On 07/17/2020 02:06 PM, Will Deacon wrote: > On Fri, Jul 17, 2020 at 10:32:53AM +0530, Anshuman Khandual wrote: >> >> >> On 07/16/2020 11:55 PM, Mike Kravetz wrote: >>> >From 17c8f37afbf42fe7412e6eebb3619c6e0b7e1c3c Mon Sep 17 00:00:00 2001 >>> From: Mike Kravetz <mike.kravetz@xxxxxxxxxx> >>> Date: Tue, 14 Jul 2020 15:54:46 -0700 >>> Subject: [PATCH] hugetlb: move cma reservation to code setting up gigantic >>> hstate >>> >>> Instead of calling hugetlb_cma_reserve() directly from arch specific >>> code, call from hugetlb_add_hstate when adding a gigantic hstate. >>> hugetlb_add_hstate is either called from arch specific huge page setup, >>> or as the result of hugetlb command line processing. In either case, >>> this is late enough in the init process that all numa memory information >>> should be initialized. And, it is early enough to still use early >>> memory allocator. >> >> This assumes that hugetlb_add_hstate() is called from the arch code at >> the right point in time for the generic HugeTLB to do the required CMA >> reservation which is not ideal. I guess it must have been a reason why >> CMA reservation should always called by the platform code which knows >> the boot sequence timing better. > > Ha, except we've moved it around two or three times already in the last > month or so, so I'd say we don't have a clue when to call it in the arch > code. The arch dependency is not going way with this change either. Just that its getting transferred to hugetlb_add_hstate() which gets called from arch_initcall() in every architecture. The perfect timing here happens to be because of arch_initcall() instead. This is probably fine, as long as 0. hugetlb_add_hstate() is always called at arch_initcall() 1. N_MEMORY mask is guaranteed to be initialized at arch_initcall() 2. CMA reservation is available to be called at arch_initcall()
