linux-kernel - [PATCH v6 12/15] highmem: define clear

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Message-Id: <20250902080816.3715913-13-ankur.a.arora@oracle.com>
Date: Tue,  2 Sep 2025 01:08:13 -0700
From: Ankur Arora <ankur.a.arora@...cle.com>
To: linux-kernel@...r.kernel.org, linux-mm@...ck.org, x86@...nel.org
Cc: akpm@...ux-foundation.org, david@...hat.com, bp@...en8.de,
        dave.hansen@...ux.intel.com, hpa@...or.com, mingo@...hat.com,
        mjguzik@...il.com, luto@...nel.org, peterz@...radead.org,
        acme@...nel.org, namhyung@...nel.org, tglx@...utronix.de,
        willy@...radead.org, raghavendra.kt@....com,
        boris.ostrovsky@...cle.com, konrad.wilk@...cle.com,
        ankur.a.arora@...cle.com
Subject: [PATCH v6 12/15] highmem: define clear_highpages()

Define clear_user_highpages() which clears sequentially using the
single page variant.

With !CONFIG_HIGHMEM, pages are contiguous so use the range clearing
primitive clear_user_pages().

Signed-off-by: Ankur Arora <ankur.a.arora@...cle.com>
---
 include/linux/highmem.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index 6234f316468c..eeb0b7bc0a22 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -207,6 +207,18 @@ static inline void clear_user_highpage(struct page *page, unsigned long vaddr)
 }
 #endif
 
+#ifndef clear_user_highpages
+static inline void clear_user_highpages(struct page *page, unsigned long vaddr,
+					unsigned int npages)
+{
+	if (!IS_ENABLED(CONFIG_HIGHMEM))
+		clear_user_pages(page_address(page), vaddr, page, npages);
+	else
+		for (int i = 0; i < npages; i++)
+			clear_user_highpage(page+i, vaddr + i * PAGE_SIZE);
+}
+#endif
+
 #ifndef vma_alloc_zeroed_movable_folio
 /**
  * vma_alloc_zeroed_movable_folio - Allocate a zeroed page for a VMA.
-- 
2.31.1