[PATCH 05/12] mm: allow a NULL fn callback in apply_to_page_range
Tvrtko Ursulin
tvrtko.ursulin at linux.intel.com
Thu Sep 24 07:30:37 UTC 2020
From: Christoph Hellwig <hch at lst.de>
Besides calling the callback on each page, apply_to_page_range also has
the effect of pre-faulting all PTEs for the range. To support callers
that only need the pre-faulting, make the callback optional.
Based on a patch from Minchan Kim <minchan at kernel.org>.
Signed-off-by: Christoph Hellwig <hch at lst.de>
---
mm/memory.c | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)
diff --git a/mm/memory.c b/mm/memory.c
index 469af373ae76..a60136046d7f 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2231,13 +2231,15 @@ static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
arch_enter_lazy_mmu_mode();
- do {
- if (create || !pte_none(*pte)) {
- err = fn(pte++, addr, data);
- if (err)
- break;
- }
- } while (addr += PAGE_SIZE, addr != end);
+ if (fn) {
+ do {
+ if (create || !pte_none(*pte)) {
+ err = fn(pte++, addr, data);
+ if (err)
+ break;
+ }
+ } while (addr += PAGE_SIZE, addr != end);
+ }
*mask |= PGTBL_PTE_MODIFIED;
arch_leave_lazy_mmu_mode();
--
2.25.1
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