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From: "Kunwu Chan" Message-ID: <919735cd6015f1057e076af00c615b6cdce0635d@linux.dev> TLS-Required: No Subject: Re: [PATCH 0/2] Proxy Execution fixes for v7.1-rc To: "John Stultz" , "LKML" Cc: "John Stultz" , "Vineeth Pillai" , "Sonam Sanju" , "Sean Christopherson" , "Tejun Heo" , "Joel Fernandes" , "Qais Yousef" , "Ingo Molnar" , "Peter Zijlstra" , "Juri Lelli" , "Vincent Guittot" , "Dietmar Eggemann" , "Valentin Schneider" , "Steven Rostedt" , "Will Deacon" , "Waiman Long" , "Boqun Feng" , "Paul E. McKenney" , "Metin Kaya" , "Xuewen Yan" , "K Prateek Nayak" , "Thomas Gleixner" , "Daniel Lezcano" , "Suleiman Souhlal" , "kuyo chang" , "hupu" , kernel-team@android.com In-Reply-To: <20260427183848.698551-1-jstultz@google.com> References: <20260427183848.698551-1-jstultz@google.com> X-Migadu-Flow: FLOW_OUT April 28, 2026 at 2:38 AM, "John Stultz" wro= te: >=20 >=20Hey 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. >=20 >=20I 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 >=20 >=20Again, a huge thanks to Vineeth for uncovering these issues > that have evaded all my stress testing so far! >=20 >=20Thanks > -john >=20 >=20[1]: https://lore.kernel.org/lkml/20260320125633.2290675-1-vineeth@bi= tbyteword.org/ >=20 Thanks=20John, 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 > Cc: Sonam Sanju > Cc: Sean Christopherson > Cc: Kunwu Chan > Cc: Tejun Heo > Cc: Joel Fernandes > Cc: Qais Yousef > Cc: Ingo Molnar > Cc: Peter Zijlstra > Cc: Juri Lelli > Cc: Vincent Guittot > Cc: Dietmar Eggemann > Cc: Valentin Schneider > Cc: Steven Rostedt > Cc: Will Deacon > Cc: Waiman Long > Cc: Boqun Feng > Cc: "Paul E. McKenney" > Cc: Metin Kaya > Cc: Xuewen Yan > Cc: K Prateek Nayak > Cc: Thomas Gleixner > Cc: Daniel Lezcano > Cc: Suleiman Souhlal > Cc: kuyo chang > Cc: hupu > Cc: kernel-team@android.com >=20 >=20John Stultz (2): > sched: proxy-exec: Close race causing workqueue work being delayed > locking: mutex: Fix proxy-exec potentially deactivating tasks marked > TASK_RUNNING >=20 >=20 kernel/locking/mutex.c | 1 + > kernel/sched/core.c | 11 +++++++++++ > 2 files changed, 12 insertions(+) >=20 >=20--=20 >=202.54.0.545.g6539524ca2-goog >