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=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=unavailable 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 7C2DDC43460 for ; Wed, 21 Apr 2021 10:52:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4283E6144E for ; Wed, 21 Apr 2021 10:52:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236243AbhDUKws (ORCPT ); Wed, 21 Apr 2021 06:52:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37390 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236175AbhDUKwl (ORCPT ); Wed, 21 Apr 2021 06:52:41 -0400 Received: from mail-ed1-x549.google.com (mail-ed1-x549.google.com [IPv6:2a00:1450:4864:20::549]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9046EC06174A for ; Wed, 21 Apr 2021 03:52:06 -0700 (PDT) Received: by mail-ed1-x549.google.com with SMTP id bf25-20020a0564021a59b0290385169cebf8so7427403edb.8 for ; Wed, 21 Apr 2021 03:52:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=S7gKkVqw6gJJUkQX3/NKZ5hEYF7HuP5mcybwHhcoGA8=; b=BKLqZcruEVs1tQhMgavhobMYH3pkurizK7K0prlTtT7UrKBFybRppZodySbtpHep4Q dahuNpp+xKHhDa+OyyRnw8e2sf/QI9FxUpG+uLlUXHrf2chSK+ctL7VnE3D26Z4yixzt aqrvmWwUE9nVzIqIDx963uaNsvyOloDReUzMky+nBXxdQBFjLZuyH05HxCwsqKB2cnQ3 4mGy0+AnDgPt4VsmVV67b2DM0GvFf9qXOzs3jKk56lYF0E6l2UPZ9yg+vySmVVouOi+d ZcuQyL1tcho+GmMD5X26B1MJaXgBGDD2AkS/iWonncxyQv+YGdXrwBVcfiHto03hxFSk 50Kg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=S7gKkVqw6gJJUkQX3/NKZ5hEYF7HuP5mcybwHhcoGA8=; b=jvPCh8OyaF9OYmfzGH5ehWFY8er49dLoUX0v/Iyj3R3uEmKEWu5PYLQEJLkzpCJ1Kw 63sMwaFBSdvv3rcje3Z/yGRpmGR82AFvcsHe4a772rivqFjeVtOyeDs7uU0C+k0irU7z HMETdOI22JkEB4HhCrR/OwRIAjHg62vr22r0YySUOj0mnILRdA7gBZqPyHDLcaL3ZRFf WMlmO145JYZtLEwN94dWyVdPlOxQI537z5neJQ1sfKAJm3vWqUPq3edpctAOBCAWhLuA ZZfF5ndXnjpu7Bq4nwa/1yCCJgxXhjmDHz+usmU5RooRN1Pon8YskvZI92NwVmE19Pcw Xz9w== X-Gm-Message-State: AOAM531B5HXRMpU8hfso0Cm7hhZhnvfb1TwWJxQ7e6VhlhQO41NhSYho NQCvWoLASOlv0/jvzEAPpBeSrmQsUg== X-Google-Smtp-Source: ABdhPJyjCmPDiQcNUfvf1eIuCw4ql8YdC3rYLPuX10VxgctCoYcEuZQUMCVPDf2UQQgpokCHE10ey+Upqw== X-Received: from elver.muc.corp.google.com ([2a00:79e0:15:13:c552:ee7c:6a14:80cc]) (user=elver job=sendgmr) by 2002:a17:906:3d41:: with SMTP id q1mr31542346ejf.282.1619002325029; Wed, 21 Apr 2021 03:52:05 -0700 (PDT) Date: Wed, 21 Apr 2021 12:51:31 +0200 In-Reply-To: <20210421105132.3965998-1-elver@google.com> Message-Id: <20210421105132.3965998-3-elver@google.com> Mime-Version: 1.0 References: <20210421105132.3965998-1-elver@google.com> X-Mailer: git-send-email 2.31.1.368.gbe11c130af-goog Subject: [PATCH v2 2/3] kfence: maximize allocation wait timeout duration From: Marco Elver To: elver@google.com, akpm@linux-foundation.org Cc: glider@google.com, dvyukov@google.com, jannh@google.com, mark.rutland@arm.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, kasan-dev@googlegroups.com, hdanton@sina.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Signed-off-by: Marco Elver --- mm/kfence/core.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/mm/kfence/core.c b/mm/kfence/core.c index 235d726f88bc..9742649f3f88 100644 --- a/mm/kfence/core.c +++ b/mm/kfence/core.c @@ -20,6 +20,7 @@ #include #include #include +#include #include #include #include @@ -621,7 +622,16 @@ static void toggle_allocation_gate(struct work_struct *work) /* Enable static key, and await allocation to happen. */ static_branch_enable(&kfence_allocation_key); - 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)); + } /* Disable static key and reset timer. */ static_branch_disable(&kfence_allocation_key); -- 2.31.1.368.gbe11c130af-goog 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=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL 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 428E4C433B4 for ; Wed, 21 Apr 2021 10:52:08 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id BF1AA613FB for ; Wed, 21 Apr 2021 10:52:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BF1AA613FB Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; 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Wed, 21 Apr 2021 03:52:05 -0700 (PDT) Date: Wed, 21 Apr 2021 12:51:31 +0200 In-Reply-To: <20210421105132.3965998-1-elver@google.com> Message-Id: <20210421105132.3965998-3-elver@google.com> Mime-Version: 1.0 References: <20210421105132.3965998-1-elver@google.com> X-Mailer: git-send-email 2.31.1.368.gbe11c130af-goog Subject: [PATCH v2 2/3] kfence: maximize allocation wait timeout duration From: Marco Elver To: elver@google.com, akpm@linux-foundation.org Cc: glider@google.com, dvyukov@google.com, jannh@google.com, mark.rutland@arm.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, kasan-dev@googlegroups.com, hdanton@sina.com Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 9427740002E1 X-Stat-Signature: hrweeb34jgetuhu39w4rsangsgn84wik Received-SPF: none (flex--elver.bounces.google.com>: No applicable sender policy available) receiver=imf17; identity=mailfrom; envelope-from="<31QOAYAUKCOYMTdMZOWWOTM.KWUTQVcf-UUSdIKS.WZO@flex--elver.bounces.google.com>"; helo=mail-ej1-f74.google.com; client-ip=209.85.218.74 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1619002323-194433 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: 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. Signed-off-by: Marco Elver --- mm/kfence/core.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/mm/kfence/core.c b/mm/kfence/core.c index 235d726f88bc..9742649f3f88 100644 --- a/mm/kfence/core.c +++ b/mm/kfence/core.c @@ -20,6 +20,7 @@ #include #include #include +#include #include #include #include @@ -621,7 +622,16 @@ static void toggle_allocation_gate(struct work_struct *work) /* Enable static key, and await allocation to happen. */ static_branch_enable(&kfence_allocation_key); - 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)); + } /* Disable static key and reset timer. */ static_branch_disable(&kfence_allocation_key); -- 2.31.1.368.gbe11c130af-goog