linux-kernel - [PATCH 05/19] mm/gup: Detect huge pfnmap entries in gup-fast

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Message-ID: <20240809160909.1023470-6-peterx@redhat.com>
Date: Fri,  9 Aug 2024 12:08:55 -0400
From: Peter Xu <peterx@...hat.com>
To: linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Cc: Sean Christopherson <seanjc@...gle.com>,
	Oscar Salvador <osalvador@...e.de>,
	Jason Gunthorpe <jgg@...dia.com>,
	Axel Rasmussen <axelrasmussen@...gle.com>,
	linux-arm-kernel@...ts.infradead.org,
	x86@...nel.org,
	peterx@...hat.com,
	Will Deacon <will@...nel.org>,
	Gavin Shan <gshan@...hat.com>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Zi Yan <ziy@...dia.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Catalin Marinas <catalin.marinas@....com>,
	Ingo Molnar <mingo@...hat.com>,
	Alistair Popple <apopple@...dia.com>,
	Borislav Petkov <bp@...en8.de>,
	David Hildenbrand <david@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	kvm@...r.kernel.org,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Alex Williamson <alex.williamson@...hat.com>,
	Yan Zhao <yan.y.zhao@...el.com>
Subject: [PATCH 05/19] mm/gup: Detect huge pfnmap entries in gup-fast

Since gup-fast doesn't have the vma reference, teach it to detect such huge
pfnmaps by checking the special bit for pmd/pud too, just like ptes.

Signed-off-by: Peter Xu <peterx@...hat.com>
---
 mm/gup.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/mm/gup.c b/mm/gup.c
index d19884e097fd..a49f67a512ee 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -3038,6 +3038,9 @@ static int gup_fast_pmd_leaf(pmd_t orig, pmd_t *pmdp, unsigned long addr,
 	if (!pmd_access_permitted(orig, flags & FOLL_WRITE))
 		return 0;
 
+	if (pmd_special(orig))
+		return 0;
+
 	if (pmd_devmap(orig)) {
 		if (unlikely(flags & FOLL_LONGTERM))
 			return 0;
@@ -3082,6 +3085,9 @@ static int gup_fast_pud_leaf(pud_t orig, pud_t *pudp, unsigned long addr,
 	if (!pud_access_permitted(orig, flags & FOLL_WRITE))
 		return 0;
 
+	if (pud_special(orig))
+		return 0;
+
 	if (pud_devmap(orig)) {
 		if (unlikely(flags & FOLL_LONGTERM))
 			return 0;
-- 
2.45.0