From cfa92b6d52071aaa8f27d21affdcb14e7448fbc1 Mon Sep 17 00:00:00 2001
From: John Stultz <jstultz@google.com>
Date: Fri, 22 Sep 2023 04:36:01 +0000
Subject: [PATCH] locking/ww_mutex/test: Make sure we bail out instead of
livelock
Git-commit: cfa92b6d52071aaa8f27d21affdcb14e7448fbc1
Patch-mainline: v6.7-rc1
References: bsc#1219953
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 <zhijianx.li@intel.com>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230922043616.19282-4-jstultz@google.com
Signed-off-by: Jiri Wiesner <jwiesner@suse.de>
---
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 @@ static void stress_inorder_work(struct work_struct *work)
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);
--
2.35.3