i386: vmalloc size fix (e621bd18) · Commits · 戴 / test

Booting kernel with vmalloc=[any size<=16m] will oops on my pc (i386/1G memory). BUG_ON in arch/x86/mm/init_32.c triggered: BUG_ON((unsigned long)high_memory > VMALLOC_START); It's due to the vm area hole. In include/asm-x86/pgtable_32.h: #define VMALLOC_OFFSET (8 * 1024 * 1024) #define VMALLOC_START (((unsigned long)high_memory + 2 * VMALLOC_OFFSET - 1) \ & ~(VMALLOC_OFFSET - 1)) There's several related point: 1. MAXMEM : (-__PAGE_OFFSET - __VMALLOC_RESERVE). The space after VMALLOC_END is included as well, I set it to (VMALLOC_END - PAGE_OFFSET - __VMALLOC_RESERVE) 2. VMALLOC_OFFSET is not considered in __VMALLOC_RESERVE fixed by adding VMALLOC_OFFSET to it. 3. VMALLOC_START : (((unsigned long)high_memory + 2 * VMALLOC_OFFSET - 1) & ~(VMALLOC_OFFSET - 1)) So it's not always 8M, bigger than 8M possible. I set it to ((unsigned long)high_memory + VMALLOC_OFFSET) 4. the VMALLOC_RESERVE is an unused macro, so remove it here. Signed-off-by:

Dave Young <hidave.darkstar@gmail.com> Cc: akpm@linux-foundation.org Cc: hidave.darkstar@gmail.com Signed-off-by:

Ingo Molnar <mingo@elte.hu> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org>

arch/x86/mm/pgtable_32.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -123,7 +123,8 @@ static int __init parse_vmalloc(char *arg)
		if (!arg)
		return -EINVAL;

		__VMALLOC_RESERVE = memparse(arg, &arg);
		/* Add VMALLOC_OFFSET to the parsed value due to vm area guard hole*/
		__VMALLOC_RESERVE = memparse(arg, &arg) + VMALLOC_OFFSET;
		return 0;
		}
		early_param("vmalloc", parse_vmalloc);

include/asm-x86/page_32.h

+0 −3

Original line number	Diff line number	Diff line
		@@ -89,9 +89,6 @@ extern int nx_enabled;
		extern unsigned int __VMALLOC_RESERVE;
		extern int sysctl_legacy_va_layout;

		#define VMALLOC_RESERVE ((unsigned long)__VMALLOC_RESERVE)
		#define MAXMEM (-__PAGE_OFFSET - __VMALLOC_RESERVE)

		extern void find_low_pfn_range(void);
		extern unsigned long init_memory_mapping(unsigned long start,
		unsigned long end);

include/asm-x86/pgtable_32.h

+3 −2

Original line number	Diff line number	Diff line
		@@ -56,8 +56,7 @@ void paging_init(void);
		* area for the same reason. ;)
		*/
		#define VMALLOC_OFFSET (8 * 1024 * 1024)
		#define VMALLOC_START (((unsigned long)high_memory + 2 * VMALLOC_OFFSET - 1) \
		& ~(VMALLOC_OFFSET - 1))
		#define VMALLOC_START ((unsigned long)high_memory + VMALLOC_OFFSET)
		#ifdef CONFIG_X86_PAE
		#define LAST_PKMAP 512
		#else
		@@ -73,6 +72,8 @@ void paging_init(void);
		# define VMALLOC_END (FIXADDR_START - 2 * PAGE_SIZE)
		#endif

		#define MAXMEM (VMALLOC_END - PAGE_OFFSET - __VMALLOC_RESERVE)

		/*
		* Define this if things work differently on an i386 and an i486:
		* it will (on an i486) warn about kernel memory accesses that are

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