From: Tejun Heo Date: Wed, 3 Sep 2025 21:33:28 +0000 (-1000) Subject: sched_ext: Keep bypass on between enable failure and scx_disable_workfn() X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=4a1d9d73aabc8f97f48c4f84f936de3b265ffd6f;p=thirdparty%2Fkernel%2Fstable.git sched_ext: Keep bypass on between enable failure and scx_disable_workfn() scx_enable() turns on the bypass mode while enable is in progress. If enabling fails, it turns off the bypass mode and then triggers scx_error(). scx_error() will trigger scx_disable_workfn() which will turn on the bypass mode again and unload the failed scheduler. This moves the system out of bypass mode between the enable error path and the disable path, which is unnecessary and can be brittle - e.g. the thread running scx_enable() may already be on the failed scheduler and can be switched out before it triggers scx_error() leading to a stall. The watchdog would eventually kick in, so the situation isn't critical but is still suboptimal. There is nothing to be gained by turning off the bypass mode between scx_enable() failure and scx_disable_workfn(). Keep bypass on. Signed-off-by: Tejun Heo Acked-by: Andrea Righi --- diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index 7f799345c8994..fda2b4e85ee37 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -5794,7 +5794,7 @@ err_unlock: err_disable_unlock_all: scx_cgroup_unlock(); percpu_up_write(&scx_fork_rwsem); - scx_bypass(false); + /* we'll soon enter disable path, keep bypass on */ err_disable: mutex_unlock(&scx_enable_mutex); /*