Re: [PATCH 01/33] powerpc: use mm zones more sensibly

[Benjamin Herrenschmidt]

On Tue, 2018-10-09 at 15:24 +0200, Christoph Hellwig wrote:
>   * Find the least restrictive zone that is entirely below the
> @@ -324,11 +305,14 @@ void __init paging_init(void)
> printk(KERN_DEBUG "Memory hole size: %ldMB\n",
>(long int)((top_of_ram - total_ram) >> 20));
>  
> +#ifdef CONFIG_ZONE_DMA
> +   max_zone_pfns[ZONE_DMA] = min(max_low_pfn, 0x7fffUL >> 
> PAGE_SHIFT);
> +#endif
> +   max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
>  #ifdef CONFIG_HIGHMEM
> -   limit_zone_pfn(ZONE_NORMAL, lowmem_end_addr >> PAGE_SHIFT);
> +   max_zone_pfns[ZONE_HIGHMEM] = max_pfn
   ^
Missing a  ";" here  --|

Sorry ... works with that fix on an old laptop with highmem.

>  #endif
> -   limit_zone_pfn(TOP_ZONE, top_of_ram >> PAGE_SHIFT);
> -   zone_limits_final = true;
> +
> free_area_init_nodes(max_zone_pfns);
>  

[PATCH 01/33] powerpc: use mm zones more sensibly

[Christoph Hellwig]

Powerpc has somewhat odd usage where ZONE_DMA is used for all memory on
common 64-bit configfs, and ZONE_DMA32 is used for 31-bit schemes.

Move to a scheme closer to what other architectures use (and I dare to
say the intent of the system):

 - ZONE_DMA: optionally for memory < 31-bit
 - ZONE_NORMAL: everything addressable by the kernel
 - ZONE_HIGHMEM: memory > 32-bit for 32-bit kernels

Also provide information on how ZONE_DMA is used by defining
ARCH_ZONE_DMA_BITS.

Contains various fixes from Benjamin Herrenschmidt.

Signed-off-by: Christoph Hellwig 
---
 arch/powerpc/Kconfig  |  6 +--
 arch/powerpc/include/asm/page.h   |  2 +
 arch/powerpc/include/asm/pgtable.h|  1 -
 arch/powerpc/kernel/dma-swiotlb.c |  6 +--
 arch/powerpc/kernel/dma.c |  7 +--
 arch/powerpc/mm/mem.c | 50 +++
 arch/powerpc/platforms/85xx/corenet_generic.c | 10 
 arch/powerpc/platforms/85xx/qemu_e500.c   |  9 
 include/linux/mmzone.h|  2 +-
 9 files changed, 24 insertions(+), 69 deletions(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index a80669209155..06996df07cad 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -380,7 +380,7 @@ config PPC_ADV_DEBUG_DAC_RANGE
depends on PPC_ADV_DEBUG_REGS && 44x
default y
 
-config ZONE_DMA32
+config ZONE_DMA
bool
default y if PPC64
 
@@ -879,10 +879,6 @@ config ISA
  have an IBM RS/6000 or pSeries machine, say Y.  If you have an
  embedded board, consult your board documentation.
 
-config ZONE_DMA
-   bool
-   default y
-
 config GENERIC_ISA_DMA
bool
depends on ISA_DMA_API
diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
index f6a1265face2..fc8c9ac0c6be 100644
--- a/arch/powerpc/include/asm/page.h
+++ b/arch/powerpc/include/asm/page.h
@@ -354,4 +354,6 @@ typedef struct page *pgtable_t;
 #endif /* __ASSEMBLY__ */
 #include 
 
+#define ARCH_ZONE_DMA_BITS 31
+
 #endif /* _ASM_POWERPC_PAGE_H */
diff --git a/arch/powerpc/include/asm/pgtable.h 
b/arch/powerpc/include/asm/pgtable.h
index 14c79a7dc855..9bafb38e959e 100644
--- a/arch/powerpc/include/asm/pgtable.h
+++ b/arch/powerpc/include/asm/pgtable.h
@@ -37,7 +37,6 @@ extern unsigned long empty_zero_page[];
 
 extern pgd_t swapper_pg_dir[];
 
-void limit_zone_pfn(enum zone_type zone, unsigned long max_pfn);
 int dma_pfn_limit_to_zone(u64 pfn_limit);
 extern void paging_init(void);
 
diff --git a/arch/powerpc/kernel/dma-swiotlb.c 
b/arch/powerpc/kernel/dma-swiotlb.c
index 88f3963ca30f..93a4622563c6 100644
--- a/arch/powerpc/kernel/dma-swiotlb.c
+++ b/arch/powerpc/kernel/dma-swiotlb.c
@@ -108,12 +108,8 @@ int __init swiotlb_setup_bus_notifier(void)
 
 void __init swiotlb_detect_4g(void)
 {
-   if ((memblock_end_of_DRAM() - 1) > 0x) {
+   if ((memblock_end_of_DRAM() - 1) > 0x)
ppc_swiotlb_enable = 1;
-#ifdef CONFIG_ZONE_DMA32
-   limit_zone_pfn(ZONE_DMA32, (1ULL << 32) >> PAGE_SHIFT);
-#endif
-   }
 }
 
 static int __init check_swiotlb_enabled(void)
diff --git a/arch/powerpc/kernel/dma.c b/arch/powerpc/kernel/dma.c
index dbfc7056d7df..6551685a4ed0 100644
--- a/arch/powerpc/kernel/dma.c
+++ b/arch/powerpc/kernel/dma.c
@@ -50,7 +50,7 @@ static int dma_nommu_dma_supported(struct device *dev, u64 
mask)
return 1;
 
 #ifdef CONFIG_FSL_SOC
-   /* Freescale gets another chance via ZONE_DMA/ZONE_DMA32, however
+   /* Freescale gets another chance via ZONE_DMA, however
 * that will have to be refined if/when they support iommus
 */
return 1;
@@ -94,13 +94,10 @@ void *__dma_nommu_alloc_coherent(struct device *dev, size_t 
size,
}
 
switch (zone) {
+#ifdef CONFIG_ZONE_DMA
case ZONE_DMA:
flag |= GFP_DMA;
break;
-#ifdef CONFIG_ZONE_DMA32
-   case ZONE_DMA32:
-   flag |= GFP_DMA32;
-   break;
 #endif
};
 #endif /* CONFIG_FSL_SOC */
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 5c8530d0c611..8bff7e893bde 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -69,15 +69,12 @@ pte_t *kmap_pte;
 EXPORT_SYMBOL(kmap_pte);
 pgprot_t kmap_prot;
 EXPORT_SYMBOL(kmap_prot);
-#define TOP_ZONE ZONE_HIGHMEM
 
 static inline pte_t *virt_to_kpte(unsigned long vaddr)
 {
return pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(vaddr),
vaddr), vaddr), vaddr);
 }
-#else
-#define TOP_ZONE ZONE_NORMAL
 #endif
 
 int page_is_ram(unsigned long pfn)
@@ -246,35 +243,19 @@ static int __init mark_nonram_nosave(void)
 }
 #endif
 
-static bool zone_limits_final;
-
-/*
- * The memory zones past TOP_ZONE are managed by generic mm code.
- * These should be set to zero since that's what every other
- * architecture does.
- */
-static unsigned long max_zone_pfns[MA