linux-kernel - [PATCH v1] mm/memory: fix folio_set_dirty() vs. folio_mark_dirty() in zap_pte

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Date: Mon, 22 Jan 2024 18:17:51 +0100
From: David Hildenbrand <david@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: linux-mm@...ck.org,
	David Hildenbrand <david@...hat.com>,
	Ryan Roberts <ryan.roberts@....com>,
	Matthew Wilcox <willy@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH v1] mm/memory: fix folio_set_dirty() vs. folio_mark_dirty() in zap_pte_range()

The correct folio replacement for "set_page_dirty()" is
"folio_mark_dirty()", not "folio_set_dirty()". Using the latter won't
properly inform the FS using the dirty_folio() callback.

This has been found by code inspection, but likely this can result in
some real trouble when zapping dirty PTEs that point at clean pagecache
folios.

Reported-by: Ryan Roberts <ryan.roberts@....com>
Closes: https://lkml.kernel.org/r/2445cedb-61fb-422c-8bfb-caf0a2beed62@arm.com
Fixes: c46265030b0f ("mm/memory: page_remove_rmap() -> folio_remove_rmap_pte()")
Cc: Matthew Wilcox (Oracle) <willy@...radead.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: David Hildenbrand <david@...hat.com>
---
 mm/memory.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/memory.c b/mm/memory.c
index 7e1f4849463aa..89bcae0b224d6 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1464,7 +1464,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 			delay_rmap = 0;
 			if (!folio_test_anon(folio)) {
 				if (pte_dirty(ptent)) {
-					folio_set_dirty(folio);
+					folio_mark_dirty(folio);
 					if (tlb_delay_rmap(tlb)) {
 						delay_rmap = 1;
 						force_flush = 1;
-- 
2.43.0