* Re: [RFC] hotplug, memory: move register_memory_resource out of the lock_memory_hotplug
2014-01-14 18:24 [RFC] hotplug, memory: move register_memory_resource out of the lock_memory_hotplug Nathan Zimmer
@ 2014-01-14 23:13 ` Andrew Morton
2014-01-15 1:05 ` David Rientjes
2014-01-15 0:58 ` David Rientjes
2014-01-15 1:12 ` Yasuaki Ishimatsu
2 siblings, 1 reply; 6+ messages in thread
From: Andrew Morton @ 2014-01-14 23:13 UTC (permalink / raw)
To: Nathan Zimmer
Cc: Tang Chen, Wen Congyang, Kamezawa Hiroyuki, Yasuaki Ishimatsu,
Rafael J. Wysocki, Hedi, Mike Travis, linux-mm, linux-kernel
On Tue, 14 Jan 2014 12:24:34 -0600 Nathan Zimmer <nzimmer@sgi.com> wrote:
> We don't need to do register_memory_resource() since it has its own lock and
> doesn't make any callbacks.
>
> Also register_memory_resource return NULL on failure so we don't have anything
> to cleanup at this point.
>
>
> The reason for this rfc is I was doing some experiments with hotplugging of
> memory on some of our larger systems. While it seems to work, it can be quite
> slow. With some preliminary digging I found that lock_memory_hotplug is
> clearly ripe for breakup.
>
> It could be broken up per nid or something but it also covers the
> online_page_callback. The online_page_callback shouldn't be very hard to break
> out.
>
> Also there is the issue of various structures(wmarks come to mind) that are
> only updated under the lock_memory_hotplug that would need to be dealt with.
>
> ...
>
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1097,17 +1097,18 @@ int __ref add_memory(int nid, u64 start, u64 size)
> struct resource *res;
> int ret;
>
> - lock_memory_hotplug();
> -
> res = register_memory_resource(start, size);
> ret = -EEXIST;
> if (!res)
> - goto out;
> + return ret;
>
> { /* Stupid hack to suppress address-never-null warning */
> void *p = NODE_DATA(nid);
> new_pgdat = !p;
> }
> +
> + lock_memory_hotplug();
> +
> new_node = !node_online(nid);
> if (new_node) {
> pgdat = hotadd_new_pgdat(nid, start);
Looks sane to me.
register_memory_resource() makes me cry. Please review:
From: Andrew Morton <akpm@linux-foundation.org>
Subject: mm/memory_hotplug.c: register_memory_resource() fixes
- register_memory_resource() should not go BUG on ENOMEM. That's
appropriate at system boot time, but not at memory-hotplug time. Fix.
- register_memory_resource()'s caller is incorrectly replacing
request_resource()'s -EBUSY with -EEXIST. Fix this by propagating
errors appropriately.
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: Hedi <hedi@sgi.com>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mike Travis <travis@sgi.com>
Cc: Nathan Zimmer <nzimmer@sgi.com>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/memory_hotplug.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff -puN mm/memory_hotplug.c~mm-memory_hotplugc-register_memory_resource-fixes mm/memory_hotplug.c
--- a/mm/memory_hotplug.c~mm-memory_hotplugc-register_memory_resource-fixes
+++ a/mm/memory_hotplug.c
@@ -64,17 +64,21 @@ void unlock_memory_hotplug(void)
static struct resource *register_memory_resource(u64 start, u64 size)
{
struct resource *res;
+ int err;
+
res = kzalloc(sizeof(struct resource), GFP_KERNEL);
- BUG_ON(!res);
+ if (!res)
+ return ERR_PTR(-ENOMEM);
res->name = "System RAM";
res->start = start;
res->end = start + size - 1;
res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
- if (request_resource(&iomem_resource, res) < 0) {
+ err = request_resource(&iomem_resource, res);
+ if (err) {
pr_debug("System RAM resource %pR cannot be added\n", res);
