4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Joerg Roedel joro@8bytes.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@sympatico.ca Signed-off-by: Joerg Roedel jroedel@suse.de Reviewed-by: Thomas Gleixner tglx@linutronix.de Cc: Andrea Arcangeli aarcange@redhat.com Cc: Andy Lutomirski luto@kernel.org Cc: Boris Ostrovsky boris.ostrovsky@oracle.com Cc: Borislav Petkov bp@alien8.de Cc: Brian Gerst brgerst@gmail.com Cc: Dave Hansen dave.hansen@intel.com Cc: David Laight David.Laight@aculab.com Cc: Denys Vlasenko dvlasenk@redhat.com Cc: Eduardo Valentin eduval@amazon.com Cc: Greg KH gregkh@linuxfoundation.org Cc: Jiri Kosina jkosina@suse.cz Cc: Josh Poimboeuf jpoimboe@redhat.com Cc: Juergen Gross jgross@suse.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Pavel Machek pavel@ucw.cz Cc: Peter Zijlstra peterz@infradead.org Cc: Waiman Long llong@redhat.com Cc: Will Deacon will.deacon@arm.com Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20180411152437.GC15462@8bytes.org Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.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(