linux-kernel - [PATCH v2 2/5] mm/memory: remove PageAnonExclusive sanity-check in restore_exclusive

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Message-ID: <20250226132257.2826043-3-david@redhat.com>
Date: Wed, 26 Feb 2025 14:22:54 +0100
From: David Hildenbrand <david@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: linux-mm@...ck.org,
	David Hildenbrand <david@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jérôme Glisse <jglisse@...hat.com>,
	Simona Vetter <simona@...ll.ch>,
	Alistair Popple <apopple@...dia.com>,
	Jason Gunthorpe <jgg@...dia.com>
Subject: [PATCH v2 2/5] mm/memory: remove PageAnonExclusive sanity-check in restore_exclusive_pte()

In commit b832a354d787 ("mm/memory: page_add_anon_rmap() ->
folio_add_anon_rmap_pte()") we accidentally changed the sanity check to
essentially ignore anonymous folio by mis-placing the "!" ... but we really
always only get anonymous folios in restore_exclusive_pte().

However, in the meantime we removed the separate "writable
device-exclusive entries" and always detect if the PTE can be writable
using can_change_pte_writable() -- which also consults
PageAnonExclusive.

So let's just get rid of this sanity check completely.

Signed-off-by: David Hildenbrand <david@...hat.com>
---
 mm/memory.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index 567b45e5d149e..507045fa719cc 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -740,9 +740,6 @@ static void restore_exclusive_pte(struct vm_area_struct *vma,
 			pte = pte_mkdirty(pte);
 		pte = pte_mkwrite(pte, vma);
 	}
-
-	VM_BUG_ON_FOLIO(pte_write(pte) && (!folio_test_anon(folio) &&
-					   PageAnonExclusive(page)), folio);
 	set_pte_at(vma->vm_mm, address, ptep, pte);

 	/*
-- 
2.48.1