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

Browse source 
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: Thomas Hellstrom <thellstrom@vmware.com>
Tested-by: Frans Pop <elendil@planet.nl>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha>@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: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Pallipadi, Venkatesh 2009-03-12 17:45:27 -07:00 committed by Ingo Molnar
parent 6a5c05f002
commit 4bb9c5c021
3 changed files with 20 additions and 6 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

5
arch/x86/mm/pat.c
View file

@ -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)

15
include/linux/mm.h
View file

@ -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)

6
mm/memory.c
View file

@ -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;
}