On Mon, Jul 24, 2017 at 11:02:29AM -0400, Brian Foster wrote:
> If a dquot has an id of U32_MAX, the next lookup index increment
> overflows the uint32_t back to 0. This starts the lookup sequence
> over from the beginning, repeats indefinitely and results in a
> livelock.
>
> Update xfs_qm_dquot_walk() to explicitly check for the lookup
> overflow and exit the loop.
>
> Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx>
Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
--D
> ---
> fs/xfs/xfs_qm.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c
> index 6ce948c..15751dc 100644
> --- a/fs/xfs/xfs_qm.c
> +++ b/fs/xfs/xfs_qm.c
> @@ -111,6 +111,9 @@ xfs_qm_dquot_walk(
> skipped = 0;
> break;
> }
> + /* we're done if id overflows back to zero */
> + if (!next_index)
> + break;
> }
>
> if (skipped) {
> --
> 2.9.4
>
> --
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