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Date: Thu, 23 May 2013 00:09:46 +0200
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: Toshi Kani <toshi.kani@...com>
Cc: ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
LKML <linux-kernel@...r.kernel.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Wen Congyang <wency@...fujitsu.com>,
Tang Chen <tangchen@...fujitsu.com>,
Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Jiang Liu <liuj97@...il.com>,
Vasilis Liaskovitis <vasilis.liaskovitis@...fitbricks.com>,
linux-mm@...ck.org
Subject: [PATCH *5/5] Memory hotplug / ACPI: Simplify memory removal (was: Re: [PATCH 5/5] ACPI / memhotplug: Drop unnecessary code)
On Monday, May 20, 2013 01:55:33 PM Toshi Kani wrote:
> On Mon, 2013-05-20 at 21:47 +0200, Rafael J. Wysocki wrote:
> > On Monday, May 20, 2013 11:27:56 AM Toshi Kani wrote:
> > > On Sun, 2013-05-19 at 01:34 +0200, Rafael J. Wysocki wrote:
> > > > From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
>
> :
>
> > > > - lock_memory_hotplug();
> > > > -
> > > > - /*
> > > > - * we have offlined all memory blocks like this:
> > > > - * 1. lock memory hotplug
> > > > - * 2. offline a memory block
> > > > - * 3. unlock memory hotplug
> > > > - *
> > > > - * repeat step1-3 to offline the memory block. All memory blocks
> > > > - * must be offlined before removing memory. But we don't hold the
> > > > - * lock in the whole operation. So we should check whether all
> > > > - * memory blocks are offlined.
> > > > - */
> > > > -
> > > > - ret = walk_memory_range(start_pfn, end_pfn, NULL,
> > > > - is_memblock_offlined_cb);
> > > > - if (ret) {
> > > > - unlock_memory_hotplug();
> > > > - return ret;
> > > > - }
> > > > -
> > >
> > > I think the above procedure is still useful for safe guard.
> >
> > But then it shoud to BUG_ON() instead of returning an error (which isn't very
> > useful for anything now).
>
> Right since we cannot fail at that state.
>
> > > > - /* remove memmap entry */
> > > > - firmware_map_remove(start, start + size, "System RAM");
> > > > -
> > > > - arch_remove_memory(start, size);
> > > > -
> > > > - try_offline_node(nid);
> > >
> > > The above procedure performs memory hot-delete specific operations and
> > > is necessary.
> >
> > OK, I see. I'll replace this patch with something simpler, then.
>
> Thanks.
The replacement patch is appended.
Thanks,
Rafael
---
From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Subject: Memory hotplug / ACPI: Simplify memory removal
Now that the memory offlining should be taken care of by the
companion device offlining code in acpi_scan_hot_remove(), the
ACPI memory hotplug driver doesn't need to offline it in
remove_memory() any more. Moreover, since the return value of
remove_memory() is not used, it's better to make it be a void
function and trigger a BUG() if the memory scheduled for removal is
not offline.
Change the code in accordance with the above observations.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
drivers/acpi/acpi_memhotplug.c | 13 +------
include/linux/memory_hotplug.h | 2 -
mm/memory_hotplug.c | 71 ++++-------------------------------------
3 files changed, 12 insertions(+), 74 deletions(-)
Index: linux-pm/include/linux/memory_hotplug.h
===================================================================
--- linux-pm.orig/include/linux/memory_hotplug.h
+++ linux-pm/include/linux/memory_hotplug.h
@@ -252,7 +252,7 @@ extern int add_memory(int nid, u64 start
extern int arch_add_memory(int nid, u64 start, u64 size);
extern int offline_pages(unsigned long start_pfn, unsigned long nr_pages);
extern bool is_memblock_offlined(struct memory_block *mem);
-extern int remove_memory(int nid, u64 start, u64 size);
+extern void remove_memory(int nid, u64 start, u64 size);
extern int sparse_add_one_section(struct zone *zone, unsigned long start_pfn,
int nr_pages);
extern void sparse_remove_one_section(struct zone *zone, struct mem_section *ms);
Index: linux-pm/drivers/acpi/acpi_memhotplug.c
