The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x fa1944bbe6220eb929e2c02e5e8706b908565711 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024120641-carat-unwired-140a@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From fa1944bbe6220eb929e2c02e5e8706b908565711 Mon Sep 17 00:00:00 2001 From: Xiao Ni xni@redhat.com Date: Wed, 6 Nov 2024 17:51:24 +0800 Subject: [PATCH] md/raid5: Wait sync io to finish before changing group cnt

One customer reports a bug: raid5 is hung when changing thread cnt while resync is running. The stripes are all in conf->handle_list and new threads can't handle them.

Commit b39f35ebe86d ("md: don't quiesce in mddev_suspend()") removes pers->quiesce from mddev_suspend/resume. Before this patch, mddev_suspend needs to wait for all ios including sync io to finish. Now it's used to only wait normal io.

Fix this by calling raid5_quiesce from raid5_store_group_thread_cnt directly to wait all sync requests to finish before changing the group cnt.

Fixes: b39f35ebe86d ("md: don't quiesce in mddev_suspend()") Cc: stable@vger.kernel.org Signed-off-by: Xiao Ni xni@redhat.com Reviewed-by: Yu Kuai yukuai3@huawei.com Link: https://lore.kernel.org/r/20241106095124.74577-1-xni@redhat.com Signed-off-by: Song Liu song@kernel.org

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index f5ac81dd21b2..f09e7677ee9f 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -7176,6 +7176,8 @@ raid5_store_group_thread_cnt(struct mddev *mddev, const char *page, size_t len) err = mddev_suspend_and_lock(mddev); if (err) return err; + raid5_quiesce(mddev, true); + conf = mddev->private; if (!conf) err = -ENODEV; @@ -7197,6 +7199,8 @@ raid5_store_group_thread_cnt(struct mddev *mddev, const char *page, size_t len) kfree(old_groups); } } + + raid5_quiesce(mddev, false); mddev_unlock_and_resume(mddev);

return err ?: len;