linux-kernel - [PATCH 4.14 191/496] btrfs: use kvzalloc to allocate btrfs_fs

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Message-Id: <20180528100327.993313441@linuxfoundation.org>
Date:   Mon, 28 May 2018 11:59:36 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jeff Mahoney <jeffm@...e.com>,
        David Sterba <dsterba@...e.com>,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 4.14 191/496] btrfs: use kvzalloc to allocate btrfs_fs_info

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jeff Mahoney <jeffm@...e.com>

[ Upstream commit a8fd1f71749387c9a1053a83ff1c16287499a4e7 ]

The srcu_struct in btrfs_fs_info scales in size with NR_CPUS.  On
kernels built with NR_CPUS=8192, this can result in kmalloc failures
that prevent mounting.

There is work in progress to try to resolve this for every user of
srcu_struct but using kvzalloc will work around the failures until
that is complete.

As an example with NR_CPUS=512 on x86_64: the overall size of
subvol_srcu is 3460 bytes, fs_info is 6496.

Signed-off-by: Jeff Mahoney <jeffm@...e.com>
Reviewed-by: David Sterba <dsterba@...e.com>
Signed-off-by: David Sterba <dsterba@...e.com>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/btrfs/ctree.h |    2 +-
 fs/btrfs/super.c |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2969,7 +2969,7 @@ static inline void free_fs_info(struct b
 	kfree(fs_info->super_copy);
 	kfree(fs_info->super_for_commit);
 	security_free_mnt_opts(&fs_info->security_opts);
-	kfree(fs_info);
+	kvfree(fs_info);
 }
 
 /* tree mod log functions from ctree.c */
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -1581,7 +1581,7 @@ static struct dentry *btrfs_mount(struct
 	 * it for searching for existing supers, so this lets us do that and
 	 * then open_ctree will properly initialize everything later.
 	 */
-	fs_info = kzalloc(sizeof(struct btrfs_fs_info), GFP_KERNEL);
+	fs_info = kvzalloc(sizeof(struct btrfs_fs_info), GFP_KERNEL);
 	if (!fs_info) {
 		error = -ENOMEM;
 		goto error_sec_opts;