From: Yu Kuai <yukuai3@xxxxxxxxxx> [ Upstream commit 6efddf1e32e2a264694766ca485a4f5e04ee82a7 ] 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> Signed-off-by: Song Liu <song@xxxxxxxxxx> Link: https://lore.kernel.org/r/20230310073855.1337560-3-yukuai1@xxxxxxxxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- 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 d5c362b1602b6..bb73a541bb193 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -8028,16 +8028,16 @@ 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) { -- 2.39.2
