kernel/git/next/linux-next.git/mm/balloon_compaction.c, branch master

mm: rename balloon_compaction.(c|h) to balloon.(c|h)

2026-01-31T22:22:35+00:00

Even without CONFIG_BALLOON_COMPACTION this infrastructure implements basic list and page management for a memory balloon. Link: https://lkml.kernel.org/r/20260119230133.3551867-21-david@kernel.org Signed-off-by: David Hildenbrand (Red Hat) Reviewed-by: Lorenzo Stoakes Acked-by: Michael S. Tsirkin Cc: Arnd Bergmann Cc: Christophe Leroy Cc: Eugenio Pérez Cc: Greg Kroah-Hartman Cc: Jason Wang Cc: Jerrin Shaji George Cc: Jonathan Corbet Cc: Liam Howlett Cc: Madhavan Srinivasan Cc: Michael Ellerman Cc: Michal Hocko Cc: Mike Rapoport Cc: Nicholas Piggin Cc: Oscar Salvador Cc: SeongJae Park Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Xuan Zhuo Cc: Zi Yan Signed-off-by: Andrew Morton

mm/balloon_compaction: mark remaining functions for having proper kerneldoc

2026-01-31T22:22:34+00:00

Looks like all we are missing for proper kerneldoc is another "*". Link: https://lkml.kernel.org/r/20260119230133.3551867-18-david@kernel.org Signed-off-by: David Hildenbrand (Red Hat) Reviewed-by: Lorenzo Stoakes Acked-by: Michael S. Tsirkin Cc: Arnd Bergmann Cc: Christophe Leroy Cc: Eugenio Pérez Cc: Greg Kroah-Hartman Cc: Jason Wang Cc: Jerrin Shaji George Cc: Jonathan Corbet Cc: Liam Howlett Cc: Madhavan Srinivasan Cc: Michael Ellerman Cc: Michal Hocko Cc: Mike Rapoport Cc: Nicholas Piggin Cc: Oscar Salvador Cc: SeongJae Park Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Xuan Zhuo Cc: Zi Yan Signed-off-by: Andrew Morton

mm/balloon_compaction: assert that the balloon_pages_lock is held

2026-01-31T22:22:34+00:00

Let's add some sanity checks for holding the balloon_pages_lock when we're effectively inflating/deflating a page. Link: https://lkml.kernel.org/r/20260119230133.3551867-17-david@kernel.org Signed-off-by: David Hildenbrand (Red Hat) Reviewed-by: Lorenzo Stoakes Acked-by: Michael S. Tsirkin Cc: Arnd Bergmann Cc: Christophe Leroy Cc: Eugenio Pérez Cc: Greg Kroah-Hartman Cc: Jason Wang Cc: Jerrin Shaji George Cc: Jonathan Corbet Cc: Liam Howlett Cc: Madhavan Srinivasan Cc: Michael Ellerman Cc: Michal Hocko Cc: Mike Rapoport Cc: Nicholas Piggin Cc: Oscar Salvador Cc: SeongJae Park Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Xuan Zhuo Cc: Zi Yan Signed-off-by: Andrew Morton

mm/balloon_compaction: move internal helpers to balloon_compaction.c

2026-01-31T22:22:34+00:00

Let's move the helpers that are not required by drivers anymore. While at it, drop the doc of balloon_page_device() as it is trivial. [david@kernel.org: move balloon_page_device() under CONFIG_BALLOON_COMPACTION] Link: https://lkml.kernel.org/r/27f0adf1-54c1-4d99-8b7f-fd45574e7f41@kernel.org Link: https://lkml.kernel.org/r/20260119230133.3551867-16-david@kernel.org Signed-off-by: David Hildenbrand (Red Hat) Reviewed-by: Lorenzo Stoakes Acked-by: Michael S. Tsirkin Cc: Arnd Bergmann Cc: Christophe Leroy Cc: Eugenio Pérez Cc: Greg Kroah-Hartman Cc: Jason Wang Cc: Jerrin Shaji George Cc: Jonathan Corbet Cc: Liam Howlett Cc: Madhavan Srinivasan Cc: Michael Ellerman Cc: Michal Hocko Cc: Mike Rapoport Cc: Nicholas Piggin Cc: Oscar Salvador Cc: SeongJae Park Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Xuan Zhuo Cc: Zi Yan Signed-off-by: Andrew Morton

mm/balloon_compaction: fold balloon_mapping_gfp_mask() into balloon_page_alloc()

2026-01-31T22:22:34+00:00

Let's just remove balloon_mapping_gfp_mask(). Link: https://lkml.kernel.org/r/20260119230133.3551867-15-david@kernel.org Signed-off-by: David Hildenbrand (Red Hat) Reviewed-by: Lorenzo Stoakes Acked-by: Michael S. Tsirkin Cc: Arnd Bergmann Cc: Christophe Leroy Cc: Eugenio Pérez Cc: Greg Kroah-Hartman Cc: Jason Wang Cc: Jerrin Shaji George Cc: Jonathan Corbet Cc: Liam Howlett Cc: Madhavan Srinivasan Cc: Michael Ellerman Cc: Michal Hocko Cc: Mike Rapoport Cc: Nicholas Piggin Cc: Oscar Salvador Cc: SeongJae Park Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Xuan Zhuo Cc: Zi Yan Signed-off-by: Andrew Morton

mm/balloon_compaction: remove balloon_page_push/pop()

