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

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Message-ID: <43aeaa2c-c266-4d6e-921d-80b99ceb418b@linux.ibm.com>
Date: Thu, 23 Jan 2025 16:00:13 +0530
From: Hari Bathini <hbathini@...ux.ibm.com>
To: Sourabh Jain <sourabhjain@...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



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/

> 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>

> 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),