[3.5.y.z,extended,stable] Patch "x86/mm: account for PGDIR_SIZE alignment" has been added to staging queue

Message ID 1368614064-25164-1-git-send-email-luis.henriques@canonical.com
State New
Headers show

Commit Message

Luis Henriques May 15, 2013, 10:34 a.m.
This is a note to let you know that I have just added a patch titled

    x86/mm: account for PGDIR_SIZE alignment

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:


If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see



From ca72c2a18cb8b82b1bdbf4f73e423f19e599cc3f Mon Sep 17 00:00:00 2001
From: Jerry Hoemann <jerry.hoemann@hp.com>
Date: Tue, 30 Apr 2013 15:15:55 -0600
Subject: [PATCH] x86/mm: account for PGDIR_SIZE alignment

Patch for 3.0-stable.  Function find_early_table_space removed upstream.

Fixes panic in alloc_low_page due to pgt_buf overflow during

find_early_table_space sizes pgt_buf based upon the size of the
memory being mapped, but it does not take into account the alignment
of the memory.  When the region being mapped spans a 512GB (PGDIR_SIZE)
alignment, a panic from alloc_low_pages occurs.

kernel_physical_mapping_init takes into account PGDIR_SIZE alignment.
This causes an extra call to alloc_low_page to be made.  This extra call
isn't accounted for by find_early_table_space and causes a kernel panic.

Change is to take into account PGDIR_SIZE alignment in find_early_table_space.

Signed-off-by: Jerry Hoemann <jerry.hoemann@hp.com>
Signed-off-by: Luis Henriques<luis.henriques@canonical.com>
 arch/x86/mm/init.c | 5 +++++
 1 file changed, 5 insertions(+)



diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 4e4dcda..4779d7c 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -45,11 +45,15 @@  static void __init find_early_table_space(struct map_range *mr, int nr_range)
 	int i;
 	unsigned long puds = 0, pmds = 0, ptes = 0, tables;
 	unsigned long start = 0, good_end;
+	unsigned long pgd_extra = 0;
 	phys_addr_t base;

 	for (i = 0; i < nr_range; i++) {
 		unsigned long range, extra;

+		if ((mr[i].end >> PGDIR_SHIFT) - (mr[i].start >> PGDIR_SHIFT))
+			pgd_extra++;
 		range = mr[i].end - mr[i].start;
 		puds += (range + PUD_SIZE - 1) >> PUD_SHIFT;

@@ -74,6 +78,7 @@  static void __init find_early_table_space(struct map_range *mr, int nr_range)
 	tables = roundup(puds * sizeof(pud_t), PAGE_SIZE);
 	tables += roundup(pmds * sizeof(pmd_t), PAGE_SIZE);
 	tables += roundup(ptes * sizeof(pte_t), PAGE_SIZE);
+	tables += (pgd_extra * PAGE_SIZE);

 #ifdef CONFIG_X86_32
 	/* for fixmap */