From: Sebastian Andrzej Siewior Date: Fri, 5 Nov 2021 20:40:52 +0000 (-0700) Subject: mm: page_alloc: use migrate_disable() in drain_local_pages_wq() X-Git-Tag: v6.6.17~8900^2~143 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=9c25cbfcb38462803a3d68f5d88e66a587f5f045;p=platform%2Fkernel%2Flinux-rpi.git mm: page_alloc: use migrate_disable() in drain_local_pages_wq() drain_local_pages_wq() disables preemption to avoid CPU migration during CPU hotplug and can't use cpus_read_lock(). Using migrate_disable() works here, too. The scheduler won't take the CPU offline until the task left the migrate-disable section. The problem with disabled preemption here is that drain_local_pages() acquires locks which are turned into sleeping locks on PREEMPT_RT and can't be acquired with disabled preemption. Use migrate_disable() in drain_local_pages_wq(). Link: https://lkml.kernel.org/r/20211015210933.viw6rjvo64qtqxn4@linutronix.de Signed-off-by: Sebastian Andrzej Siewior Cc: Thomas Gleixner Cc: Peter Zijlstra Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 6714039..2aafc33 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3141,9 +3141,9 @@ static void drain_local_pages_wq(struct work_struct *work) * cpu which is alright but we also have to make sure to not move to * a different one. */ - preempt_disable(); + migrate_disable(); drain_local_pages(drain->zone); - preempt_enable(); + migrate_enable(); } /*