linux-kernel - [PATCH] x86-64: fix page table accounting

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Message-Id: <506DAFBA020000780009FA8C@nat28.tlf.novell.com>
Date:	Thu, 04 Oct 2012 14:48:10 +0100
From:	"Jan Beulich" <JBeulich@...e.com>
To:	<mingo@...e.hu>, <tglx@...utronix.de>, <hpa@...or.com>
Cc:	"Hugh Dickins" <hughd@...gle.com>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] 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-by: Hugh Dickins <hughd@...gle.com>
Signed-off-by: Jan Beulich <jbeulich@...e.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;
 			}



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