From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752626AbaEOTDG (ORCPT ); Thu, 15 May 2014 15:03:06 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44095 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751163AbaEOTDE (ORCPT ); Thu, 15 May 2014 15:03:04 -0400 Date: Thu, 15 May 2014 15:02:53 -0400 From: Dave Jones To: Linux Kernel Cc: sds@tycho.nsa.gov, pmoore@redhat.com, eparis@redhat.com Subject: [1/2] conditionally reschedule in mls_convert_context while loading selinux policy. Message-ID: <20140515190253.GA16816@redhat.com> Mail-Followup-To: Dave Jones , Linux Kernel , sds@tycho.nsa.gov, pmoore@redhat.com, eparis@redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On a slow machine (with debugging enabled), upgrading selinux policy may take a considerable amount of time. Long enough that the softlockup detector gets triggered. The backtrace looks like this.. > BUG: soft lockup - CPU#2 stuck for 23s! [load_policy:19045] > Call Trace: > [] symcmp+0xf/0x20 > [] hashtab_search+0x47/0x80 > [] mls_convert_context+0xdc/0x1c0 > [] convert_context+0x378/0x460 > [] ? security_context_to_sid_core+0x240/0x240 > [] sidtab_map+0x45/0x80 > [] security_load_policy+0x3ff/0x580 > [] ? sched_clock_cpu+0xa8/0x100 > [] ? sched_clock_local+0x1d/0x80 > [] ? sched_clock_cpu+0xa8/0x100 > [] ? __change_page_attr_set_clr+0x82a/0xa50 > [] ? sched_clock_local+0x1d/0x80 > [] ? sched_clock_cpu+0xa8/0x100 > [] ? __change_page_attr_set_clr+0x82a/0xa50 > [] ? sched_clock_cpu+0xa8/0x100 > [] ? retint_restore_args+0xe/0xe > [] ? trace_hardirqs_on_caller+0xfd/0x1c0 > [] ? trace_hardirqs_on_thunk+0x3a/0x3f > [] ? rcu_irq_exit+0x68/0xb0 > [] ? retint_restore_args+0xe/0xe > [] sel_write_load+0xa7/0x770 > [] ? vfs_write+0x1c3/0x200 > [] ? security_file_permission+0x1e/0xa0 > [] vfs_write+0xbb/0x200 > [] ? fget_light+0x397/0x4b0 > [] SyS_write+0x47/0xa0 > [] tracesys+0xdd/0xe2 Stephen Smalley suggested: > Maybe put a cond_resched() within the ebitmap_for_each_positive_bit() > loop in mls_convert_context()? That seems to do the trick. Tested by downgrading and re-upgrading selinux-policy-targeted. Signed-off-by: Dave Jones --- security/selinux/ss/mls.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/security/selinux/ss/mls.c b/security/selinux/ss/mls.c index c85bc1ec040c..d307b37ddc2b 100644 --- a/security/selinux/ss/mls.c +++ b/security/selinux/ss/mls.c @@ -492,6 +492,8 @@ int mls_convert_context(struct policydb *oldp, rc = ebitmap_set_bit(&bitmap, catdatum->value - 1, 1); if (rc) return rc; + + cond_resched(); } ebitmap_destroy(&c->range.level[l].cat); c->range.level[l].cat = bitmap; -- 1.9.0