Re: [PATCH 5.4.y 5.10.y 5.15.y 6.1.y 6.6.y 6.12.y 6.13.y 6.14.y] x86/e820: Fix handling of subpage regions when calculating nosave ranges in e820__register_nosave_regions()

[Sasha Levin <sashal@kernel.org>]

[ Sasha's backport helper bot ]

Hi,

Summary of potential issues:
⚠️ Found matching upstream commit but patch is missing proper reference to it

Found matching upstream commit: f2f29da9f0d4367f6ff35e0d9d021257bb53e273

Status in newer kernel trees:
6.14.y | Not found
6.13.y | Not found
6.12.y | Not found
6.6.y | Not found
6.1.y | Not found
5.15.y | Not found
5.10.y | Not found

Note: The patch differs from the upstream commit:
---
1:  f2f29da9f0d43 ! 1:  f3ea523486c43 x86/e820: Fix handling of subpage regions when calculating nosave ranges in e820__register_nosave_regions()
    @@ Commit message
         Cc: stable@vger.kernel.org
         Link: https://lore.kernel.org/r/20250406-fix-e820-nosave-v3-1-f3787bc1ee1d@qtmlabs.xyz
         Closes: https://lore.kernel.org/all/Z4WFjBVHpndct7br@desktop0a/
    +    (cherry picked from commit f2f29da9f0d4367f6ff35e0d9d021257bb53e273)
    +    Signed-off-by: Myrrh Periwinkle <myrrhperiwinkle@qtmlabs.xyz>
     
      ## arch/x86/kernel/e820.c ##
     @@ arch/x86/kernel/e820.c: void __init e820__memory_setup_extended(u64 phys_addr, u32 data_len)
    @@ arch/x86/kernel/e820.c: void __init e820__memory_setup_extended(u64 phys_addr, u
     -
     -		pfn = PFN_DOWN(entry->addr + entry->size);
     -
    - 		if (entry->type != E820_TYPE_RAM)
    + 		if (entry->type != E820_TYPE_RAM && entry->type != E820_TYPE_RESERVED_KERN)
     -			register_nosave_region(PFN_UP(entry->addr), pfn);
     +			continue;
      
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-5.4.y        |  Success    |  Success   |
| stable/linux-5.10.y       |  Success    |  Success   |
| stable/linux-5.15.y       |  Success    |  Success   |
| stable/linux-6.1.y        |  Success    |  Success   |
| stable/linux-6.6.y        |  Success    |  Success   |
| stable/linux-6.12.y       |  Success    |  Success   |
| stable/linux-6.13.y       |  Success    |  Success   |
| stable/linux-6.14.y       |  Success    |  Success   |