Re: [tip:x86/urgent] x86, range: fix missing merge during add range

["Christian König" <christian.koenig@amd.com>]

Am 17.05.2013 21:12, schrieb tip-bot for Yinghai Lu:
> Commit-ID:  fbe06b7bae7c9cf6ab05168fce5ee93b2f4bae7c
> Gitweb:     http://git.kernel.org/tip/fbe06b7bae7c9cf6ab05168fce5ee93b2f4bae7c
> Author:     Yinghai Lu <yinghai@kernel.org>
> AuthorDate: Fri, 17 May 2013 11:49:10 -0700
> Committer:  H. Peter Anvin <hpa@linux.intel.com>
> CommitDate: Fri, 17 May 2013 11:49:10 -0700
>
> x86, range: fix missing merge during add range
>
> Christian found v3.9 does not work with E350 with EFI is enabled.
>
> [    1.658832] Trying to unpack rootfs image as initramfs...
> [    1.679935] BUG: unable to handle kernel paging request at ffff88006e3fd000
> [    1.686940] IP: [<ffffffff813661df>] memset+0x1f/0xb0
> [    1.692010] PGD 1f77067 PUD 1f7a067 PMD 61420067 PTE 0
>
> but early memtest report all memory could be accessed without problem.
>
> early page table is set in following sequence:
> [    0.000000] init_memory_mapping: [mem 0x00000000-0x000fffff]
> [    0.000000] init_memory_mapping: [mem 0x6e600000-0x6e7fffff]
> [    0.000000] init_memory_mapping: [mem 0x6c000000-0x6e5fffff]
> [    0.000000] init_memory_mapping: [mem 0x00100000-0x6bffffff]
> [    0.000000] init_memory_mapping: [mem 0x6e800000-0x6ea07fff]
> but later efi_enter_virtual_mode try set mapping again wrongly.
> [    0.010644] pid_max: default: 32768 minimum: 301
> [    0.015302] init_memory_mapping: [mem 0x640c5000-0x6e3fcfff]
> that means it fails with pfn_range_is_mapped.
>
> It turns out that we have a bug in add_range_with_merge and it does not
> merge range properly when new add one fill the hole between two exsiting
> ranges. In the case when [mem 0x00100000-0x6bffffff] is the hole between
> [mem 0x00000000-0x000fffff] and [mem 0x6c000000-0x6e7fffff].
>
> Fix the add_range_with_merge by calling itself recursively.
>
> Reported-by: "Christian König" <christian.koenig@amd.com>
> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
> Link: http://lkml.kernel.org/r/CAE9FiQVofGoSk7q5-0irjkBxemqK729cND4hov-1QCBJDhxpgQ@mail.gmail.com
> Cc: <stable@vger.kernel.org> v3.9
> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

Tested-by: Christian König <christian.koenig@amd.com>

> ---
>   kernel/range.c | 8 +++++---
>   1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/range.c b/kernel/range.c
> index 071b0ab..eb911db 100644
> --- a/kernel/range.c
> +++ b/kernel/range.c
> @@ -48,9 +48,11 @@ int add_range_with_merge(struct range *range, int az, int nr_range,
>   		final_start = min(range[i].start, start);
>   		final_end = max(range[i].end, end);
>   
> -		range[i].start = final_start;
> -		range[i].end =  final_end;
> -		return nr_range;
> +		/* clear it and add it back for further merge */
> +		range[i].start = 0;
> +		range[i].end =  0;
> +		return add_range_with_merge(range, az, nr_range,
> +			final_start, final_end);
>   	}
>   
>   	/* Need to add it: */
>