[PATCH 1/8] audit: avoid soft lockup due to audit_log_start() incorrect loop termination

Commit 82919919 caused the wait for auditd timeout condition to loop endlessly rather than fall through to the error recovery code. BUG: soft lockup - CPU#0 stuck for 22s! [preload:785] RIP: 0010:[<ffffffff810fb240>] [<ffffffff810fb240>] audit_log_start+0xf0/0x460 Call Trace: [<ffffffff810aca40>] ? try_to_wake_up+0x310/0x310 [<ffffffff81100fd1>] audit_log_exit+0x51/0xcb0 [<ffffffff811020b5>] __audit_syscall_exit+0x275/0x2d0 [<ffffffff816ec540>] sysret_audit+0x17/0x21 If the timeout condition goes negative, the loop continues endlessly instead of breaking out and going to the failure code and allow other processes to run when auditd is unable to drain the queue fast enough. This can easily be triggered by readahead-collector, in particular during installations. The readahead-collector (ab)uses the audit interface and sometimes gets stuck in a 'stopped' state. To trigger: readahead-collector -f & pkill -SIGSTOP readahead-collector top See: https://lkml.org/lkml/2013/8/28/626 https://lkml.org/lkml/2013/9/2/471 https://lkml.org/lkml/2013/9/3/4 Signed-off-by: Luiz Capitulino <lcapitulino(a)redhat.com&gt; Signed-off-by: Konstantin Khlebnikov <khlebnikov(a)openvz.org&gt; Signed-off-by: Dan Duval <dan.duval(a)oracle.com&gt; Signed-off-by: Chuck Anderson <chuck.anderson(a)oracle.com&gt; Signed-off-by: Richard Guy Briggs <rgb(a)redhat.com&gt; --- kernel/audit.c | 5 +++-- 1 files changed, 3 insertions(+), 2 deletions(-) diff --git a/kernel/audit.c b/kernel/audit.c index 91e53d0..7b0e23a 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -1117,9 +1117,10 @@ struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask, sleep_time = timeout_start + audit_backlog_wait_time - jiffies; - if ((long)sleep_time > 0) + if ((long)sleep_time > 0) { wait_for_auditd(sleep_time); - continue; + continue; + } } if (audit_rate_check() && printk_ratelimit()) printk(KERN_WARNING -- 1.7.1