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[172.10.233.147]) by smtp.gmail.com with ESMTPSA id 00721157ae682-84ca68c1b14sm34163727b3.21.2026.08.24.06.58.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 24 Aug 2026 06:58:58 -0700 (PDT) Date: Mon, 24 Aug 2026 06:58:54 -0700 (PDT) From: Hugh Dickins To: Andrew Morton cc: Ackerley Tng , Alexander Viro , Baolin Wang , Barry Song , Binbin Wu , Christian Brauner , Christoph Hellwig , Christoph Lameter , Claudio Imbrenda , David Hildenbrand , JP Kobryn , Jan Kara , Jens Axboe , Johannes Weiner , Kairui Song , Kiryl Shutsemau , Lance Yang , Leonardo Bras , Lorenzo Stoakes , Marcelo Tosatti , Matthew Wilcox , Mel Gorman , Miaohe Lin , Michal Hocko , Minchan Kim , Muchun Song , Oscar Salvador , Peter Zijlstra , Qi Zheng , Rik van Riel , Sebastian Andrzej Siewior , Shakeel Butt , Suren Baghdasaryan , Vlastimil Babka , Yang Shi , Yu Zhao , Zach O'Keefe , Zi Yan , linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 03/25] mm/fbatch: temporarily disable lazyfree and mlock+munlock batching In-Reply-To: <14a16945-529b-8bc0-ab38-3ea97e54e223@google.com> Message-ID: <9593975e-8732-999a-73d1-37fd332eb840@google.com> References: <14a16945-529b-8bc0-ab38-3ea97e54e223@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII 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 --- mm/folio.c | 2 ++ mm/mlock.c | 3 +++ 2 files changed, 5 insertions(+) diff --git a/mm/folio.c b/mm/folio.c index b2bce6b77498..a7010ae3edff 100644 --- a/mm/folio.c +++ b/mm/folio.c @@ -218,6 +218,8 @@ 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 efa6716e4dfb..14c02e155d68 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