===================================================================
--- linux-pm.orig/drivers/acpi/acpi_memhotplug.c
+++ linux-pm/drivers/acpi/acpi_memhotplug.c
@@ -271,13 +271,11 @@ static int acpi_memory_enable_device(str
return 0;
}
-static int acpi_memory_remove_memory(struct acpi_memory_device *mem_device)
+static void acpi_memory_remove_memory(struct acpi_memory_device *mem_device)
{
acpi_handle handle = mem_device->device->handle;
- int result = 0, nid;
struct acpi_memory_info *info, *n;
-
- nid = acpi_get_node(handle);
+ int nid = acpi_get_node(handle);
list_for_each_entry_safe(info, n, &mem_device->res_list, list) {
if (!info->enabled)
@@ -287,15 +285,10 @@ static int acpi_memory_remove_memory(str
nid = memory_add_physaddr_to_nid(info->start_addr);
acpi_unbind_memory_blocks(info, handle);
- result = remove_memory(nid, info->start_addr, info->length);
- if (result)
- return result;
-
+ remove_memory(nid, info->start_addr, info->length);
list_del(&info->list);
kfree(info);
}
-
- return result;
}
static void acpi_memory_device_free(struct acpi_memory_device *mem_device)
Index: linux-pm/mm/memory_hotplug.c
===================================================================
--- linux-pm.orig/mm/memory_hotplug.c
+++ linux-pm/mm/memory_hotplug.c
@@ -1670,24 +1670,6 @@ int walk_memory_range(unsigned long star
}
#ifdef CONFIG_MEMORY_HOTREMOVE
-/**
- * offline_memory_block_cb - callback function for offlining memory block
- * @mem: the memory block to be offlined
- * @arg: buffer to hold error msg
- *
- * Always return 0, and put the error msg in arg if any.
- */
-static int offline_memory_block_cb(struct memory_block *mem, void *arg)
-{
- int *ret = arg;
- int error = device_offline(&mem->dev);
-
- if (error != 0 && *ret == 0)
- *ret = error;
-
- return 0;
-}
-
static int is_memblock_offlined_cb(struct memory_block *mem, void *arg)
{
int ret = !is_memblock_offlined(mem);
@@ -1813,54 +1795,22 @@ void try_offline_node(int nid)
}
EXPORT_SYMBOL(try_offline_node);
-int __ref remove_memory(int nid, u64 start, u64 size)
+void __ref remove_memory(int nid, u64 start, u64 size)
{
- unsigned long start_pfn, end_pfn;
- int ret = 0;
- int retry = 1;
-
- start_pfn = PFN_DOWN(start);
- end_pfn = PFN_UP(start + size - 1);
-
- /*
- * When CONFIG_MEMCG is on, one memory block may be used by other
- * blocks to store page cgroup when onlining pages. But we don't know
- * in what order pages are onlined. So we iterate twice to offline
- * memory:
- * 1st iterate: offline every non primary memory block.
- * 2nd iterate: offline primary (i.e. first added) memory block.
- */
-repeat:
- walk_memory_range(start_pfn, end_pfn, &ret,
- offline_memory_block_cb);
- if (ret) {
- if (!retry)
- return ret;
-
- retry = 0;
- ret = 0;
- goto repeat;
- }
+ int ret;
lock_memory_hotplug();
/*
- * we have offlined all memory blocks like this:
- * 1. lock memory hotplug
- * 2. offline a memory block
- * 3. unlock memory hotplug
- *
- * repeat step1-3 to offline the memory block. All memory blocks
- * must be offlined before removing memory. But we don't hold the
- * lock in the whole operation. So we should check whether all
- * memory blocks are offlined.
+ * All memory blocks must be offlined before removing memory. Check
+ * whether all memory blocks in question are offline and trigger a BUG()
+ * if this is not the case.
*/
-
- ret = walk_memory_range(start_pfn, end_pfn, NULL,
+ ret = walk_memory_range(PFN_DOWN(start), PFN_UP(start + size - 1), NULL,
is_memblock_offlined_cb);
if (ret) {
unlock_memory_hotplug();
- return ret;
+ BUG();
}
/* remove memmap entry */
@@ -1871,17 +1821,12 @@ repeat:
try_offline_node(nid);
unlock_memory_hotplug();
-
- return 0;
}
#else
int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
{
return -EINVAL;
}
-int remove_memory(int nid, u64 start, u64 size)
-{
- return -EINVAL;
-}
+void remove_memory(int nid, u64 start, u64 size) {}
#endif /* CONFIG_MEMORY_HOTREMOVE */
EXPORT_SYMBOL_GPL(remove_memory);
--
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