From: Stephen Smalley <sds@tycho.nsa.gov>
To: Dave Jones <davej@redhat.com>,
Linux Kernel <linux-kernel@vger.kernel.org>,
pmoore@redhat.com, eparis@redhat.com
Subject: Re: [1/2] conditionally reschedule in mls_convert_context while loading selinux policy.
Date: Thu, 15 May 2014 15:18:07 -0400 [thread overview]
Message-ID: <537512EF.1070207@tycho.nsa.gov> (raw)
In-Reply-To: <20140515190253.GA16816@redhat.com>
On 05/15/2014 03:02 PM, Dave Jones wrote:
> 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:
> > [<ffffffff81221ddf>] symcmp+0xf/0x20
> > [<ffffffff81221c27>] hashtab_search+0x47/0x80
> > [<ffffffff8122e96c>] mls_convert_context+0xdc/0x1c0
> > [<ffffffff812294e8>] convert_context+0x378/0x460
> > [<ffffffff81229170>] ? security_context_to_sid_core+0x240/0x240
> > [<ffffffff812221b5>] sidtab_map+0x45/0x80
> > [<ffffffff8122bb9f>] security_load_policy+0x3ff/0x580
> > [<ffffffff810788a8>] ? sched_clock_cpu+0xa8/0x100
> > [<ffffffff810786dd>] ? sched_clock_local+0x1d/0x80
> > [<ffffffff810788a8>] ? sched_clock_cpu+0xa8/0x100
> > [<ffffffff8103096a>] ? __change_page_attr_set_clr+0x82a/0xa50
> > [<ffffffff810786dd>] ? sched_clock_local+0x1d/0x80
> > [<ffffffff810788a8>] ? sched_clock_cpu+0xa8/0x100
> > [<ffffffff8103096a>] ? __change_page_attr_set_clr+0x82a/0xa50
> > [<ffffffff810788a8>] ? sched_clock_cpu+0xa8/0x100
> > [<ffffffff81534ddc>] ? retint_restore_args+0xe/0xe
> > [<ffffffff8109c82d>] ? trace_hardirqs_on_caller+0xfd/0x1c0
> > [<ffffffff81279a2e>] ? trace_hardirqs_on_thunk+0x3a/0x3f
> > [<ffffffff810d28a8>] ? rcu_irq_exit+0x68/0xb0
> > [<ffffffff81534ddc>] ? retint_restore_args+0xe/0xe
> > [<ffffffff8121e947>] sel_write_load+0xa7/0x770
> > [<ffffffff81139633>] ? vfs_write+0x1c3/0x200
> > [<ffffffff81210e8e>] ? security_file_permission+0x1e/0xa0
> > [<ffffffff8113952b>] vfs_write+0xbb/0x200
> > [<ffffffff811581c7>] ? fget_light+0x397/0x4b0
> > [<ffffffff81139c27>] SyS_write+0x47/0xa0
> > [<ffffffff8153bde4>] 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 <davej@redhat.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
>
> ---
> 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;
>
next prev parent reply other threads:[~2014-05-15 19:36 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-15 19:02 [1/2] conditionally reschedule in mls_convert_context while loading selinux policy Dave Jones
2014-05-15 19:18 ` Stephen Smalley [this message]
2014-05-15 21:15 ` Paul Moore
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