Subject: Re: [PATCH v5 1/4] powerpc/crash: sort crash memory ranges before preparing elfcorehdr

From: Mike Rapoport <[email-masked]>
Date: Thu, 12 Feb 2026 16:43:38 +0200

On Thu, Feb 12, 2026 at 06:09:58PM +0800, Jinjie Ruan wrote:
> From: Sourabh Jain <[email-masked]>
> 
> During a memory hot-remove event, the elfcorehdr is rebuilt to exclude
> the removed memory. While updating the crash memory ranges for this
> operation, the crash memory ranges array can become unsorted. This
> happens because remove_mem_range() may split a memory range into two
> parts and append the higher-address part as a separate range at the end
> of the array.
> 
> So far, no issues have been observed due to the unsorted crash memory
> ranges. However, this could lead to problems once crash memory range
> removal is handled by generic code, as introduced in the upcoming
> patches in this series.
> 
> Currently, powerpc uses a platform-specific function,
> remove_mem_range(), to exclude hot-removed memory from the crash memory
> ranges. This function performs the same task as the generic
> crash_exclude_mem_range() in crash_core.c. The generic helper also
> ensures that the crash memory ranges remain sorted. So remove the
> redundant powerpc-specific implementation and instead call
> crash_exclude_mem_range_guarded() (which internally calls
> crash_exclude_mem_range()) to exclude the hot-removed memory ranges.
> 
> Cc: Andrew Morton <[email-masked]>
> Cc: Baoquan he <[email-masked]>
> Cc: Jinjie Ruan <[email-masked]>
> Cc: Hari Bathini <[email-masked]>
> Cc: Madhavan Srinivasan <[email-masked]>
> Cc: Mahesh Salgaonkar <[email-masked]>
> Cc: Michael Ellerman <[email-masked]>
> Cc: Ritesh Harjani (IBM) <[email-masked]>
> Cc: Shivang Upadhyay <[email-masked]>
> Cc: [email-masked]
> Signed-off-by: Sourabh Jain <[email-masked]>
> ---
>  arch/powerpc/include/asm/kexec_ranges.h |  4 +-
>  arch/powerpc/kexec/crash.c              |  5 +-
>  arch/powerpc/kexec/ranges.c             | 87 +------------------------
>  3 files changed, 7 insertions(+), 89 deletions(-)

This looks like a nice improvement!
FWIW

Acked-by: Mike Rapoport (Microsoft) <[email-masked]>

-- 
Sincerely yours,
Mike.