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authorJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>2010-09-21 12:01:51 -0700
committerH. Peter Anvin <hpa@linux.intel.com>2010-10-19 13:57:08 -0700
commit617d34d9e5d8326ec8f188c616aa06ac59d083fe (patch)
tree763d02b7713bad65ba819a8334bb0e95d4370352 /arch/x86/include/asm/pgtable.h
parent44235dcde416104b8e1db7606c283f4c0149c760 (diff)
x86, mm: Hold mm->page_table_lock while doing vmalloc_sync
Take mm->page_table_lock while syncing the vmalloc region. This prevents a race with the Xen pagetable pin/unpin code, which expects that the page_table_lock is already held. If this race occurs, then Xen can see an inconsistent page type (a page can either be read/write or a pagetable page, and pin/unpin converts it between them), which will cause either the pin or the set_p[gm]d to fail; either will crash the kernel. vmalloc_sync_all() should be called rarely, so this extra use of page_table_lock should not interfere with its normal users. The mm pointer is stashed in the pgd page's index field, as that won't be otherwise used for pgds. Reported-by: Ian Campbell <ian.cambell@eu.citrix.com> Originally-by: Jan Beulich <jbeulich@novell.com> LKML-Reference: <4CB88A4C.1080305@goop.org> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86/include/asm/pgtable.h')
-rw-r--r--arch/x86/include/asm/pgtable.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 2d0a33bd2971..ada823a13c7c 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -28,6 +28,8 @@ extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)];
extern spinlock_t pgd_lock;
extern struct list_head pgd_list;
+extern struct mm_struct *pgd_page_get_mm(struct page *page);
+
#ifdef CONFIG_PARAVIRT
#include <asm/paravirt.h>
#else /* !CONFIG_PARAVIRT */