linux-kernel - [tip:x86/urgent] x86, cma: Reserve DMA contiguous area after initmem

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Message-ID: <tip-3c325f8233c35fb35dec3744ba01634aab4ea36a@git.kernel.org>
Date:	Mon, 27 Oct 2014 23:39:34 -0700
From:	tip-bot for Weijie Yang <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	mina86@...a86.com, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org, weijie.yang.kh@...il.com,
	fengguang.wu@...el.com, linux-mm@...ck.org, tglx@...utronix.de,
	mingo@...nel.org, weijie.yang@...sung.com,
	m.szyprowski@...sung.com, hpa@...or.com
Subject: [tip:x86/urgent] x86, cma:
  Reserve DMA contiguous area after initmem_init()

Commit-ID:  3c325f8233c35fb35dec3744ba01634aab4ea36a
Gitweb:     http://git.kernel.org/tip/3c325f8233c35fb35dec3744ba01634aab4ea36a
Author:     Weijie Yang <weijie.yang@...sung.com>
AuthorDate: Fri, 24 Oct 2014 17:00:34 +0800
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 28 Oct 2014 07:36:50 +0100

x86, cma: Reserve DMA contiguous area after initmem_init()

Fengguang Wu reported a boot crash on the x86 platform
via the 0-day Linux Kernel Performance Test:

  cma: dma_contiguous_reserve: reserving 31 MiB for global area
  BUG: Int 6: CR2   (null)
  [<41850786>] dump_stack+0x16/0x18
  [<41d2b1db>] early_idt_handler+0x6b/0x6b
  [<41072227>] ? __phys_addr+0x2e/0xca
  [<41d4ee4d>] cma_declare_contiguous+0x3c/0x2d7
  [<41d6d359>] dma_contiguous_reserve_area+0x27/0x47
  [<41d6d4d1>] dma_contiguous_reserve+0x158/0x163
  [<41d33e0f>] setup_arch+0x79b/0xc68
  [<41d2b7cf>] start_kernel+0x9c/0x456
  [<41d2b2ca>] i386_start_kernel+0x79/0x7d

(See details at: https://lkml.org/lkml/2014/10/8/708)

It is because dma_contiguous_reserve() is called before
initmem_init() in x86, the variable high_memory is not
initialized but accessed by __pa(high_memory) in
dma_contiguous_reserve().

This patch moves dma_contiguous_reserve() after initmem_init()
so that high_memory is initialized before accessed.

Reported-by: Fengguang Wu <fengguang.wu@...el.com>
Signed-off-by: Weijie Yang <weijie.yang@...sung.com>
Acked-by: Andrew Morton <akpm@...ux-foundation.org>
Acked-by: Marek Szyprowski <m.szyprowski@...sung.com>
Acked-by: Michal Nazarewicz <mina86@...a86.com>
Cc: iamjoonsoo.kim@....com
Cc: 'Linux-MM' <linux-mm@...ck.org>
Cc: 'Weijie Yang' <weijie.yang.kh@...il.com>
Link: http://lkml.kernel.org/r/000101cfef69%2431e528a0%2495af79e0%24%25yang@samsung.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/kernel/setup.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 235cfd3..ab08aa2 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1128,7 +1128,6 @@ void __init setup_arch(char **cmdline_p)
 	setup_real_mode();
 
 	memblock_set_current_limit(get_max_mapped());
-	dma_contiguous_reserve(max_pfn_mapped << PAGE_SHIFT);
 
 	/*
 	 * NOTE: On x86-32, only from this point on, fixmaps are ready for use.
@@ -1159,6 +1158,7 @@ void __init setup_arch(char **cmdline_p)
 	early_acpi_boot_init();
 
 	initmem_init();
+	dma_contiguous_reserve(max_pfn_mapped << PAGE_SHIFT);
 
 	/*
 	 * Reserve memory for crash kernel after SRAT is parsed so that it
--
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