Commit 4bb9c5c0 authored by Pallipadi, Venkatesh's avatar Pallipadi, Venkatesh Committed by Ingo Molnar
Browse files

VM, x86, PAT: Change is_linear_pfn_mapping to not use vm_pgoff 

Impact: fix false positive PAT warnings - also fix VirtalBox hang

Use of vma->vm_pgoff to identify the pfnmaps that are fully
mapped at mmap time is broken. vm_pgoff is set by generic mmap
code even for cases where drivers are setting up the mappings
at the fault time.

The problem was originally reported here:

 http://marc.info/?l=linux-kernel&m=123383810628583&w=2

Change is_linear_pfn_mapping logic to overload VM_INSERTPAGE
flag along with VM_PFNMAP to mean full PFNMAP setup at mmap
time.

Problem also tracked at:

 http://bugzilla.kernel.org/show_bug.cgi?id=12800



Reported-by: default avatarThomas Hellstrom <thellstrom@vmware.com>
Tested-by: default avatarFrans Pop <elendil@planet.nl>
Signed-off-by: default avatarVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: default avatarSuresh Siddha <suresh.b.siddha&gt;@intel.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: "ebiederm@xmission.com" <ebiederm@xmission.com>
Cc: <stable@kernel.org> # only for 2.6.29.1, not .28
LKML-Reference: <20090313004527.GA7176@linux-os.sc.intel.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 6a5c05f0

arch/x86/mm/pat.c

+3 −2
Original line number Diff line number Diff line
@@ -641,10 +641,11 @@ static int reserve_pfn_range(u64 paddr, unsigned long size, pgprot_t *vma_prot, 
	is_ram = pat_pagerange_is_ram(paddr, paddr + size);



	/*

	 * reserve_pfn_range() doesn't support RAM pages.

	 * reserve_pfn_range() doesn't support RAM pages. Maintain the current

	 * behavior with RAM pages by returning success.

	 */

	if (is_ram != 0)

		return -EINVAL;

		return 0;



	ret = reserve_memtype(paddr, paddr + size, want_flags, &flags);

	if (ret)

include/linux/mm.h

+13 −2
Original line number Diff line number Diff line
@@ -98,7 +98,7 @@ extern unsigned int kobjsize(const void *objp); 
#define VM_HUGETLB	0x00400000	/* Huge TLB Page VM */

#define VM_NONLINEAR	0x00800000	/* Is non-linear (remap_file_pages) */

#define VM_MAPPED_COPY	0x01000000	/* T if mapped copy of data (nommu mmap) */

#define VM_INSERTPAGE	0x02000000	/* The vma has had "vm_insert_page()" done on it */

#define VM_INSERTPAGE	0x02000000	/* The vma has had "vm_insert_page()" done on it. Refer note in VM_PFNMAP_AT_MMAP below */

#define VM_ALWAYSDUMP	0x04000000	/* Always include in core dumps */



#define VM_CAN_NONLINEAR 0x08000000	/* Has ->fault & does nonlinear pages */
@@ -126,6 +126,17 @@ extern unsigned int kobjsize(const void *objp); 
 */

#define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_RESERVED | VM_PFNMAP)



/*

 * pfnmap vmas that are fully mapped at mmap time (not mapped on fault).

 * Used by x86 PAT to identify such PFNMAP mappings and optimize their handling.

 * Note VM_INSERTPAGE flag is overloaded here. i.e,

 * VM_INSERTPAGE && !VM_PFNMAP implies

 *     The vma has had "vm_insert_page()" done on it

 * VM_INSERTPAGE && VM_PFNMAP implies

 *     The vma is PFNMAP with full mapping at mmap time

 */

#define VM_PFNMAP_AT_MMAP (VM_INSERTPAGE | VM_PFNMAP)



/*

 * mapping from the currently active vm_flags protection bits (the

 * low four bits) to a page protection mask..
@@ -145,7 +156,7 @@ extern pgprot_t protection_map[16]; 
 */

static inline int is_linear_pfn_mapping(struct vm_area_struct *vma)

{

	return ((vma->vm_flags & VM_PFNMAP) && vma->vm_pgoff);

	return ((vma->vm_flags & VM_PFNMAP_AT_MMAP) == VM_PFNMAP_AT_MMAP);

}



static inline int is_pfn_mapping(struct vm_area_struct *vma)

mm/memory.c

+4 −2
Original line number Diff line number Diff line
@@ -1665,9 +1665,10 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, 
	 * behaviour that some programs depend on. We mark the "original"

	 * un-COW'ed pages by matching them up with "vma->vm_pgoff".

	 */

	if (addr == vma->vm_start && end == vma->vm_end)

	if (addr == vma->vm_start && end == vma->vm_end) {

		vma->vm_pgoff = pfn;

	else if (is_cow_mapping(vma->vm_flags))

		vma->vm_flags |= VM_PFNMAP_AT_MMAP;

	} else if (is_cow_mapping(vma->vm_flags))

		return -EINVAL;



	vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
@@ -1679,6 +1680,7 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, 
		 * needed from higher level routine calling unmap_vmas

		 */

		vma->vm_flags &= ~(VM_IO | VM_RESERVED | VM_PFNMAP);

		vma->vm_flags &= ~VM_PFNMAP_AT_MMAP;

		return -EINVAL;

	}

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