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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id D5608C43334 for ; Thu, 30 Jun 2022 02:28:14 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 593FC6B0074; Wed, 29 Jun 2022 22:28:14 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 543B86B0075; Wed, 29 Jun 2022 22:28:14 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 40AE98E0001; Wed, 29 Jun 2022 22:28:14 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 31B8B6B0074 for ; Wed, 29 Jun 2022 22:28:14 -0400 (EDT) Received: from smtpin22.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 052D63468B for ; Thu, 30 Jun 2022 02:28:13 +0000 (UTC) X-FDA: 79633317708.22.A938640 Received: from out2.migadu.com (out2.migadu.com [188.165.223.204]) by imf23.hostedemail.com (Postfix) with ESMTP id 7BA8514002E for ; Thu, 30 Jun 2022 02:28:13 +0000 (UTC) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1656556092; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=/lD2AZO8ox5TTpHPepM0dCwWaQ9BZ891lb7mETr4gnI=; b=ghGF/odGZnpA1wVO6LTYB67lU0fj83SJj0Hcgvg9hCzjqf1jt5b4QzvW50nhEzNNnX8x0N w6PWytI7Zrs8obu0Js7WqF2Cpt7WQ5Y6boEsDpFbYgSLPUGa5gb58DUTtpLLZ2o2bv9wQw PBpXkK2HvoYlLCWUCnYuX+F4aP8Yv+Q= From: Naoya Horiguchi To: linux-mm@kvack.org Cc: Andrew Morton , David Hildenbrand , Mike Kravetz , Miaohe Lin , Liu Shixin , Yang Shi , Oscar Salvador , Muchun Song , Naoya Horiguchi , linux-kernel@vger.kernel.org Subject: [PATCH v3 1/9] mm/hugetlb: check gigantic_page_runtime_supported() in return_unused_surplus_pages() Date: Thu, 30 Jun 2022 11:27:47 +0900 Message-Id: <20220630022755.3362349-2-naoya.horiguchi@linux.dev> In-Reply-To: <20220630022755.3362349-1-naoya.horiguchi@linux.dev> References: <20220630022755.3362349-1-naoya.horiguchi@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Migadu-Auth-User: linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1656556093; a=rsa-sha256; cv=none; b=a/mKXHXCQojgP4OS34Bh9CMMe4yXa7JyWzkSNyBsH5ZO97egPZddAxTkUyFG5HOdNgWFO0 RA47L+7sX2vl+dkgcX+DWiZciokNvE8aqPM0E8xW8bmJ6Wa7OdCJWSXnsa3hovM7Us+AIh FDfkz+6bBuKxATtAY35+neUr5q8Gp+o= ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="ghGF/odG"; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf23.hostedemail.com: domain of naoya.horiguchi@linux.dev designates 188.165.223.204 as permitted sender) smtp.mailfrom=naoya.horiguchi@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1656556093; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=/lD2AZO8ox5TTpHPepM0dCwWaQ9BZ891lb7mETr4gnI=; b=DBiMh5gRW3YPmbNqB3Mdp0WNWIbRjEec1vOm7e8Nwx0g8MB7yWjtgLaPb1XehIJiwquUh0 wm3/muasDS0/sYkD8HlFy5jLXnVcCf9NLNAzMyBkDF2RLiZh2uWya/btX9Eib/CkNyyReH +XJ+Ztu59UcNJ9Z5i+eEBr8sY6/Mguo= Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="ghGF/odG"; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf23.hostedemail.com: domain of naoya.horiguchi@linux.dev designates 188.165.223.204 as permitted sender) smtp.mailfrom=naoya.horiguchi@linux.dev X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 7BA8514002E X-Stat-Signature: 6xgbttn1p57g3nt17ei8ozcgm1hz3fam X-Rspam-User: X-HE-Tag: 1656556093-433594 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: Naoya Horiguchi I found a weird state of 1GB hugepage pool, caused by the following procedure: - run a process reserving all free 1GB hugepages, - shrink free 1GB hugepage pool to zero (i.e. writing 0 to /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages), then - kill the reserving process. , then all the hugepages are free *and* surplus at the same time. $ cat /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages 3 $ cat /sys/kernel/mm/hugepages/hugepages-1048576kB/free_hugepages 3 $ cat /sys/kernel/mm/hugepages/hugepages-1048576kB/resv_hugepages 0 $ cat /sys/kernel/mm/hugepages/hugepages-1048576kB/surplus_hugepages 3 This state is resolved by reserving and allocating the pages then freeing them again, so this seems not to result in serious problem. But it's a little surprising (shrinking pool suddenly fails). This behavior is caused by hstate_is_gigantic() check in return_unused_surplus_pages(). This was introduced so long ago in 2008 by commit aa888a74977a ("hugetlb: support larger than MAX_ORDER"), and at that time the gigantic pages were not supposed to be allocated/freed at run-time. Now kernel can support runtime allocation/free, so let's check gigantic_page_runtime_supported() together. Signed-off-by: Naoya Horiguchi --- v2 -> v3: - Fixed typo in patch description, - add !gigantic_page_runtime_supported() check instead of removing hstate_is_gigantic() check (suggested by Miaohe and Muchun) - add a few more !gigantic_page_runtime_supported() check in set_max_huge_pages() (by Mike). --- mm/hugetlb.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index a57e1be41401..e67540dbbf88 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2432,8 +2432,7 @@ static void return_unused_surplus_pages(struct hstate *h, /* Uncommit the reservation */ h->resv_huge_pages -= unused_resv_pages; - /* Cannot return gigantic pages currently */ - if (hstate_is_gigantic(h)) + if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported()) goto out; /* @@ -3318,7 +3317,8 @@ static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid, * the user tries to allocate gigantic pages but let the user free the * boottime allocated gigantic pages. */ - if (hstate_is_gigantic(h) && !IS_ENABLED(CONFIG_CONTIG_ALLOC)) { + if (hstate_is_gigantic(h) && (!IS_ENABLED(CONFIG_CONTIG_ALLOC) || + !gigantic_page_runtime_supported())) { if (count > persistent_huge_pages(h)) { spin_unlock_irq(&hugetlb_lock); mutex_unlock(&h->resize_lock); @@ -3366,6 +3366,19 @@ static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid, goto out; } + /* + * We can not decrease gigantic pool size if runtime modification + * is not supported. + */ + if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported()) { + if (count < persistent_huge_pages(h)) { + spin_unlock_irq(&hugetlb_lock); + mutex_unlock(&h->resize_lock); + NODEMASK_FREE(node_alloc_noretry); + return -EINVAL; + } + } + /* * Decrease the pool size * First return free pages to the buddy allocator (being careful -- 2.25.1