+ mm-lru_add_drain_all-do-local-lru_add_drain-first.patch added to mm-hotfixes-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm: lru_add_drain_all() do local lru_add_drain() first
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-lru_add_drain_all-do-local-lru_add_drain-first.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-lru_add_drain_all-do-local-lru_add_drain-first.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Hugh Dickins <hughd@google.com>
Subject: mm: lru_add_drain_all() do local lru_add_drain() first
Date: Mon, 8 Sep 2025 15:24:54 -0700 (PDT)

No numbers to back this up, but it seemed obvious to me, that if there are
competing lru_add_drain_all()ers, the work will be minimized if each
flushes its own local queues before locking and doing cross-CPU drains.

Link: https://lkml.kernel.org/r/33389bf8-f79d-d4dd-b7a4-680c4aa21b23@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@kernel.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Keir Fraser <keirf@google.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Li Zhe <lizhe.67@bytedance.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shivank Garg <shivankg@amd.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Xu <weixugc@google.com>
Cc: Will Deacon <will@kernel.org>
Cc: yangge <yangge1116@126.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/swap.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/mm/swap.c~mm-lru_add_drain_all-do-local-lru_add_drain-first
+++ a/mm/swap.c
@@ -834,6 +834,9 @@ static inline void __lru_add_drain_all(b
 	 */
 	this_gen = smp_load_acquire(&lru_drain_gen);
 
+	/* It helps everyone if we do our own local drain immediately. */
+	lru_add_drain();
+
 	mutex_lock(&lock);
 
 	/*
_

Patches currently in -mm which might be from hughd@google.com are

mm-gup-check-ref_count-instead-of-lru-before-migration.patch
mm-gup-local-lru_add_drain-to-avoid-lru_add_drain_all.patch
mm-revert-mm-gup-clear-the-lru-flag-of-a-page-before-adding-to-lru-batch.patch
mm-revert-mm-vmscanc-fix-oom-on-swap-stress-test.patch
mm-folio_may_be_lru_cached-unless-folio_test_large.patch
mm-lru_add_drain_all-do-local-lru_add_drain-first.patch