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Wysocki" , Danilo Krummrich , Andrew Morton Cc: Vishal Verma , Ying Huang , Dan Williams , Miaohe Lin , Naoya Horiguchi , linux-mm@kvack.org, linux-cxl@vger.kernel.org, driver-core@lists.linux.dev, linux-kernel@vger.kernel.org, Muchun Song , stable@vger.kernel.org, muchun.song@linux.dev Subject: [PATCH v2 3/3] drivers/base/memory: fix locking for poison accounting lookup Date: Tue, 28 Apr 2026 16:52:19 +0800 Message-Id: <20260428085219.1316047-4-songmuchun@bytedance.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20260428085219.1316047-1-songmuchun@bytedance.com> References: <20260428085219.1316047-1-songmuchun@bytedance.com> Precedence: bulk X-Mailing-List: driver-core@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit memblk_nr_poison_inc() and memblk_nr_poison_sub() call find_memory_block_by_id(), which requires device_hotplug_lock to serialize the xarray lookup against memory block removal. Take device_hotplug_lock around the lookup and nr_hwpoison update so the memory block cannot disappear between xa_load() and get_device(). Fixes: 5033091de814 ("mm/hwpoison: introduce per-memory_block hwpoison counter") Cc: stable@vger.kernel.org Signed-off-by: Muchun Song --- drivers/base/memory.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/base/memory.c b/drivers/base/memory.c index 6981b55d582a..f76aee29e9a5 100644 --- a/drivers/base/memory.c +++ b/drivers/base/memory.c @@ -1228,23 +1228,29 @@ int walk_dynamic_memory_groups(int nid, walk_memory_groups_func_t func, void memblk_nr_poison_inc(unsigned long pfn) { const unsigned long block_id = pfn_to_block_id(pfn); - struct memory_block *mem = find_memory_block_by_id(block_id); + struct memory_block *mem; + lock_device_hotplug(); + mem = find_memory_block_by_id(block_id); if (mem) { atomic_long_inc(&mem->nr_hwpoison); put_device(&mem->dev); } + unlock_device_hotplug(); } void memblk_nr_poison_sub(unsigned long pfn, long i) { const unsigned long block_id = pfn_to_block_id(pfn); - struct memory_block *mem = find_memory_block_by_id(block_id); + struct memory_block *mem; + lock_device_hotplug(); + mem = find_memory_block_by_id(block_id); if (mem) { atomic_long_sub(i, &mem->nr_hwpoison); put_device(&mem->dev); } + unlock_device_hotplug(); } static unsigned long memblk_nr_poison(struct memory_block *mem) -- 2.20.1