From: David Hildenbrand <david@redhat.com>
Date: Mon, 2 Oct 2023 14:29:47 +0000 (+0200)
Subject: mm/rmap: move SetPageAnonExclusive() out of page_move_anon_rmap()
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=5ca432896a4ce6d69fffc3298b24c0dd9bdb871f;p=linux.git

mm/rmap: move SetPageAnonExclusive() out of page_move_anon_rmap()

Patch series "mm/rmap: convert page_move_anon_rmap() to
folio_move_anon_rmap()".

Convert page_move_anon_rmap() to folio_move_anon_rmap(), letting the
callers handle PageAnonExclusive.  I'm including cleanup patch #3 because
it fits into the picture and can be done cleaner by the conversion.


This patch (of 3):

Let's move it into the caller: there is a difference between whether an
anon folio can only be mapped by one process (e.g., into one VMA), and
whether it is truly exclusive (e.g., no references -- including GUP --
from other processes).

Further, for large folios the page might not actually be pointing at the
head page of the folio, so it better be handled in the caller.  This is a
preparation for converting page_move_anon_rmap() to consume a folio.

Link: https://lkml.kernel.org/r/20231002142949.235104-1-david@redhat.com
Link: https://lkml.kernel.org/r/20231002142949.235104-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index aa02245561326..76ead290f1c82 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1377,6 +1377,7 @@ vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf)
 		pmd_t entry;
 
 		page_move_anon_rmap(page, vma);
+		SetPageAnonExclusive(page);
 		folio_unlock(folio);
 reuse:
 		if (unlikely(unshare)) {
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 2878e0e6bac5c..35d924f749723 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5652,8 +5652,10 @@ retry_avoidcopy:
 	 * owner and can reuse this page.
 	 */
 	if (folio_mapcount(old_folio) == 1 && folio_test_anon(old_folio)) {
-		if (!PageAnonExclusive(&old_folio->page))
+		if (!PageAnonExclusive(&old_folio->page)) {
 			page_move_anon_rmap(&old_folio->page, vma);
+			SetPageAnonExclusive(&old_folio->page);
+		}
 		if (likely(!unshare))
 			set_huge_ptep_writable(vma, haddr, ptep);
 
diff --git a/mm/memory.c b/mm/memory.c
index ceffe96f2a0e3..21fba1c9a6c73 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3481,6 +3481,7 @@ static vm_fault_t do_wp_page(struct vm_fault *vmf)
 		 * sunglasses. Hit it.
 		 */
 		page_move_anon_rmap(vmf->page, vma);
+		SetPageAnonExclusive(vmf->page);
 		folio_unlock(folio);
 reuse:
 		if (unlikely(unshare)) {
diff --git a/mm/rmap.c b/mm/rmap.c
index c6bb2339e35b2..6f1ea1491118c 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1152,7 +1152,6 @@ void page_move_anon_rmap(struct page *page, struct vm_area_struct *vma)
 	 * folio_test_anon()) will not see one without the other.
 	 */
 	WRITE_ONCE(folio->mapping, anon_vma);
-	SetPageAnonExclusive(page);
 }
 
 /**