[Kernel-packages] [Bug 1602299] Re: bcache is unstable on ppc64el

** Tags added: patch -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1602299 Title: bcache is unstable on ppc64el Status in linux package in Ubuntu: Confirmed Bug description:

[Kernel-packages] [Bug 1602299] Re: bcache is unstable on ppc64el

This is hopefully the last iteration on a stable targeted fix for bcache on non-4k architectures. Noting that this possibly applies to 4.6 (if that gets used for Yakkety) but needs at least some rework for 4.7 as it looks like submit_bio* functions changed arguments with rc2. ** Patch added:

[Kernel-packages] [Bug 1602299] Re: bcache is unstable on ppc64el

Not sure. That talks about the location of the super block. It does not seem to change the size. But then it could be that this papers over things if the offset of data in the page returned by __bread depends on the relative location of a disk section within a page size area. So reading block one

[Kernel-packages] [Bug 1602299] Re: bcache is unstable on ppc64el

So I believe the problem is the hackish way to acquire buffer pages for internal biovec structures. This is done by taking a reference on the page which is returned by __bread() in read_super(). With 4k pages and reading 4k from sector 1 bh->b_data will always be the start of a page. But with

Re: [Kernel-packages] [Bug 1602299] Re: bcache is unstable on ppc64el

This looks relevant: https://www.redhat.com/archives/dm-devel/2016-June/msg00015.html On Tue, Jul 19, 2016 at 5:19 AM, Stefan Bader wrote: > While I have not found out where exactly things go wrong, I could > confirm that this is related to ppc64el builds using a

[Kernel-packages] [Bug 1602299] Re: bcache is unstable on ppc64el

While I have not found out where exactly things go wrong, I could confirm that this is related to ppc64el builds using a 64k page size. I build a test kernel with 4k page size and installed it inside the VM. With that bcache-super-show will will reflect the correct status after activation and also

[Kernel-packages] [Bug 1602299] Re: bcache is unstable on ppc64el

** Changed in: linux (Ubuntu) Importance: Undecided => High ** Tags added: kernel-da-key -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1602299 Title: bcache is unstable on ppc64el

[Kernel-packages] [Bug 1602299] Re: bcache is unstable on ppc64el

Recreated on a test system. The fact that the superblock gets written to is expected. Though for ppc64el this seems to go wrong at early stages. I am comparing the results on a ppc64el vm and a x86 vm. After setting up bcache and attaching the cache to the backing dev, the output of

[Kernel-packages] [Bug 1602299] Re: bcache is unstable on ppc64el

** Attachment added: "lp_1602299.tgz" https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1602299/+attachment/4699510/+files/lp_1602299.tgz -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu.

[Kernel-packages] [Bug 1602299] Re: bcache is unstable on ppc64el

Here's my recreate: On Power8 system with Xenial, KVM enabled. 1. sudo apt-get install uvtool uvtool-libvirt 2. wget http://people.canonical.com/~rharper/bugs/lp_1602299/lp_1602299.tgz 3. tar xzvf lp_1602299.tgz 4. cd lp_1602299 5. uvt-simplestreams-libvirt sync --source