From: Tiezhu Yang <yangtiezhu@loongson.cn>
To: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org,
Xuefeng Li <lixuefeng@loongson.cn>,
Juxin Gao <gaojuxin@loongson.cn>
Subject: [PATCH v3 3/3] MIPS: Make sparse_init() using top-down allocation
Date: Tue, 21 Apr 2020 19:59:46 +0800 [thread overview]
Message-ID: <1587470386-27133-4-git-send-email-yangtiezhu@loongson.cn> (raw)
In-Reply-To: <1587470386-27133-1-git-send-email-yangtiezhu@loongson.cn>
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>
---
v3:
- no changes
v2:
- modify the patch subject
arch/mips/kernel/setup.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index 5481a0c..8db533c 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -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));
--
2.1.0
next prev parent reply other threads:[~2020-04-21 12:00 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-21 11:59 [PATCH v3 0/3] MIPS: Fix some issues about arch_mem_init() Tiezhu Yang
2020-04-21 11:59 ` [PATCH v3 1/3] MIPS: Do not initialise globals to 0 Tiezhu Yang
2020-04-21 11:59 ` [PATCH v3 2/3] MIPS: Cleanup code about plat_mem_setup() Tiezhu Yang
2020-04-21 11:59 ` Tiezhu Yang [this message]
2020-04-21 15:06 ` [PATCH v3 0/3] MIPS: Fix some issues about arch_mem_init() Thomas Bogendoerfer
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