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authorVaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>2015-06-29 10:47:55 +0530
committerMichael Ellerman <mpe@ellerman.id.au>2015-07-06 12:06:42 +1000
commitd8ea782b56d9d2c46a47b3231cfd16ecfb538c60 (patch)
treef5d75974559e419469156ecb9e43477480083bda /arch/powerpc/platforms/powernv/opal-prd.c
parentd770e558e21961ad6cfdf0ff7df0eb5d7d4f0754 (diff)
powerpc/powernv: Fix vma page prot flags in opal-prd driver
opal-prd driver will mmap() firmware code/data area as private mapping to prd user space daemon. Write to this page will trigger COW faults. The new COW pages are normal kernel RAM pages accounted by the kernel and are not special. vma->vm_page_prot value will be used at page fault time for the new COW pages, while pgprot_t value passed in remap_pfn_range() is used for the initial page table entry. Hence: * Do not add _PAGE_SPECIAL in vma, but only for remap_pfn_range() * Also remap_pfn_range() will add the _PAGE_SPECIAL flag using pte_mkspecial() call, hence no need to specify in the driver This fix resolves the page accounting warning shown below: BUG: Bad rss-counter state mm:c0000007d34ac600 idx:1 val:19 The above warning is triggered since _PAGE_SPECIAL was incorrectly being set for the normal kernel COW pages. Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> Acked-by: Jeremy Kerr <jk@ozlabs.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/platforms/powernv/opal-prd.c')
-rw-r--r--arch/powerpc/platforms/powernv/opal-prd.c9
1 files changed, 4 insertions, 5 deletions
diff --git a/arch/powerpc/platforms/powernv/opal-prd.c b/arch/powerpc/platforms/powernv/opal-prd.c
index 46cb3feb0a13..4ece8e40dd54 100644
--- a/arch/powerpc/platforms/powernv/opal-prd.c
+++ b/arch/powerpc/platforms/powernv/opal-prd.c
@@ -112,6 +112,7 @@ static int opal_prd_open(struct inode *inode, struct file *file)
static int opal_prd_mmap(struct file *file, struct vm_area_struct *vma)
{
size_t addr, size;
+ pgprot_t page_prot;
int rc;
pr_devel("opal_prd_mmap(0x%016lx, 0x%016lx, 0x%lx, 0x%lx)\n",
@@ -125,13 +126,11 @@ static int opal_prd_mmap(struct file *file, struct vm_area_struct *vma)
if (!opal_prd_range_is_valid(addr, size))
return -EINVAL;
- vma->vm_page_prot = __pgprot(pgprot_val(phys_mem_access_prot(file,
- vma->vm_pgoff,
- size, vma->vm_page_prot))
- | _PAGE_SPECIAL);
+ page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
+ size, vma->vm_page_prot);
rc = remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff, size,
- vma->vm_page_prot);
+ page_prot);
return rc;
}

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