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=-15.7 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,URIBL_BLOCKED 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 F3AB9C2BB48 for ; Tue, 15 Dec 2020 03:09:02 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A5DC8233FD for ; Tue, 15 Dec 2020 03:09:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A5DC8233FD 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 40D4B8D001B; Mon, 14 Dec 2020 22:09:02 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 396506B00D9; Mon, 14 Dec 2020 22:09:02 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 285028D001B; Mon, 14 Dec 2020 22:09:02 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0044.hostedemail.com [216.40.44.44]) by kanga.kvack.org (Postfix) with ESMTP id 0EDF36B00D8 for ; Mon, 14 Dec 2020 22:09:02 -0500 (EST) Received: from smtpin21.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id D5A3E3631 for ; Tue, 15 Dec 2020 03:09:01 +0000 (UTC) X-FDA: 77594034882.21.month59_041058e27420 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin21.hostedemail.com (Postfix) with ESMTP id AED87180442CD for ; Tue, 15 Dec 2020 03:09:01 +0000 (UTC) X-HE-Tag: month59_041058e27420 X-Filterd-Recvd-Size: 2667 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf19.hostedemail.com (Postfix) with ESMTP for ; Tue, 15 Dec 2020 03:09:01 +0000 (UTC) Date: Mon, 14 Dec 2020 19:08:59 -0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1608001740; bh=9uiPdRLVZJkkDatTBi0orKDJ2WyYqfzle2A9x9h+fQ4=; h=From:To:Subject:In-Reply-To:From; b=QAoFMctC6khPgDvL4iTtjWIV1w1GeA5/gOR+nTMnpWCVOUQODBjyoLnj4YQpNjQeH 1GW5tKotbwWQl1syh9HlFCaQn+wSgVRkWs384RqqA2glvpiDdner8Bbt0no4/DEQiI lZ6xsMyPPtBgYmH4icGxaCeUPefAD7FnuSE4LS2w= From: Andrew Morton To: akpm@linux-foundation.org, david@redhat.com, linux-mm@kvack.org, longman@redhat.com, mm-commits@vger.kernel.org, torvalds@linux-foundation.org, urezki@gmail.com, willy@infradead.org Subject: [patch 098/200] mm/vmalloc: Fix unlock order in s_stop() Message-ID: <20201215030859.OyhgKMLgu%akpm@linux-foundation.org> In-Reply-To: <20201214190237.a17b70ae14f129e2dca3d204@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: Waiman Long Subject: mm/vmalloc: Fix unlock order in s_stop() When multiple locks are acquired, they should be released in reverse order. For s_start() and s_stop() in mm/vmalloc.c, that is not the case. s_start: mutex_lock(&vmap_purge_lock); spin_lock(&vmap_area_lock); s_stop : mutex_unlock(&vmap_purge_lock); spin_unlock(&vmap_area_lock); This unlock sequence, though allowed, is not optimal. If a waiter is present, mutex_unlock() will need to go through the slowpath of waking up the waiter with preemption disabled. Fix that by releasing the spinlock first before the mutex. Link: https://lkml.kernel.org/r/20201213180843.16938-1-longman@redhat.com Fixes: e36176be1c39 ("mm/vmalloc: rework vmap_area_lock") Signed-off-by: Waiman Long Reviewed-by: Uladzislau Rezki (Sony) Reviewed-by: David Hildenbrand Cc: Matthew Wilcox Signed-off-by: Andrew Morton --- mm/vmalloc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/mm/vmalloc.c~mm-vmalloc-fix-unlock-order-in-s_stop +++ a/mm/vmalloc.c @@ -3465,11 +3465,11 @@ static void *s_next(struct seq_file *m, } static void s_stop(struct seq_file *m, void *p) - __releases(&vmap_purge_lock) __releases(&vmap_area_lock) + __releases(&vmap_purge_lock) { - mutex_unlock(&vmap_purge_lock); spin_unlock(&vmap_area_lock); + mutex_unlock(&vmap_purge_lock); } static void show_numa_info(struct seq_file *m, struct vm_struct *v) _