From: Andrew Morton <akpm@linux-foundation.org>
To: wency@cn.fujitsu.com
Cc: linux-s390@vger.kernel.org, linux-ia64@vger.kernel.org,
len.brown@intel.com, linux-acpi@vger.kernel.org,
linux-sh@vger.kernel.org, x86@kernel.org,
linux-kernel@vger.kernel.org, cmetcalf@tilera.com,
linux-mm@kvack.org, isimatu.yasuaki@jp.fujitsu.com,
paulus@samba.org, minchan.kim@gmail.com,
kosaki.motohiro@jp.fujitsu.com, rientjes@google.com,
sparclinux@vger.kernel.org, cl@linux.com,
linuxppc-dev@lists.ozlabs.org, liuj97@gmail.com
Subject: Re: [RFC v8 PATCH 08/20] memory-hotplug: remove /sys/firmware/memmap/X sysfs
Date: Fri, 31 Aug 2012 14:06:23 -0700 [thread overview]
Message-ID: <20120831140623.8d13bd2c.akpm@linux-foundation.org> (raw)
In-Reply-To: <1346148027-24468-9-git-send-email-wency@cn.fujitsu.com>
On Tue, 28 Aug 2012 18:00:15 +0800
wency@cn.fujitsu.com wrote:
> From: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
>
> When (hot)adding memory into system, /sys/firmware/memmap/X/{end, start, type}
> sysfs files are created. But there is no code to remove these files. The patch
> implements the function to remove them.
>
> Note : The code does not free firmware_map_entry since there is no way to free
> memory which is allocated by bootmem.
>
> ....
>
> +#define to_memmap_entry(obj) container_of(obj, struct firmware_map_entry, kobj)
It would be better to implement this as an inlined C function. That
has improved type safety and improved readability.
> +static void release_firmware_map_entry(struct kobject *kobj)
> +{
> + struct firmware_map_entry *entry = to_memmap_entry(kobj);
> + struct page *page;
> +
> + page = virt_to_page(entry);
> + if (PageSlab(page) || PageCompound(page))
That PageCompound() test looks rather odd. Why is this done?
> + kfree(entry);
> +
> + /* There is no way to free memory allocated from bootmem*/
> +}
This function is a bit ugly - poking around in page flags to determine
whether or not the memory came from bootmem. It would be cleaner to
use a separate boolean. Although I guess we can live with it as you
have it here.
> static struct kobj_type memmap_ktype = {
> + .release = release_firmware_map_entry,
> .sysfs_ops = &memmap_attr_ops,
> .default_attrs = def_attrs,
> };
> @@ -123,6 +139,16 @@ static int firmware_map_add_entry(u64 start, u64 end,
> return 0;
> }
>
> +/**
> + * firmware_map_remove_entry() - Does the real work to remove a firmware
> + * memmap entry.
> + * @entry: removed entry.
> + **/
> +static inline void firmware_map_remove_entry(struct firmware_map_entry *entry)
> +{
> + list_del(&entry->list);
> +}
Is there no locking to protect that list?
> /*
> * Add memmap entry on sysfs
> */
> @@ -144,6 +170,31 @@ static int add_sysfs_fw_map_entry(struct firmware_map_entry *entry)
> return 0;
> }
>
> +/*
> + * Remove memmap entry on sysfs
> + */
> +static inline void remove_sysfs_fw_map_entry(struct firmware_map_entry *entry)
> +{
> + kobject_put(&entry->kobj);
> +}
> +
> +/*
> + * Search memmap entry
> + */
> +
> +struct firmware_map_entry * __meminit
> +find_firmware_map_entry(u64 start, u64 end, const char *type)
A better name would be firmware_map_find_entry(). To retain the (good)
convention that symbols exported from here all start with
"firmware_map_".
> +{
> + struct firmware_map_entry *entry;
> +
> + list_for_each_entry(entry, &map_entries, list)
> + if ((entry->start == start) && (entry->end == end) &&
> + (!strcmp(entry->type, type)))
> + return entry;
> +
> + return NULL;
> +}
> +
> /**
> * firmware_map_add_hotplug() - Adds a firmware mapping entry when we do
> * memory hotplug.
> @@ -196,6 +247,32 @@ int __init firmware_map_add_early(u64 start, u64 end, const char *type)
> return firmware_map_add_entry(start, end, type, entry);
> }
>
> +/**
> + * firmware_map_remove() - remove a firmware mapping entry
> + * @start: Start of the memory range.
> + * @end: End of the memory range.
> + * @type: Type of the memory range.
> + *
> + * removes a firmware mapping entry.
> + *
> + * Returns 0 on success, or -EINVAL if no entry.
> + **/
> +int __meminit firmware_map_remove(u64 start, u64 end, const char *type)
> +{
> + struct firmware_map_entry *entry;
> +
> + entry = find_firmware_map_entry(start, end - 1, type);
> + if (!entry)
> + return -EINVAL;
> +
> + firmware_map_remove_entry(entry);
> +
> + /* remove the memmap entry */
> + remove_sysfs_fw_map_entry(entry);
> +
> + return 0;
> +}
Again, the lack of locking looks bad.
> ...
>
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1052,9 +1052,9 @@ int offline_memory(u64 start, u64 size)
> return 0;
> }
>
> -int remove_memory(int nid, u64 start, u64 size)
> +int __ref remove_memory(int nid, u64 start, u64 size)
Why was __ref added?
