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Date: Fri, 22 Mar 2019 12:15:22 +0100 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, Nikolay Borisov <nborisov@...e.com>, Filipe Manana <fdmanana@...e.com>, David Sterba <dsterba@...e.com> Subject: [PATCH 4.19 169/280] Btrfs: setup a nofs context for memory allocation at __btrfs_set_acl 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Filipe Manana <fdmanana@...e.com> commit a0873490660246db587849a9e172f2b7b21fa88a upstream. We are holding a transaction handle when setting an acl, therefore we can not allocate the xattr value buffer using GFP_KERNEL, as we could deadlock if reclaim is triggered by the allocation, therefore setup a nofs context. Fixes: 39a27ec1004e8 ("btrfs: use GFP_KERNEL for xattr and acl allocations") CC: stable@...r.kernel.org # 4.9+ Reviewed-by: Nikolay Borisov <nborisov@...e.com> Signed-off-by: Filipe Manana <fdmanana@...e.com> Reviewed-by: David Sterba <dsterba@...e.com> Signed-off-by: David Sterba <dsterba@...e.com> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org> --- fs/btrfs/acl.c | 9 +++++++++ 1 file changed, 9 insertions(+) --- a/fs/btrfs/acl.c +++ b/fs/btrfs/acl.c @@ -9,6 +9,7 @@ #include <linux/posix_acl_xattr.h> #include <linux/posix_acl.h> #include <linux/sched.h> +#include <linux/sched/mm.h> #include <linux/slab.h> #include "ctree.h" @@ -72,8 +73,16 @@ static int __btrfs_set_acl(struct btrfs_ } if (acl) { + unsigned int nofs_flag; + size = posix_acl_xattr_size(acl->a_count); + /* + * We're holding a transaction handle, so use a NOFS memory + * allocation context to avoid deadlock if reclaim happens. + */ + nofs_flag = memalloc_nofs_save(); value = kmalloc(size, GFP_KERNEL); + memalloc_nofs_restore(nofs_flag); if (!value) { ret = -ENOMEM; goto out;
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