[PATCH v2 03/26] mm/fbatch: temporarily disable lazyfree and mlock+munlock batching
From: Hugh Dickins <hughd@google.com>
Date: 2026-09-09 09:46:52
Also in:
linux-block, linux-fsdevel, linux-mm
Subsystem:
memory management, memory management - core, memory mapping, the rest · Maintainers:
Andrew Morton, David Hildenbrand, Liam R. Howlett, Lorenzo Stoakes, Linus Torvalds
It will not matter if we occasionally get activation or deactivation wrong; but a mistaken lazyfree (MADV_FREE) would likely cause dataloss. So disable its batching while reworking the per-cpu fbatch handling, then re-enable it with more thought afterwards. Similarly disable mlock+munlock batching temporarily: they will need some redesign before re-enabling. Just insert one disabling line for now, leaving the rest of the code as it was, for consideration later. Signed-off-by: Hugh Dickins <hughd@google.com> Reviewed-By: Vlastimil Babka (SUSE) <vbabka@kernel.org> --- mm/folio.c | 2 ++ mm/mlock.c | 3 +++ 2 files changed, 5 insertions(+)
diff --git a/mm/folio.c b/mm/folio.c
index ad6c64a4c22c..b9dc4f5e10a6 100644
--- a/mm/folio.c
+++ b/mm/folio.c@@ -219,6 +219,8 @@ static void __folio_batch_add_and_move(struct folio_batch __percpu *fbatch, local_lock(&cpu_fbatches.lock); if (!folio_batch_add(this_cpu_ptr(fbatch), folio) || + /* XXX Temporarily disable lazyfree batching */ + fbatch == &cpu_fbatches.lru_lazyfree || !folio_may_be_lru_cached(folio) || lru_cache_disabled()) folio_batch_move_lru(this_cpu_ptr(fbatch), move_fn);
diff --git a/mm/mlock.c b/mm/mlock.c
index 39215a3eab1f..929abeac85d0 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c@@ -255,6 +255,7 @@ void mlock_folio(struct folio *folio) folio_get(folio); if (!folio_batch_add(fbatch, mlock_lru(folio)) || + true || /* XXX Temporarily disable mlock batching */ !folio_may_be_lru_cached(folio) || lru_cache_disabled()) mlock_folio_batch(fbatch); local_unlock(&mlock_fbatch.lock);
@@ -278,6 +279,7 @@ void mlock_new_folio(struct folio *folio) folio_get(folio); if (!folio_batch_add(fbatch, mlock_new(folio)) || + true || /* XXX Temporarily disable mlock_new batching */ !folio_may_be_lru_cached(folio) || lru_cache_disabled()) mlock_folio_batch(fbatch); local_unlock(&mlock_fbatch.lock);
@@ -299,6 +301,7 @@ void munlock_folio(struct folio *folio) */ folio_get(folio); if (!folio_batch_add(fbatch, folio) || + true || /* XXX Temporarily disable munlock batching */ !folio_may_be_lru_cached(folio) || lru_cache_disabled()) mlock_folio_batch(fbatch); local_unlock(&mlock_fbatch.lock);
--
2.51.0