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=-15.8 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 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 23DC2C433DB for ; Thu, 25 Mar 2021 10:48:54 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C366F61A01 for ; Thu, 25 Mar 2021 10:48:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C366F61A01 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 26B366B0070; Thu, 25 Mar 2021 06:48:53 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 219E56B0071; Thu, 25 Mar 2021 06:48:53 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 094A86B0074; Thu, 25 Mar 2021 06:48:53 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0121.hostedemail.com [216.40.44.121]) by kanga.kvack.org (Postfix) with ESMTP id E2B0A6B0070 for ; Thu, 25 Mar 2021 06:48:52 -0400 (EDT) Received: from smtpin05.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 8BEEF363F for ; Thu, 25 Mar 2021 10:48:52 +0000 (UTC) X-FDA: 77958073704.05.A022388 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf07.hostedemail.com (Postfix) with ESMTP id 3B25AA00026B for ; Thu, 25 Mar 2021 10:47:09 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1616669227; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=cG0AzQK4074+rn9gesZQ2PJkz4OIzsNWxFZQsnN9pwc=; b=JbtjUS+UE8pQVw8wCDbXME5aE9cW4/Ur1GPkmPeiUzn7CEvIRh5Zgt1JCvsuBsAjMV+2he stwh4NjkAXrpbdKKR5FBsZbdUE2Ihgq7Ujn+JGEhsn8l6NYvnJkqGYjgkvG6A2XQ8Bt5fQ dJTWQIrsQfD7RaH5DGM4rLJv5ab10Jo= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 60609AC3C; Thu, 25 Mar 2021 10:47:07 +0000 (UTC) Date: Thu, 25 Mar 2021 11:47:04 +0100 From: Michal Hocko To: Mike Kravetz Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Roman Gushchin , Shakeel Butt , Oscar Salvador , David Hildenbrand , Muchun Song , David Rientjes , Miaohe Lin , Peter Zijlstra , Matthew Wilcox , HORIGUCHI NAOYA , "Aneesh Kumar K . V" , Waiman Long , Peter Xu , Mina Almasry , Hillf Danton , Andrew Morton Subject: Re: [PATCH 3/8] hugetlb: add per-hstate mutex to synchronize user adjustments Message-ID: References: <20210325002835.216118-1-mike.kravetz@oracle.com> <20210325002835.216118-4-mike.kravetz@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210325002835.216118-4-mike.kravetz@oracle.com> X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 3B25AA00026B X-Stat-Signature: eezc5dj5eiishqew57cs3ipaepqmn65k Received-SPF: none (suse.com>: No applicable sender policy available) receiver=imf07; identity=mailfrom; envelope-from=""; helo=mx2.suse.de; client-ip=195.135.220.15 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1616669229-657762 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 Wed 24-03-21 17:28:30, Mike Kravetz wrote: > The helper routine hstate_next_node_to_alloc accesses and modifies the > hstate variable next_nid_to_alloc. The helper is used by the routines > alloc_pool_huge_page and adjust_pool_surplus. adjust_pool_surplus is > called with hugetlb_lock held. However, alloc_pool_huge_page can not > be called with the hugetlb lock held as it will call the page allocator. > Two instances of alloc_pool_huge_page could be run in parallel or > alloc_pool_huge_page could run in parallel with adjust_pool_surplus > which may result in the variable next_nid_to_alloc becoming invalid > for the caller and pages being allocated on the wrong node. > > Both alloc_pool_huge_page and adjust_pool_surplus are only called from > the routine set_max_huge_pages after boot. set_max_huge_pages is only > called as the reusult of a user writing to the proc/sysfs nr_hugepages, > or nr_hugepages_mempolicy file to adjust the number of hugetlb pages. > > It makes little sense to allow multiple adjustment to the number of > hugetlb pages in parallel. Add a mutex to the hstate and use it to only > allow one hugetlb page adjustment at a time. This will synchronize > modifications to the next_nid_to_alloc variable. > > Signed-off-by: Mike Kravetz Acked-by: Michal Hocko I would just recommend s@mutex@resize_lock@ so that the intention is more clear from the name. > --- > include/linux/hugetlb.h | 1 + > mm/hugetlb.c | 5 +++++ > 2 files changed, 6 insertions(+) > > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h > index a7f7d5f328dc..8817ec987d68 100644 > --- a/include/linux/hugetlb.h > +++ b/include/linux/hugetlb.h > @@ -566,6 +566,7 @@ HPAGEFLAG(Freed, freed) > #define HSTATE_NAME_LEN 32 > /* Defines one hugetlb page size */ > struct hstate { > + struct mutex mutex; > int next_nid_to_alloc; > int next_nid_to_free; > unsigned int order; > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index f9ba63fc1747..404b0b1c5258 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -2616,6 +2616,8 @@ static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid, > else > return -ENOMEM; > > + /* mutex prevents concurrent adjustments for the same hstate */ > + mutex_lock(&h->mutex); > spin_lock(&hugetlb_lock); > > /* > @@ -2648,6 +2650,7 @@ static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid, > if (hstate_is_gigantic(h) && !IS_ENABLED(CONFIG_CONTIG_ALLOC)) { > if (count > persistent_huge_pages(h)) { > spin_unlock(&hugetlb_lock); > + mutex_unlock(&h->mutex); > NODEMASK_FREE(node_alloc_noretry); > return -EINVAL; > } > @@ -2722,6 +2725,7 @@ static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid, > out: > h->max_huge_pages = persistent_huge_pages(h); > spin_unlock(&hugetlb_lock); > + mutex_unlock(&h->mutex); > > NODEMASK_FREE(node_alloc_noretry); > > @@ -3209,6 +3213,7 @@ void __init hugetlb_add_hstate(unsigned int order) > BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE); > BUG_ON(order == 0); > h = &hstates[hugetlb_max_hstate++]; > + mutex_init(&h->mutex); > h->order = order; > h->mask = ~(huge_page_size(h) - 1); > for (i = 0; i < MAX_NUMNODES; ++i) > -- > 2.30.2 > -- Michal Hocko SUSE Labs