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dkim=pass header.d=fb.com header.s=facebook header.b=m3GzsayC; dmarc=pass (policy=reject) header.from=fb.com; spf=none (imf13.hostedemail.com: domain of "prvs=3044fe4ae1=guro@fb.com" has no SPF policy when checking 67.231.145.42) smtp.mailfrom="prvs=3044fe4ae1=guro@fb.com" X-HE-Tag: 1644867976-354635 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Feb 11, 2022 at 11:35:35PM +0100, Sebastian Andrzej Siewior wrote: > During the integration of PREEMPT_RT support, the code flow around > memcg_check_events() resulted in `twisted code'. Moving the code around > and avoiding then would then lead to an additional local-irq-save > section within memcg_check_events(). While looking better, it adds a > local-irq-save section to code flow which is usually within an > local-irq-off block on non-PREEMPT_RT configurations. > > The threshold event handler is a deprecated memcg v1 feature. Instead of > trying to get it to work under PREEMPT_RT just disable it. There should > be no users on PREEMPT_RT. From that perspective it makes even less > sense to get it to work under PREEMPT_RT while having zero users. > > Make memory.soft_limit_in_bytes and cgroup.event_control return > -EOPNOTSUPP on PREEMPT_RT. Make an empty memcg_check_events() and > memcg_write_event_control() which return only -EOPNOTSUPP on PREEMPT_RT. > Document that the two knobs are disabled on PREEMPT_RT. > > Suggested-by: Michal Hocko > Suggested-by: Michal Koutný > Signed-off-by: Sebastian Andrzej Siewior Acked-by: Roman Gushchin