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huge_memory: convert do_huge_pmd_wp_page() to use a folio 

Removes many calls to compound_head().  Does not remove the assumption
that a folio may not be larger than a PMD.

Link: https://lkml.kernel.org/r/20220902194653.1739778-43-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2022-09-02 20:46:38 +01:00 committed by Andrew Morton
parent e4a2ed9490
commit 2fad3d14b9
1 changed files with 19 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

35
mm/huge_memory.c
View File

@ -1305,6 +1305,7 @@ vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf)
{
const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE;
struct vm_area_struct *vma = vmf->vma;
struct folio *folio;
struct page *page;
unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
pmd_t orig_pmd = vmf->orig_pmd;
@ -1326,46 +1327,48 @@ vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf)
}
page = pmd_page(orig_pmd);
folio = page_folio(page);
VM_BUG_ON_PAGE(!PageHead(page), page);
/* Early check when only holding the PT lock. */
if (PageAnonExclusive(page))
goto reuse;
if (!trylock_page(page)) {
get_page(page);
if (!folio_trylock(folio)) {
folio_get(folio);
spin_unlock(vmf->ptl);
lock_page(page);
folio_lock(folio);
spin_lock(vmf->ptl);
if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
spin_unlock(vmf->ptl);
unlock_page(page);
put_page(page);
folio_unlock(folio);
folio_put(folio);
return 0;
}
put_page(page);
folio_put(folio);
}
/* Recheck after temporarily dropping the PT lock. */
if (PageAnonExclusive(page)) {
unlock_page(page);
folio_unlock(folio);
goto reuse;
}
/*
* See do_wp_page(): we can only reuse the page exclusively if there are
* no additional references. Note that we always drain the LRU
* pagevecs immediately after adding a THP.
* See do_wp_page(): we can only reuse the folio exclusively if
* there are no additional references. Note that we always drain
* the LRU pagevecs immediately after adding a THP.
*/
if (page_count(page) > 1 + PageSwapCache(page) * thp_nr_pages(page))
if (folio_ref_count(folio) >
1 + folio_test_swapcache(folio) * folio_nr_pages(folio))
goto unlock_fallback;
if (PageSwapCache(page))
try_to_free_swap(page);
if (page_count(page) == 1) {
if (folio_test_swapcache(folio))
folio_free_swap(folio);
if (folio_ref_count(folio) == 1) {
pmd_t entry;
page_move_anon_rmap(page, vma);
unlock_page(page);
folio_unlock(folio);
reuse:
if (unlikely(unshare)) {
spin_unlock(vmf->ptl);
@ -1380,7 +1383,7 @@ reuse:
}
unlock_fallback:
unlock_page(page);
folio_unlock(folio);
spin_unlock(vmf->ptl);
fallback:
__split_huge_pmd(vma, vmf->pmd, vmf->address, false, NULL);