From owner-svn-src-head@freebsd.org Sat Nov 28 01:21:12 2020 Return-Path: Delivered-To: svn-src-head@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 95C5F46FE71; Sat, 28 Nov 2020 01:21:12 +0000 (UTC) (envelope-from kevans@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4CjYbr31P2z4jVQ; Sat, 28 Nov 2020 01:21:12 +0000 (UTC) (envelope-from kevans@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 58B711E7F1; Sat, 28 Nov 2020 01:21:12 +0000 (UTC) (envelope-from kevans@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id 0AS1LCxg098245; Sat, 28 Nov 2020 01:21:12 GMT (envelope-from kevans@FreeBSD.org) Received: (from kevans@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id 0AS1LCeV098244; Sat, 28 Nov 2020 01:21:12 GMT (envelope-from kevans@FreeBSD.org) Message-Id: <202011280121.0AS1LCeV098244@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: kevans set sender to kevans@FreeBSD.org using -f From: Kyle Evans Date: Sat, 28 Nov 2020 01:21:12 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r368116 - head/sys/kern X-SVN-Group: head X-SVN-Commit-Author: kevans X-SVN-Commit-Paths: head/sys/kern X-SVN-Commit-Revision: 368116 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 28 Nov 2020 01:21:12 -0000 Author: kevans Date: Sat Nov 28 01:21:11 2020 New Revision: 368116 URL: https://svnweb.freebsd.org/changeset/base/368116 Log: kern: cpuset: drop the lock to allocate domainsets Restructure the loop a little bit to make it a little more clear how it really operates: we never allocate any domains at the beginning of the first iteration, and it will run until we've satisfied the amount we need or we encounter an error. The lock is now taken outside of the loop to make stuff inside the loop easier to evaluate w.r.t. locking. This fixes it to not try and allocate any domains for the freelist under the spinlock, which would have happened before if we needed any new domains. Reported by: syzbot+6743fa07b9b7528dc561@syzkaller.appspotmail.com Reviewed by: markj MFC after: 3 days Differential Revision: https://reviews.freebsd.org/D27371 Modified: head/sys/kern/kern_cpuset.c Modified: head/sys/kern/kern_cpuset.c ============================================================================== --- head/sys/kern/kern_cpuset.c Sat Nov 28 01:16:59 2020 (r368115) +++ head/sys/kern/kern_cpuset.c Sat Nov 28 01:21:11 2020 (r368116) @@ -794,14 +794,11 @@ cpuset_modify_domain(struct cpuset *set, struct domain return (EPERM); domainset_freelist_init(&domains, 0); domain = domainset_create(domain); - ndomains = needed = 0; - do { - if (ndomains < needed) { - domainset_freelist_add(&domains, needed - ndomains); - ndomains = needed; - } + ndomains = 0; + + mtx_lock_spin(&cpuset_lock); + for (;;) { root = cpuset_getroot(set); - mtx_lock_spin(&cpuset_lock); dset = root->cs_domain; /* * Verify that we have access to this set of domains. @@ -826,7 +823,15 @@ cpuset_modify_domain(struct cpuset *set, struct domain &needed, 0); if (error) goto out; - } while (ndomains < needed); + if (ndomains >= needed) + break; + + /* Dropping the lock; we'll need to re-evaluate again. */ + mtx_unlock_spin(&cpuset_lock); + domainset_freelist_add(&domains, needed - ndomains); + ndomains = needed; + mtx_lock_spin(&cpuset_lock); + } dset = set->cs_domain; cpuset_update_domain(set, domain, dset, &domains); out: