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X-OriginatorOrg: arm.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Dec 2025 09:37:15.4836 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 7e0e470d-b78b-4116-ec62-08de3e190793 X-MS-Exchange-CrossTenant-Id: f34e5979-57d9-4aaa-ad4d-b122a662184d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=f34e5979-57d9-4aaa-ad4d-b122a662184d;Ip=[4.158.2.129];Helo=[outbound-uk1.az.dlp.m.darktrace.com] X-MS-Exchange-CrossTenant-AuthSource: AM3PEPF0000A796.eurprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DU0PR08MB9510 Hi, > On Fri 12-12-25 16:18:32, Yeoreum Yun wrote: > > linear_map_split_to_ptes() and __kpti_install_ng_mappings() > > are called as callback of stop_machine(). > > That means these functions context are preemption disabled. > > > > Unfortunately, under PREEMPT_RT, the pagetable_alloc() or > > __get_free_pages() couldn't be called in this context > > since spin lock that becomes sleepable on RT, > > potentially causing a sleep during page allocation. > > > > To address this, pagetable_alloc_nolock(). > > As you cannot tolerate allocation failure and this is pretty much > permanent allocation (AFAIU) why don't you use a static allocation? Because of when bbl2_noabort is supported, that pages doesn't need to. If static alloc, that would be a waste in the system where bbl2_noabort is supported. When I tested, these extra pages are more than 40 in my FVP. So, it would be better dynamic allocation and I think since it's quite a early time, it's probably not failed that's why former code runs as it is. -- Sincerely, Yeoreum Yun