From: Richard Weinberger <richard@nod.at>
To: Real Name <enjoymindful@gmail.com>
Cc: user-mode-linux-devel@lists.sourceforge.net,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] delete unnecessary bootmem struct page array
Date: Mon, 16 Jun 2014 08:50:33 +0200 [thread overview]
Message-ID: <539E93B9.5070407@nod.at> (raw)
In-Reply-To: <20140616032852.GA1763@name>
Am 16.06.2014 05:28, schrieb Real Name:
> On Sat, Jun 14, 2014 at 11:44:04AM +0200, Richard Weinberger wrote:
>> Hi!
>>
>> Am 03.06.2014 07:30, schrieb Real Name:
>>> From: Honggang Li <enjoymindful@gmail.com>
>>>
>>> The patch based on linux-next-2014-06-02.
>>>
>>> The old init_maps function does two things:
>>> 1) allocates and initializes one struct page array for bootmem
>>> 2) count the number of total pages
>>>
>>> After removed the source code related to the unnecessary array, the name
>>> 'init_maps' is some kind of improper named, as it just count the number of
>>> total page numbers. So, I renamed the function as 'mem_total_pages'.
>>>
>>> I tested the patch through repeat reboot the uml kernel many times.
>>> [real@name linux-next]$ make ARCH=um defconfig
>>> [real@name linux-next]$ make ARCH=um linux
>>> [real@name linux-next]$ file linux
>>> linux: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.32, not stripped
>>> [real@name linux-next]$ ./linux ubda=/home/real/linux-next/Fedora20-AMD64-root_fs mem=256m && sync && echo 1
>>> [real@name linux-next]$ ./linux ubda=/home/real/linux-next/Fedora20-AMD64-root_fs mem=256m && sync && echo 2
>>> (repeat reboot the uml kernel many times..)
>>
>> Can you please include in the changelog the commit sha1 which made the old init_maps() obsolete?
>> I had a look at the pre-git linux tree, looks like init_maps() wasn't touched for more than 10 years.
>
> hi, richard
>
> what is the pre-git linux tree? I searched it with google, but failed.
>
> The v2.6.12 kernel is the oldest one available from the linux-next git tree. And it has duplicated
> struct page arrays. So, any suggestion how to find the commit you wanted?
https://git.kernel.org/cgit/linux/kernel/git/tglx/history.git
> linux-2.4.20 + uml-patch-2.4.20-8 works on *old* redhat-9 virtual machine. And it seems has duplicated
> struct page array too.
>
And if you remove it here too UML still works?
Thanks,
//richard
> The first struct page array
> ------------------------
> linux-2.4.20/arch/um/kernel/physmem.c
> 157 int init_maps(unsigned long len)
> 158 {
> 159 struct page *p, *map;
> 160 int i, n;
> 161
> 162 n = len >> PAGE_SHIFT;
> 163 len = n * sizeof(struct page);
> 164
> 165 if(kmalloc_ok){
> 166 map = kmalloc(len, GFP_KERNEL);
> 167 if(map == NULL) map = vmalloc(len);
> 168 }
> 169 else map = alloc_bootmem_low_pages(len);
> 170
> 171 if(map == NULL)
> 172 return(-ENOMEM);
> 173
> 174 for(i = 0; i < n; i++){
> 175 p = &map[i];
> 176 set_page_count(p, 0);
> 177 SetPageReserved(p);
> 178 INIT_LIST_HEAD(&p->list);
> 179 }
> 180
> 181 mem_map = map;
> 182 max_mapnr = n;
> 183 return(0);
> 184 }
>
>
> The second struct page array
> -----------------------
> mm/memory.c
> 73 mem_map_t * mem_map; // global define
>
> mm/page_alloc.c
> 839 void __init free_area_init(unsigned long *zones_size)
> 840 {
> 841 free_area_init_core(0, &contig_page_data, &mem_map, zones_size, 0, 0, 0);
> 842 }
>
> --------
> mm/page_alloc.c
> 685 void __init free_area_init_core(int nid, pg_data_t *pgdat, struct page **gmap,
> 686 unsigned long *zones_size, unsigned long zone_start_paddr,
> 687 unsigned long *zholes_size, struct page *lmem_map)
> 688 {
> ........
> 716 map_size = (totalpages + 1)*sizeof(struct page);
> 717 if (lmem_map == (struct page *)0) {
> 718 lmem_map = (struct page *) alloc_bootmem_node(pgdat, map_size);
> 719 lmem_map = (struct page *)(PAGE_OFFSET +
> 720 MAP_ALIGN((unsigned long)lmem_map - PAGE_OFFSET));
> 721 }
> 722 *gmap = pgdat->node_mem_map = lmem_map;
>
>
>>
>> Thanks,
>> //richard
>>
>>> Honggang Li (1):
>>> delete unnecessary bootmem struct page array
>>>
>>> arch/um/include/shared/mem_user.h | 2 +-
>>> arch/um/kernel/physmem.c | 32 ++++++--------------------------
>>> arch/um/kernel/um_arch.c | 7 +------
>>> 3 files changed, 8 insertions(+), 33 deletions(-)
>>>
next prev parent reply other threads:[~2014-06-16 6:50 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-03 5:30 [PATCH v2] delete unnecessary bootmem struct page array Real Name
2014-06-03 5:30 ` [uml-devel] " Real Name
2014-06-03 5:30 ` [PATCH] " Real Name
2014-06-03 5:30 ` [uml-devel] " Real Name
2014-06-09 5:49 ` [PATCH v2] " Real Name
2014-06-09 8:59 ` [uml-devel] " Toralf Förster
2014-06-14 9:44 ` Richard Weinberger
2014-06-16 3:28 ` Real Name
2014-06-16 3:28 ` [uml-devel] " Real Name
2014-06-16 6:50 ` Richard Weinberger [this message]
2014-06-16 8:12 ` Real Name
2014-06-16 8:28 ` Real Name
2014-06-16 9:15 ` Geert Uytterhoeven
2014-06-16 10:30 ` Real Name
2014-06-16 10:30 ` Real Name
2014-07-17 23:10 ` Real Name
2014-06-16 6:58 ` [uml-devel] " Geert Uytterhoeven
2014-06-16 7:21 ` Paul Bolle
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=539E93B9.5070407@nod.at \
--to=richard@nod.at \
--cc=enjoymindful@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=user-mode-linux-devel@lists.sourceforge.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.