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[2a02:3100:a979:9501:3df6:d7fa:8a5a:6c5]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c25f4172032sm115066066b.22.2026.09.03.08.43.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Sep 2026 08:43:49 -0700 (PDT) Date: Thu, 3 Sep 2026 17:43:47 +0200 From: Karl Mehltretter To: Sebastian Andrzej Siewior Cc: Peter Zijlstra , Thomas Gleixner , Clark Williams , Steven Rostedt , Boqun Feng , Lyude Paul , Joel Fernandes , Alexander Potapenko , linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev Subject: Re: [PATCH] softirq: Preserve interrupt context during IRQ exit Message-ID: References: <20260903112737.49551-1-kmehltretter@gmail.com> <20260903122017.ZRsTFeks@linutronix.de> Precedence: bulk X-Mailing-List: linux-rt-devel@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260903122017.ZRsTFeks@linutronix.de> On Thu, Sep 03, 2026 at 02:20:17PM +0100, Sebastian Andrzej Siewior wrote: > On 2026-09-03 13:27:37 [+0200], Karl Mehltretter wrote: > > __irq_exit_rcu() drops HARDIRQ_OFFSET before deferred hrtimer rearm, > > softirq dispatch, and timersd wakeup. This work is still on the IRQ > > return path, but in_task() reports task context. > > Is this new? I don't remember seeing this before. > > Sebastian irq_exit() dropped the hardirq count before invoking softirqs in v2.6.12-rc2, the beginning of git history. The newer additions to that window are the timersd wakeup added by 49a17639508c and the deferred hrtimer-rearm hook added by 7e641e52cf5f. Thanks, Karl