Re: [PATCH v6 06/10] mm/memory_hotplug: add offline_and_remove_memory_ranges()

[Gregory Price <gourry@gourry.net>]

On Thu, Jul 09, 2026 at 04:45:51PM +0800, Richard Cheng wrote:
> On Tue, Jun 30, 2026 at 05:18:38PM +0800, Gregory Price wrote:
> > +/**
> > + * offline_and_remove_memory_ranges - offline and remove multiple memory ranges
> > + * @ranges: array of physical address ranges to offline and remove
> > + * @nr_ranges: number of entries in @ranges
> > + *
> > + * Offline and remove several memory ranges as one operation, serialized
> > + * against other hotplug operations by a single lock_device_hotplug().
> > + *
> > + * This offlines all ranges before removing any of them.  If offlining any
> > + * range fails, the entire process is reverted and nothing is removed.
> > + * This provides a fully atomic semantic for unplugging an entire device.
> > + *
> > + * Each range must be memory-block aligned in start and size.
> > + *
> > + * Return: 0 on success, negative errno otherwise.  On failure no range has
> > + * been removed.
> > + */
> 
> I think this can return 1, and it shouldn't.
> device_offline() returns 1 when a block is already offline, and phase 1 passes that value through as-is.
> 

I just realized try_offline_memory_block() already clamps the value to 0

static int try_offline_memory_block(struct memory_block *mem, void *arg)
{
...
    rc = device_offline(&mem->dev);
...
    /* Ignore if already offline. */
    return rc < 0 ? rc : 0;
}

But this is a bit non-obvious, let me see about making this a little
bit clearer.

~Gregory