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Subject: Re: [syzbot] general protection fault in lmLogSync (2)
Author: koike@igalia.com
#syz test
diff --git a/fs/jfs/jfs_logmgr.c b/fs/jfs/jfs_logmgr.c
index 5b1c5da04163..1fa202fc0458 100644
--- a/fs/jfs/jfs_logmgr.c
+++ b/fs/jfs/jfs_logmgr.c
@@ -74,12 +74,6 @@ static struct lbuf *log_redrive_list;
static DEFINE_SPINLOCK(log_redrive_lock);
-/*
- * log read/write serialization (per log)
- */
-#define LOG_LOCK_INIT(log) mutex_init(&(log)->loglock)
-#define LOG_LOCK(log) mutex_lock(&((log)->loglock))
-#define LOG_UNLOCK(log) mutex_unlock(&((log)->loglock))
/*
diff --git a/fs/jfs/jfs_logmgr.h b/fs/jfs/jfs_logmgr.h
index 8b8994e48cd0..09e0ef6aecce 100644
--- a/fs/jfs/jfs_logmgr.h
+++ b/fs/jfs/jfs_logmgr.h
@@ -402,6 +402,13 @@ struct jfs_log {
int no_integrity; /* 3: flag to disable journaling to disk */
};
+/*
+ * log read/write serialization (per log)
+ */
+#define LOG_LOCK_INIT(log) mutex_init(&(log)->loglock)
+#define LOG_LOCK(log) mutex_lock(&((log)->loglock))
+#define LOG_UNLOCK(log) mutex_unlock(&((log)->loglock))
+
/*
* Log flag
*/
diff --git a/fs/jfs/jfs_umount.c b/fs/jfs/jfs_umount.c
index 8ec43f53f686..8547bb5cd3f4 100644
--- a/fs/jfs/jfs_umount.c
+++ b/fs/jfs/jfs_umount.c
@@ -20,6 +20,7 @@
#include "jfs_superblock.h"
#include "jfs_dmap.h"
#include "jfs_imap.h"
+#include "jfs_logmgr.h"
#include "jfs_metapage.h"
#include "jfs_debug.h"
@@ -63,6 +64,12 @@ int jfs_umount(struct super_block *sb)
diUnmount(ipimap, 0);
diFreeSpecial(ipimap);
+ /*
+ * Hold log lock so write_special_inodes (lmLogSync) cannot see
+ * this sbi with a NULL inode pointer while iterating log->sb_list.
+ */
+ if (log)
+ LOG_LOCK(log);
sbi->ipimap = NULL;
/*
@@ -88,6 +95,8 @@ int jfs_umount(struct super_block *sb)
diFreeSpecial(ipbmap);
sbi->ipbmap = NULL;
+ if (log)
+ LOG_UNLOCK(log);
/*
* Make sure all metadata makes it to disk before we mark
--
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