Le 29/05/2024 à 10:02, Oscar Salvador a écrit : > [Vous ne recevez pas souvent de courriers de osalvador@xxxxxxxx. D?couvrez pourquoi ceci est important ? https://aka.ms/LearnAboutSenderIdentification ] > > On Mon, May 27, 2024 at 03:30:06PM +0200, Christophe Leroy wrote: >> In order to fit better with standard Linux page tables layout, add >> support for 8M pages using contiguous PTE entries in a standard >> page table. Page tables will then be populated with 1024 similar >> entries and two PMD entries will point to that page table. >> >> The PMD entries also get a flag to tell it is addressing an 8M page, >> this is required for the HW tablewalk assistance. >> >> Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx> >> Reviewed-by: Oscar Salvador <osalvador@xxxxxxx> >> --- > ... >> +#define __HAVE_ARCH_HUGE_PTEP_GET >> +static inline pte_t huge_ptep_get(struct mm_struct *mm, unsigned long addr, pte_t *ptep) >> +{ >> + if (ptep_is_8m_pmdp(mm, addr, ptep)) >> + ptep = pte_offset_kernel((pmd_t *)ptep, 0); > > Yes, you are right that this should have had the addr aligned down. > > I can speak for others, but for me it is more clear to think of it this way: > > 1) check if ptep points to the first PMD entry for address > 2) if it does, we know that the PMD describes a 8MB hugepage > 3) return the PMD But it is not exactly the way I see it, maybe I'm wrong but from my point of view: 1) check if ptep points to the first PMD entry for address 2) if it does, we know that the PMD relates to a 8MB hugepage 3) Return the first PTE in the page table pointed by the said PMD entry. > > That is why I thought that directly calling pmd_page_vaddr() gave a more clear > overview. > > Now, feel free to ignore this if you think this is not clear or adds confusion, > I just wanted to give my insight reflecting on what I considered more > logical. For me using pte_offset_kernel() make it more clear that we want a PTE in a page table, and not some raw information at a given address pointed to by a huge-PMD. Am I wrong ? > > > -- > Oscar Salvador > SUSE Labs
