[PATCH v3 04/24] mm/balloon_compaction: improve comments for WARN_ON_ONCE(!b_dev_info)
From: "David Hildenbrand (Red Hat)" <david@kernel.org>
Date: 2026-01-19 23:02:09
Also in:
linux-doc, linux-mm, lkml, virtualization
Subsystem:
memory management, the rest · Maintainers:
Andrew Morton, Linus Torvalds
Let's clarify a bit by extending the comments. Signed-off-by: David Hildenbrand (Red Hat) <david@kernel.org> --- mm/balloon_compaction.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c
index 03c5dbabb1565..85eea88cea083 100644
--- a/mm/balloon_compaction.c
+++ b/mm/balloon_compaction.c@@ -222,7 +222,11 @@ static void balloon_page_putback(struct page *page) struct balloon_dev_info *b_dev_info = balloon_page_device(page); unsigned long flags; - /* Isolated balloon pages cannot get deflated. */ + /* + * When we isolated the page, the page was still inflated in a balloon + * device. As isolated balloon pages cannot get deflated, we still have + * a balloon device here. + */ if (WARN_ON_ONCE(!b_dev_info)) return;
@@ -241,7 +245,11 @@ static int balloon_page_migrate(struct page *newpage, struct page *page, VM_BUG_ON_PAGE(!PageLocked(page), page); VM_BUG_ON_PAGE(!PageLocked(newpage), newpage); - /* Isolated balloon pages cannot get deflated. */ + /* + * When we isolated the page, the page was still inflated in a balloon + * device. As isolated balloon pages cannot get deflated, we still have + * a balloon device here. + */ if (WARN_ON_ONCE(!balloon)) return -EAGAIN;
--
2.52.0