Re: [PATCH v2 3/5] mm: page_isolation: do not take slab pages for free

[Johannes Weiner]

On Tue, Nov 03, 2026 at 05:16:49PM +0100, Vlastimil Babka (SUSE) wrote:
> From: Josef Bacik <josef@xxxxxxxxxxxxxx>
> 
> page_is_unmovable() regards a page with a reference count of zero as free
> or about to be freed. Since slab allocates frozen pages, they will
> be wrongly considered to be freed if order 0 (higher-order compound
> pages are caught earlier).
> 
> If such slabs are the only unmovable pages of a memory block, memory
> offlining now isolates the block, this can lead to offline_pages()
> looping without progress.
> 
> Thus detect the slab pages as removable to return -EBUSY, as would
> happen before commit 9aec2fb0fd5e ("slab: allocate frozen pages").
> 
> Fixes: 9aec2fb0fd5e ("slab: allocate frozen pages")
> Assisted-by: LLM
> Signed-off-by: Josef Bacik <josef@xxxxxxxxxxxxxx>
> Signed-off-by: David Hildenbrand (Arm) <david@xxxxxxxxxx>
> Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>
> Signed-off-by: Vlastimil Babka (SUSE) <vbabka@xxxxxxxxxx>

Reviewed-by: Johannes Weiner <hannes@xxxxxxxxxxx>