linux-kernel - [PATCH v3 1/3] crash: Fix x86_32 crash memory reserve dead loop bug

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Message-ID: <20240718035444.2977105-2-ruanjinjie@huawei.com>
Date: Thu, 18 Jul 2024 11:54:42 +0800
From: Jinjie Ruan <ruanjinjie@...wei.com>
To: <linux@...linux.org.uk>, <catalin.marinas@....com>, <will@...nel.org>,
	<paul.walmsley@...ive.com>, <palmer@...belt.com>, <aou@...s.berkeley.edu>,
	<tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
	<dave.hansen@...ux.intel.com>, <hpa@...or.com>, <bhe@...hat.com>,
	<vgoyal@...hat.com>, <dyoung@...hat.com>, <arnd@...db.de>, <afd@...com>,
	<linus.walleij@...aro.org>, <akpm@...ux-foundation.org>,
	<eric.devolder@...cle.com>, <gregkh@...uxfoundation.org>,
	<javierm@...hat.com>, <deller@....de>, <robh@...nel.org>,
	<hbathini@...ux.ibm.com>, <thunder.leizhen@...wei.com>,
	<chenjiahao16@...wei.com>, <linux-kernel@...r.kernel.org>,
	<kexec@...ts.infradead.org>, <linux-arm-kernel@...ts.infradead.org>,
	<linux-riscv@...ts.infradead.org>
CC: <ruanjinjie@...wei.com>
Subject: [PATCH v3 1/3] crash: Fix x86_32 crash memory reserve dead loop bug

On x86_32 Qemu machine with 1GB memory, the cmdline "crashkernel=1G,high"
will cause system stall as below:

	ACPI: Reserving FACP table memory at [mem 0x3ffe18b8-0x3ffe192b]
	ACPI: Reserving DSDT table memory at [mem 0x3ffe0040-0x3ffe18b7]
	ACPI: Reserving FACS table memory at [mem 0x3ffe0000-0x3ffe003f]
	ACPI: Reserving APIC table memory at [mem 0x3ffe192c-0x3ffe19bb]
	ACPI: Reserving HPET table memory at [mem 0x3ffe19bc-0x3ffe19f3]
	ACPI: Reserving WAET table memory at [mem 0x3ffe19f4-0x3ffe1a1b]
	143MB HIGHMEM available.
	879MB LOWMEM available.
	  mapped low ram: 0 - 36ffe000
	  low ram: 0 - 36ffe000
	 (stall here)

The reason is that the CRASH_ADDR_LOW_MAX is equal to CRASH_ADDR_HIGH_MAX
on x86_32, the first high crash kernel memory reservation will fail, then
go into the "retry" loop and never came out as below.

-> reserve_crashkernel_generic() and high is true
 -> alloc at [CRASH_ADDR_LOW_MAX, CRASH_ADDR_HIGH_MAX] fail
    -> alloc at [0, CRASH_ADDR_LOW_MAX] fail and repeatedly
       (because CRASH_ADDR_LOW_MAX = CRASH_ADDR_HIGH_MAX).

Fix it by prevent crashkernel=,high from being parsed successfully on 32bit
system with a architecture-defined macro.

After this patch, the 'crashkernel=,high' for 32bit system can't succeed,
and it has no chance to call reserve_crashkernel_generic(), therefore this
issue on x86_32 is solved.

Fixes: 9c08a2a139fe ("x86: kdump: use generic interface to simplify crashkernel reservation code")
Signed-off-by: Jinjie Ruan <ruanjinjie@...wei.com>
Signed-off-by: Baoquan He <bhe@...hat.com>
Tested-by: Jinjie Ruan <ruanjinjie@...wei.com>
---
v3:
- Fix it as Baoquan suggested.
- Update the commit message.
v2:
- Peel off the other two patches.
- Update the commit message and fix tag.
---
 arch/arm64/include/asm/crash_reserve.h | 2 ++
 arch/riscv/include/asm/crash_reserve.h | 2 ++
 arch/x86/include/asm/crash_reserve.h   | 1 +
 kernel/crash_reserve.c                 | 2 +-
 4 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/crash_reserve.h b/arch/arm64/include/asm/crash_reserve.h
index 4afe027a4e7b..bf362c1a612f 100644
--- a/arch/arm64/include/asm/crash_reserve.h
+++ b/arch/arm64/include/asm/crash_reserve.h
@@ -7,4 +7,6 @@
 
 #define CRASH_ADDR_LOW_MAX              arm64_dma_phys_limit
 #define CRASH_ADDR_HIGH_MAX             (PHYS_MASK + 1)
+
+#define HAVE_ARCH_CRASHKERNEL_RESERVATION_HIGH
 #endif
diff --git a/arch/riscv/include/asm/crash_reserve.h b/arch/riscv/include/asm/crash_reserve.h
index 013962e63587..8d7a8fc1d459 100644
--- a/arch/riscv/include/asm/crash_reserve.h
+++ b/arch/riscv/include/asm/crash_reserve.h
@@ -7,5 +7,7 @@
 #define CRASH_ADDR_LOW_MAX		dma32_phys_limit
 #define CRASH_ADDR_HIGH_MAX		memblock_end_of_DRAM()
 
+#define HAVE_ARCH_CRASHKERNEL_RESERVATION_HIGH
+
 extern phys_addr_t memblock_end_of_DRAM(void);
 #endif
diff --git a/arch/x86/include/asm/crash_reserve.h b/arch/x86/include/asm/crash_reserve.h
index 7835b2cdff04..24c2327f9a16 100644
--- a/arch/x86/include/asm/crash_reserve.h
+++ b/arch/x86/include/asm/crash_reserve.h
@@ -26,6 +26,7 @@ extern unsigned long swiotlb_size_or_default(void);
 #else
 # define CRASH_ADDR_LOW_MAX     SZ_4G
 # define CRASH_ADDR_HIGH_MAX    SZ_64T
+#define HAVE_ARCH_CRASHKERNEL_RESERVATION_HIGH
 #endif
 
 # define DEFAULT_CRASH_KERNEL_LOW_SIZE crash_low_size_default()
diff --git a/kernel/crash_reserve.c b/kernel/crash_reserve.c
index 5b2722a93a48..c5213f123e19 100644
--- a/kernel/crash_reserve.c
+++ b/kernel/crash_reserve.c
@@ -306,7 +306,7 @@ int __init parse_crashkernel(char *cmdline,
 	/* crashkernel=X[@offset] */
 	ret = __parse_crashkernel(cmdline, system_ram, crash_size,
 				crash_base, NULL);
-#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
+#ifdef HAVE_ARCH_CRASHKERNEL_RESERVATION_HIGH
 	/*
 	 * If non-NULL 'high' passed in and no normal crashkernel
 	 * setting detected, try parsing crashkernel=,high|low.
-- 
2.34.1