Commit 96db66d9 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Andrew Morton
Browse files

mm: convert ksm_might_need_to_copy() to work on folios 



Patch series "Finish two folio conversions".

Most callers of page_add_new_anon_rmap() and
lru_cache_add_inactive_or_unevictable() have been converted to their folio
equivalents, but there are still a few stragglers.  There's a bit of
preparatory work in ksm and unuse_pte(), but after that it's pretty
mechanical.


This patch (of 9):

Accept a folio as an argument and return a folio result.  Removes a call
to compound_head() in do_swap_page(), and prevents folio & page from
getting out of sync in unuse_pte().

Reviewed-by: default avatarDavid Hildenbrand <david@redhat.com>
[willy@infradead.org: fix smatch warning]
  Link: https://lkml.kernel.org/r/ZXnPtblC6A1IkyAB@casper.infradead.org
[david@redhat.com: only adjust the page if the folio changed]
  Link: https://lkml.kernel.org/r/6a8f2110-fa91-4c10-9eae-88315309a6e3@redhat.com
Link: https://lkml.kernel.org/r/20231211162214.2146080-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20231211162214.2146080-2-willy@infradead.org


Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: default avatarDavid Hildenbrand <david@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent a2bf6a9c

include/linux/ksm.h

+3 −3
Original line number Diff line number Diff line
@@ -76,7 +76,7 @@ static inline void ksm_exit(struct mm_struct *mm) 
 * We'd like to make this conditional on vma->vm_flags & VM_MERGEABLE,

 * but what if the vma was unmerged while the page was swapped out?

 */

struct page *ksm_might_need_to_copy(struct page *page,

struct folio *ksm_might_need_to_copy(struct folio *folio,

			struct vm_area_struct *vma, unsigned long addr);



void rmap_walk_ksm(struct folio *folio, struct rmap_walk_control *rwc);
@@ -129,10 +129,10 @@ static inline int ksm_madvise(struct vm_area_struct *vma, unsigned long start, 
	return 0;

}



static inline struct page *ksm_might_need_to_copy(struct page *page,

static inline struct folio *ksm_might_need_to_copy(struct folio *folio,

			struct vm_area_struct *vma, unsigned long addr)

{

	return page;

	return folio;

}



static inline void rmap_walk_ksm(struct folio *folio,

mm/ksm.c

+11 −10
Original line number Diff line number Diff line
@@ -2873,30 +2873,30 @@ void __ksm_exit(struct mm_struct *mm) 
	trace_ksm_exit(mm);

}



struct page *ksm_might_need_to_copy(struct page *page,

struct folio *ksm_might_need_to_copy(struct folio *folio,

			struct vm_area_struct *vma, unsigned long addr)

{

	struct folio *folio = page_folio(page);

	struct page *page = folio_page(folio, 0);

	struct anon_vma *anon_vma = folio_anon_vma(folio);

	struct folio *new_folio;



	if (folio_test_large(folio))

		return page;

		return folio;



	if (folio_test_ksm(folio)) {

		if (folio_stable_node(folio) &&

		    !(ksm_run & KSM_RUN_UNMERGE))

			return page;	/* no need to copy it */

			return folio;	/* no need to copy it */

	} else if (!anon_vma) {

		return page;		/* no need to copy it */

		return folio;		/* no need to copy it */

	} else if (folio->index == linear_page_index(vma, addr) &&

			anon_vma->root == vma->anon_vma->root) {

		return page;		/* still no need to copy it */

		return folio;		/* still no need to copy it */

	}

	if (PageHWPoison(page))

		return ERR_PTR(-EHWPOISON);

	if (!folio_test_uptodate(folio))

		return page;		/* let do_swap_page report the error */

		return folio;		/* let do_swap_page report the error */



	new_folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, addr, false);

	if (new_folio &&
@@ -2905,9 +2905,10 @@ struct page *ksm_might_need_to_copy(struct page *page, 
		new_folio = NULL;

	}

	if (new_folio) {

		if (copy_mc_user_highpage(&new_folio->page, page, addr, vma)) {

		if (copy_mc_user_highpage(folio_page(new_folio, 0), page,

								addr, vma)) {

			folio_put(new_folio);

			memory_failure_queue(page_to_pfn(page), 0);

			memory_failure_queue(folio_pfn(folio), 0);

			return ERR_PTR(-EHWPOISON);

		}

		folio_set_dirty(new_folio);
@@ -2918,7 +2919,7 @@ struct page *ksm_might_need_to_copy(struct page *page, 
#endif

	}



	return new_folio ? &new_folio->page : NULL;

	return new_folio;

}



void rmap_walk_ksm(struct folio *folio, struct rmap_walk_control *rwc)

mm/memory.c

+7 −4
Original line number Diff line number Diff line
@@ -3942,15 +3942,18 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) 
		 * page->index of !PageKSM() pages would be nonlinear inside the

		 * anon VMA -- PageKSM() is lost on actual swapout.

		 */

		page = ksm_might_need_to_copy(page, vma, vmf->address);

		if (unlikely(!page)) {

		folio = ksm_might_need_to_copy(folio, vma, vmf->address);

		if (unlikely(!folio)) {

			ret = VM_FAULT_OOM;

			folio = swapcache;

			goto out_page;

		} else if (unlikely(PTR_ERR(page) == -EHWPOISON)) {

		} else if (unlikely(folio == ERR_PTR(-EHWPOISON))) {

			ret = VM_FAULT_HWPOISON;

			folio = swapcache;

			goto out_page;

		}

		folio = page_folio(page);

		if (folio != swapcache)

			page = folio_page(folio, 0);



		/*

		 * If we want to map a page that's in the swapcache writable, we

mm/swapfile.c

+5 −3
Original line number Diff line number Diff line
@@ -1749,11 +1749,13 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, 
	int ret = 1;



	swapcache = page;

	page = ksm_might_need_to_copy(page, vma, addr);

	if (unlikely(!page))

	folio = ksm_might_need_to_copy(folio, vma, addr);

	if (unlikely(!folio))

		return -ENOMEM;

	else if (unlikely(PTR_ERR(page) == -EHWPOISON))

	else if (unlikely(folio == ERR_PTR(-EHWPOISON)))

		hwpoisoned = true;

	else

		page = folio_file_page(folio, swp_offset(entry));



	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);

	if (unlikely(!pte || !pte_same_as_swp(ptep_get(pte),