linux-kernel - [PATCH v2 5/6] locks: prink more detail when there are leaked locks

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Message-Id: <1452261014-1682-6-git-send-email-jeff.layton@primarydata.com>
Date:	Fri,  8 Jan 2016 08:50:13 -0500
From:	Jeff Layton <jlayton@...chiereds.net>
To:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:	Dmitry Vyukov <dvyukov@...gle.com>,
	"J. Bruce Fields" <bfields@...ldses.org>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	syzkaller <syzkaller@...glegroups.com>,
	Kostya Serebryany <kcc@...gle.com>,
	Alexander Potapenko <glider@...gle.com>,
	Sasha Levin <sasha.levin@...cle.com>,
	Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH v2 5/6] locks: prink more detail when there are leaked locks

Right now, we just get WARN_ON_ONCE, which is not particularly helpful.
Have it dump some info about the locks and the inode to make it easier
to track down leaked locks in the future.

Signed-off-by: Jeff Layton <jeff.layton@...marydata.com>
---
 fs/locks.c | 33 +++++++++++++++++++++++++++++----
 1 file changed, 29 insertions(+), 4 deletions(-)

diff --git a/fs/locks.c b/fs/locks.c
index ed9ab930d093..ca272eb63c30 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -233,15 +233,40 @@ out:
 	return ctx;
 }
 
+static void
+locks_dump_ctx_list(struct list_head *list, char *list_type)
+{
+	struct file_lock *fl;
+
+	list_for_each_entry(fl, list, fl_list) {
+		pr_warn("%s: fl_owner=%p fl_flags=0x%x fl_type=0x%x fl_pid=%u\n", list_type, fl->fl_owner, fl->fl_flags, fl->fl_type, fl->fl_pid);
+	}
+}
+
+static void
+locks_check_ctx_lists(struct inode *inode)
+{
+	struct file_lock_context *ctx = inode->i_flctx;
+
+	if (unlikely(!list_empty(&ctx->flc_flock) ||
+		     !list_empty(&ctx->flc_posix) ||
+		     !list_empty(&ctx->flc_lease))) {
+		pr_warn("Leaked locks on dev=0x%x:0x%x ino=0x%lx:\n",
+			MAJOR(inode->i_sb->s_dev), MINOR(inode->i_sb->s_dev),
+			inode->i_ino);
+		locks_dump_ctx_list(&ctx->flc_flock, "FLOCK");
+		locks_dump_ctx_list(&ctx->flc_posix, "POSIX");
+		locks_dump_ctx_list(&ctx->flc_lease, "LEASE");
+	}
+}
+
 void
 locks_free_lock_context(struct inode *inode)
 {
 	struct file_lock_context *ctx = inode->i_flctx;
 
-	if (ctx) {
-		WARN_ON_ONCE(!list_empty(&ctx->flc_flock));
-		WARN_ON_ONCE(!list_empty(&ctx->flc_posix));
-		WARN_ON_ONCE(!list_empty(&ctx->flc_lease));
+	if (unlikely(ctx)) {
+		locks_check_ctx_lists(inode);
 		kmem_cache_free(flctx_cache, ctx);
 	}
 }
-- 
2.5.0