linux-kernel - Re: [PATCH] arm: make the size of vmalloc in cmdline and meminfo uniform

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Date:   Wed, 19 May 2021 12:39:16 +0800
From:   "Xu, Yanfei" <yanfei.xu@...driver.com>
To:     "Russell King (Oracle)" <linux@...linux.org.uk>
Cc:     rppt@...nel.org, ardb@...nel.org, linus.walleij@...aro.org,
        akpm@...ux-foundation.org, carver4lio@....com,
        tiantao6@...ilicon.com, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm: make the size of vmalloc in cmdline and meminfo
 uniform



On 5/18/21 8:06 PM, Russell King (Oracle) wrote:
> [Please note: This e-mail is from an EXTERNAL e-mail address]
> 
> On Tue, May 18, 2021 at 12:29:32PM +0100, Russell King (Oracle) wrote:
>> On Tue, May 18, 2021 at 07:12:54PM +0800, Yanfei Xu wrote:
>>> The value of "vmalloc=" set in cmdline is always 8M more than the value
>>> of "VmallocTotal" in meminfo. When use the "vmalloc=" parameter, user
>>> expect to get the size what they input, and no need to consider the 8M
>>> "hole" hided in codes. This commit make real vmalloc size equal to value
>>> of "vmalloc=" in cmdline.
>>>
>>> Also, the commit will reduce the size of vmalloc printed in boot message
>>> by 8M when the size set in cmdline is irrational.
>>
>> Hi,
>>
>> I think I'd like to do several cleanups with this:
>>
>> 1. change vmalloc_min to be an unsigned long.
>> 2. exclude VMALLOC_OFFSET from vmalloc_min, moving it into
>>     adjust_lowmem_bounds where vmalloc_min is used.
>> 3. rename vmalloc_min to be vmalloc_start
>> 4. enforce vmalloc_start to be a multiple of 2MiB
>> 5. in early_vmalloc(), calculate vmalloc_max as:
>>        VMALLOC_END - (PAGE_OFFSET + SZ_32M + VMALLOC_OFFSET)
>>     and use that to set the upper bound of vmalloc_reserve (which is
>>     something your patch doesn't do, which I think is a bug.
>>
>> Thoughts?
> 
> I've slightly modified the above idea, and will shortly follow up with
> some patches to show the idea a bit better...
> 

Thanks for making it better!

Regards,
Yanfei
> --
> RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
> FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
>