From 6b101e2a3ce4d2a0312087598bd1ab4a1db2ac40 Mon Sep 17 00:00:00 2001 From: Joonsoo Kim Date: Wed, 10 Dec 2014 15:41:12 -0800 Subject: [PATCH] mm/CMA: fix boot regression due to physical address of high_memory high_memory isn't direct mapped memory so retrieving it's physical address isn't appropriate. But, it would be useful to check physical address of highmem boundary so it's justfiable to get physical address from it. In x86, there is a validation check if CONFIG_DEBUG_VIRTUAL and it triggers following boot failure reported by Ingo. ... BUG: Int 6: CR2 00f06f53 ... Call Trace: dump_stack+0x41/0x52 early_idt_handler+0x6b/0x6b cma_declare_contiguous+0x33/0x212 dma_contiguous_reserve_area+0x31/0x4e dma_contiguous_reserve+0x11d/0x125 setup_arch+0x7b5/0xb63 start_kernel+0xb8/0x3e6 i386_start_kernel+0x79/0x7d To fix boot regression, this patch implements workaround to avoid validation check in x86 when retrieving physical address of high_memory. __pa_nodebug() used by this patch is implemented only in x86 so there is no choice but to use dirty #ifdef. [akpm@linux-foundation.org: tweak comment] Signed-off-by: Joonsoo Kim Reported-by: Ingo Molnar Tested-by: Ingo Molnar Cc: Marek Szyprowski Cc: Russell King Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/cma.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/mm/cma.c b/mm/cma.c index fde706e1284f..8e9ec13d31db 100644 --- a/mm/cma.c +++ b/mm/cma.c @@ -215,9 +215,21 @@ int __init cma_declare_contiguous(phys_addr_t base, bool fixed, struct cma **res_cma) { phys_addr_t memblock_end = memblock_end_of_DRAM(); - phys_addr_t highmem_start = __pa(high_memory); + phys_addr_t highmem_start; int ret = 0; +#ifdef CONFIG_X86 + /* + * high_memory isn't direct mapped memory so retrieving its physical + * address isn't appropriate. But it would be useful to check the + * physical address of the highmem boundary so it's justfiable to get + * the physical address from it. On x86 there is a validation check for + * this case, so the following workaround is needed to avoid it. + */ + highmem_start = __pa_nodebug(high_memory); +#else + highmem_start = __pa(high_memory); +#endif pr_debug("%s(size %pa, base %pa, limit %pa alignment %pa)\n", __func__, &size, &base, &limit, &alignment); -- 2.20.1