Messages in this thread | | | Subject | Re: [PATCH 2/2] arm64: mm: fix kdump broken with ZONE_DMA reintroduced | From | chenzhou <> | Date | Fri, 8 Jan 2021 09:09:46 +0800 |
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On 2021/1/7 22:25, Catalin Marinas wrote: > On Sat, Dec 26, 2020 at 11:34:58AM +0100, Nicolas Saenz Julienne wrote: >> On Sat, 2020-12-26 at 11:35 +0800, Chen Zhou wrote: >>> If the memory reserved for crash dump kernel falled in ZONE_DMA32, >>> the devices in crash dump kernel need to use ZONE_DMA will alloc fail. >>> >>> Fix this by reserving low memory in ZONE_DMA if CONFIG_ZONE_DMA is >>> enabled, otherwise, reserving in ZONE_DMA32. >>> >>> Fixes: bff3b04460a8 ("arm64: mm: reserve CMA and crashkernel in ZONE_DMA32") >> I'm not so sure this counts as a fix, if someone backports it it'll probably >> break things as it depends on the series that dynamically sizes DMA zones. >> >>> Signed-off-by: Chen Zhou <chenzhou10@huawei.com> >>> --- >> Why not doing the same with CMA? You'll probably have to move the >> dma_contiguous_reserve() call into bootmem_init() so as to make sure that >> arm64_dma_phys_limit is populated. > Do we need the arm64_dma32_phys_limit at all? I can see the > (arm64_dma_phys_limit ? : arm64_dma32_phys_limit) pattern in several > places but I think we can just live with the arm64_dma_phys_limit. Yes, arm64_dma_phys_limit is enough. > > Also, I don't think we need any early ARCH_LOW_ADDRESS_LIMIT. It's only > used by memblock_alloc_low() and that's called from swiotlb_init() > after arm64_dma_phys_limit was initialised. > > What about something like below (on top of you ARCH_LOW_ADDRESS_LIMIT > fix but I can revert that)? I haven't tested it in all configurations > yet. > > diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h > index 69ad25fbeae4..ca2cd75d3286 100644 > --- a/arch/arm64/include/asm/processor.h > +++ b/arch/arm64/include/asm/processor.h > @@ -94,8 +94,7 @@ > #endif /* CONFIG_ARM64_FORCE_52BIT */ > > extern phys_addr_t arm64_dma_phys_limit; > -extern phys_addr_t arm64_dma32_phys_limit; > -#define ARCH_LOW_ADDRESS_LIMIT ((arm64_dma_phys_limit ? : arm64_dma32_phys_limit) - 1) > +#define ARCH_LOW_ADDRESS_LIMIT (arm64_dma_phys_limit - 1) > > struct debug_info { > #ifdef CONFIG_HAVE_HW_BREAKPOINT > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > index 7deddf56f7c3..596a94bf5ed6 100644 > --- a/arch/arm64/mm/init.c > +++ b/arch/arm64/mm/init.c > @@ -59,7 +59,6 @@ EXPORT_SYMBOL(memstart_addr); > * bit addressable memory area. > */ > phys_addr_t arm64_dma_phys_limit __ro_after_init; > -phys_addr_t arm64_dma32_phys_limit __ro_after_init; > > #ifdef CONFIG_KEXEC_CORE > /* > @@ -84,7 +83,7 @@ static void __init reserve_crashkernel(void) > > if (crash_base == 0) { > /* Current arm64 boot protocol requires 2MB alignment */ > - crash_base = memblock_find_in_range(0, arm64_dma32_phys_limit, > + crash_base = memblock_find_in_range(0, arm64_dma_phys_limit, > crash_size, SZ_2M); > if (crash_base == 0) { > pr_warn("cannot allocate crashkernel (size:0x%llx)\n", > @@ -196,6 +195,7 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max) > unsigned long max_zone_pfns[MAX_NR_ZONES] = {0}; > unsigned int __maybe_unused acpi_zone_dma_bits; > unsigned int __maybe_unused dt_zone_dma_bits; > + phys_addr_t dma32_phys_limit = max_zone_phys(32); > > #ifdef CONFIG_ZONE_DMA > acpi_zone_dma_bits = fls64(acpi_iort_dma_get_max_cpu_address()); > @@ -205,8 +205,12 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max) > max_zone_pfns[ZONE_DMA] = PFN_DOWN(arm64_dma_phys_limit); > #endif > #ifdef CONFIG_ZONE_DMA32 > - max_zone_pfns[ZONE_DMA32] = PFN_DOWN(arm64_dma32_phys_limit); > + max_zone_pfns[ZONE_DMA32] = PFN_DOWN(dma32_phys_limit); > + if (!arm64_dma_phys_limit) > + arm64_dma_phys_limit = dma32_phys_limit; > #endif > + if (!arm64_dma_phys_limit) > + arm64_dma_phys_limit = PHYS_MASK + 1; > max_zone_pfns[ZONE_NORMAL] = max; > > free_area_init(max_zone_pfns); > @@ -394,16 +398,9 @@ void __init arm64_memblock_init(void) > > early_init_fdt_scan_reserved_mem(); > > - if (IS_ENABLED(CONFIG_ZONE_DMA32)) > - arm64_dma32_phys_limit = max_zone_phys(32); > - else > - arm64_dma32_phys_limit = PHYS_MASK + 1; > - > reserve_elfcorehdr(); > > high_memory = __va(memblock_end_of_DRAM() - 1) + 1; > - > - dma_contiguous_reserve(arm64_dma32_phys_limit); > } > > void __init bootmem_init(void) > @@ -438,6 +435,11 @@ void __init bootmem_init(void) > sparse_init(); > zone_sizes_init(min, max); > > + /* > + * Reserve the CMA area after arm64_dma_phys_limit was initialised. > + */ > + dma_contiguous_reserve(arm64_dma_phys_limit); > + > /* > * request_standard_resources() depends on crashkernel's memory being > * reserved, so do it here. > @@ -455,7 +457,7 @@ void __init bootmem_init(void) > void __init mem_init(void) > { > if (swiotlb_force == SWIOTLB_FORCE || > - max_pfn > PFN_DOWN(arm64_dma_phys_limit ? : arm64_dma32_phys_limit)) > + max_pfn > PFN_DOWN(arm64_dma_phys_limit)) > swiotlb_init(1); > else > swiotlb_force = SWIOTLB_NO_FORCE; > . >
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