[PATCH v4 3/3] locking/selftests: Add testcases for fs_reclaim

[Daniel Vetter]

Since I butchered this I figured better to make sure we have testcases
for this now. Since we only have a locking context for __GFP_FS that's
the only thing we're testing right now.

Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: linux-fsdevel@xxxxxxxxxxxxxxx
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Cc: Qian Cai <cai@xxxxxx>
Cc: linux-xfs@xxxxxxxxxxxxxxx
Cc: Thomas Hellström (Intel) <thomas_os@xxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Cc: linux-rdma@xxxxxxxxxxxxxxx
Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Cc: Christian König <christian.koenig@xxxxxxx>
Cc: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
 lib/locking-selftest.c | 47 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/lib/locking-selftest.c b/lib/locking-selftest.c
index a899b3f0e2e5..ad47c3358e30 100644
--- a/lib/locking-selftest.c
+++ b/lib/locking-selftest.c
@@ -15,6 +15,7 @@
 #include <linux/mutex.h>
 #include <linux/ww_mutex.h>
 #include <linux/sched.h>
+#include <linux/sched/mm.h>
 #include <linux/delay.h>
 #include <linux/lockdep.h>
 #include <linux/spinlock.h>
@@ -2357,6 +2358,50 @@ static void queued_read_lock_tests(void)
 	pr_cont("\n");
 }
 
+static void fs_reclaim_correct_nesting(void)
+{
+	fs_reclaim_acquire(GFP_KERNEL);
+	might_alloc(GFP_NOFS);
+	fs_reclaim_release(GFP_KERNEL);
+}
+
+static void fs_reclaim_wrong_nesting(void)
+{
+	fs_reclaim_acquire(GFP_KERNEL);
+	might_alloc(GFP_KERNEL);
+	fs_reclaim_release(GFP_KERNEL);
+}
+
+static void fs_reclaim_protected_nesting(void)
+{
+	unsigned int flags;
+
+	fs_reclaim_acquire(GFP_KERNEL);
+	flags = memalloc_nofs_save();
+	might_alloc(GFP_KERNEL);
+	memalloc_nofs_restore(flags);
+	fs_reclaim_release(GFP_KERNEL);
+}
+
+static void fs_reclaim_tests(void)
+{
+	printk("  --------------------\n");
+	printk("  | fs_reclaim tests |\n");
+	printk("  --------------------\n");
+
+	print_testname("correct nesting");
+	dotest(fs_reclaim_correct_nesting, SUCCESS, 0);
+	pr_cont("\n");
+
+	print_testname("wrong nesting");
+	dotest(fs_reclaim_wrong_nesting, FAILURE, 0);
+	pr_cont("\n");
+
+	print_testname("protected nesting");
+	dotest(fs_reclaim_protected_nesting, SUCCESS, 0);
+	pr_cont("\n");
+}
+
 void locking_selftest(void)
 {
 	/*
@@ -2478,6 +2523,8 @@ void locking_selftest(void)
 	if (IS_ENABLED(CONFIG_QUEUED_RWLOCKS))
 		queued_read_lock_tests();
 
+	fs_reclaim_tests();
+
 	if (unexpected_testcase_failures) {
 		printk("-----------------------------------------------------------------\n");
 		debug_locks = 0;
-- 
2.29.2