The patch below does not apply to the 4.4-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 <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 827aa18e7b903c5ff3b3cd8fec328a99b1dbd411 Mon Sep 17 00:00:00 2001
From: Filipe Manana <fdmanana@xxxxxxxx>
Date: Mon, 10 Dec 2018 17:53:35 +0000
Subject: [PATCH] Btrfs: use nofs context when initializing security xattrs to
avoid deadlock
When initializing the security xattrs, we are holding a transaction handle
therefore we need to use a GFP_NOFS context in order to avoid a deadlock
with reclaim in case it's triggered.
Fixes: 39a27ec1004e8 ("btrfs: use GFP_KERNEL for xattr and acl allocations")
Reviewed-by: Nikolay Borisov <nborisov@xxxxxxxx>
Signed-off-by: Filipe Manana <fdmanana@xxxxxxxx>
Reviewed-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
diff --git a/fs/btrfs/xattr.c b/fs/btrfs/xattr.c
index ea78c3d6dcfc..f141b45ce349 100644
--- a/fs/btrfs/xattr.c
+++ b/fs/btrfs/xattr.c
@@ -11,6 +11,7 @@
#include <linux/security.h>
#include <linux/posix_acl_xattr.h>
#include <linux/iversion.h>
+#include <linux/sched/mm.h>
#include "ctree.h"
#include "btrfs_inode.h"
#include "transaction.h"
@@ -422,9 +423,15 @@ static int btrfs_initxattrs(struct inode *inode,
{
const struct xattr *xattr;
struct btrfs_trans_handle *trans = fs_info;
+ unsigned int nofs_flag;
char *name;
int err = 0;
+ /*
+ * We're holding a transaction handle, so use a NOFS memory allocation
+ * context to avoid deadlock if reclaim happens.
+ */
+ nofs_flag = memalloc_nofs_save();
for (xattr = xattr_array; xattr->name != NULL; xattr++) {
name = kmalloc(XATTR_SECURITY_PREFIX_LEN +
strlen(xattr->name) + 1, GFP_KERNEL);
@@ -440,6 +447,7 @@ static int btrfs_initxattrs(struct inode *inode,
if (err < 0)
break;
}
+ memalloc_nofs_restore(nofs_flag);
return err;
}
