Hi Vaidy, > 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 <sva...@linux.vnet.ibm.com>
Acked-by: Jeremy Kerr <j...@ozlabs.org> Cheers, Jeremy _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev