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[PATCH v2] MIPS: Kernel crashes on boot with SPARSEMEM + HIGHMEM enabled

To: Ralf Baechle <ralf@linux-mips.org>
Subject: [PATCH v2] MIPS: Kernel crashes on boot with SPARSEMEM + HIGHMEM enabled
From: Kevin Cernekee <cernekee@gmail.com>
Date: Thu, 31 Mar 2011 17:27:07 -0700
Cc: Michael Sundius <msundius@cisco.com>, David VomLehn <dvomlehn@cisco.com>, Dave Hansen <dave@linux.vnet.ibm.com>, Andy Whitcroft <apw@shadowen.org>, Jon Fraser <jfraser@broadcom.com>, <linux-mips@linux-mips.org>, <linux-kernel@vger.kernel.org>, <stable@kernel.org>
Original-recipient: rfc822;linux-mips@linux-mips.org
Sender: linux-mips-bounce@linux-mips.org
User-agent: vim 7.2
From: Michael Sundius <msundius@cisco.com>

Fix 3 problems in the MIPS SPARSEMEM implementation:

1) mem_init() sets/clears PG_reserved on all pages in the HIGHMEM range
without checking to see whether the page descriptor actually exists.

2) bootmem_init() never calls memory_present() on HIGHMEM pages, so
page descriptors are never created for them if SPARSEMEM is enabled.

3) bootmem_init() calls memory_present() on lowmem pages before bootmem
is fully set up.  This is bad because memory_present() can allocate
bootmem in some circumstances (e.g. if SPARSEMEM_EXTREME ever got
enabled).

Signed-off-by: Michael Sundius <msundius@cisco.com>
Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Cc: stable@kernel.org
---
 arch/mips/kernel/setup.c |   18 +++++++++++++++++-
 arch/mips/mm/init.c      |    3 +++
 2 files changed, 20 insertions(+), 1 deletions(-)

diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index 8ad1d56..1f9f902 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -390,7 +390,6 @@ static void __init bootmem_init(void)
 
                /* Register lowmem ranges */
                free_bootmem(PFN_PHYS(start), size << PAGE_SHIFT);
-               memory_present(0, start, end);
        }
 
        /*
@@ -402,6 +401,23 @@ static void __init bootmem_init(void)
         * Reserve initrd memory if needed.
         */
        finalize_initrd();
+
+       /*
+        * Call memory_present() on all valid ranges, for SPARSEMEM.
+        * This must be done after setting up bootmem, since memory_present()
+        * may allocate bootmem.
+        */
+       for (i = 0; i < boot_mem_map.nr_map; i++) {
+               unsigned long start, end;
+
+               if (boot_mem_map.map[i].type != BOOT_MEM_RAM)
+                       continue;
+
+               start = PFN_UP(boot_mem_map.map[i].addr);
+               end   = PFN_DOWN(boot_mem_map.map[i].addr
+                                   + boot_mem_map.map[i].size);
+               memory_present(0, start, end);
+       }
 }
 
 #endif /* CONFIG_SGI_IP27 */
diff --git a/arch/mips/mm/init.c b/arch/mips/mm/init.c
index 279599e..78a4cf2 100644
--- a/arch/mips/mm/init.c
+++ b/arch/mips/mm/init.c
@@ -392,6 +392,9 @@ void __init mem_init(void)
        for (tmp = highstart_pfn; tmp < highend_pfn; tmp++) {
                struct page *page = pfn_to_page(tmp);
 
+               if (!pfn_valid(tmp))
+                       continue;
+
                if (!page_is_ram(tmp)) {
                        SetPageReserved(page);
                        continue;
-- 
1.7.4.2

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