linux-kernel - Re: [PATCH] mm: mmap: Simplify the failure return working flow

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Date:	Thu, 20 Aug 2015 09:27:42 +0800
From:	gchen gchen <xili_gchen_5257@...mail.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	kernel mailing list <linux-kernel@...r.kernel.org>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	"riel@...hat.com" <riel@...hat.com>, Michal Hocko <mhocko@...e.cz>,
	"sasha.levin@...cle.com" <sasha.levin@...cle.com>,
	Linux Memory <linux-mm@...ck.org>
Subject: Re: [PATCH] mm: mmap: Simplify the failure return working flow


On Tue, 18 Aug 2015 15:57:08 -0700 akpm@...ux-foundation.org wrote:
>
> On Wed, 19 Aug 2015 06:27:58 +0800 Chen Gang
> <xili_gchen_5257@...mail.com> wrote:
>
>> From: Chen Gang <xili_gchen_5257@...mail.com>
>
> As sent, this patch is From:you@...mail and Signed-off-by:you@...il.
>
> This is peculiar.  I'm assuming that it should have been From:you@...il and
> I have made that change to my copy of the patch.
>
> You can do this yourself by putting an explicit From: line at the start
> of the changelog.
>

Yes, it is really peculiar, the reason is gmail is not stable in China.
I have to send mail in my hotmail address.

But I still want to use my gmail as Signed-off-by, since I have already
used it, and also its name is a little formal than my hotmail.

Welcome any ideas, suggestions and completions for it (e.g. if it is
necessary to let send mail and Signed-off-by mail be the same, I shall
try).

[...]

> So,
>
> --- a/mm/mmap.c~mm-mmap-simplify-the-failure-return-working-flow-fix
> +++ a/mm/mmap.c
> @@ -2952,7 +2952,7 @@ struct vm_area_struct *copy_vma(struct v
>         } else {
>                 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
>                 if (!new_vma)
> -                       return NULL;
> +                       goto out;
>                 *new_vma = *vma;
>                 new_vma->vm_start = addr;
>                 new_vma->vm_end = addr + len;
> @@ -2971,10 +2971,11 @@ struct vm_area_struct *copy_vma(struct v
>         }
>         return new_vma;
>
> - out_free_mempol:
> +out_free_mempol:
>         mpol_put(vma_policy(new_vma));
> - out_free_vma:
> +out_free_vma:
>         kmem_cache_free(vm_area_cachep, new_vma);
> +out:
>         return NULL;
>  }
>

It is OK to me, thanks.

During these days (2-4 months), I shall try to make some patches for
Linux mm:

 - I am learning Linux kernel mmu, so I can re-use part of code to user
   mode (add softmmu to qemu linux user in my working time). Then I can
   try some mm patches when I am reading related code.

 - At present, cross-building various archs with allmodconfig looks OK
   (have no many issues), so for me, I can stop and start another parts
   (e.g. mmu, loongson machine of mips arch, ...).

Welcome any ideas, suggestions and completions for it:

 - Assume I am not quite familiar with mmu -- in honest, I feel I am
   really not.

 - Is it possible to build the related 'softmmu' as a module which can
   be used by both kernel mode and user mode (if really it is, I shall
   try to perform it -- I can do it in my working time).

 - ...

Thanks.
--
Chen Gang

Open, share, and attitude like air, water, and life which God blessed