> On Sep 13, 2023, at 18:54, Usama Arif <usama.arif@xxxxxxxxxxxxx> wrote: > > The new boot flow when it comes to initialization of gigantic pages > is as follows: > - At boot time, for a gigantic page during __alloc_bootmem_hugepage, > the region after the first struct page is marked as noinit. > - This results in only the first struct page to be > initialized in reserve_bootmem_region. As the tail struct pages are > not initialized at this point, there can be a significant saving > in boot time if HVO succeeds later on. > - Later on in the boot, the head page is prepped and the first > HUGETLB_VMEMMAP_RESERVE_SIZE / sizeof(struct page) - 1 tail struct pages > are initialized. > - HVO is attempted. If it is not successful, then the rest of the > tail struct pages are initialized. If it is successful, no more > tail struct pages need to be initialized saving significant boot time. > > The WARN_ON for increased ref count in gather_bootmem_prealloc was changed > to a VM_BUG_ON. This is OK as there should be no speculative references > this early in boot process. The VM_BUG_ON's are there just in case such code > is introduced. > > Signed-off-by: Usama Arif <usama.arif@xxxxxxxxxxxxx> Reviewed-by: Muchun Song <songmuchun@xxxxxxxxxxxxx> Thanks for your work.
