On Wed, 2 May 2012 22:05:44 -0700 Karl Newman <siliconfiend@xxxxxxxxx> wrote: > Hi, > > I'm attempting to use kernel 3.4-rc? but keep running into a kernel panic on > boot, with RIP pointing to bitmap_create. I tried 3.4-rc1, 3.4-rc4 and > 3.4-rc5 and they all have the kernel panic, while 3.3.4 boots fine. I have > my root on raid 5 with an internal bitmap, and the kernel panic occurs if I > use the built-in kernel autodetect or during the root array assembly via > mdadm inside a dracut-generated initramfs. I bisected it down to the > following commit: > 61a0d80ce4ab5b4fb9ecb38f1fb19654778b71ed > > md/bitmap: discard CHUNK_BLOCK_SHIFT macro > > Be redefining ->chunkshift as the shift from sectors to chunks rather than > bytes to chunks, we can just use "bitmap->chunkshift" which is shorter than > the macro call, and less indirect. > > Signed-off-by: NeilBrown <neilb@xxxxxxx> > > My bisect testing including a scary commit where 2 of 3 drives had their > UUIDs zeroed when I booted with it! Fortunately I found the mailing list > archives with the solution and I was able to recover everything and keep > bisecting (although I was tempted to quit and just give the range of > commits...). > > I hope this fix can make it into the next 3.4-rc kernel. I do too, but first I would need to know what the fix is, and I cannot see anything in that commit what would change the behaviour of md at all. Do you have a copy of the full stack trace provided when Linux crashed? That could be useful. Also what bitmap chunk size are you using? Maybe the output of mdadm -X and mdadm -E of one of the devices in the array would help. Thanks a lot for the report and going to the trouble of bisecting, it is really appreciated. NeilBrown
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