Re: [tip: core/urgent] entry/rseq: Fix hard lockup on granted time slice extension

[Thomas Gleixner <tglx@linutronix.de>]

On Sat, Aug 08 2026 at 10:36, Peter Zijlstra wrote:
> On Fri, Aug 07, 2026 at 11:15:19PM +0200, Thomas Gleixner wrote:
>> 	rseq = curr->rseq.usrptr;
>> 	scoped_user_rw_access(rseq, efault) {
>> 
>> That's user access which requires interrupts to be enabled.
>
> Well, you can do user access with IRQs disabled just fine, you just get
> more efault.

Sure, but then you need a manual fault handler, which requires that
interrupts are enabled :)

>> So the thing [wm]e f*cked up royally was to invoke
>> hrtimer_rearm_deferred_tif() with interrupts enabled and that needs to
>> be fixed.
>> 
>> Of course all of this can be figured out from the copious amount of
>> comments which got added to explain all of this magic.
>
> Bah, its spread out over too damn many functions is what :/

That and comments are missing at crucial places :(