I have a machine that won't boot in 3.16 and it looks like it is probably because /dev/sda3 is detected as not having a valid superblock under 3.16, but is with 3.15. I have the following Fedora bug for this: https://bugzilla.redhat.com/show_bug.cgi?id=1111442mdadm --examine /dev/sda3 Under 3.15 mdadm says the following about /dev/sda3: /dev/sda3: Magic : a92b4efc Version : 1.2 Feature Map : 0x0 Array UUID : 9e06cb82:14b726e2:af554f00:b9b73901 Name : bruno.wolff.to:13 (local to host bruno.wolff.to) Creation Time : Thu Jun 30 06:22:05 2011 Raid Level : raid1 Raid Devices : 1 Avail Dev Size : 167770112 (80.00 GiB 85.90 GB) Array Size : 83884984 (80.00 GiB 85.90 GB) Used Dev Size : 167769968 (80.00 GiB 85.90 GB) Data Offset : 2048 sectors Super Offset : 8 sectors Unused Space : before=1968 sectors, after=144 sectors State : clean Device UUID : 350f0baa:0622d7da:bc485abd:a4b765f9 Update Time : Sun Jun 22 12:22:42 2014 Checksum : 3e3671a9 - correct Events : 7031153 Device Role : Active device 0 Array State : A ('A' == active, '.' == missing, 'R' == replacing)
It is odd that mdadm doesn't recognise sda3 under 3.16, but blkid does: /dev/sda3: UUID="9e06cb82-14b7-26e2-af55-4f00b9b73901" UUID_SUB="350f0baa-0622-d7da-bc48-5abda4b765f9" LABEL="bruno.wolff.to:13" TYPE="linux_raid_member" PARTUUID="6c3efcfe-03" Maybe something did something to sda3... changed the device size or partition offset or something. Can you 'dd' the first 8K of sda3 to somewhere for each kernel, then compare them?
Created attachment 140671 [details] superblock under 3.15 I haven't got a 3.16 copy yet. dracut doesn't have dd and I need to set up a live image for 3.16 so that I can boot to where I'll have a copy of dd. (sda3 has my root file system on it.) I thought that maybe the dump from 3.15 might be useful by itself, if there is some sort of corruption. Probably it will be tomorrow night before I get a live image tested.
I retested this on 3.16.0-0.rc2.git0.1.fc21 and still see the problem. Fedora kernels before this were broken in other ways on i686 so I need a live image with this kernel to boot 3.16 on the problem machine. There is a new nightly compose that I should be able to use after work today.
Created attachment 140911 [details] blkid output from 3.16 live instance Created attachment 911900 [details] blkid output from live image instance I got a live image to boot, but it was pretty unstable and locked up a few times (requiring reboots) while I was collecting info. dd indicated that /dev/sda3 was 0 bytes long. So that suggests that the difference isn't in md, but rather in some other part of I/O. The device is created and blkid reports some information about it.
fdisk doesn't seem to show anything odd about the partition table: fdisk -l /dev/sda Disk /dev/sda: 298,1 GiB, 320072933376 bytes, 625142448 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0x6c3efcfe Device Boot Start End Sectors Size Id Type /dev/sda1 * 2048 2099199 2097152 1G fd Linux raid autodetect /dev/sda2 2099200 23070719 20971520 10G fd Linux raid autodetect /dev/sda3 23070720 190842879 167772160 80G fd Linux raid autodetect /dev/sda4 190842880 625142447 434299568 207,1G fd Linux raid autodetect
As you say, this doesn't sound like a an md problem. Only think I can suggest is to try running "blockdev --rereadpt /dev/sda" and see if that makes the partitions appear properly. You probably need to reassign this to "block layer" or something like that. Or hope the fedora bugzilla will find an answer for you.
I have a suggestion to try out the patch at https://lkml.org/lkml/2014/6/23/96 and I should be able to test it tonight and report back.
I tried out the patch referenced in comment 7 and it did seem to get me past the place I was having this problem. The system still didn't finish booting, but I suspect that is a different problem.
Your patch to include/linux/uio.h fixed https://bugzilla.kernel.org/show_bug.cgi?id=78911 for me. After applying it and rebuilding I can mount my swap partition again.
The fix for this is now in Linus' tree: http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=0b86dbf675e0170a191a9ca18e5e99fd39a678c0