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Message-Id: <20180528100245.071626281@linuxfoundation.org>
Date: Mon, 28 May 2018 12:01:23 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org,
"David H. Gutteridge" <dhgutteridge@...patico.ca>,
Joerg Roedel <jroedel@...e.de>,
Thomas Gleixner <tglx@...utronix.de>,
Andrea Arcangeli <aarcange@...hat.com>,
Andy Lutomirski <luto@...nel.org>,
Boris Ostrovsky <boris.ostrovsky@...cle.com>,
Borislav Petkov <bp@...en8.de>,
Brian Gerst <brgerst@...il.com>,
Dave Hansen <dave.hansen@...el.com>,
David Laight <David.Laight@...lab.com>,
Denys Vlasenko <dvlasenk@...hat.com>,
Eduardo Valentin <eduval@...zon.com>,
Jiri Kosina <jkosina@...e.cz>,
Josh Poimboeuf <jpoimboe@...hat.com>,
Juergen Gross <jgross@...e.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Pavel Machek <pavel@....cz>,
Peter Zijlstra <peterz@...radead.org>,
Waiman Long <llong@...hat.com>,
Will Deacon <will.deacon@....com>, aliguori@...zon.com,
daniel.gruss@...k.tugraz.at, hughd@...gle.com, keescook@...gle.com,
linux-mm@...ck.org, Ingo Molnar <mingo@...nel.org>,
Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 4.16 050/272] x86/pgtable: Dont set huge PUD/PMD on non-leaf entries
4.16-stable review patch. If anyone has any objections, please let me know.
------------------
From: Joerg Roedel <joro@...tes.org>
[ Upstream commit e3e288121408c3abeed5af60b87b95c847143845 ]
The pmd_set_huge() and pud_set_huge() functions are used from
the generic ioremap() code to establish large mappings where this
is possible.
But the generic ioremap() code does not check whether the
PMD/PUD entries are already populated with a non-leaf entry,
so that any page-table pages these entries point to will be
lost.
Further, on x86-32 with SHARED_KERNEL_PMD=0, this causes a
BUG_ON() in vmalloc_sync_one() when PMD entries are synced
from swapper_pg_dir to the current page-table. This happens
because the PMD entry from swapper_pg_dir was promoted to a
huge-page entry while the current PGD still contains the
non-leaf entry. Because both entries are present and point
to a different page, the BUG_ON() triggers.
This was actually triggered with pti-x32 enabled in a KVM
virtual machine by the graphics driver.
A real and better fix for that would be to improve the
page-table handling in the generic ioremap() code. But that is
out-of-scope for this patch-set and left for later work.
Reported-by: David H. Gutteridge <dhgutteridge@...patico.ca>
Signed-off-by: Joerg Roedel <jroedel@...e.de>
Reviewed-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Andrea Arcangeli <aarcange@...hat.com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Dave Hansen <dave.hansen@...el.com>
Cc: David Laight <David.Laight@...lab.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: Eduardo Valentin <eduval@...zon.com>
Cc: Greg KH <gregkh@...uxfoundation.org>
Cc: Jiri Kosina <jkosina@...e.cz>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Juergen Gross <jgross@...e.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Pavel Machek <pavel@....cz>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Waiman Long <llong@...hat.com>
Cc: Will Deacon <will.deacon@....com>
Cc: aliguori@...zon.com
Cc: daniel.gruss@...k.tugraz.at
Cc: hughd@...gle.com
Cc: keescook@...gle.com
Cc: linux-mm@...ck.org
Link: http://lkml.kernel.org/r/20180411152437.GC15462@8bytes.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
arch/x86/mm/pgtable.c | 9 +++++++++
1 file changed, 9 insertions(+)
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -1,6 +1,7 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/mm.h>
#include <linux/gfp.h>
+#include <linux/hugetlb.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
#include <asm/tlb.h>
@@ -636,6 +637,10 @@ int pud_set_huge(pud_t *pud, phys_addr_t
(mtrr != MTRR_TYPE_WRBACK))
return 0;
+ /* Bail out if we are we on a populated non-leaf entry: */
+ if (pud_present(*pud) && !pud_huge(*pud))
+ return 0;
+
prot = pgprot_4k_2_large(prot);
set_pte((pte_t *)pud, pfn_pte(
@@ -664,6 +669,10 @@ int pmd_set_huge(pmd_t *pmd, phys_addr_t
return 0;
}
+ /* Bail out if we are we on a populated non-leaf entry: */
+ if (pmd_present(*pmd) && !pmd_huge(*pmd))
+ return 0;
+
prot = pgprot_4k_2_large(prot);
set_pte((pte_t *)pmd, pfn_pte(
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