FAILED: patch "[PATCH] kasan: prevent cpu_quarantine corruption when CPU offline and" failed to apply to 4.14-stable tree

The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 31fa985b4196f8a66f027672e9bf2b81fea0417c Mon Sep 17 00:00:00 2001
From: Zqiang <[email protected]>
Date: Wed, 27 Apr 2022 12:41:56 -0700
Subject: [PATCH] kasan: prevent cpu_quarantine corruption when CPU offline and
cache shrink occur at same time

kasan_quarantine_remove_cache() is called in kmem_cache_shrink()/ destroy(). The kasan_quarantine_remove_cache() call is protected by cpuslock in kmem_cache_destroy() to ensure serialization with kasan_cpu_offline().

However the kasan_quarantine_remove_cache() call is not protected by cpuslock in kmem_cache_shrink(). When a CPU is going offline and cache shrink occurs at same time, the cpu_quarantine may be corrupted by interrupt (per_cpu_remove_cache operation).

So add a cpu_quarantine offline flags check in per_cpu_remove_cache().

[[email protected]: add comment, per Zqiang]

index 08291ed33e93..0a9def8ce5e8 100644
@@ -315,6 +315,13 @@ static void per_cpu_remove_cache(void *arg)
 	struct qlist_head *q;
 
 	q = this_cpu_ptr(&cpu_quarantine);
+	/*
+	 * Ensure the ordering between the writing to q->offline and
+	 * per_cpu_remove_cache.  Prevent cpu_quarantine from being corrupted
+	 * by interrupt.
+	 */
+	if (READ_ONCE(q->offline))
+		return;
 	qlist_move_cache(q, &to_free, cache);
 	qlist_free_all(&to_free, cache);
 }