Hi Trond, [....] >> 1) In the above piece of code, the *ppage value from ops- >>sendpage >> function is finally passed on to Kmap by the lower level code >to >> get the virtual address of the page. >> 2) In some corner cases the value of *ppage pointer is NULL. >> 3) When highmem is enabled and a NULL pointer is passed to >> Kmap, then kmap finally crashes. But in the case when highmem >> is disabled, then kmap returns a junk value for NULL pointer. >> >> Highmem Enabled , kmap( NULL )-----> kernel crashes. >> >> Highmem disabled, kmap( NULL )-----> junk value is returned. >> Subsequently this message is observed on >> the console. >> >> "RPC call returned error 14" >> >> 4) Now the question is why is the value of *ppage = NULL is >passed >> from the above piece of code to lower layers. >> Should that not have handled *ppage = NULL? and kmap should >not >> have received a NULL pointer? > >I wouldn't expect *ppage to be NULL under any circumstances, so I'm >really curious as to what is happening here. > >Could you perhaps add a printk() to that section of code to print out >the values of 'xdr->page_base', 'xdr->page_len', 'len' and 'remainder' >in the case where *ppage == NULL? > Thanks for the response. I added a printk just before err = sock->ops->sendpage(sock, *ppage, base, len, flags); So here are values when *ppage is NULL. xdr->page_base= 0xCE9 xdr->page_len=0x400 len=0xE9 remainder=0x0. Thanks, Sricharan -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
