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Guanyou.ChenandGreg Kroah-Hartman
39e53c516c
[ Upstream commit63c1a12bc0] Commited4fb6d7ef("hrtimer: Use and report correct timerslack values for realtime tasks") sets timer_slack_ns to 0 for RT tasks in __setscheduler_params(). However, when an RT task with SCHED_RESET_ON_FORK creates child threads, the children inherit timer_slack_ns=0 from the parent. sched_fork() resets the child's policy to SCHED_NORMAL but does not restore timer_slack_ns, leaving the child permanently running with zero slack. Fix this by restoring timer_slack_ns from default_timer_slack_ns in sched_fork() when resetting from RT/DL to NORMAL policy, matching the existing behavior in __setscheduler_params(). Note: this fix alone requires a correct default_timer_slack_ns to be effective. See the following patch for that fix. Fixes:ed4fb6d7ef("hrtimer: Use and report correct timerslack values for realtime tasks") Reported-by: Qiaoting.Lin <linqiaoting@xiaomi.com> Signed-off-by: Guanyou.Chen <chenguanyou@xiaomi.com> Signed-off-by: Chunhui.Li <chunhui.li@mediatek.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://patch.msgid.link/20260522131000.1664983-2-chenguanyou@xiaomi.com Signed-off-by: Sasha Levin <sashal@kernel.org>