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=-3.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 46B00C2BA1A for ; Tue, 7 Apr 2020 03:07:36 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E9F8E215A4 for ; Tue, 7 Apr 2020 03:07:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="FKWhBPH9" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E9F8E215A4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 992658E0048; Mon, 6 Apr 2020 23:07:35 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 91A528E0001; Mon, 6 Apr 2020 23:07:35 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 830FE8E0048; Mon, 6 Apr 2020 23:07:35 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0140.hostedemail.com [216.40.44.140]) by kanga.kvack.org (Postfix) with ESMTP id 654088E0001 for ; Mon, 6 Apr 2020 23:07:35 -0400 (EDT) Received: from smtpin05.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 1FAEE80196AD for ; Tue, 7 Apr 2020 03:07:35 +0000 (UTC) X-FDA: 76679573670.05.rat97_7c635fa856008 X-HE-Tag: rat97_7c635fa856008 X-Filterd-Recvd-Size: 6061 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf44.hostedemail.com (Postfix) with ESMTP for ; Tue, 7 Apr 2020 03:07:34 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5512921775; Tue, 7 Apr 2020 03:07:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586228854; bh=nckWLgDLH9435u+m4sy3++/CRX3C8l2fWMd3DBgkP68=; h=Date:From:To:Subject:In-Reply-To:From; b=FKWhBPH95A3NmqtHjQSd+aJ8AW4I/zCTZjy3tLp71aypmRZNMvX00hSoana8TjMDt PcXqUx4yrFL/Mm71xT0Xv0Rl0fpF02w4XUEpG/6DdKzEHC2O1v/hXgE89RFH7HYtaY dDjO07Y/QhH+KdqnfMRp7gJ84fAlEhiKitfsXPZM= Date: Mon, 06 Apr 2020 20:07:32 -0700 From: Andrew Morton To: akpm@linux-foundation.org, benh@kernel.crashing.org, bhe@redhat.com, david@redhat.com, ehabkost@redhat.com, gregkh@linuxfoundation.org, haiyangz@microsoft.com, imammedo@redhat.com, kys@microsoft.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, mpe@ellerman.id.au, osalvador@suse.de, paulus@samba.org, rafael@kernel.org, richard.weiyang@gmail.com, sthemmin@microsoft.com, torvalds@linux-foundation.org, vkuznets@redhat.com, wei.liu@kernel.org, yuhuang@redhat.com Subject: [patch 067/166] hv_balloon: don't check for memhp_auto_online manually Message-ID: <20200407030732.LbZajmtfs%akpm@linux-foundation.org> In-Reply-To: <20200406200254.a69ebd9e08c4074e41ddebaf@linux-foundation.org> User-Agent: s-nail v14.8.16 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: From: David Hildenbrand Subject: hv_balloon: don't check for memhp_auto_online manually We get the MEM_ONLINE notifier call if memory is added right from the kernel via add_memory() or later from user space. Let's get rid of the "ha_waiting" flag - the wait event has an inbuilt mechanism (->done) for that. Initialize the wait event only once and reinitialize before adding memory. Unconditionally call complete() and wait_for_completion_timeout(). If there are no waiters, complete() will only increment ->done - which will be reset by reinit_completion(). If complete() has already been called, wait_for_completion_timeout() will not wait. There is still the chance for a small race between concurrent reinit_completion() and complete(). If complete() wins, we would not wait - which is tolerable (and the race exists in current code as well). Note: We only wait for "some" memory to get onlined, which seems to be good enough for now. [akpm@linux-foundation.org: register_memory_notifier() after init_completion(), per David] Link: http://lkml.kernel.org/r/20200317104942.11178-6-david@redhat.com Signed-off-by: David Hildenbrand Reviewed-by: Vitaly Kuznetsov Reviewed-by: Baoquan He Cc: "K. Y. Srinivasan" Cc: Haiyang Zhang Cc: Stephen Hemminger Cc: Wei Liu Cc: Oscar Salvador Cc: "Rafael J. Wysocki" Cc: Wei Yang Cc: Benjamin Herrenschmidt Cc: Eduardo Habkost Cc: Greg Kroah-Hartman Cc: Igor Mammedov Cc: Michael Ellerman Cc: Paul Mackerras Cc: Yumei Huang Signed-off-by: Andrew Morton --- drivers/hv/hv_balloon.c | 25 ++++++++++--------------- 1 file changed, 10 insertions(+), 15 deletions(-) --- a/drivers/hv/hv_balloon.c~hv_balloon-dont-check-for-memhp_auto_online-manually +++ a/drivers/hv/hv_balloon.c @@ -533,7 +533,6 @@ struct hv_dynmem_device { * State to synchronize hot-add. */ struct completion ol_waitevent; - bool ha_waiting; /* * This thread handles hot-add * requests from the host as well as notifying @@ -634,10 +633,7 @@ static int hv_memory_notifier(struct not switch (val) { case MEM_ONLINE: case MEM_CANCEL_ONLINE: - if (dm_device.ha_waiting) { - dm_device.ha_waiting = false; - complete(&dm_device.ol_waitevent); - } + complete(&dm_device.ol_waitevent); break; case MEM_OFFLINE: @@ -726,8 +722,7 @@ static void hv_mem_hot_add(unsigned long has->covered_end_pfn += processed_pfn; spin_unlock_irqrestore(&dm_device.ha_lock, flags); - init_completion(&dm_device.ol_waitevent); - dm_device.ha_waiting = !memhp_auto_online; + reinit_completion(&dm_device.ol_waitevent); nid = memory_add_physaddr_to_nid(PFN_PHYS(start_pfn)); ret = add_memory(nid, PFN_PHYS((start_pfn)), @@ -753,15 +748,14 @@ static void hv_mem_hot_add(unsigned long } /* - * Wait for the memory block to be onlined when memory onlining - * is done outside of kernel (memhp_auto_online). Since the hot - * add has succeeded, it is ok to proceed even if the pages in - * the hot added region have not been "onlined" within the - * allowed time. + * Wait for memory to get onlined. If the kernel onlined the + * memory when adding it, this will return directly. Otherwise, + * it will wait for user space to online the memory. This helps + * to avoid adding memory faster than it is getting onlined. As + * adding succeeded, it is ok to proceed even if the memory was + * not onlined in time. */ - if (dm_device.ha_waiting) - wait_for_completion_timeout(&dm_device.ol_waitevent, - 5*HZ); + wait_for_completion_timeout(&dm_device.ol_waitevent, 5 * HZ); post_status(&dm_device); } } @@ -1706,6 +1700,7 @@ static int balloon_probe(struct hv_devic #ifdef CONFIG_MEMORY_HOTPLUG set_online_page_callback(&hv_online_page); + init_completion(&dm_device.ol_waitevent); register_memory_notifier(&hv_memory_nb); #endif _