[PATCH] x86-64: fix page table accounting

[PATCH] x86-64: fix page table accounting

[Jan Beulich]

Commit 20167d3421a089a1bf1bd680b150dc69c9506810 ("x86-64: Fix
accounting in kernel_physical_mapping_init()") went a little too far
by entirely removing the counting of pre-populated page tables: This
should be done at boot time (to cover the page tables set up in early
boot code), but shouldn't be done during memory hot add.

Hence, re-add the removed increments of "pages", but make them and the
one in phys_pte_init() conditional upon !after_bootmem.

Reported-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>

---
Not sure if this ought to be copied to stable@.

---
 arch/x86/mm/init_64.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- 3.6/arch/x86/mm/init_64.c
+++ 3.6-x86_64-page-table-count/arch/x86/mm/init_64.c
@@ -386,7 +386,8 @@ phys_pte_init(pte_t *pte_page, unsigned
 		 * these mappings are more intelligent.
 		 */
 		if (pte_val(*pte)) {
-			pages++;
+			if (!after_bootmem)
+				pages++;
 			continue;
 		}
 
@@ -451,6 +452,8 @@ phys_pmd_init(pmd_t *pmd_page, unsigned
 			 * attributes.
 			 */
 			if (page_size_mask & (1 << PG_LEVEL_2M)) {
+				if (!after_bootmem)
+					pages++;
 				last_map_addr = next;
 				continue;
 			}
@@ -526,6 +529,8 @@ phys_pud_init(pud_t *pud_page, unsigned
 			 * attributes.
 			 */
 			if (page_size_mask & (1 << PG_LEVEL_1G)) {
+				if (!after_bootmem)
+					pages++;
 				last_map_addr = next;
 				continue;
 			}

Re: [PATCH] x86-64: fix page table accounting

[Hugh Dickins]

On Thu, 4 Oct 2012, Jan Beulich wrote:

> Commit 20167d3421a089a1bf1bd680b150dc69c9506810 ("x86-64: Fix
> accounting in kernel_physical_mapping_init()") went a little too far
> by entirely removing the counting of pre-populated page tables: This
> should be done at boot time (to cover the page tables set up in early
> boot code), but shouldn't be done during memory hot add.
> 
> Hence, re-add the removed increments of "pages", but make them and the
> one in phys_pte_init() conditional upon !after_bootmem.
> 
> Reported-by: Hugh Dickins <hughd@google.com>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

I think this has not yet been picked up: perhaps it's awaiting an
Acked-by: Hugh Dickins <hughd@google.com>
or a
Tested-by: Hugh Dickins <hughd@google.com>
but I hesitated to give those because you understand what's going
on here much better than I pretend to.

> 
> ---
> Not sure if this ought to be copied to stable@.

I guess not.  Much as I like my kernels to show good meminfo numbers,
I was recently saying that David Rientjes's patches to get Unevictable
and Mlocked right were not important enough for stable, and I think
those numbers are more interesting to most people than the DirectMaps.
But I'd be happily overruled on all three patches.

Hugh

> 
> ---
>  arch/x86/mm/init_64.c |    7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> --- 3.6/arch/x86/mm/init_64.c
> +++ 3.6-x86_64-page-table-count/arch/x86/mm/init_64.c
> @@ -386,7 +386,8 @@ phys_pte_init(pte_t *pte_page, unsigned
>  		 * these mappings are more intelligent.
>  		 */
>  		if (pte_val(*pte)) {
> -			pages++;
> +			if (!after_bootmem)
> +				pages++;
>  			continue;
>  		}
>  
> @@ -451,6 +452,8 @@ phys_pmd_init(pmd_t *pmd_page, unsigned
>  			 * attributes.
>  			 */
>  			if (page_size_mask & (1 << PG_LEVEL_2M)) {
> +				if (!after_bootmem)
> +					pages++;
>  				last_map_addr = next;
>  				continue;
>  			}
> @@ -526,6 +529,8 @@ phys_pud_init(pud_t *pud_page, unsigned
>  			 * attributes.
>  			 */
>  			if (page_size_mask & (1 << PG_LEVEL_1G)) {
> +				if (!after_bootmem)
> +					pages++;
>  				last_map_addr = next;
>  				continue;
>  			}

[tip:x86/urgent] x86-64: Fix page table accounting

[tip-bot for Jan Beulich]

Commit-ID:  876ee61aadf01aa0db981b5d249cbdd53dc28b5e
Gitweb:     http://git.kernel.org/tip/876ee61aadf01aa0db981b5d249cbdd53dc28b5e
Author:     Jan Beulich <JBeulich@suse.com>
AuthorDate: Thu, 4 Oct 2012 14:48:10 +0100
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 24 Oct 2012 10:50:25 +0200

x86-64: Fix page table accounting

Commit 20167d3421a089a1bf1bd680b150dc69c9506810 ("x86-64: Fix
accounting in kernel_physical_mapping_init()") went a little too
far by entirely removing the counting of pre-populated page
tables: this should be done at boot time (to cover the page
tables set up in early boot code), but shouldn't be done during
memory hot add.

Hence, re-add the removed increments of "pages", but make them
and the one in phys_pte_init() conditional upon !after_bootmem.

Reported-Acked-and-Tested-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: <stable@kernel.org>
Link: http://lkml.kernel.org/r/506DAFBA020000780009FA8C@nat28.tlf.novell.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/mm/init_64.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 2b6b4a3..3baff25 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -386,7 +386,8 @@ phys_pte_init(pte_t *pte_page, unsigned long addr, unsigned long end,
 		 * these mappings are more intelligent.
 		 */
 		if (pte_val(*pte)) {
-			pages++;
+			if (!after_bootmem)
+				pages++;
 			continue;
 		}
 
@@ -451,6 +452,8 @@ phys_pmd_init(pmd_t *pmd_page, unsigned long address, unsigned long end,
 			 * attributes.
 			 */
 			if (page_size_mask & (1 << PG_LEVEL_2M)) {
+				if (!after_bootmem)
+					pages++;
 				last_map_addr = next;
 				continue;
 			}
@@ -526,6 +529,8 @@ phys_pud_init(pud_t *pud_page, unsigned long addr, unsigned long end,
 			 * attributes.
 			 */
 			if (page_size_mask & (1 << PG_LEVEL_1G)) {
+				if (!after_bootmem)
+					pages++;
 				last_map_addr = next;
 				continue;
 			}