From: b32955@freescale.com (Huang Shijie)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/2] ARM: mmu: fix the hang when we steal a section unaligned size memory
Date: Thu, 13 Jun 2013 16:57:05 +0800 [thread overview]
Message-ID: <1371113826-1231-1-git-send-email-b32955@freescale.com> (raw)
If we want to steal 128K memory in the machine_desc->reserve() hook, we
will hang up immediately.
The hang reason is like this:
[1] Stealing 128K makes the left memory is not aligned with the SECTION_SIZE.
[2] So when the map_lowmem() tries to maps the lowmem memory banks,
it will call the memblock_alloc(in early_alloc_aligned()) to allocate
a page to store the pte. This pte page is in the unaligned region
which is not mapped yet.
[3] And when we use the memset() in the early_alloc_aligned(), we will hang
right now.
[4] The hang only occurs in the map_lowmem(). After the map_lowmem(), we have
setup the PTE mappings. So in the later places, such as
dma_contiguous_remap(), the hang will never occurs,
This patch adds a global variable, in_map_lowmem, to check if we are in
the map_lowmem() or not. If we are in the map_lowmem(), and we steal
a SECTION_SIZE unaligned memory, we will use the memblock_alloc_base()
to allocate the pte page. The @max_addr for memblock_alloc_base() is the
last mapped address.
Signed-off-by: Huang Shijie <b32955@freescale.com>
---
arch/arm/mm/mmu.c | 34 ++++++++++++++++++++++++++++++----
1 files changed, 30 insertions(+), 4 deletions(-)
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index faa36d7..56d1a22 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -113,6 +113,8 @@ static struct cachepolicy cache_policies[] __initdata = {
}
};
+static bool in_map_lowmem __initdata;
+
#ifdef CONFIG_CPU_CP15
/*
* These are useful for identifying cache coherency
@@ -595,10 +597,32 @@ static void __init *early_alloc(unsigned long sz)
return early_alloc_aligned(sz, sz);
}
-static pte_t * __init early_pte_alloc(pmd_t *pmd, unsigned long addr, unsigned long prot)
+static void __init *early_alloc_max_addr(unsigned long sz, phys_addr_t maddr)
+{
+ void *ptr;
+
+ if (maddr == MEMBLOCK_ALLOC_ACCESSIBLE)
+ return early_alloc_aligned(sz, sz);
+
+ ptr = __va(memblock_alloc_base(sz, sz, maddr));
+ memset(ptr, 0, sz);
+ return ptr;
+}
+
+static pte_t * __init early_pte_alloc(pmd_t *pmd, unsigned long addr,
+ unsigned long end, unsigned long prot)
{
if (pmd_none(*pmd)) {
- pte_t *pte = early_alloc(PTE_HWTABLE_OFF + PTE_HWTABLE_SIZE);
+ pte_t *pte;
+ phys_addr_t maddr = MEMBLOCK_ALLOC_ACCESSIBLE;
+
+ if (in_map_lowmem && (end & SECTION_MASK)) {
+ end &= PGDIR_MASK;
+ BUG_ON(!end);
+ maddr = __virt_to_phys(end);
+ }
+ pte = early_alloc_max_addr(PTE_HWTABLE_OFF + PTE_HWTABLE_SIZE,
+ maddr);
__pmd_populate(pmd, __pa(pte), prot);
}
BUG_ON(pmd_bad(*pmd));
@@ -609,7 +633,7 @@ static void __init alloc_init_pte(pmd_t *pmd, unsigned long addr,
unsigned long end, unsigned long pfn,
const struct mem_type *type)
{
- pte_t *pte = early_pte_alloc(pmd, addr, type->prot_l1);
+ pte_t *pte = early_pte_alloc(pmd, addr, end, type->prot_l1);
do {
set_pte_ext(pte, pfn_pte(pfn, __pgprot(type->prot_pte)), 0);
pfn++;
@@ -1253,7 +1277,7 @@ static void __init kmap_init(void)
{
#ifdef CONFIG_HIGHMEM
pkmap_page_table = early_pte_alloc(pmd_off_k(PKMAP_BASE),
- PKMAP_BASE, _PAGE_KERNEL_TABLE);
+ PKMAP_BASE, 0, _PAGE_KERNEL_TABLE);
#endif
}
@@ -1261,6 +1285,7 @@ static void __init map_lowmem(void)
{
struct memblock_region *reg;
+ in_map_lowmem = 1;
/* Map all the lowmem memory banks. */
for_each_memblock(memory, reg) {
phys_addr_t start = reg->base;
@@ -1279,6 +1304,7 @@ static void __init map_lowmem(void)
create_mapping(&map);
}
+ in_map_lowmem = 0;
}
/*
--
1.7.1
next reply other threads:[~2013-06-13 8:57 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-13 8:57 Huang Shijie [this message]
2013-06-13 8:57 ` [PATCH 2/2] ARM: mm: dump the memblock info in the later place Huang Shijie
2013-06-17 2:44 ` [PATCH 1/2] ARM: mmu: fix the hang when we steal a section unaligned size memory Huang Shijie
2013-06-18 15:29 ` Will Deacon
2013-06-18 16:52 ` Russell King - ARM Linux
2013-06-19 2:36 ` Huang Shijie
2013-06-19 8:28 ` Russell King - ARM Linux
2013-06-19 8:47 ` Huang Shijie
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