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X-OriginatorOrg: arm.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Dec 2025 09:32:06.8769 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 9eea9896-67f3-4125-7c3b-08de3e184fa8 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: DB5PEPF00014B8A.eurprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: FRZPR08MB11047 Hi David, > On 12/18/25 09:37, Yeoreum Yun wrote: > > [...] > > > > I think it would be better to use only __GFP_HIGH in here since > > > > when kpti_install_ng_mappings() is called, "kswpd" doesn't created yet. > > > > and to allocate page with assurance, It would be good to use > > > > min_reserved to. > > > > > > > > Am I missing something? > > > > > > Personally I think we should just use "GFP_KERNEL | __GFP_ZERO". Anything else > > > would make this allocation look special, which it is not. If we fail to allocate > > > at this point in boot, we have bigger problems. > > > > But I'm not sure *HOW effective* to use GFP_KERNEL in here. > > Since it's before the any filesystem inited. > > IOW, in this context, almost there would be no *page cache* > > and I think it seems meaningless to use "GFP_KERNEL" and "direct > > reclaim" > > > > So to get success for allocation, __GFP_HIGH | _GFP_ZERO seems much > > better. > > Unless there is a real reason to confuse readers why this is very special, > just go with "GFP_KERNEL | __GFP_ZERO", really. > > In particular if it doesn't matter in practice? Or does it and we are not > getting your point? My worries was - kpti_install_ng_mappings() is called while in "smp_init()" which is before creating the kswapd thread via module_init(). Just wondered whether it allows to call wakeup_kswapd() before kswapd is created. - Similar reason kcompactd too. - Just wonder how much direct reclaim is effecitve since when kpti_install_ng_mappings() called before each filesystem initialised where not much of page cache in usage. TBH (1) and (2) seems fine since each wakeup function checks the waitqueue. but because of (3), I think not GFP_KERNEL but __GFP_HIGH | __GFP_DIRECT_RECLAIM | __GFP_ZERO (?) Am I missing? -- Sincerely, Yeoreum Yun