[PATCH 18/28] Copying of the pgd range must happen under the pgd_lock

Jeremy Fitzhardinge
2007-04-14T21:24:05Z

[-- Attachment #1: i386-pgd-clone-under-lock-fix.patch --]
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Copying of the pgd range must happen under the pgd_lock. This got broken by
the paravirt changes in the -mm tree. Badness can result if you copy the pgd
before being added to the list when splitting or rejoining large pages.

From: Zachary Amsden <zach@vmware.com>
Signed-off-by: Zachary Amsden <zach@vmware.com>
Acked-by: William Lee Irwin III <wli@holomorphy.com>
---
arch/i386/mm/pgtable.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)

===================================================================
--- a/arch/i386/mm/pgtable.c
+++ b/arch/i386/mm/pgtable.c
@@ -241,18 +241,16 @@ void pgd_ctor(void *pgd, struct kmem_cac
/* !PAE, no pagetable sharing */
memset(pgd, 0, USER_PTRS_PER_PGD*sizeof(pgd_t));

+ spin_lock_irqsave(&pgd_lock, flags);
+
+ /* must happen under lock */
clone_pgd_range((pgd_t *)pgd + USER_PTRS_PER_PGD,
swapper_pg_dir + USER_PTRS_PER_PGD,
KERNEL_PGD_PTRS);
-
- spin_lock_irqsave(&pgd_lock, flags);
-
- /* must happen under lock */
paravirt_alloc_pd_clone(__pa(pgd) >> PAGE_SHIFT,
__pa(swapper_pg_dir) >> PAGE_SHIFT,
USER_PTRS_PER_PGD,
KERNEL_PGD_PTRS);
-
pgd_list_add(pgd);
spin_unlock_irqrestore(&pgd_lock, flags);
}

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