On Thu, Mar 10, 2022 at 05:43:03PM +0800, Jiasheng Jiang wrote:
> As the potential failure of the kmem_zalloc() without __GFP_NOFAIL,
> it should be better to check it in order to avoid the dereference
> of NULL pointer.
>
> Fixes: 5880f2d78ff1 ("xfs: create rmap update intent log items")
> Signed-off-by: Jiasheng Jiang <jiasheng@xxxxxxxxxxx>
> ---
> fs/xfs/xfs_rmap_item.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/fs/xfs/xfs_rmap_item.c b/fs/xfs/xfs_rmap_item.c
> index c3966b4c58ef..66395faeeb87 100644
> --- a/fs/xfs/xfs_rmap_item.c
> +++ b/fs/xfs/xfs_rmap_item.c
> @@ -143,6 +143,7 @@ xfs_rui_init(
> else
> ruip = kmem_cache_zalloc(xfs_rui_cache,
> GFP_KERNEL | __GFP_NOFAIL);
> + ASSERT(ruip);
>
> xfs_log_item_init(mp, &ruip->rui_item, XFS_LI_RUI, &xfs_rui_item_ops);
Setting aside for a moment the fact that we'll crash immediately on the
very next line anyways --
The defer ops code will never create an rmap intent item with nextents >
XFS_RUI_MAX_FAST_EXTENTS, so the only way that we'd end up in the
kmem_zalloc path is if one came in via log recovery. We're allowed to
fail log recovery, so why not return NULL if kmem_zalloc fails, and then
patch xlog_recover_rui_commit_pass2 to return ENOMEM if it cannot
allocate ruip?
While we're on this topic -- do the other xfs log intent items need
similar corrections in the xfs_*_init() callers?
--D
> ruip->rui_format.rui_nextents = nextents;
> --
> 2.25.1
>
