Messages in this thread | | | Date | Fri, 19 May 2023 16:54:41 -0400 | From | Paul Moore <> | Subject | Re: [PATCH v2 5/5] audit: do not use exclusive wait in audit_receive() |
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On May 11, 2023 Eiichi Tsukata <eiichi.tsukata@nutanix.com> wrote: > > kauditd thread issues wake_up() before it goes to sleep. The wake_up() > call wakes up only one process as waiter side uses exclusive wait. > This can be problematic when there are multiple processes (one is in > audit_receive() and others are in audit_log_start()) waiting on > audit_backlog_wait queue. > > For example, if there are two processes waiting: > > Process (A): in audit_receive() > Process (B): in audit_log_start() > > And (A) is at the head of the wait queue. Then kauditd's wake_up() only > wakes up (A) leaving (B) as it is even if @audit_queue is drained. As a > result, (B) can be blocked for up to backlog_wait_time. > > To prevent the issue, use non-exclusive wait in audit_receive() so that > kauditd can wake up all waiters in audit_receive(). > > Fixes: 8f110f530635 ("audit: ensure userspace is penalized the same as the kernel when under pressure") > Signed-off-by: Eiichi Tsukata <eiichi.tsukata@nutanix.com> > --- > kernel/audit.c | 17 +++++++++++------ > 1 file changed, 11 insertions(+), 6 deletions(-)
This was also discussed in the last patchset.
-- paul-moore.com
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