linux-kernel - Re: [PATCH v2 4/6] powerpc/kdump: preserve user-specified memory limit

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Message-ID: <feff3c37-4998-43a5-9636-121c87e5d393@linux.ibm.com>
Date: Thu, 23 Jan 2025 16:52:09 +0530
From: Sourabh Jain <sourabhjain@...ux.ibm.com>
To: Hari Bathini <hbathini@...ux.ibm.com>, linuxppc-dev@...ts.ozlabs.org
Cc: Andrew Morton <akpm@...ux-foundation.org>, Baoquan he <bhe@...hat.com>,
        Madhavan Srinivasan <maddy@...ux.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>, kexec@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Mahesh Salgaonkar <mahesh@...ux.ibm.com>
Subject: Re: [PATCH v2 4/6] powerpc/kdump: preserve user-specified memory
 limit

Hello Hari,


On 23/01/25 16:00, Hari Bathini wrote:
>
>
> On 21/01/25 5:24 pm, Sourabh Jain wrote:
>> Commit 59d58189f3d9 ("crash: fix crash memory reserve exceed system
>> memory bug") fails crashkernel parsing if the crash size is found to be
>> higher than system RAM, which makes the memory_limit adjustment code
>> ineffective due to an early exit from reserve_crashkernel().
>>
>> Regardless lets not violated the user-specified memory limit by
>
> s/violated/violate/

Noted. It will be fixed in next version.

>
>> adjusting it. Remove this adjustment to ensure all reservations stay
>> within the limit. Commit f94f5ac07983 ("powerpc/fadump: Don't update
>> the user-specified memory limit") did the same for fadump.
>>
>
> Acked-by: Hari Bathini <hbathini@...ux.ibm.com>

Thanks for the Ack!

- Sourabh Jain


>
>> Cc: Andrew Morton <akpm@...ux-foundation.org>
>> Cc: Baoquan he <bhe@...hat.com>
>> Cc: Hari Bathini <hbathini@...ux.ibm.com>
>> CC: Madhavan Srinivasan <maddy@...ux.ibm.com>
>> Cc: Michael Ellerman <mpe@...erman.id.au>
>> Cc: kexec@...ts.infradead.org
>> Cc: linux-kernel@...r.kernel.org
>> Reviewed-by: Mahesh Salgaonkar <mahesh@...ux.ibm.com>
>> Signed-off-by: Sourabh Jain <sourabhjain@...ux.ibm.com>
>> ---
>>   arch/powerpc/kexec/core.c | 8 --------
>>   1 file changed, 8 deletions(-)
>>
>> diff --git a/arch/powerpc/kexec/core.c b/arch/powerpc/kexec/core.c
>> index b8333a49ea5d..4945b33322ae 100644
>> --- a/arch/powerpc/kexec/core.c
>> +++ b/arch/powerpc/kexec/core.c
>> @@ -150,14 +150,6 @@ void __init reserve_crashkernel(void)
>>           return;
>>       }
>>   -    /* Crash kernel trumps memory limit */
>> -    if (memory_limit && memory_limit <= crashk_res.end) {
>> -        memory_limit = crashk_res.end + 1;
>> -        total_mem_sz = memory_limit;
>> -        printk("Adjusted memory limit for crashkernel, now 0x%llx\n",
>> -               memory_limit);
>> -    }
>> -
>>       printk(KERN_INFO "Reserving %ldMB of memory at %ldMB "
>>               "for crashkernel (System RAM: %ldMB)\n",
>>               (unsigned long)(crash_size >> 20),
>