20 Dec
2021
20 Dec
'21
6:52 p.m.
On Mon, Dec 20, 2021 at 06:37:30PM +0000, Matthew Wilcox wrote:
+++ b/mm/memory.c @@ -3626,7 +3626,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES); dec_mm_counter_fast(vma->vm_mm, MM_SWAPENTS); pte = mk_pte(page, vma->vm_page_prot);
- if ((vmf->flags & FAULT_FLAG_WRITE) && reuse_swap_page(page, NULL)) {
- if ((vmf->flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) { pte = maybe_mkwrite(pte_mkdirty(pte), vma); vmf->flags &= ~FAULT_FLAG_WRITE; ret |= VM_FAULT_WRITE;
[...]
@@ -1673,17 +1665,14 @@ static int page_trans_huge_map_swapcount(struct page *page, int *total_mapcount,
- reuse_swap_page() returns false, but it may be always overwritten
- (see the other implementation for CONFIG_SWAP=n).
*/ -bool reuse_swap_page(struct page *page, int *total_map_swapcount) +bool reuse_swap_page(struct page *page) {
- int count, total_mapcount, total_swapcount;
- int count, total_swapcount;
VM_BUG_ON_PAGE(!PageLocked(page), page); if (unlikely(PageKsm(page))) return false;
- count = page_trans_huge_map_swapcount(page, &total_mapcount,
&total_swapcount);- if (total_map_swapcount)
*total_map_swapcount = total_mapcount + total_swapcount;
- count = page_trans_huge_map_swapcount(page, &total_swapcount); if (count == 1 && PageSwapCache(page) && (likely(!PageTransCompound(page)) || /* The remaining swap count will be freed soon */
It makes me wonder if reuse_swap_page() can also be based on refcount instead of mapcount?