> {
> - int ret = -EBUSY;
> + int ret = 0;
> lock_memory_hotplug();
> /*
> * The memory might become online by other task, even if you offine it.
>
> ...
>
next prev parent reply other threads:[~2012-08-31 21:06 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-28 10:00 [RFC v8 PATCH 00/20] memory-hotplug: hot-remove physical memory wency
2012-08-28 10:00 ` [RFC v8 PATCH 01/20] memory-hotplug: rename remove_memory() to offline_memory()/offline_pages() wency
2012-08-28 10:00 ` [RFC v8 PATCH 02/20] memory-hotplug: implement offline_memory() wency
2012-08-28 10:00 ` [RFC v8 PATCH 03/20] memory-hotplug: store the node id in acpi_memory_device wency
2012-08-28 10:00 ` [RFC v8 PATCH 04/20] memory-hotplug: offline and remove memory when removing the memory device wency
2012-08-31 20:55 ` Andrew Morton
2012-09-03 1:30 ` Wen Congyang
2012-08-28 10:00 ` [RFC v8 PATCH 05/20] memory-hotplug: check whether memory is present or not wency
2012-08-28 10:00 ` [RFC v8 PATCH 06/20] memory-hotplug: export the function acpi_bus_remove() wency
2012-08-28 10:00 ` [RFC v8 PATCH 07/20] memory-hotplug: call acpi_bus_remove() to remove memory device wency
2012-08-28 10:00 ` [RFC v8 PATCH 08/20] memory-hotplug: remove /sys/firmware/memmap/X sysfs wency
2012-08-31 21:06 ` Andrew Morton [this message]
2012-09-03 5:51 ` Wen Congyang
2012-09-04 23:16 ` Andrew Morton
2012-09-05 1:41 ` Wen Congyang
2012-09-03 7:31 ` Wen Congyang
2012-08-28 10:00 ` [RFC v8 PATCH 09/20] memory-hotplug: does not release memory region in PAGES_PER_SECTION chunks wency
2012-08-28 10:00 ` [RFC v8 PATCH 10/20] memory-hotplug: add memory_block_release wency
2012-08-28 10:00 ` [RFC v8 PATCH 11/20] memory-hotplug: remove_memory calls __remove_pages wency
2012-08-28 10:00 ` [RFC v8 PATCH 12/20] memory-hotplug: introduce new function arch_remove_memory() wency
2012-08-28 10:00 ` [RFC v8 PATCH 13/20] memory-hotplug: check page type in get_page_bootmem wency
2012-08-31 21:30 ` Andrew Morton
2012-09-04 3:46 ` Wen Congyang
2012-09-04 9:54 ` Yasuaki Ishimatsu
2012-08-28 10:00 ` [RFC v8 PATCH 14/20] memory-hotplug: move register_page_bootmem_info_node and put_page_bootmem for sparse-vmemmap wency
2012-08-28 10:00 ` [RFC v8 PATCH 15/20] memory-hotplug: implement register_page_bootmem_info_section of sparse-vmemmap wency
2012-08-28 10:00 ` [RFC v8 PATCH 16/20] memory-hotplug: free memmap " wency
2012-08-28 10:00 ` [RFC v8 PATCH 17/20] memory_hotplug: clear zone when the memory is removed wency
2012-08-28 10:00 ` [RFC v8 PATCH 18/20] memory-hotplug: add node_device_release wency
2012-08-28 10:00 ` [RFC v8 PATCH 19/20] memory-hotplug: remove sysfs file of node wency
2012-08-28 10:00 ` [RFC v8 PATCH 20/20] memory-hotplug: clear hwpoisoned flag when onlining pages wency
2012-08-31 20:49 ` [RFC v8 PATCH 00/20] memory-hotplug: hot-remove physical memory Andrew Morton
2012-09-10 1:46 ` Yasuaki Ishimatsu
2012-09-10 2:01 ` Wen Congyang
2012-09-10 13:52 ` Vasilis Liaskovitis
2012-09-11 0:27 ` Jerry
2012-09-11 1:23 ` Minchan Kim
2012-09-11 5:18 ` Jerry
2012-09-11 5:39 ` Wen Congyang
2012-09-12 6:17 ` Minchan Kim
2012-09-11 1:25 ` Wen Congyang
2012-09-12 5:20 ` Wen Congyang
2012-09-12 17:18 ` Vasilis Liaskovitis
2012-09-18 9:39 ` Wen Congyang
2012-09-19 17:02 ` Vasilis Liaskovitis
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=20120831140623.8d13bd2c.akpm@linux-foundation.org \
--to=akpm@linux-foundation.org \
--cc=cl@linux.com \
--cc=cmetcalf@tilera.com \
--cc=isimatu.yasuaki@jp.fujitsu.com \
--cc=kosaki.motohiro@jp.fujitsu.com \
--cc=len.brown@intel.com \
--cc=linux-acpi@vger.kernel.org \
--cc=linux-ia64@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-s390@vger.kernel.org \
--cc=linux-sh@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=liuj97@gmail.com \
--cc=minchan.kim@gmail.com \
--cc=paulus@samba.org \
--cc=rientjes@google.com \
--cc=sparclinux@vger.kernel.org \
--cc=wency@cn.fujitsu.com \
--cc=x86@kernel.org \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).