Re: [PATCH 2/5] mm: rmap: add a ZONE_DEVICE folio warning in folio_referenced()
From: Alistair Popple <apopple@nvidia.com>
Date: 2026-02-24 06:35:14
Also in:
linux-mm, lkml
On 2026-02-24 at 12:56 +1100, Baolin Wang [off-list ref] wrote...
The folio_referenced() is used to test whether a folio was referenced during reclaim. Moreover, ZONE_DEVICE folios are controlled by their device driver, have a lifetime tied to that driver, and are never placed on the LRU list. That means we should never try to reclaim ZONE_DEVICE folios, so add a warning to catch this unexpected behavior in folio_referenced() to avoid confusion, as discussed in the previous thread[1].
Agree with this so one you've handled Rik's comment feel free to add: Reviewed-by: Alistair Popple <apopple@nvidia.com>
quoted hunk ↗ jump to hunk
[1] https://lore.kernel.org/all/16fb7985-ec0f-4b56-91e7-404c5114f899@kernel.org/ (local) Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> --- mm/rmap.c | 1 + 1 file changed, 1 insertion(+)diff --git a/mm/rmap.c b/mm/rmap.c index bff8f222004e..be785dfc9336 100644 --- a/mm/rmap.c +++ b/mm/rmap.c@@ -1065,6 +1065,7 @@ int folio_referenced(struct folio *folio, int is_locked, .invalid_vma = invalid_folio_referenced_vma, }; + VM_WARN_ON_FOLIO(folio_is_zone_device(folio), folio); *vm_flags = 0; if (!pra.mapcount) return 0;-- 2.47.3