linux-kernel - [GIT pull] x86/urgent for v5.18-rc7

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Date:   Sun, 15 May 2022 11:25:08 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org
Subject: [GIT pull] x86/urgent for v5.18-rc7

Linus,

please pull the latest x86/urgent branch from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86-urgent-2022-05-15

up to:  280abe14b6e0: x86/mm: Fix marking of unused sub-pmd ranges


A single fix for the handling of unpopulated sub-pmd spaces. The copy &
pasta from the corresponding s390 code screwed up the address calculation
for marking the sub-pmd ranges via memset by omitting the ALIGN_DOWN() to
calculate the proper start address. It's a mystery why this code is not
generic and shared because there is nothing architecture specific in there,
but that's too intrusive for a backportable fix.

Thanks,

	tglx

------------------>
Adrian-Ken Rueegsegger (1):
      x86/mm: Fix marking of unused sub-pmd ranges


 arch/x86/mm/init_64.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 96d34ebb20a9..e2942335d143 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -902,6 +902,8 @@ static void __meminit vmemmap_use_sub_pmd(unsigned long start, unsigned long end
 
 static void __meminit vmemmap_use_new_sub_pmd(unsigned long start, unsigned long end)
 {
+	const unsigned long page = ALIGN_DOWN(start, PMD_SIZE);
+
 	vmemmap_flush_unused_pmd();
 
 	/*
@@ -914,8 +916,7 @@ static void __meminit vmemmap_use_new_sub_pmd(unsigned long start, unsigned long
 	 * Mark with PAGE_UNUSED the unused parts of the new memmap range
 	 */
 	if (!IS_ALIGNED(start, PMD_SIZE))
-		memset((void *)start, PAGE_UNUSED,
-			start - ALIGN_DOWN(start, PMD_SIZE));
+		memset((void *)page, PAGE_UNUSED, start - page);
 
 	/*
 	 * We want to avoid memset(PAGE_UNUSED) when populating the vmemmap of