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MIPS: Make sparse_init() using top-down allocation

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In the current code, if CONFIG_SWIOTLB is set, when failed to get IO TLB
memory from the low pages by plat_swiotlb_setup(), it may lead to the boot
process failed with kernel panic.

(1) On the Loongson and SiByte platform
arch/mips/loongson64/dma.c
arch/mips/sibyte/common/dma.c
void __init plat_swiotlb_setup(void)
{
	swiotlb_init(1);
}

kernel/dma/swiotlb.c
void  __init
swiotlb_init(int verbose)
{
...
	vstart = memblock_alloc_low(PAGE_ALIGN(bytes), PAGE_SIZE);
	if (vstart && !swiotlb_init_with_tbl(vstart, io_tlb_nslabs, verbose))
		return;
...
	pr_warn("Cannot allocate buffer");
	no_iotlb_memory = true;
}

phys_addr_t swiotlb_tbl_map_single()
{
...
	if (no_iotlb_memory)
		panic("Can not allocate SWIOTLB buffer earlier ...");
...
}

(2) On the Cavium OCTEON platform
arch/mips/cavium-octeon/dma-octeon.c
void __init plat_swiotlb_setup(void)
{
...
	octeon_swiotlb = memblock_alloc_low(swiotlbsize, PAGE_SIZE);
	if (!octeon_swiotlb)
		panic("%s: Failed to allocate %zu bytes align=%lx\n",
		      __func__, swiotlbsize, PAGE_SIZE);
...
}

Because IO_TLB_DEFAULT_SIZE is 64M, if the rest size of low memory is less
than 64M when call plat_swiotlb_setup(), we can easily reproduce the panic
case.

In order to reduce the possibility of kernel panic when failed to get IO
TLB memory under CONFIG_SWIOTLB, it is better to allocate low memory as
small as possible before plat_swiotlb_setup(), so make sparse_init() using
top-down allocation.

Reported-by: Juxin Gao <gaojuxin@loongson.cn>
Co-developed-by: Juxin Gao <gaojuxin@loongson.cn>
Signed-off-by: Juxin Gao <gaojuxin@loongson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
This commit is contained in:
Tiezhu Yang 2020-04-21 19:59:46 +08:00 committed by Thomas Bogendoerfer
parent 2a3d47c94e
commit 269b3a9ac5
1 changed files with 10 additions and 0 deletions
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10
arch/mips/kernel/setup.c
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@ -700,7 +700,17 @@ static void __init arch_mem_init(char **cmdline_p)
memblock_reserve(crashk_res.start, resource_size(&crashk_res));
#endif
device_tree_init();
/*
* In order to reduce the possibility of kernel panic when failed to
* get IO TLB memory under CONFIG_SWIOTLB, it is better to allocate
* low memory as small as possible before plat_swiotlb_setup(), so
* make sparse_init() using top-down allocation.
*/
memblock_set_bottom_up(false);
sparse_init();
memblock_set_bottom_up(true);
plat_swiotlb_setup();
dma_contiguous_reserve(PFN_PHYS(max_low_pfn));