linux-kernel - Re: [PATCH] vmalloc: Removing incorrect logs when vmalloc failed

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Message-ID: <3cf13a05-a6b8-aa2f-752d-f9a25a1005f9@huawei.com>
Date:   Wed, 8 Jul 2020 08:51:33 +0800
From:   "tiantao (H)" <tiantao6@...wei.com>
To:     Uladzislau Rezki <urezki@...il.com>,
        Anshuman Khandual <anshuman.khandual@....com>,
        Tian Tao <tiantao6@...ilicon.com>
CC:     <akpm@...ux-foundation.org>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>, <linuxarm@...wei.com>
Subject: Re: [PATCH] vmalloc: Removing incorrect logs when vmalloc failed



在 2020/7/7 21:24, Uladzislau Rezki 写道:
> On Tue, Jul 07, 2020 at 03:18:54PM +0530, Anshuman Khandual wrote:
>>
>>
>> On 07/07/2020 02:43 PM, Tian Tao wrote:
>>> It is not possible to increase size with vmalloc=<size> in arm64
>>> architecture and it will mislead.however vmalloc return failure
>>> is a rare occurrence in 'many architectures including arm64'.
>>
>> But there is a chance that vmalloc() might work on architectures
>> that support 'vmalloc=' command line i.e after a change and this
>> information here might be helpful in those cases.
>>
> Agree. At least i see a few users of it:
> 
> <snip>
> urezki@...38:~/data/coding/linux-next.git$ grep -rn early_param ./arch/ | grep vmalloc
> ./arch/arm/mm/mmu.c:1152:early_param("vmalloc", early_vmalloc);
> ./arch/unicore32/mm/mmu.c:276:early_param("vmalloc", early_vmalloc);
> ./arch/x86/mm/pgtable_32.c:86:early_param("vmalloc", parse_vmalloc);
> urezki@...38:~/data/coding/linux-next.git$
> <snip>
> 
I'm actually having this problem with the arm64 architecture at centos 
7.6 and pagesize is 64K.
I followed the prompts and added vmalloc=<size> to the command to 
increase the size of the vmalloc.and found out it's not worked.
It took me some time to find out that this doesn't work for the arm64 
architecture, so this log is misleading on arm64.
I think it's better not to be prompted than to be prompted incorrectly.
I'm sure there will be others with similar problems.
So I'd like to solve this problem this time, Please help me with your 
suggestions.
If I change the PATCH to the following, will you accept it?

       if (!(gfp_mask & __GFP_NOWARN) && printk_ratelimit())
+#ifdef CONFIG_ARM64 && CONFIG_XXX
+        pr_warn("vmap allocation for size %lu failed\n", size);
+#else
           pr_warn("vmap allocation for size %lu failed: use 
vmalloc=<size> to increase size\n",
               size);
+#endif

> Thanks!
> 
> --
> Vlad Rezki
> 
> .
>