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Mon, 11 May 2026 05:04:42 -0700 (PDT) From: Muchun Song To: Andrew Morton , Vlastimil Babka , linux-mm@kvack.org Cc: Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , Zi Yan , zihan zhou <15645113830zzh@gmail.com>, yaowenchao , linux-kernel@vger.kernel.org, Muchun Song , muchun.song@linux.dev Subject: [PATCH] mm/page_alloc: Fix zone reserve update serialization Date: Mon, 11 May 2026 20:04:09 +0800 Message-ID: <20260511120409.2264209-1-songmuchun@bytedance.com> X-Mailer: git-send-email 2.54.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 1D7364000E X-Stat-Signature: r5uh69oi49rz9jrs9s973uwhgwnsky4c X-HE-Tag: 1778501084-186058 X-HE-Meta: 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 y/35WaRV BE+3L5qE8pdmd+v8b+x92roZumIBgh+h6YPcTaUY08dijR/NyWmBc0MXDavY6EZZ20LFB3D3nkmPIxJor2ltM9UOFfM/u4gxIQ1aVdp0JYRr073mYw7GbB3MKH0hrXkluy2cy95e+k4i9QLqyDvKAWB8OhNUbdAvD2FW7qCpfvWGEU6vrAfRNFnX8IUgjeck91HpfwX6/0hIwDw/6KYeglYAzV5heiEh4JhIKBkuS6U5yd7RBFNtPrnWIZXr8BEKBQ/Xt5aq8IpM8zUjXqY2tYEBvyFNrUi091L/UzelnbAslBdbDPk6Hr27R2w1c6K+T3OBorChRnvsYUVomBU7l09UKH4Tddx+UEGEUOe4rciJD0x5JNP0VBzMJT6fWns39wo9fkYOXP7iriU62Yl+k3gNy0Q== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Serialize lowmem reserve and watermark updates with the same lock so calculate_totalreserve_pages() cannot observe partially updated zone reserve state. Fixes: 9726891fe753 ("mm: page_alloc: fix missed updates of lowmem_reserve in adjust_managed_page_count") Signed-off-by: Muchun Song --- mm/page_alloc.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 3a56825a7fc5..0989067da588 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -6384,6 +6384,8 @@ static void calculate_totalreserve_pages(void) trace_mm_calculate_totalreserve_pages(totalreserve_pages); } +static DEFINE_SPINLOCK(zone_reserve_lock); + /* * setup_per_zone_lowmem_reserve - called whenever * sysctl_lowmem_reserve_ratio changes. Ensures that each zone @@ -6394,6 +6396,8 @@ static void setup_per_zone_lowmem_reserve(void) { struct pglist_data *pgdat; enum zone_type i, j; + + guard(spinlock_irqsave)(&zone_reserve_lock); /* * For a given zone node_zones[i], lowmem_reserve[j] (j > i) * represents how many pages in zone i must effectively be kept @@ -6509,11 +6513,9 @@ static void __setup_per_zone_wmarks(void) void setup_per_zone_wmarks(void) { struct zone *zone; - static DEFINE_SPINLOCK(lock); - spin_lock(&lock); - __setup_per_zone_wmarks(); - spin_unlock(&lock); + scoped_guard(spinlock_irqsave, &zone_reserve_lock) + __setup_per_zone_wmarks(); /* * The watermark size have changed so update the pcpu batch base-commit: e98d21c170b01ddef366f023bbfcf6b31509fa83 -- 2.54.0