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author | Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> | 2010-09-21 19:01:51 (GMT) |
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committer | H. Peter Anvin <hpa@linux.intel.com> | 2010-10-19 20:57:08 (GMT) |
commit | 617d34d9e5d8326ec8f188c616aa06ac59d083fe (patch) | |
tree | 763d02b7713bad65ba819a8334bb0e95d4370352 /arch/x86/mm/init_64.c | |
parent | 44235dcde416104b8e1db7606c283f4c0149c760 (diff) | |
download | linux-fsl-qoriq-617d34d9e5d8326ec8f188c616aa06ac59d083fe.tar.xz |
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/mm/init_64.c')
-rw-r--r-- | arch/x86/mm/init_64.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index 1ad7c0f..4d323fb 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -116,12 +116,19 @@ void sync_global_pgds(unsigned long start, unsigned long end) spin_lock_irqsave(&pgd_lock, flags); list_for_each_entry(page, &pgd_list, lru) { pgd_t *pgd; + spinlock_t *pgt_lock; + pgd = (pgd_t *)page_address(page) + pgd_index(address); + pgt_lock = &pgd_page_get_mm(page)->page_table_lock; + spin_lock(pgt_lock); + if (pgd_none(*pgd)) set_pgd(pgd, *pgd_ref); else BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref)); + + spin_unlock(pgt_lock); } spin_unlock_irqrestore(&pgd_lock, flags); } |