From cfa92b6d52071aaa8f27d21affdcb14e7448fbc1 Mon Sep 17 00:00:00 2001 From: John Stultz Date: Fri, 22 Sep 2023 04:36:01 +0000 Subject: [PATCH] locking/ww_mutex/test: Make sure we bail out instead of livelock I've seen what appears to be livelocks in the stress_inorder_work() function, and looking at the code it is clear we can have a case where we continually retry acquiring the locks and never check to see if we have passed the specified timeout. This patch reworks that function so we always check the timeout before iterating through the loop again. I believe others may have hit this previously here: https://lore.kernel.org/lkml/895ef450-4fb3-5d29-a6ad-790657106a5a@intel.com/ Reported-by: Li Zhijian Signed-off-by: John Stultz Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20230922043616.19282-4-jstultz@google.com --- kernel/locking/test-ww_mutex.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/kernel/locking/test-ww_mutex.c b/kernel/locking/test-ww_mutex.c index 358d66150426..78719e1ef1b1 100644 --- a/kernel/locking/test-ww_mutex.c +++ b/kernel/locking/test-ww_mutex.c @@ -465,17 +465,18 @@ retry: ww_mutex_unlock(&locks[order[n]]); if (err == -EDEADLK) { - ww_mutex_lock_slow(&locks[order[contended]], &ctx); - goto retry; + if (!time_after(jiffies, stress->timeout)) { + ww_mutex_lock_slow(&locks[order[contended]], &ctx); + goto retry; + } } + ww_acquire_fini(&ctx); if (err) { pr_err_once("stress (%s) failed with %d\n", __func__, err); break; } - - ww_acquire_fini(&ctx); } while (!time_after(jiffies, stress->timeout)); kfree(order);