On Thu, 13 Jun 2013 10:32:48 +0900
HATAYAMA Daisuke <d.hatay...@jp.fujitsu.com> wrote:
> > Perhaps one open issue remains:
> >
> > Can we remove the page from the page cache if __read_vmcore() fails?
> >
>
> Yes, use page_cache_release() after unlocking the page like:
>
> if (__read_vmcore(buf, PAGE_SIZE, &src, 0) < 0) {
> unlock_page(page);
> + page_cache_release(page);
> return VM_FAULT_SIGBUS;
> }
>
> BTW, you now keep file->f_mapping in vma->vm_private_data, but the vma
> already has the file object in its vma->vm_file member. You can get the
> mapping by vma->vm_file->f_mapping without necessity of vma->vm_private_data.
Hello Hatayama,
Here the new function:
static int mmap_vmcore_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct address_space *mapping = vma->vm_file->f_mapping;
pgoff_t index = vmf->pgoff;
struct page *page;
loff_t src;
char *buf;
int rc;
page = find_or_create_page(mapping, index, GFP_KERNEL);
if (!page)
return VM_FAULT_OOM;
if (!PageUptodate(page)) {
src = index << PAGE_CACHE_SHIFT;
buf = (void *) (page_to_pfn(page) << PAGE_SHIFT);
rc = __read_vmcore(buf, PAGE_SIZE, &src, 0);
if (rc < 0) {
unlock_page(page);
page_cache_release(page);
return (rc == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS;
}
SetPageUptodate(page);
}
unlock_page(page);
vmf->page = page;
return 0;
}
Thanks for all the constructive feedback!
Best Regards,
Michael
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