On Wed, Sep 15, 2021 at 06:45:33PM +0100, Alan J. Wylie wrote:
564005805aadec9cb7e5dc4e14071b8f87cd6b58 is the first bad commit commit 564005805aadec9cb7e5dc4e14071b8f87cd6b58 Author: Frederic Weisbecker frederic@kernel.org Date: Mon Jul 26 14:55:10 2021 +0200
posix-cpu-timers: Force next expiration recalc after itimer reset[ Upstream commit 406dd42bd1ba0c01babf9cde169bb319e52f6147 ] When an itimer deactivates a previously armed expiration, it simply doesn't do anything. As a result the process wide cputime counter keeps running and the tick dependency stays set until it reaches the old ghost expiration value. This can be reproduced with the following snippet: void trigger_process_counter(void) { struct itimerval n = {}; n.it_value.tv_sec = 100; setitimer(ITIMER_VIRTUAL, &n, NULL); n.it_value.tv_sec = 0; setitimer(ITIMER_VIRTUAL, &n, NULL); } Fix this with resetting the relevant base expiration. This is similar to disarming a timer. Signed-off-by: Frederic Weisbecker frederic@kernel.org Signed-off-by: Thomas Gleixner tglx@linutronix.de Acked-by: Peter Zijlstra (Intel) peterz@infradead.org Link: https://lore.kernel.org/r/20210726125513.271824-4-frederic@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org
Right, this should fix the issue: https://lore.kernel.org/lkml/20210913145332.232023-1-frederic@kernel.org/
Thanks!