Messages in this thread | | | Date | Wed, 15 Sep 2021 20:31:52 +0200 | From | Frederic Weisbecker <> | Subject | Re: Regression in posix-cpu-timers.c (was Re: Linux 5.14.4) |
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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!
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