Re: [PATCH 0/2] Proxy Execution fixes for v7.1-rc

[Kunwu Chan]

April 28, 2026 at 2:38 AM, "John Stultz" <jstultz@xxxxxxxxxx mailto:jstultz@xxxxxxxxxx?to=%22John%20Stultz%22%20%3Cjstultz%40google.com%3E > wrote:


> 
> Hey All,
>  So in testing with the full Proxy Execution series,
> Vineeth Pillai managed to trip some interesting bugs which
> initially looked to be KVM or RCU related[1], which he later
> diagnosed as Proxy Execution related and created a useful test
> driver to reproduce.
> 
> I found these same issues could be triggered with the upstream
> portions of Proxy Execution, so I wanted to send along these
> fixes for 7.1-rc
> 
> Again, a huge thanks to Vineeth for uncovering these issues
> that have evaded all my stress testing so far!
> 
> Thanks
> -john
> 
> [1]: https://lore.kernel.org/lkml/20260320125633.2290675-1-vineeth@xxxxxxxxxxxxxxx/
> 
Thanks John, Vineeth.

>From the SRCU side, this helps explain the earlier KVM/RCU-looking
stall pattern as a downstream symptom, with trigger likely in
proxy-exec scheduler/mutex interaction.

It would be good to confirm whether the original workload still
reproduces (process_srcu pending + irqfd-side stalls) after applying
this series, and whether there is a proxy-exec on/off comparison
under the same setup.

Thanks for driving this down.

> Cc: Vineeth Pillai <vineethrp@xxxxxxxxxx>
> Cc: Sonam Sanju <sonam.sanju@xxxxxxxxx>
> Cc: Sean Christopherson <seanjc@xxxxxxxxxx>
> Cc: Kunwu Chan <kunwu.chan@xxxxxxxxx>
> Cc: Tejun Heo <tj@xxxxxxxxxx>
> Cc: Joel Fernandes <joelagnelf@xxxxxxxxxx>
> Cc: Qais Yousef <qyousef@xxxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Juri Lelli <juri.lelli@xxxxxxxxxx>
> Cc: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
> Cc: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
> Cc: Valentin Schneider <vschneid@xxxxxxxxxx>
> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
> Cc: Will Deacon <will@xxxxxxxxxx>
> Cc: Waiman Long <longman@xxxxxxxxxx>
> Cc: Boqun Feng <boqun.feng@xxxxxxxxx>
> Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
> Cc: Metin Kaya <Metin.Kaya@xxxxxxx>
> Cc: Xuewen Yan <xuewen.yan94@xxxxxxxxx>
> Cc: K Prateek Nayak <kprateek.nayak@xxxxxxx>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
> Cc: Suleiman Souhlal <suleiman@xxxxxxxxxx>
> Cc: kuyo chang <kuyo.chang@xxxxxxxxxxxx>
> Cc: hupu <hupu.gm@xxxxxxxxx>
> Cc: kernel-team@xxxxxxxxxxx
> 
> John Stultz (2):
>  sched: proxy-exec: Close race causing workqueue work being delayed
>  locking: mutex: Fix proxy-exec potentially deactivating tasks marked
>  TASK_RUNNING
> 
>  kernel/locking/mutex.c | 1 +
>  kernel/sched/core.c | 11 +++++++++++
>  2 files changed, 12 insertions(+)
> 
> -- 
> 2.54.0.545.g6539524ca2-goog
>