On Wed, 2011-01-05 at 16:01 +0100, Marc Kleine-Budde wrote: > On 01/05/2011 03:53 PM, Trond Myklebust wrote: > > On Wed, 2011-01-05 at 14:40 +0100, Uwe Kleine-KÃnig wrote: > >> Hi Russell, > >> > >> On Wed, Jan 05, 2011 at 11:27:01AM +0000, Russell King - ARM Linux wrote: > >>> On Wed, Jan 05, 2011 at 12:05:17PM +0100, Uwe Kleine-KÃnig wrote: > >>>> Hello Trond, > >>>> > >>>> On Wed, Jan 05, 2011 at 09:40:14AM +0100, Uwe Kleine-KÃnig wrote: > >>>>> On Mon, Jan 03, 2011 at 07:22:38PM -0500, Trond Myklebust wrote: > >>>>>> The question is whether this is something happening on the server or the > >>>>>> client. Does an older client kernel boot without any trouble? > >>>>> I will set up a boot test with 2.6.37 (for statistics) and 2.6.36 to > >>>>> compare with. If you don't consider .36 to be old enough let me now. > >>>>> Once the setup is done it should be easy to test .35 (say), too. > >>>>> > >>>> Marc (cc'd) saw similar[1] problems with .37, when using .36.2 the > >>>> problems didn't occur. This was more reliable to trigger and he was so > >>>> kind to bisect the problem. > >>>> > >>>> When testing v2.6.36-rc3-51-gafa8ccc init hanged. > >>>> (babddc72a9468884ce1a23db3c3d54b0afa299f0 is the first bad commit with > >>>> this hang.) Commit 56e4ebf877b6043c289bda32a5a7385b80c17dee makes the > >>>> "init hangs" problem the "fileid changed on tab" problem. > >>>> > >>>> I could only reproduce that on armv5 machines (imx27, imx28 and at91) > >>>> but not on armv6 (imx35). > >>> > >>> FYI, I've seen the "fileid changed" problem, and it looked like a 32-bit > >>> truncation of the fileid. It occurred several times on successive > >>> reboots, so I tried to capture a tcpdump trace off the server (Linux > >>> 2.6.23-rc8-ga64314e6 - its ancient because I've had issues with buggy > >>> IDE drivers trying to move it forward.) However, for the last couple > >>> of weeks I've been unable to reproduce it. > >>> > >>> The client was based on 2.6.37-rc6. > >>> > >>> The "fileid changed" messages popped up after mounting an export with > >>> 'nolock,intr,rsize=4096,soft', and then trying to use bash completion > >>> and 'ls' in a few subdirectories - and entries were missing from the > >>> directory lists without 'ls' reporting any errors (which I think is bad > >>> behaviour in itself.) > >> There was a bug in at least -rc5[1] that was considered already fixed in > >> -rc4[2]. The later announcements didn't mention it anymore. > >> > >>> I don't know why it's stopped producing the errors, although once it > >>> went I never investigated it any further (was far too busy trying to > >>> get AMBA DMA support working.) > >> It seems it was fixed for most users though. Trond? > > > > As I said, I can't reproduce it. > > > > I'm seeing a lot of mention of ARM above. Is anyone seeing this bug on > > x86, or does it appear to be architecture-specific? > > It _seems_ to be ARMv5 specific[1]. Uwe did some tests and figured out > that disabling dcache on ARMv5 "fixes" the problem, but > CONFIG_CPU_DCACHE_WRITETHROUGH isn't enough. > > [1] Uwe fails to reproduce it on ARMv6. The ARMv6 has a L2 cache and > uses IIRC different instructions to flush the L1 caches. (please correct > me, if I'm wrong, ARM guys :) > > cheers, Marc OK. So,the new behaviour in 2.6.37 is that we're writing to a series of pages via the usual kmap_atomic()/kunmap_atomic() and kmap()/kunmap() interfaces, but we can end up reading them via a virtual address range that gets set up via vm_map_ram() (that range gets set up before the write occurs). Do we perhaps need an invalidate_kernel_vmap_range() before we can read the data on ARM in this kind of scenario? -- 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
