Re: [PATCH] x86: fix init_memory_mapping over boundary v2

[Yinghai Lu]

On Sat, Jun 28, 2008 at 12:47 AM, Ingo Molnar <mingo@xxxxxxx> wrote:
>
> * Yinghai Lu <yhlu.kernel@xxxxxxxxx> wrote:
>
>> On Sat, Jun 28, 2008 at 12:02 AM, Ingo Molnar <mingo@xxxxxxx> wrote:
>> >
>> > * Ingo Molnar <mingo@xxxxxxx> wrote:
>> >
>> >> * Yinghai Lu <yhlu.kernel@xxxxxxxxx> wrote:
>> >>
>> >> > some end boundary is only page alignment, instead of 2M alignment, so
>> >> > call ker_phycial_mapping_init three times. then don't overmap above
>> >> > the max_low_pfn
>> >>
>> >> applied to tip/x86/unify-setup, thanks Yinghai.
>> >
>> > -tip testing found a 32-bit spontaneous reboot during bootup, with this
>> > config:
>> >
>> >  http://redhat.com/~mingo/misc/config-Sat_Jun_28_08_43_52_CEST_2008.bad
>> >
>> > no serial log produced at all.
>> even with console=uart8250,io,0x03f8,115200n8 ?
>
> correct, i use earlyprintk=serial,ttyS0,115200.
>
> i just re-tested it - doing "git merge tip/x86/unify-setup" in the
> tip/master branch triggers the failure with that config on a wide range
> of 32-bit boxes.

please check attached v3..., that is less intrusive.

YH
[PATCH] x86: fix init_memory_mapping over boundary v3

some end boundary is only page alignment, instead of 2M alignment,

v2: make init_memory_mapping more solid: start could be any value other than 0
v3: fix NON PAE by handling left over in kernel_physical_mapping

Signed-off-by: Yinghai Lu <yhlu.kernel@xxxxxxxxx>

---
 arch/x86/mm/init_32.c |   24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)

Index: linux-2.6/arch/x86/mm/init_32.c
===================================================================
--- linux-2.6.orig/arch/x86/mm/init_32.c
+++ linux-2.6/arch/x86/mm/init_32.c
@@ -195,7 +195,7 @@ static void __init kernel_physical_mappi
 	unsigned pages_2m = 0, pages_4k = 0;
 	unsigned limit_pfn = end >> PAGE_SHIFT;
 
-	pgd_idx = pgd_index(PAGE_OFFSET);
+	pgd_idx = pgd_index(start + PAGE_OFFSET);
 	pgd = pgd_base + pgd_idx;
 	pfn = start >> PAGE_SHIFT;
 
@@ -218,7 +218,8 @@ static void __init kernel_physical_mappi
 			 * and overlapping MTRRs into large pages can cause
 			 * slowdowns.
 			 */
-			if (cpu_has_pse && !(pgd_idx == 0 && pmd_idx == 0)) {
+			if (cpu_has_pse && !(pgd_idx == 0 && pmd_idx == 0) &&
+				(pfn + PTRS_PER_PTE) <= limit_pfn) {
 				unsigned int addr2;
 				pgprot_t prot = PAGE_KERNEL_LARGE;
 
@@ -233,13 +234,12 @@ static void __init kernel_physical_mappi
 				set_pmd(pmd, pfn_pmd(pfn, prot));
 
 				pfn += PTRS_PER_PTE;
-				max_pfn_mapped = pfn;
 				continue;
 			}
 			pte = one_page_table_init(pmd);
 
 			for (pte_ofs = 0;
-			     pte_ofs < PTRS_PER_PTE && pfn < max_low_pfn;
+			     pte_ofs < PTRS_PER_PTE && pfn < limit_pfn;
 			     pte++, pfn++, pte_ofs++, addr += PAGE_SIZE) {
 				pgprot_t prot = PAGE_KERNEL;
 
@@ -249,7 +249,6 @@ static void __init kernel_physical_mappi
 				pages_4k++;
 				set_pte(pte, pfn_pte(pfn, prot));
 			}
-			max_pfn_mapped = pfn;
 		}
 	}
 	update_page_count(PG_LEVEL_2M, pages_2m);
@@ -729,7 +728,7 @@ void __init setup_bootmem_allocator(void
 
 static void __init find_early_table_space(unsigned long end)
 {
-	unsigned long puds, pmds, tables, start;
+	unsigned long puds, pmds, ptes, tables, start;
 
 	puds = (end + PUD_SIZE - 1) >> PUD_SHIFT;
 	tables = PAGE_ALIGN(puds * sizeof(pud_t));
@@ -737,10 +736,15 @@ static void __init find_early_table_spac
 	pmds = (end + PMD_SIZE - 1) >> PMD_SHIFT;
 	tables += PAGE_ALIGN(pmds * sizeof(pmd_t));
 
-	if (!cpu_has_pse) {
-		int ptes = (end + PAGE_SIZE - 1) >> PAGE_SHIFT;
-		tables += PAGE_ALIGN(ptes * sizeof(pte_t));
-	}
+	if (cpu_has_pse) {
+		unsigned long extra;
+		extra = end - ((end>>21) << 21);
+		extra += (2UL<<20);
+		ptes = (extra + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	} else
+		ptes = (end + PAGE_SIZE - 1) >> PAGE_SHIFT;
+
+	tables += PAGE_ALIGN(ptes * sizeof(pte_t));
 
 	/*
 	 * RED-PEN putting page tables only on node 0 could