On Mon, 2011-09-12 at 11:46 +0530, Sricharan R wrote: > 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 Can you please tell me what the mount options are for this setup? Are you running any applications that might be using O_DIRECT writes? Cheers Trond -- Trond Myklebust Linux NFS client maintainer NetApp Trond.Myklebust@xxxxxxxxxx www.netapp.com -- 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
