On Mon, Oct 05, 2015 at 12:44:55PM +0200, Christian Melki wrote: > Joerg, > > I already sent the patch for Kconfig change to the list. > But I discovered something even more disturbing which I mailed Konrad about. > With the change my machine does not hang any more, but instead corrupts data > which is written. The data however is readable on the machine which > corrupted it, unreadable on the other machine without the patch. I don't > understand what is going on. I have never encountered "selective" file > corruption of fs on different machines. The fs itself checks out cleanly > with badblock control (ext4). I fail to understand what is happening.
And I believe this ended up being an operator error? With the patch you sent, you didn't include your SoB (Signed-off-By). I would like to include your patch but I cannot with your SoB. It is matter of reading to Documentation/SubmittingPatches and just consenting to the Certificate in there. If you are uncomfortable with that - that is OK, I can make this patch myself (a one liner :-)) but I figured it owuld be nice for you to have all the credit. > > Regards, > Christian > > -------- Forwarded Message -------- > Subject: SWIOTLB on 32-bit PAE > Date: Mon, 5 Oct 2015 10:31:39 +0200 > From: Christian Melki <christian.me...@t2data.com> > To: linux-kernel@vger.kernel.org > CC: konrad.w...@oracle.com > > Hi, > > I discovered that my 32-bit PAE 4.2.0 kernel (no IOMMU code) would hang > when writing to my USB disk. The kernel spews million(-ish messages per > sec) to syslog, effectively "hanging" userspace with my kernel. > > Oct 2 14:33:06 voodoochild kernel: [ 223.287447] nommu_map_sg: > overflow 25dcac000+1024 of device mask ffffffff > Oct 2 14:33:06 voodoochild kernel: [ 223.287448] nommu_map_sg: > overflow 25dcac000+1024 of device mask ffffffff > Oct 2 14:33:06 voodoochild kernel: [ 223.287449] nommu_map_sg: > overflow 25dcac000+1024 of device mask ffffffff > ... etc ... > > In my kernel config I noticed that SWIOTLB was not on. It seems SWIOTLB > is provided for 64-bit and 32-bit with IOMMU/AGPGART code. But if I > compiled the kernel with PAE and no IOMMU and no other GART code, I > would not get SWIOTLB. I'd like to think that SWIOTLB should be selected > for 32-bit PAE as default. > > I have attached a oneliner patch which does that. > The patch works for me. The issue where the kernel more or less runs > endless bashing of (nommu_?)map_sg when failing is another problem I > guess. I expected the kernel/drivers to have some more graceful > handling, but I know to little about this area to have a proper opinion. > > Regards, > Christian > > > > diff -urN linux-4.2.orig/arch/x86/Kconfig linux-4.2/arch/x86/Kconfig > --- linux-4.2.orig/arch/x86/Kconfig 2015-10-05 08:56:58.933313678 +0200 > +++ linux-4.2/arch/x86/Kconfig 2015-10-05 09:00:00.916306025 +0200 > @@ -1282,6 +1282,7 @@ > config X86_PAE > bool "PAE (Physical Address Extension) Support" > depends on X86_32 && !HIGHMEM4G > + select SWIOTLB > ---help--- > PAE is required for NX support, and furthermore enables > larger swapspace support for non-overcommit purposes. It > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
