bug somewhere else. Otherwise, many other > users of DECLARE_WORK() or __WORK_INITIALIZER() would have > the same problem. Right. I should have replied earlier to this patch. Andrew already dropped this patch here from his patch collection. It turns out the problem is in function static_obj() from lockdep, which doesn't recognize the __initdata section for all platforms. Please look at this patch on the LKML instead, which fixes the real problem: [PATCH v2] lockdep: Fix static memory detection even more Thanks! Helge ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2023-08-15 12:45 UTC | newest] Thread overview: 3+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2023-08-11 17:11 [PATCH] watchdog: Fix lockdep warning Helge Deller 2023-08-15 11:54 ` Petr Mladek 2023-08-15 12:44 ` Helge Deller
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