Re: [PATCH v6 1/5] powerpc/crash: sort crash memory ranges before preparing elfcorehdr

From: Baoquan He <bhe@redhat.com>
To: Jinjie Ruan <ruanjinjie@huawei.com>
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Subject: Re: [PATCH v6 1/5] powerpc/crash: sort crash memory ranges before preparing elfcorehdr
Date: Thu, 26 Feb 2026 17:24:21 +0800	[thread overview]
Message-ID: <aaARRZh9k_0oG3Qo@MiWiFi-R3L-srv> (raw)
In-Reply-To: <20260224085342.387996-2-ruanjinjie@huawei.com>

On 02/24/26 at 04:53pm, Jinjie Ruan wrote:
> From: Sourabh Jain <sourabhjain@linux.ibm.com>
> 
> 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 <akpm@linux-foundation.org>
> Cc: Baoquan he <bhe@redhat.com>
> Cc: Jinjie Ruan <ruanjinjie@huawei.com>
> Cc: Hari Bathini <hbathini@linux.ibm.com>
> Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
> Cc: Mahesh Salgaonkar <mahesh@linux.ibm.com>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
> Cc: Shivang Upadhyay <shivangu@linux.ibm.com>
> Cc: linux-kernel@vger.kernel.org
> Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
> Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>

You should add your own Signed-off-by since you sent it out.

> ---
>  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(-)
......snip...