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Date: Wed, 10 Sep 2008 10:18:43 +0200
From: Ingo Molnar <mingo@...e.hu>
To: Jeremy Fitzhardinge <jeremy@...p.org>,
Andrew Morton <akpm@...ux-foundation.org>
Cc: alex.nixon@...rix.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] xen: fix pinning when not using split pte locks
* Jeremy Fitzhardinge <jeremy@...p.org> wrote:
> Andrew Morton wrote:
> > What are the effects of the bug which you fixed?
> >
> > Do you consider this to be 2.6.27 material? 2.6.26.x? 2.6.25.x?
> >
>
> This is a fix for a bug which only exists in tip.git.
instead of putting it into the x86 tree i've split out the mm patch into
a separate, -git based isolated topic branch (tip/core/xen) - the
coordinates for it are below. The commit ID is:
4ef2d41: mm: define USE_SPLIT_PTLOCKS rather than repeating expression
Andrew, any objection to this approach? If it's fine to you then after
testing this commit will eventually go to linux-next via
tip/auto-core-next. (the x86 tree merges this tree and i've applied the
Xen fix after that merge.)
Ingo
----------------------------------------------->
the latest tip/core/xen topic tree is at:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git core/xen
------------------>
Jeremy Fitzhardinge (1):
mm: define USE_SPLIT_PTLOCKS rather than repeating expression
arch/x86/xen/mmu.c | 2 +-
include/linux/mm.h | 6 +++---
include/linux/mm_types.h | 10 ++++++----
include/linux/sched.h | 6 +++---
4 files changed, 13 insertions(+), 11 deletions(-)
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index aa37469..2e1b640 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -646,7 +646,7 @@ static spinlock_t *lock_pte(struct page *page)
{
spinlock_t *ptl = NULL;
-#if NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS
+#if USE_SPLIT_PTLOCKS
ptl = __pte_lockptr(page);
spin_lock(ptl);
#endif
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 72a15dc..4194bf8 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -919,7 +919,7 @@ static inline pmd_t *pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long a
}
#endif /* CONFIG_MMU && !__ARCH_HAS_4LEVEL_HACK */
-#if NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS
+#if USE_SPLIT_PTLOCKS
/*
* We tuck a spinlock to guard each pagetable page into its struct page,
* at page->private, with BUILD_BUG_ON to make sure that this will not
@@ -932,14 +932,14 @@ static inline pmd_t *pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long a
} while (0)
#define pte_lock_deinit(page) ((page)->mapping = NULL)
#define pte_lockptr(mm, pmd) ({(void)(mm); __pte_lockptr(pmd_page(*(pmd)));})
-#else
+#else /* !USE_SPLIT_PTLOCKS */
/*
* We use mm->page_table_lock to guard all pagetable pages of the mm.
*/
#define pte_lock_init(page) do {} while (0)
#define pte_lock_deinit(page) do {} while (0)
#define pte_lockptr(mm, pmd) ({(void)(pmd); &(mm)->page_table_lock;})
-#endif /* NR_CPUS < CONFIG_SPLIT_PTLOCK_CPUS */
+#endif /* USE_SPLIT_PTLOCKS */
static inline void pgtable_page_ctor(struct page *page)
{
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index bf33413..9d49fa3 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -21,11 +21,13 @@
struct address_space;
-#if NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS
+#define USE_SPLIT_PTLOCKS (NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS)
+
+#if USE_SPLIT_PTLOCKS
typedef atomic_long_t mm_counter_t;
-#else /* NR_CPUS < CONFIG_SPLIT_PTLOCK_CPUS */
+#else /* !USE_SPLIT_PTLOCKS */
typedef unsigned long mm_counter_t;
-#endif /* NR_CPUS < CONFIG_SPLIT_PTLOCK_CPUS */
+#endif /* !USE_SPLIT_PTLOCKS */
/*
* Each physical page in the system has a struct page associated with
@@ -65,7 +67,7 @@ struct page {
* see PAGE_MAPPING_ANON below.
*/
};
-#if NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS
+#if USE_SPLIT_PTLOCKS
spinlock_t ptl;
#endif
struct kmem_cache *slab; /* SLUB: Pointer to slab */
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 3d9120c..272c353 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -352,7 +352,7 @@ arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
extern void arch_unmap_area(struct mm_struct *, unsigned long);
extern void arch_unmap_area_topdown(struct mm_struct *, unsigned long);
-#if NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS
+#if USE_SPLIT_PTLOCKS
/*
* The mm counters are not protected by its page_table_lock,
* so must be incremented atomically.
@@ -363,7 +363,7 @@ extern void arch_unmap_area_topdown(struct mm_struct *, unsigned long);
#define inc_mm_counter(mm, member) atomic_long_inc(&(mm)->_##member)
#define dec_mm_counter(mm, member) atomic_long_dec(&(mm)->_##member)
-#else /* NR_CPUS < CONFIG_SPLIT_PTLOCK_CPUS */
+#else /* !USE_SPLIT_PTLOCKS */
/*
* The mm counters are protected by its page_table_lock,
* so can be incremented directly.
@@ -374,7 +374,7 @@ extern void arch_unmap_area_topdown(struct mm_struct *, unsigned long);
#define inc_mm_counter(mm, member) (mm)->_##member++
#define dec_mm_counter(mm, member) (mm)->_##member--
-#endif /* NR_CPUS < CONFIG_SPLIT_PTLOCK_CPUS */
+#endif /* !USE_SPLIT_PTLOCKS */
#define get_mm_rss(mm) \
(get_mm_counter(mm, file_rss) + get_mm_counter(mm, anon_rss))
--
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