2026-01-31T22:22:33+00:00

Let's remove these helpers as they are unused now. Link: https://lkml.kernel.org/r/20260119230133.3551867-14-david@kernel.org Signed-off-by: David Hildenbrand (Red Hat) Reviewed-by: Lorenzo Stoakes Acked-by: Michael S. Tsirkin Cc: Arnd Bergmann Cc: Christophe Leroy Cc: Eugenio Pérez Cc: Greg Kroah-Hartman Cc: Jason Wang Cc: Jerrin Shaji George Cc: Jonathan Corbet Cc: Liam Howlett Cc: Madhavan Srinivasan Cc: Michael Ellerman Cc: Michal Hocko Cc: Mike Rapoport Cc: Nicholas Piggin Cc: Oscar Salvador Cc: SeongJae Park Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Xuan Zhuo Cc: Zi Yan Signed-off-by: Andrew Morton

mm/balloon_compaction: make balloon_mops static

2026-01-31T22:22:33+00:00

There is no need to expose this anymore, so let's just make it static. Link: https://lkml.kernel.org/r/20260119230133.3551867-11-david@kernel.org Signed-off-by: David Hildenbrand (Red Hat) Reviewed-by: Lorenzo Stoakes Acked-by: Michael S. Tsirkin Cc: Arnd Bergmann Cc: Christophe Leroy Cc: Eugenio Pérez Cc: Greg Kroah-Hartman Cc: Jason Wang Cc: Jerrin Shaji George Cc: Jonathan Corbet Cc: Liam Howlett Cc: Madhavan Srinivasan Cc: Michael Ellerman Cc: Michal Hocko Cc: Mike Rapoport Cc: Nicholas Piggin Cc: Oscar Salvador Cc: SeongJae Park Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Xuan Zhuo Cc: Zi Yan Signed-off-by: Andrew Morton

mm/balloon_compaction: remove dependency on page lock

2026-01-31T22:22:32+00:00

Let's stop using the page lock in balloon code and instead use only the balloon_device_lock. As soon as we set the PG_movable_ops flag, we might now get isolation callbacks for that page as we are no longer holding the page lock. In there, we'll simply synchronize using the balloon_device_lock. So in balloon_page_isolate() lookup the balloon_dev_info through page->private under balloon_device_lock. It's crucial that we update page->private under the balloon_device_lock, so the isolation callback can properly deal with concurrent deflation. Consequently, make sure that balloon_page_finalize() is called under balloon_device_lock as we remove a page from the list and clear page->private. balloon_page_insert() is already called with the balloon_device_lock held. Note that the core will still lock the pages, for example in isolate_movable_ops_page(). The lock is there still relevant for handling the PageMovableOpsIsolated flag, but that can be later changed to use an atomic test-and-set instead, or moved into the movable_ops backends. Link: https://lkml.kernel.org/r/20260119230133.3551867-10-david@kernel.org Signed-off-by: David Hildenbrand (Red Hat) Acked-by: Michael S. Tsirkin Cc: Arnd Bergmann Cc: Christophe Leroy Cc: Eugenio Pérez Cc: Greg Kroah-Hartman Cc: Jason Wang Cc: Jerrin Shaji George Cc: Jonathan Corbet Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Madhavan Srinivasan Cc: Michael Ellerman Cc: Michal Hocko Cc: Mike Rapoport Cc: Nicholas Piggin Cc: Oscar Salvador Cc: SeongJae Park Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Xuan Zhuo Cc: Zi Yan Signed-off-by: Andrew Morton

mm/balloon_compaction: use a device-independent balloon (list) lock

2026-01-31T22:22:32+00:00

In order to remove the dependency on the page lock for balloon pages, we need a lock that is independent of the page. It's crucial that we can handle the scenario where balloon deflation (clearing page->private) can race with page isolation (using page->private to obtain the balloon_dev_info where the lock currently resides). The current lock in balloon_dev_info is therefore not suitable. Fortunately, we never really have more than a single balloon device per VM, so we can just keep it simple and use a static lock to protect all balloon devices. Based on this change we will remove the dependency on the page lock next. Link: https://lkml.kernel.org/r/20260119230133.3551867-9-david@kernel.org Signed-off-by: David Hildenbrand (Red Hat) Acked-by: Michael S. Tsirkin Cc: Arnd Bergmann Cc: Christophe Leroy Cc: Eugenio Pérez Cc: Greg Kroah-Hartman Cc: Jason Wang Cc: Jerrin Shaji George Cc: Jonathan Corbet Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Madhavan Srinivasan Cc: Michael Ellerman Cc: Michal Hocko Cc: Mike Rapoport Cc: Nicholas Piggin Cc: Oscar Salvador Cc: SeongJae Park Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Xuan Zhuo Cc: Zi Yan Signed-off-by: Andrew Morton

mm/balloon_compaction: centralize adjust_managed_page_count() handling

2026-01-31T22:22:32+00:00

Let's centralize it, by allowing for the driver to enable this handling through a new flag (bool for now) in the balloon device info. Note that we now adjust the counter when adding/removing a page into the balloon list: when removing a page to deflate it, it will now happen before the driver communicated with hypervisor, not afterwards. This shouldn't make a difference in practice. Link: https://lkml.kernel.org/r/20260119230133.3551867-7-david@kernel.org Signed-off-by: David Hildenbrand (Red Hat) Acked-by: Liam R. Howlett Acked-by: Michael S. Tsirkin Cc: Arnd Bergmann Cc: Christophe Leroy Cc: Eugenio Pérez Cc: Greg Kroah-Hartman Cc: Jason Wang Cc: Jerrin Shaji George Cc: Jonathan Corbet Cc: Lorenzo Stoakes Cc: Madhavan Srinivasan Cc: Michael Ellerman Cc: Michal Hocko Cc: Mike Rapoport Cc: Nicholas Piggin Cc: Oscar Salvador Cc: SeongJae Park Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Xuan Zhuo Cc: Zi Yan Signed-off-by: Andrew Morton