[PATCH v13 12/22] mm: pagewalk: Allow walking without vma
From: Steven Price <steven.price@arm.com>
Date: 2019-10-24 09:38:09
Also in:
linux-mm, lkml
Subsystem:
memory management, memory management - core, the rest · Maintainers:
Andrew Morton, David Hildenbrand, Linus Torvalds
Since 48684a65b4e3: "mm: pagewalk: fix misbehavior of walk_page_range for vma(VM_PFNMAP)", page_table_walk() will report any kernel area as a hole, because it lacks a vma. This means each arch has re-implemented page table walking when needed, for example in the per-arch ptdump walker. Remove the requirement to have a vma except when trying to split huge pages. Signed-off-by: Steven Price <steven.price@arm.com> --- mm/pagewalk.c | 25 +++++++++++++++++-------- 1 file changed, 17 insertions(+), 8 deletions(-)
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index fc4d98a3a5a0..4139e9163aee 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c@@ -38,7 +38,7 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end, do { again: next = pmd_addr_end(addr, end); - if (pmd_none(*pmd) || !walk->vma) { + if (pmd_none(*pmd)) { if (ops->pte_hole) err = ops->pte_hole(addr, next, walk); if (err)
@@ -61,9 +61,14 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end, if (!ops->pte_entry) continue; - split_huge_pmd(walk->vma, pmd, addr); - if (pmd_trans_unstable(pmd)) - goto again; + if (walk->vma) { + split_huge_pmd(walk->vma, pmd, addr); + if (pmd_trans_unstable(pmd)) + goto again; + } else if (pmd_leaf(*pmd)) { + continue; + } + err = walk_pte_range(pmd, addr, next, walk); if (err) break;
@@ -84,7 +89,7 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end, do { again: next = pud_addr_end(addr, end); - if (pud_none(*pud) || !walk->vma) { + if (pud_none(*pud)) { if (ops->pte_hole) err = ops->pte_hole(addr, next, walk); if (err)
@@ -98,9 +103,13 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end, break; } - split_huge_pud(walk->vma, pud, addr); - if (pud_none(*pud)) - goto again; + if (walk->vma) { + split_huge_pud(walk->vma, pud, addr); + if (pud_none(*pud)) + goto again; + } else if (pud_leaf(*pud)) { + continue; + } if (ops->pmd_entry || ops->pte_entry) err = walk_pmd_range(pud, addr, next, walk);
--
2.20.1
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