On Thu, Mar 9, 2023 at 11:39 PM Yu Kuai <yukuai1@xxxxxxxxxxxxxxx> wrote:
>
> From: Yu Kuai <yukuai3@xxxxxxxxxx>
>
> status_resync() will calculate 'curr_resync - recovery_active' to show
> user a progress bar like following:
>
> [============>........] resync = 61.4%
>
> 'curr_resync' and 'recovery_active' is updated in md_do_sync(), and
> status_resync() can read them concurrently, hence it's possible that
> 'curr_resync - recovery_active' can overflow to a huge number. In this
> case status_resync() will be stuck in the loop to print a large amount
> of '=', which will end up soft lockup.
>
> Fix the problem by setting 'resync' to MD_RESYNC_ACTIVE in this case,
> this way resync in progress will be reported to user.
>
> Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
Looks good. Applied to md-next.
Thanks,
Song
> ---
> drivers/md/md.c | 18 +++++++++---------
> 1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 546b1b81eb28..98970bbe32bf 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -8009,16 +8009,16 @@ static int status_resync(struct seq_file *seq, struct mddev *mddev)
> } else if (resync > max_sectors) {
> resync = max_sectors;
> } else {
> - resync -= atomic_read(&mddev->recovery_active);
> - if (resync < MD_RESYNC_ACTIVE) {
> - /*
> - * Resync has started, but the subtraction has
> - * yielded one of the special values. Force it
> - * to active to ensure the status reports an
> - * active resync.
> - */
> + res = atomic_read(&mddev->recovery_active);
> + /*
> + * Resync has started, but the subtraction has overflowed or
> + * yielded one of the special values. Force it to active to
> + * ensure the status reports an active resync.
> + */
> + if (resync < res || resync - res < MD_RESYNC_ACTIVE)
> resync = MD_RESYNC_ACTIVE;
> - }
> + else
> + resync -= res;
> }
>
> if (resync == MD_RESYNC_NONE) {
> --
> 2.31.1
>
