From: Yu Kuai Date: Fri, 27 Mar 2026 14:07:29 +0000 (+0800) Subject: md: wake raid456 reshape waiters before suspend X-Git-Url: http://git.ipfire.org/index.cgi?a=commitdiff_plain;h=cf86bb53b9c92354904a328e947a05ffbfdd1840;p=thirdparty%2Fkernel%2Flinux.git md: wake raid456 reshape waiters before suspend During raid456 reshape, direct IO across the reshape position can sleep in raid5_make_request() waiting for reshape progress while still holding an active_io reference. If userspace then freezes reshape and writes md/suspend_lo or md/suspend_hi, mddev_suspend() kills active_io and waits for all in-flight IO to drain. This can deadlock: the IO needs reshape progress to continue, but the reshape thread is already frozen, so the active_io reference is never dropped and suspend never completes. raid5_prepare_suspend() already wakes wait_for_reshape for dm-raid. Do the same for normal md suspend when reshape is already interrupted, so waiting raid456 IO can abort, drop its reference, and let suspend finish. The mdadm test tests/25raid456-reshape-deadlock reproduces the hang. Fixes: 714d20150ed8 ("md: add new helpers to suspend/resume array") Link: https://lore.kernel.org/linux-raid/20260327140729.2030564-1-yukuai@fnnas.com/ Signed-off-by: Yu Kuai --- diff --git a/drivers/md/md.c b/drivers/md/md.c index 67e2b501d94fb..5fb5ae8368bac 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -487,6 +487,17 @@ int mddev_suspend(struct mddev *mddev, bool interruptible) } percpu_ref_kill(&mddev->active_io); + + /* + * RAID456 IO can sleep in wait_for_reshape while still holding an + * active_io reference. If reshape is already interrupted or frozen, + * wake those waiters so they can abort and drop the reference instead + * of deadlocking suspend. + */ + if (mddev->pers && mddev->pers->prepare_suspend && + reshape_interrupted(mddev)) + mddev->pers->prepare_suspend(mddev); + if (interruptible) err = wait_event_interruptible(mddev->sb_wait, percpu_ref_is_zero(&mddev->active_io));