Re: [PATCH v6 09/10] dax/kmem: add sysfs interface for atomic whole-device hotplug

[Gregory Price <gourry@gourry.net>]

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On Tue, Jun 30, 2026 at 05:18:41PM -0400, Gregory Price wrote:
> There is no atomic mechanism to offline and remove an entire
> multi-block DAX kmem device.  This is presently done in two steps:

... snip snip snip ...

Sashiko pointed out a false-positive, but adding a fixup patch
here that adds additional consistency.

On total failure - release all resources.  This makes the sysfs
interface consistent with the probe failure path.

Just attaching a fixup here, since technically it's not a bug,
could fold in separately

~Gregory

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From e341860c83fd5d5e8549d8adbf71a484c8990c5f Mon Sep 17 00:00:00 2001
From: Gregory Price <gourry@gourry.net>
Date: Tue, 30 Jun 2026 14:49:06 -0700
Subject: [PATCH] fixup! dax/kmem: add sysfs interface for atomic whole-device
 hotplug

---
 drivers/dax/kmem.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
index 19effe0da3dc..f597d8a99c1f 100644
--- a/drivers/dax/kmem.c
+++ b/drivers/dax/kmem.c
@@ -380,8 +380,11 @@ static ssize_t state_store(struct device *dev, struct device_attribute *attr,
 		return rc;
 
 	rc = dax_kmem_do_hotplug(dev_dax, data, online_type);
-	if (rc < 0)
+	if (rc < 0) {
+		/* Total failure, drop the reservations we took. */
+		dax_kmem_cleanup_resources(dev_dax, data);
 		return rc;
+	}
 
 	data->state = online_type;
 	return len;
-- 
2.53.0-Meta