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Commit e69e9d4a authored by HATAYAMA Daisuke's avatar HATAYAMA Daisuke Committed by Linus Torvalds
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vmalloc: introduce remap_vmalloc_range_partial 



We want to allocate ELF note segment buffer on the 2nd kernel in vmalloc
space and remap it to user-space in order to reduce the risk that memory
allocation fails on system with huge number of CPUs and so with huge ELF
note segment that exceeds 11-order block size.

Although there's already remap_vmalloc_range for the purpose of
remapping vmalloc memory to user-space, we need to specify user-space
range via vma.
 Mmap on /proc/vmcore needs to remap range across multiple objects, so
the interface that requires vma to cover full range is problematic.

This patch introduces remap_vmalloc_range_partial that receives user-space
range as a pair of base address and size and can be used for mmap on
/proc/vmcore case.

remap_vmalloc_range is rewritten using remap_vmalloc_range_partial.

[akpm@linux-foundation.org: use PAGE_ALIGNED()]
Signed-off-by: default avatarHATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
Cc: Lisa Mitchell <lisa.mitchell@hp.com>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent cef2ac3f

include/linux/vmalloc.h

+4 −0
Original line number Diff line number Diff line
@@ -82,6 +82,10 @@ extern void *vmap(struct page **pages, unsigned int count, 
			unsigned long flags, pgprot_t prot);

extern void vunmap(const void *addr);



extern int remap_vmalloc_range_partial(struct vm_area_struct *vma,

				       unsigned long uaddr, void *kaddr,

				       unsigned long size);



extern int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,

							unsigned long pgoff);

void vmalloc_sync_all(void);

mm/vmalloc.c

+45 −22
Original line number Diff line number Diff line
@@ -1476,10 +1476,9 @@ static void __vunmap(const void *addr, int deallocate_pages) 
	if (!addr)

		return;



	if ((PAGE_SIZE-1) & (unsigned long)addr) {

		WARN(1, KERN_ERR "Trying to vfree() bad address (%p)\n", addr);

	if (WARN(!PAGE_ALIGNED(addr), "Trying to vfree() bad address (%p)\n",

			addr));

		return;

	}



	area = remove_vm_area(addr);

	if (unlikely(!area)) {
@@ -2148,42 +2147,43 @@ long vwrite(char *buf, char *addr, unsigned long count) 
}



/**

 *	remap_vmalloc_range  -  map vmalloc pages to userspace

 *	@vma:		vma to cover (map full range of vma)

 *	@addr:		vmalloc memory

 *	@pgoff:		number of pages into addr before first page to map

 *	remap_vmalloc_range_partial  -  map vmalloc pages to userspace

 *	@vma:		vma to cover

 *	@uaddr:		target user address to start at

 *	@kaddr:		virtual address of vmalloc kernel memory

 *	@size:		size of map area

 *

 *	Returns:	0 for success, -Exxx on failure

 *

 *	This function checks that addr is a valid vmalloc'ed area, and

 *	that it is big enough to cover the vma. Will return failure if

 *	that criteria isn't met.

 *	This function checks that @kaddr is a valid vmalloc'ed area,

 *	and that it is big enough to cover the range starting at

 *	@uaddr in @vma. Will return failure if that criteria isn't

 *	met.

 *

 *	Similar to remap_pfn_range() (see mm/memory.c)

 */

int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,

						unsigned long pgoff)

int remap_vmalloc_range_partial(struct vm_area_struct *vma, unsigned long uaddr,

				void *kaddr, unsigned long size)

{

	struct vm_struct *area;

	unsigned long uaddr = vma->vm_start;

	unsigned long usize = vma->vm_end - vma->vm_start;



	if ((PAGE_SIZE-1) & (unsigned long)addr)

	size = PAGE_ALIGN(size);



	if (!PAGE_ALIGNED(uaddr) || !PAGE_ALIGNED(kaddr))

		return -EINVAL;



	area = find_vm_area(addr);

	area = find_vm_area(kaddr);

	if (!area)

		return -EINVAL;



	if (!(area->flags & VM_USERMAP))

		return -EINVAL;



	if (usize + (pgoff << PAGE_SHIFT) > area->size - PAGE_SIZE)

	if (kaddr + size > area->addr + area->size)

		return -EINVAL;



	addr += pgoff << PAGE_SHIFT;

	do {

		struct page *page = vmalloc_to_page(addr);

		struct page *page = vmalloc_to_page(kaddr);

		int ret;



		ret = vm_insert_page(vma, uaddr, page);
@@ -2191,14 +2191,37 @@ int remap_vmalloc_range(struct vm_area_struct *vma, void *addr, 
			return ret;



		uaddr += PAGE_SIZE;

		addr += PAGE_SIZE;

		usize -= PAGE_SIZE;

	} while (usize > 0);

		kaddr += PAGE_SIZE;

		size -= PAGE_SIZE;

	} while (size > 0);



	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;



	return 0;

}

EXPORT_SYMBOL(remap_vmalloc_range_partial);



/**

 *	remap_vmalloc_range  -  map vmalloc pages to userspace

 *	@vma:		vma to cover (map full range of vma)

 *	@addr:		vmalloc memory

 *	@pgoff:		number of pages into addr before first page to map

 *

 *	Returns:	0 for success, -Exxx on failure

 *

 *	This function checks that addr is a valid vmalloc'ed area, and

 *	that it is big enough to cover the vma. Will return failure if

 *	that criteria isn't met.

 *

 *	Similar to remap_pfn_range() (see mm/memory.c)

 */

int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,

						unsigned long pgoff)

{

	return remap_vmalloc_range_partial(vma, vma->vm_start,

					   addr + (pgoff << PAGE_SHIFT),

					   vma->vm_end - vma->vm_start);

}

EXPORT_SYMBOL(remap_vmalloc_range);



/*