On 04.12.19 15:54, Qian Cai wrote: > > >> On Dec 3, 2019, at 6:02 AM, David Hildenbrand <david@xxxxxxxxxx> wrote: >> >> On 06.11.19 16:05, Steven Price wrote: >>> On 06/11/2019 13:31, Qian Cai wrote: >>>> >>>> >>>>> On Nov 4, 2019, at 2:35 PM, Qian Cai <cai@xxxxxx> wrote: >>>>> >>>>> On Fri, 2019-11-01 at 14:09 +0000, Steven Price wrote: >>> [...] >>>>>> Changes since v14: >>>>>> https://lore.kernel.org/lkml/20191028135910.33253-1-steven.price@xxxxxxx/ >>>>>> * Switch walk_page_range() into two functions, the existing >>>>>> walk_page_range() now still requires VMAs (and treats areas without a >>>>>> VMA as a 'hole'). The new walk_page_range_novma() ignores VMAs and >>>>>> will report the actual page table layout. This fixes the previous >>>>>> breakage of /proc/<pid>/pagemap >>>>>> * New patch at the end of the series which reduces the 'level' numbers >>>>>> by 1 to simplify the code slightly >>>>>> * Added tags >>>>> >>>>> Does this new version also take care of this boot crash seen with v14? Suppose >>>>> it is now breaking CONFIG_EFI_PGT_DUMP=y? The full config is, >>>>> >>>>> https://raw.githubusercontent.com/cailca/linux-mm/master/x86.config >>>>> >>>> >>>> V15 is indeed DOA here. >>> >>> Thanks for finding this, it looks like EFI causes issues here. The below fixes >>> this for me (booting in QEMU). >>> >>> Andrew: do you want me to send out the entire series again for this fix, or >>> can you squash this into mm-pagewalk-allow-walking-without-vma.patch? >>> >>> Thanks, >>> >>> Steve >>> >>> ---8<--- >>> diff --git a/mm/pagewalk.c b/mm/pagewalk.c >>> index c7529dc4f82b..70dcaa23598f 100644 >>> --- a/mm/pagewalk.c >>> +++ b/mm/pagewalk.c >>> @@ -90,7 +90,7 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end, >>> split_huge_pmd(walk->vma, pmd, addr); >>> if (pmd_trans_unstable(pmd)) >>> goto again; >>> - } else if (pmd_leaf(*pmd)) { >>> + } else if (pmd_leaf(*pmd) || !pmd_present(*pmd)) { >>> continue; >>> } >>> >>> @@ -141,7 +141,7 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end, >>> split_huge_pud(walk->vma, pud, addr); >>> if (pud_none(*pud)) >>> goto again; >>> - } else if (pud_leaf(*pud)) { >>> + } else if (pud_leaf(*pud) || !pud_present(*pud)) { >>> continue; >>> } >>> >>> >> >> Even with this fix, booting for me under QEMU fails. See >> >> https://lore.kernel.org/linux-mm/b7ce62f2-9a48-6e48-6685-003431e521aa@xxxxxxxxxx/ >> > > Yes, for some reasons, this starts to crash on almost all arches here, so it might be worth > for Andrew to revert those in the meantime while allowing Steven to rework. I agree, this produces too much noise. -- Thanks, David / dhildenb
