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From: Muchun Song In-Reply-To: Date: Thu, 30 Apr 2026 15:59:33 +0800 Cc: Usama Arif , Oscar Salvador , Miaohe Lin , Muchun Song , Vishal Verma , Ying Huang , Dan Williams , Naoya Horiguchi , linux-mm@kvack.org, linux-cxl@vger.kernel.org, driver-core@lists.linux.dev, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Greg Kroah-Hartman , Rafael J Wysocki , Danilo Krummrich , Andrew Morton Content-Transfer-Encoding: quoted-printable Message-Id: References: <20260429101134.1358607-1-usama.arif@linux.dev> To: "David Hildenbrand (Arm)" X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 44D69120003 X-Stat-Signature: iapnw84w14wqo4q1k9ckstzzaku676bx X-Rspam-User: X-HE-Tag: 1777536046-452551 X-HE-Meta: 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 fZaZVFW4 AKpPztbVaZyEpSzYuj+YsRY4PwSO84EKvsdrJRx1zlU6X0qc9J9JMwA2pm0OJBf6S1zgROmKXjOo1RHpR+NtD0VHRfgWJKg4GKJAniwbtgxksoXcVGLY1Uu6r7fZZ7+cUVVjuW6e9RtR1IcGVCL3qxNwLYkodsETTFGC+rU9+Xdrg5/CBUt5JHEJFxjf7ecT4YThAm94ZjHlSTMvYZ9u4Mr8LuIzXTxgU6gsfjl3ujHCkHUC2vgFkl3rgygk1IpvzDaS6EH1nYIP19UFAB8YGCmaK4y0eZZLAoHqTU1BZlbxg2UOjF3pDqSfXMBaAeWFXk/yBcKqoozGoH+BZ56+ozW5IVCTWfQ6uHEzojfxS+vgUKaBni8Nmcq87lbmz7/FEzWdaOEEaoHHh1H7vgvGbetGvAIiwrYra5XqF Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > On Apr 29, 2026, at 18:44, David Hildenbrand (Arm) = wrote: >=20 > On 4/29/26 12:11, Usama Arif wrote: >> On Wed, 29 Apr 2026 12:18:08 +0800 Muchun Song = wrote: >>=20 >>>=20 >>>=20 >>>>=20 >>>>=20 >>>> lock_device_hotplug is a mutex lock, and we already take other = mutex locks while >>>> holding lock_folio in other paths, so I am not sure I see what = should be special >>>> in this case. >>>=20 >>> Hi Oscar and Miaohe, >>>=20 >>> I saw sashiko's report [1] related to folio lock and = lock_device_hotplug. >>> Seems it is possible. You can correct me if I am wrong. >>>=20 >>> [1] = https://sashiko.dev/#/patchset/20260428085219.1316047-1-songmuchun%40byted= ance.com >>>=20 >>> We could fix this by calling action_result() without holding folio = lock. >>> What do you think? >>>=20 >>=20 >> Hello Muchun, >>=20 >> You could end up in memblk_nr_poison_sub() while holding hugetlb_lock = spin lock >> from get_huge_page_for_hwpoison(), right? >>=20 >> Lockdep would flag this as sleeping while atomic when acquiring mutex = I think. >=20 > Another thought would be, that we always call the inc/sub from memory = failure > code while we hold a folio reference and the page is not poisoned yet. >=20 > That way, memory offlining cannot continue and the memory block cannot = go away. >=20 > So we'd let out page reference keep the memory block alive. It seems unnecessary to hold lock_device_hotplug if the user already = holds a refcount on the page. I'd like to drop this patch. Thanks. >=20 > --=20 > Cheers, >=20 > David