Re: [PATCH -mm] futex-pi: fix possible pi_lock deadlock

[Ingo Molnar]

* Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:

> From: Ingo Molnar <mingo@xxxxxxx>
> 
> The lock validator detected a possible deadlock between tasklist lock 
> and task->pi_lock. Prevent the deadlock by disabling interrupts across 
> pi_lock operations.

some background about how this bug sneaked in: we have pi_lock as an 
irq-safe lock in the -rt tree but we didnt realize that it was needed in 
the pi-futex implementation too. The race window is pretty narrow there 
so it didnt trigger during testing. (the window is wider in -rt)

	Ingo
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