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Thu, 3 Jul 2025 15:46:08 +0800 Message-ID: <373d02c5-2b62-8543-b786-8fd591ad56eb@huawei.com> Date: Thu, 3 Jul 2025 15:46:08 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.15.1 Subject: Re: [PATCH v2 2/2] mm/memory_hotplug: fix hwpoisoned large folio handling in do_migrate_range To: Oscar Salvador CC: , , , , , References: <20250627125747.3094074-1-tujinjiang@huawei.com> <20250627125747.3094074-3-tujinjiang@huawei.com> From: Jinjiang Tu In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.179.13] X-ClientProxiedBy: kwepems500001.china.huawei.com (7.221.188.70) To kwepemo200002.china.huawei.com (7.202.195.209) X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: AFAF31C000A X-Stat-Signature: 3pib41x77496ujuzk5h13xgp5yh9q9p7 X-HE-Tag: 1751528773-352740 X-HE-Meta: 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 ua1yryi+ U/VOhrfhHklhL843wZlI7FMMQPpbkRQMI0HxlyotO8uZ9eBBe/iLRV2Qcbp+PD6lLYpZL4TtIEhgmCKNdHyfPrzmBArXPy/F8UgDK8vURH+Z6188c4ClQh/0Hzm8NE4HKJvAOLvsNJP8fUcg8U5hBphEPeJv8s19SPZOJVSAoc2wnv6vu6EF21FSetEG1k6OiQENvu+iNonGTT9x9rJ7eWrBtJuwXSmb2hkGeXa3WTuPTAoQFa3EsGlPfhplcGhuqXCqPMG73uoReyZw= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 在 2025/7/1 22:21, Oscar Salvador 写道: > On Fri, Jun 27, 2025 at 08:57:47PM +0800, Jinjiang Tu wrote: >> In do_migrate_range(), the hwpoisoned folio may be large folio, which >> can't be handled by unmap_poisoned_folio(). >> >> I can reproduce this issue in qemu after adding delay in memory_failure() >> >> BUG: kernel NULL pointer dereference, address: 0000000000000000 >> Workqueue: kacpi_hotplug acpi_hotplug_work_fn >> RIP: 0010:try_to_unmap_one+0x16a/0xfc0 >> >> rmap_walk_anon+0xda/0x1f0 >> try_to_unmap+0x78/0x80 >> ? __pfx_try_to_unmap_one+0x10/0x10 >> ? __pfx_folio_not_mapped+0x10/0x10 >> ? __pfx_folio_lock_anon_vma_read+0x10/0x10 >> unmap_poisoned_folio+0x60/0x140 >> do_migrate_range+0x4d1/0x600 >> ? slab_memory_callback+0x6a/0x190 >> ? notifier_call_chain+0x56/0xb0 >> offline_pages+0x3e6/0x460 >> memory_subsys_offline+0x130/0x1f0 >> device_offline+0xba/0x110 >> acpi_bus_offline+0xb7/0x130 >> acpi_scan_hot_remove+0x77/0x290 >> acpi_device_hotplug+0x1e0/0x240 >> acpi_hotplug_work_fn+0x1a/0x30 >> process_one_work+0x186/0x340 >> >> In this case, just make offline_pages() fail. >> >> Besides, do_migrate_range() may be called between memory_failure set >> hwposion flag and ioslate the folio from lru, so remove WARN_ON(). In other >> places, unmap_poisoned_folio() is called when the folio is isolated, obey >> it in do_migrate_range() too. >> >> Fixes: b15c87263a69 ("hwpoison, memory_hotplug: allow hwpoisoned pages to be offlined") >> Signed-off-by: Jinjiang Tu > ... >> @@ -2041,11 +2048,9 @@ int offline_pages(unsigned long start_pfn, unsigned long nr_pages, >> >> ret = scan_movable_pages(pfn, end_pfn, &pfn); >> if (!ret) { >> - /* >> - * TODO: fatal migration failures should bail >> - * out >> - */ >> - do_migrate_range(pfn, end_pfn); >> + ret = do_migrate_range(pfn, end_pfn); >> + if (ret) >> + break; > I am not really sure about this one. > I get the reason you're adding it, but note that migrate_pages() can also return > "fatal" errors and we don't propagate that. > > The moto has always been to migrate as much as possible, and this changes this > behaviour. > If we just skip to next pfn, offline_pages() will deadloop meaningless util received signal. It seems there is no document to guarantee memory offline have to migrate as much as possible. >