From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8D035C433B4 for ; Wed, 21 Apr 2021 02:46:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4412461421 for ; Wed, 21 Apr 2021 02:46:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234004AbhDUCqv (ORCPT ); Tue, 20 Apr 2021 22:46:51 -0400 Received: from mail.kernel.org ([198.145.29.99]:55554 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233982AbhDUCqv (ORCPT ); Tue, 20 Apr 2021 22:46:51 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 104D86141D; Wed, 21 Apr 2021 02:46:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1618973176; bh=0T7UYYRFDOkR+3kAdY/unXtC+MXk668LfY3PjmvagXQ=; h=Date:From:To:Subject:From; b=MxP3Fs27dYcYrI8PK+mAwZ/asrqBZSh3PQZMk4FDUxJBYtqrUzXw76e9jMfL7sMg9 pNRVjQAX6bDyIRGmHkcH+1UBaW1mplWqsIB6/mPmihVvf7dUZsAcCj+hn2j3zAE4/j 6xg5yVQ9c7w/EqcMgUWLXWDPr7nhevjATYRqRJWE= Date: Tue, 20 Apr 2021 19:46:15 -0700 From: akpm@linux-foundation.org To: dvyukov@google.com, elver@google.com, glider@google.com, hdanton@sina.com, jannh@google.com, mark.rutland@arm.com, mm-commits@vger.kernel.org Subject: + kfence-maximize-allocation-wait-timeout-duration.patch added to -mm tree Message-ID: <20210421024615.a-S0Fzotk%akpm@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: kfence: maximize allocation wait timeout duration has been added to the -mm tree. Its filename is kfence-maximize-allocation-wait-timeout-duration.patch This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/kfence-maximize-allocation-wait-timeout-duration.patch and later at https://ozlabs.org/~akpm/mmotm/broken-out/kfence-maximize-allocation-wait-timeout-duration.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Marco Elver Subject: kfence: maximize allocation wait timeout duration The allocation wait timeout was initially added because of warnings due to CONFIG_DETECT_HUNG_TASK=y [1]. While the 1 sec timeout is sufficient to resolve the warnings (given the hung task timeout must be 1 sec or larger) it may cause unnecessary wake-ups if the system is idle. [1] https://lkml.kernel.org/r/CADYN=9J0DQhizAGB0-jz4HOBBh+05kMBXb4c0cXMS7Qi5NAJiw@mail.gmail.com Fix it by computing the timeout duration in terms of the current sysctl_hung_task_timeout_secs value. Link: https://lkml.kernel.org/r/20210419085027.761150-3-elver@google.com Signed-off-by: Marco Elver Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: Hillf Danton Cc: Jann Horn Cc: Mark Rutland Signed-off-by: Andrew Morton --- mm/kfence/core.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) --- a/mm/kfence/core.c~kfence-maximize-allocation-wait-timeout-duration +++ a/mm/kfence/core.c @@ -20,6 +20,7 @@ #include #include #include +#include #include #include #include @@ -626,7 +627,16 @@ static void toggle_allocation_gate(struc WRITE_ONCE(kfence_timer_waiting, true); smp_mb(); /* See comment in __kfence_alloc(). */ - wait_event_timeout(allocation_wait, atomic_read(&kfence_allocation_gate), HZ); + if (sysctl_hung_task_timeout_secs) { + /* + * During low activity with no allocations we might wait a + * while; let's avoid the hung task warning. + */ + wait_event_timeout(allocation_wait, atomic_read(&kfence_allocation_gate), + sysctl_hung_task_timeout_secs * HZ / 2); + } else { + wait_event(allocation_wait, atomic_read(&kfence_allocation_gate)); + } smp_store_release(&kfence_timer_waiting, false); /* Order after wait_event(). */ /* Disable static key and reset timer. */ _ Patches currently in -mm which might be from elver@google.com are kfence-zero-guard-page-after-out-of-bounds-access.patch kfence-await-for-allocation-using-wait_event.patch kfence-maximize-allocation-wait-timeout-duration.patch kfence-use-power-efficient-work-queue-to-run-delayed-work.patch