kfree(res);
- res = NULL;
+ res = ERR_PTR(err);
}
return res;
}
@@ -1108,9 +1112,8 @@ int __ref add_memory(int nid, u64 start,
return ret;
res = register_memory_resource(start, size);
- ret = -EEXIST;
- if (!res)
- return ret;
+ if (IS_ERR(res))
+ return PTR_ERR(res);
{ /* Stupid hack to suppress address-never-null warning */
void *p = NODE_DATA(nid);
_
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [RFC] hotplug, memory: move register_memory_resource out of the lock_memory_hotplug
2014-01-14 23:13 ` Andrew Morton
@ 2014-01-15 1:05 ` David Rientjes
2014-01-15 1:16 ` Andrew Morton
0 siblings, 1 reply; 6+ messages in thread
From: David Rientjes @ 2014-01-15 1:05 UTC (permalink / raw)
To: Andrew Morton
Cc: Nathan Zimmer, Tang Chen, Wen Congyang, Kamezawa Hiroyuki,
Yasuaki Ishimatsu, Rafael J. Wysocki, Hedi, Mike Travis,
linux-mm, linux-kernel
On Tue, 14 Jan 2014, Andrew Morton wrote:
> From: Andrew Morton <akpm@linux-foundation.org>
> Subject: mm/memory_hotplug.c: register_memory_resource() fixes
>
> - register_memory_resource() should not go BUG on ENOMEM. That's
> appropriate at system boot time, but not at memory-hotplug time. Fix.
>
> - register_memory_resource()'s caller is incorrectly replacing
> request_resource()'s -EBUSY with -EEXIST. Fix this by propagating
> errors appropriately.
>
Unfortunately, -EEXIST is a special case return value for both
acpi_memory_enable_device() and hv_mem_hot_add(), so they would need to be
modified to agree concurrently with this change.
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [RFC] hotplug, memory: move register_memory_resource out of the lock_memory_hotplug
2014-01-15 1:05 ` David Rientjes
@ 2014-01-15 1:16 ` Andrew Morton
0 siblings, 0 replies; 6+ messages in thread
From: Andrew Morton @ 2014-01-15 1:16 UTC (permalink / raw)
To: David Rientjes
Cc: Nathan Zimmer, Tang Chen, Wen Congyang, Kamezawa Hiroyuki,
Yasuaki Ishimatsu, Rafael J. Wysocki, Hedi, Mike Travis,
linux-mm, linux-kernel
On Tue, 14 Jan 2014 17:05:42 -0800 (PST) David Rientjes <rientjes@google.com> wrote:
> On Tue, 14 Jan 2014, Andrew Morton wrote:
>
> > From: Andrew Morton <akpm@linux-foundation.org>
> > Subject: mm/memory_hotplug.c: register_memory_resource() fixes
> >
> > - register_memory_resource() should not go BUG on ENOMEM. That's
> > appropriate at system boot time, but not at memory-hotplug time. Fix.
> >
> > - register_memory_resource()'s caller is incorrectly replacing
> > request_resource()'s -EBUSY with -EEXIST. Fix this by propagating
> > errors appropriately.
> >
>
> Unfortunately, -EEXIST is a special case return value for both
> acpi_memory_enable_device() and hv_mem_hot_add(), so they would need to be
> modified to agree concurrently with this change.
blah, OK, thanks, I'll drop it.
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [RFC] hotplug, memory: move register_memory_resource out of the lock_memory_hotplug
2014-01-14 18:24 [RFC] hotplug, memory: move register_memory_resource out of the lock_memory_hotplug Nathan Zimmer
2014-01-14 23:13 ` Andrew Morton
@ 2014-01-15 0:58 ` David Rientjes
2014-01-15 1:12 ` Yasuaki Ishimatsu
2 siblings, 0 replies; 6+ messages in thread
From: David Rientjes @ 2014-01-15 0:58 UTC (permalink / raw)
To: Nathan Zimmer
Cc: Andrew Morton, Tang Chen, Wen Congyang, Kamezawa Hiroyuki,
Yasuaki Ishimatsu, Rafael J. Wysocki, Hedi, Mike Travis,
linux-mm, linux-kernel
On Tue, 14 Jan 2014, Nathan Zimmer wrote:
> We don't need to do register_memory_resource() since it has its own lock and
> doesn't make any callbacks.
