Re: [PATCH v22 07/16] xfs: Handle krealloc errors in xlog_recover_add_to_cont_trans

Chandan Babu R
2021-07-29T08:27:36Z

On 27 Jul 2021 at 11:50, Allison Henderson wrote:
> Because xattrs can be over a page in size, we need to handle possible
> krealloc errors to avoid warnings. If the allocation does fail, fall
> back to kmem_alloc_large, with a memcpy.
>
> The warning:
> WARNING: CPU: 1 PID: 20255 at mm/page_alloc.c:3446
> get_page_from_freelist+0x100b/0x1690
>
> is caused when sizes larger that a page are allocated with the
> __GFP_NOFAIL flag option. We encounter this error now because attr
> values can be up to 64k in size. So we cannot use __GFP_NOFAIL, and
> we need to handle the error code if the allocation fails.
>

Looks good to me.

Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>

> Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
> Reviewed-by: Darrick J. Wong <djwong@kernel.org>
> ---
> fs/xfs/xfs_log_recover.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
> index 12118d5..1212fa1 100644
> --- a/fs/xfs/xfs_log_recover.c
> +++ b/fs/xfs/xfs_log_recover.c
> @@ -2088,7 +2088,15 @@ xlog_recover_add_to_cont_trans(
> old_ptr = item->ri_buf[item->ri_cnt-1].i_addr;
> old_len = item->ri_buf[item->ri_cnt-1].i_len;
>
> - ptr = krealloc(old_ptr, len + old_len, GFP_KERNEL | __GFP_NOFAIL);
> + ptr = krealloc(old_ptr, len + old_len, GFP_KERNEL);
> + if (ptr == NULL) {
> + ptr = kmem_alloc_large(len + old_len, KM_ZERO);
> + if (ptr == NULL)
> + return -ENOMEM;
> +
> + memcpy(ptr, old_ptr, old_len);
> + }
> +
> memcpy(&ptr[old_len], dp, len);
> item->ri_buf[item->ri_cnt-1].i_len += len;
> item->ri_buf[item->ri_cnt-1].i_addr = ptr;

--
chandan