Re: v4.4-rc8 based tip tree kernel hangs on boot.

[Matt Fleming <matt@codeblueprint.co.uk>]

On Mon, 11 Jan, at 12:59:21AM, Srikar Dronamraju wrote:
> On a x86_64 machine, I see kernel v4.4-rc8 based tip tree hangs on boot.
> However v4.4-rc8 with the same config boots well on the same machine.
> 
> git bisect results are as follows
> 
> git bisect start
> # bad: [fc4e8fa9f80e0f099838f3a9997019de36d9a4ba] Merge branch 'WIP.x86/mm'
> git bisect bad fc4e8fa9f80e0f099838f3a9997019de36d9a4ba
> # good: [168309855a7d1e16db751e9c647119fe2d2dc878] Linux 4.4-rc8
> git bisect good 168309855a7d1e16db751e9c647119fe2d2dc878
> # good: [76e17c25ebc9f6619f9f8fd93f3905b0def8dc6f] Merge branch 'perf/core'
> git bisect good 76e17c25ebc9f6619f9f8fd93f3905b0def8dc6f
> # good: [e8998ce7e8ce42419d0c7bb08c105bd860eb3218] Merge branch 'timers/urgent'
> git bisect good e8998ce7e8ce42419d0c7bb08c105bd860eb3218
> # good: [af51cdabdbea5355ed388b8b3a7cf9bfc0864b9c] Merge branch 'x86/cpu'
> git bisect good af51cdabdbea5355ed388b8b3a7cf9bfc0864b9c
> # bad: [5852b88267adcc78722fc5d4f45751fb6e261bd2] Merge branch 'x86/urgent'
> git bisect bad 5852b88267adcc78722fc5d4f45751fb6e261bd2
> # bad: [c236714fd39fb26993af2d5fde9c3bfc32361323] Merge branch 'x86/fpu'
> git bisect bad c236714fd39fb26993af2d5fde9c3bfc32361323
> # bad: [ff3d0a12fb2dc123e2b46e9524ebf4e08de5c59c] Documentation/x86: Update EFI memory region description
> git bisect bad ff3d0a12fb2dc123e2b46e9524ebf4e08de5c59c
> # bad: [b61a76f8850d2979550abc42d7e09154ebb8d785] x86/efi: Map RAM into the identity page table for mixed mode
> git bisect bad b61a76f8850d2979550abc42d7e09154ebb8d785
> # bad: [edc3b9129cecd0f0857112136f5b8b1bc1d45918] x86/mm/pat: Ensure cpa->pfn only contains page frame numbers
> git bisect bad edc3b9129cecd0f0857112136f5b8b1bc1d45918
> # bad: [21cdb6b568435738cc0b303b2b3b82742396310c] x86/mm: Page align the '_end' symbol to avoid pfn conversion bugs
> git bisect bad 21cdb6b568435738cc0b303b2b3b82742396310c
> # first bad commit: [21cdb6b568435738cc0b303b2b3b82742396310c] x86/mm: Page align the '_end' symbol to avoid pfn conversion bugs
> 
> Not much info on the console, when the kernel hangs.
 
What info is there?

> Tried reverting Commit 21cdb6b56 "x86/mm: Page align the '_end'
> symbol to avoid pfn conversion bugs" but that doesnt help.

Odd. Could you try booting the tip/x86/efi branch instead? There's
only a handful of patches on that branch so it should be pretty easy
to narrow down the problematic change.