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=-9.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 8ADA0C33C8C for ; Tue, 7 Jan 2020 13:10:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5352E2081E for ; Tue, 7 Jan 2020 13:10:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="A3lGV6V4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728248AbgAGNKY (ORCPT ); Tue, 7 Jan 2020 08:10:24 -0500 Received: from mail-pf1-f193.google.com ([209.85.210.193]:40028 "EHLO mail-pf1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727814AbgAGNKX (ORCPT ); Tue, 7 Jan 2020 08:10:23 -0500 Received: by mail-pf1-f193.google.com with SMTP id q8so28591599pfh.7; Tue, 07 Jan 2020 05:10:23 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=RaAjzUEIlPB8dHsGAxIqpIrbg0uPC0pABUcdUx5ADdc=; b=A3lGV6V4UlouKWdh9++A16QLihDszm8/31Hf3r8CvmMeIj5wV+azJNtNh/dLBiRFmf AsHdi9GSe7Mi632CHVh9/Fqh9cZg71ejSEeKknGIb6QkGfjMUjzN9+P8HW3HjF4qBXO/ t1KT2NY5pDMb8FQQ1wRTWXphJ0pEFN54YTK752L1Gzky1NpzYzhJMbEje3Rt23j8uZ4y Q7Phwl/BqrmQbXUWUmSuiayl/5+JK6PbjsjsMHfouQScTV6uP1EYlbN218M/pZ9IW6m3 lBlEV81FNI5iIZwri2s6QIKo2x0UHcXJsgQVO/SSsHNFu75krdRjHtiWdGRexPS8SK2n hwJQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=RaAjzUEIlPB8dHsGAxIqpIrbg0uPC0pABUcdUx5ADdc=; b=cLcKVq5hXl8QFNZYOfIpG6dbzLZTfR6VUxPIHih48KMMhzRlXEVb6mU8RFFIKhYA6B 2igijTc+USKGqIVfQ/iEVmnkAol8X875w3FHFNrTeoZuOJoUwUJx+q+2Urv3U6zaWkgl O48G11Vf6atXOuyLZrSjbU6rrI1lHreLAa+6RH7iIajBQT0zImJFYraW5TXPZAfGvaJs b0M6p1ZPwtWE/AQzUpk9jCzUXqzSCViOSGio5NVXfZQDSfojeO8Mk7uL7xFokOgjF7NW CFJVgvAwei4ckJ58wUlhF2hTvhLMdSHSb9TdDHINen9Vpmi9k7CZlkoa4j4gDlvQOfRT FQcA== X-Gm-Message-State: APjAAAXcKtmgX9l2073ZvkYppGK/KTtcyfnO/RGMlYdPKrwnPIY927Pe UP/68VDXQIlbIWzi1t23gU4= X-Google-Smtp-Source: APXvYqzzW7OVvz54/4NAC8+Y5xPynKtH1cDHFNthbzbRZ+11LHmIo2dx++5O6uEEZAg2JXnw5C8s9A== X-Received: by 2002:aa7:874a:: with SMTP id g10mr96012117pfo.205.1578402622880; Tue, 07 Jan 2020 05:10:22 -0800 (PST) Received: from localhost.corp.microsoft.com ([167.220.255.5]) by smtp.googlemail.com with ESMTPSA id m71sm27522400pje.0.2020.01.07.05.10.19 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 07 Jan 2020 05:10:22 -0800 (PST) From: lantianyu1986@gmail.com X-Google-Original-From: Tianyu.Lan@microsoft.com To: kys@microsoft.com, haiyangz@microsoft.com, sthemmin@microsoft.com, sashal@kernel.org, michael.h.kelley@microsoft.com, david@redhat.com Cc: Tianyu Lan , linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, vkuznets@redhat.com, eric.devolder@oracle.com Subject: [RFC PATCH V2 5/10] x86/Hyper-V/Balloon: Avoid releasing ha_lock when traverse ha_region_list Date: Tue, 7 Jan 2020 21:09:45 +0800 Message-Id: <20200107130950.2983-6-Tianyu.Lan@microsoft.com> X-Mailer: git-send-email 2.14.5 In-Reply-To: <20200107130950.2983-1-Tianyu.Lan@microsoft.com> References: <20200107130950.2983-1-Tianyu.Lan@microsoft.com> Sender: linux-hyperv-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-hyperv@vger.kernel.org From: Tianyu Lan ha_lock is to protect ha_region_list. It is held in hv_online_page() and handle_pg_range(). handle_pg_range() is to traverse ha region list, find associated hot-add region and add memory into system. hv_online_page() is called inside of add_memory(). Current code is to release ha_lock before calling add_memory() to avoid holding ha_lock twice in the hv_online_page(). To avoid releasing ha_lock, add "lock_thread" in the struct hv_ dynmem_device to record thread of traversing ha region list, check "lock_thread" in the hv_online_page() and try holding ha_lock when current thread is not "lock_thread". Signed-off-by: Tianyu Lan --- drivers/hv/hv_balloon.