linux-kernel - Re: [PATCH] resource: Use 2-factor allocator calls

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Message-ID: <20180706011450.GB2762@MiWiFi-R3L-srv>
Date:   Fri, 6 Jul 2018 09:14:50 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Kees Cook <keescook@...omium.org>,
        AKASHI Takahiro <takahiro.akashi@...aro.org>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        linux-kernel@...r.kernel.org, Wei Yang <richard.weiyang@...il.com>
Subject: Re: [PATCH] resource: Use 2-factor allocator calls

Hi Andrew, Kees, 

About the implemention of walk_system_ram_res_rev(), it was posted by
AKASHI firstly for his arm kexec_file adding, later he dropped it
because he took other way and doesn't need walk_system_ram_res_rev() any
more in his patchset.

Then I found my below patch needs a walk_system_ram_res_rev(), 

	kernel/kexec_file.c: load kernel at top of system RAM if required

so I took AKASHI's patch and posted a patchset including above patch,
and AKASHI's patch, it can be seen here:
http://lkml.kernel.org/r/20180322033722.9279-1-bhe@redhat.com

Then Andrew reviewed and added comment to say this
walk_system_ram_res_rev() is not good, and suggested me to change the
singly linked list of child resource to standard list_head which is
doubly linked list, then walk_system_ram_res_rev() can be implemented
very easily to do reversed searching. So I posted v2:
http://lkml.kernel.org/r/20180408024724.16812-1-bhe@redhat.com

Now the latest post is v6:
http://lkml.kernel.org/r/20180704041038.8190-1-bhe@redhat.com

Since changing resource child tree to take doubly linked list list_head
impacts all ARCH and many components, I am still fixing issues test
robot reported since I can only test on x86. Now I plan to ask intel
0day team to tell how I can run scripts locally for all ARCH to find out
all codes impacted and fix them all at one time.

So I think we can drop the old walk_system_ram_res_rev() in v1, I am
still working on this issue. Sorry for the confusion I made because of
my mistakes.

Thanks
Baoquan

On 07/05/18 at 03:07pm, Andrew Morton wrote:
> On Wed, 4 Jul 2018 10:31:53 -0700 Kees Cook <keescook@...omium.org> wrote:
> 
> > As already done treewide, switch from open-coded multiplication to using
> > 2-factor allocation helpers.
> > 
> 
> This is against resource-add-walk_system_ram_res_rev.patch
> (http://lkml.kernel.org/r/20180322033722.9279-2-bhe@redhat.com).
> 
> That patch is awaiting (for several months!) a v2.  Will this be happening?