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authorWill Deacon <will@kernel.org>2021-01-14 15:33:49 +0000
committerWill Deacon <will@kernel.org>2021-01-21 12:50:18 +0000
commit2b635dd372f6c8f27644c662bb48d10376ce561a (patch)
tree5ab56f029d86cad3cf7ecce48701bca0ad9f40c8 /mm
parent9d3af4b448a119ac81378d3bc775f1c4a2a7ff36 (diff)
mm: Avoid modifying vmf.address in __collapse_huge_page_swapin()
In preparation for const-ifying the anonymous struct field of 'struct vm_fault', rework __collapse_huge_page_swapin() to avoid continuously updating vmf.address and instead populate a new 'struct vm_fault' on the stack for each page being processed. Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/khugepaged.c37
1 files changed, 18 insertions, 19 deletions
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 67ab391a5373..fb0fdaec34d5 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -991,38 +991,41 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
static bool __collapse_huge_page_swapin(struct mm_struct *mm,
struct vm_area_struct *vma,
- unsigned long address, pmd_t *pmd,
+ unsigned long haddr, pmd_t *pmd,
int referenced)
{
int swapped_in = 0;
vm_fault_t ret = 0;
- struct vm_fault vmf = {
- .vma = vma,
- .address = address,
- .flags = FAULT_FLAG_ALLOW_RETRY,
- .pmd = pmd,
- .pgoff = linear_page_index(vma, address),
- };
-
- vmf.pte = pte_offset_map(pmd, address);
- for (; vmf.address < address + HPAGE_PMD_NR*PAGE_SIZE;
- vmf.pte++, vmf.address += PAGE_SIZE) {
+ unsigned long address, end = haddr + (HPAGE_PMD_NR * PAGE_SIZE);
+
+ for (address = haddr; address < end; address += PAGE_SIZE) {
+ struct vm_fault vmf = {
+ .vma = vma,
+ .address = address,
+ .pgoff = linear_page_index(vma, haddr),
+ .flags = FAULT_FLAG_ALLOW_RETRY,
+ .pmd = pmd,
+ };
+
+ vmf.pte = pte_offset_map(pmd, address);
vmf.orig_pte = *vmf.pte;
- if (!is_swap_pte(vmf.orig_pte))
+ if (!is_swap_pte(vmf.orig_pte)) {
+ pte_unmap(vmf.pte);
continue;
+ }
swapped_in++;
ret = do_swap_page(&vmf);
/* do_swap_page returns VM_FAULT_RETRY with released mmap_lock */
if (ret & VM_FAULT_RETRY) {
mmap_read_lock(mm);
- if (hugepage_vma_revalidate(mm, address, &vmf.vma)) {
+ if (hugepage_vma_revalidate(mm, haddr, &vma)) {
/* vma is no longer available, don't continue to swapin */
trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0);
return false;
}
/* check if the pmd is still valid */
- if (mm_find_pmd(mm, address) != pmd) {
+ if (mm_find_pmd(mm, haddr) != pmd) {
trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0);
return false;
}
@@ -1031,11 +1034,7 @@ static bool __collapse_huge_page_swapin(struct mm_struct *mm,
trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0);
return false;
}
- /* pte is unmapped now, we need to map it */
- vmf.pte = pte_offset_map(pmd, vmf.address);
}
- vmf.pte--;
- pte_unmap(vmf.pte);
/* Drain LRU add pagevec to remove extra pin on the swapped in pages */
if (swapped_in)