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c index 185146795122..729dc5551302 100644 --- a/drivers/hv/hv_balloon.c +++ b/drivers/hv/hv_balloon.c @@ -547,6 +547,7 @@ struct hv_dynmem_device { * regions from ha_region_list. */ struct mutex ha_lock; + struct task_struct *lock_thread; /* * A list of hot-add regions. @@ -711,7 +712,6 @@ static void hv_mem_hot_add(unsigned long start, unsigned long size, for (i = 0; i < (size/HA_CHUNK); i++) { start_pfn = start + (i * HA_CHUNK); - mutex_lock(&dm_device.ha_lock); has->ha_end_pfn += HA_CHUNK; if (total_pfn > HA_CHUNK) { @@ -723,7 +723,6 @@ static void hv_mem_hot_add(unsigned long start, unsigned long size, } has->covered_end_pfn += processed_pfn; - mutex_unlock(&dm_device.ha_lock); init_completion(&dm_device.ol_waitevent); dm_device.ha_waiting = !memhp_auto_online; @@ -744,10 +743,8 @@ static void hv_mem_hot_add(unsigned long start, unsigned long size, */ do_hot_add = false; } - mutex_lock(&dm_device.ha_lock); has->ha_end_pfn -= HA_CHUNK; has->covered_end_pfn -= processed_pfn; - mutex_unlock(&dm_device.ha_lock); break; } @@ -769,8 +766,14 @@ static void hv_online_page(struct page *pg, unsigned int order) { struct hv_hotadd_state *has; unsigned long pfn = page_to_pfn(pg); + int need_unlock; + + /* If current thread hasn't hold ha_lock, take ha_lock here. */ + if (dm_device.lock_thread != current) { + mutex_lock(&dm_device.ha_lock); + need_unlock = 1; + } - mutex_lock(&dm_device.ha_lock); list_for_each_entry(has, &dm_device.ha_region_list, list) { /* The page belongs to a different HAS. */ if ((pfn < has->start_pfn) || @@ -780,7 +783,8 @@ static void hv_online_page(struct page *pg, unsigned int order) hv_bring_pgs_online(has, pfn, 1UL << order); break; } - mutex_unlock(&dm_device.ha_lock); + if (need_unlock) + mutex_unlock(&dm_device.ha_lock); } static int pfn_covered(unsigned long start_pfn, unsigned long pfn_cnt) @@ -857,6 +861,7 @@ static unsigned long handle_pg_range(unsigned long pg_start, pg_start); mutex_lock(&dm_device.ha_lock); + dm_device.lock_thread = current; list_for_each_entry(has, &dm_device.ha_region_list, list) { /* * If the pfn range we are dealing with is not in the current @@ -909,9 +914,7 @@ static unsigned long handle_pg_range(unsigned long pg_start, } else { pfn_cnt = size; } - mutex_unlock(&dm_device.ha_lock); hv_mem_hot_add(has->ha_end_pfn, size, pfn_cnt, has); - mutex_lock(&dm_device.ha_lock); } /* * If we managed to online any pages that were given to us, @@ -920,6 +923,7 @@ static unsigned long handle_pg_range(unsigned long pg_start, res = has->covered_end_pfn - old_covered_state; break; } + dm_device.lock_thread = NULL; mutex_unlock(&dm_device.ha_lock); return res; -- 2.14.5