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/ -- Thanks, David / dhildenb
