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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>
This commit is contained in:
Will Deacon 2021-01-14 15:33:49 +00:00
parent 9d3af4b448
commit 2b635dd372
1 changed files with 17 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

35
mm/khugepaged.c
View File

@ -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),
};
unsigned long address, end = haddr + (HPAGE_PMD_NR * PAGE_SIZE);
vmf.pte = pte_offset_map(pmd, address);
for (; vmf.address < address + HPAGE_PMD_NR*PAGE_SIZE;
vmf.pte++, vmf.address += 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)