On a slow machine (with debugging enabled), during a yum update I get
the soft lockup detector kicking in when it gets to reloading the selinux
policy.
It looks like this..
BUG: soft lockup - CPU#2 stuck for 23s! [load_policy:19045]
irq event stamp: 2368864
hardirqs last enabled at (2368863): [<ffffffff8152ab5d>]
__slab_alloc.constprop.78+0x4c0/0x4d7
hardirqs last disabled at (2368864): [<ffffffff8153c82a>]
apic_timer_interrupt+0x6a/0x80
softirqs last enabled at (2368554): [<ffffffff810480b9>]
__do_softirq+0x169/0x200
softirqs last disabled at (2368539): [<ffffffff8104837d>] irq_exit+0x11d/0x140
CPU: 2 PID: 19045 Comm: load_policy Not tainted 3.11.0+ #16
Hardware name: /D510MO, BIOS MOPNV10J.86A.0175.2010.0308.0620
03/08/2010
task: ffff88005ab38000 ti: ffff880019620000 task.ti: ffff880019620000
RIP: 0010:[<ffffffff81274273>] [<ffffffff81274273>] strcmp+0x23/0x40
RSP: 0018:ffff880019621818 EFLAGS: 00000246
RAX: 0000000000000063 RBX: ffff880018090ca8 RCX: 0000000000006070
RDX: ffff88000781d8f0 RSI: ffff88000781d8f1 RDI: ffff880079caed21
RBP: ffff880019621818 R08: ffff88006345a290 R09: ffff880018091680
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000292
R13: 0000000180160016 R14: ffff88007b804488 R15: ffffffff81221430
FS: 00007f73e1212800(0000) GS:ffff88007e600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f73e0857aa0 CR3: 0000000076fea000 CR4: 00000000000007e0
Stack:
ffff880019621828 ffffffff81221ddf ffff880019621850 ffffffff81221c27
ffff8800180ac6d8 ffff880019621b88 ffffffff82759620 ffff8800196218a0
ffffffff8122e96c 0000000181221e05 ffff880018091680 0000000000000080
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
Code: 0f 1f 84 00 00 00 00 00 55 48 89 e5 eb 0e 66 2e 0f 1f 84 00 00 00 00 00
84 c0 74 1c 48 83 c7 01 0f b6 47 ff 48 83 c6 01 3a 46 ff <74> eb 19 c0 83 c8 01
5d c3 0f 1f 40 00 31 c0 5d c3 66 66 66 2e
23s in the kernel is an eternity. Short of rearchitecting how policy loads are
done,
perhaps we could do something like this ? (untested, and 10000 is arbitarily
chosen, may need to be adjusted)
thoughts ?
Dave
diff --git a/security/selinux/ss/hashtab.c b/security/selinux/ss/hashtab.c
index 933e735..69a0587 100644
--- a/security/selinux/ss/hashtab.c
+++ b/security/selinux/ss/hashtab.c
@@ -75,14 +75,21 @@ void *hashtab_search(struct hashtab *h, const void *key)
{
u32 hvalue;
struct hashtab_node *cur;
+ int count;
if (!h)
return NULL;
hvalue = h->hash_value(h, key);
cur = h->htable[hvalue];
- while (cur && h->keycmp(h, key, cur->key) > 0)
+ while (cur && h->keycmp(h, key, cur->key) > 0) {
cur = cur->next;
+ count++;
+ if (count == 10000) {
+ touch_softlockup_watchdog();
+ count = 0;
+ }
+ }
if (cur == NULL || (h->keycmp(h, key, cur->key) != 0))
return NULL;
--
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