Messages in this thread | | | Date | Tue, 8 Mar 2022 16:14:55 -0500 | From | Steven Rostedt <> | Subject | sched_core_balance() releasing interrupts with pi_lock held |
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Hi Peter,
A ChromeOS bug report showed a lockdep splat that I first thought was a bad backport. But when looking at upstream, I don't see how it would work there either. The lockdep splat had:
[56064.673346] Call Trace: [56064.676066] dump_stack+0xb9/0x117 [56064.679861] ? print_usage_bug+0x2af/0x2c2 [56064.684434] mark_lock_irq+0x25e/0x27d [56064.688618] mark_lock+0x11a/0x16c [56064.692412] mark_held_locks+0x57/0x87 [56064.696595] ? _raw_spin_unlock_irq+0x2c/0x40 [56064.701460] lockdep_hardirqs_on+0xb1/0x19d [56064.706130] _raw_spin_unlock_irq+0x2c/0x40 [56064.710799] sched_core_balance+0x8a/0x4af [56064.715369] ? __balance_callback+0x1f/0x9a [56064.720030] __balance_callback+0x4f/0x9a [56064.724506] rt_mutex_setprio+0x43a/0x48b [56064.728982] task_blocks_on_rt_mutex+0x14d/0x1d5
Where I see:
task_blocks_on_rt_mutex() { spin_lock(pi_lock); rt_mutex_setprio() { balance_callback() { sched_core_balance() { spin_unlock_irq(rq);
Where spin_unlock_irq() enables interrupts while holding the pi_lock, and BOOM, lockdep (rightfully) complains.
The above was me looking at mainline, not the kernel that blew up. So, I'm guessing that this is a bug in mainline as well.
-- Steve
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