>
We need to do it, just not under lock_memory_hotplug() :).
> Also register_memory_resource return NULL on failure so we don't have anything
> to cleanup at this point.
>
>
> The reason for this rfc is I was doing some experiments with hotplugging of
> memory on some of our larger systems. While it seems to work, it can be quite
> slow. With some preliminary digging I found that lock_memory_hotplug is
> clearly ripe for breakup.
>
> It could be broken up per nid or something but it also covers the
> online_page_callback. The online_page_callback shouldn't be very hard to break
> out.
>
> Also there is the issue of various structures(wmarks come to mind) that are
> only updated under the lock_memory_hotplug that would need to be dealt with.
>
>
> cc: Andrew Morton <akpm@linux-foundation.org>
> cc: Tang Chen <tangchen@cn.fujitsu.com>
> cc: Wen Congyang <wency@cn.fujitsu.com>
> cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
> cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
> cc: Hedi <hedi@sgi.com>
> cc: Mike Travis <travis@sgi.com>
> cc: linux-mm@kvack.org
> cc: linux-kernel@vger.kernel.org
Looks like you're modifying a pre-3.12 kernel version that doesn't have
27356f54c8c3 ("mm/hotplug: verify hotplug memory range").
When your patch is signed off, feel free to add
Acked-by: David Rientjes <rientjes@google.com>
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [RFC] hotplug, memory: move register_memory_resource out of the lock_memory_hotplug
2014-01-14 18:24 [RFC] hotplug, memory: move register_memory_resource out of the lock_memory_hotplug Nathan Zimmer
2014-01-14 23:13 ` Andrew Morton
2014-01-15 0:58 ` David Rientjes
@ 2014-01-15 1:12 ` Yasuaki Ishimatsu
2 siblings, 0 replies; 6+ messages in thread
From: Yasuaki Ishimatsu @ 2014-01-15 1:12 UTC (permalink / raw)
To: Nathan Zimmer
Cc: Andrew Morton, Tang Chen, Wen Congyang, Kamezawa Hiroyuki,
Rafael J. Wysocki, Hedi, Mike Travis, linux-mm, linux-kernel
(2014/01/15 3:24), Nathan Zimmer wrote:
> We don't need to do register_memory_resource() since it has its own lock and
> doesn't make any callbacks.
>
> Also register_memory_resource return NULL on failure so we don't have anything
> to cleanup at this point.
>
>
> The reason for this rfc is I was doing some experiments with hotplugging of
> memory on some of our larger systems. While it seems to work, it can be quite
> slow. With some preliminary digging I found that lock_memory_hotplug is
> clearly ripe for breakup.
>
> It could be broken up per nid or something but it also covers the
> online_page_callback. The online_page_callback shouldn't be very hard to break
> out.
>
> Also there is the issue of various structures(wmarks come to mind) that are
> only updated under the lock_memory_hotplug that would need to be dealt with.
>
>
> cc: Andrew Morton <akpm@linux-foundation.org>
> cc: Tang Chen <tangchen@cn.fujitsu.com>
> cc: Wen Congyang <wency@cn.fujitsu.com>
> cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
> cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
> cc: Hedi <hedi@sgi.com>
> cc: Mike Travis <travis@sgi.com>
> cc: linux-mm@kvack.org
> cc: linux-kernel@vger.kernel.org
>
>
> ---
The patch seems good to me.
Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Thanks,
Yasuaki Ishimatsu
> mm/memory_hotplug.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 1ad92b4..62a0cd1 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1097,17 +1097,18 @@ int __ref add_memory(int nid, u64 start, u64 size)
> struct resource *res;
> int ret;
>
> - lock_memory_hotplug();
> -
> res = register_memory_resource(start, size);
> ret = -EEXIST;
> if (!res)
> - goto out;
> + return ret;
>
> { /* Stupid hack to suppress address-never-null warning */
> void *p = NODE_DATA(nid);
> new_pgdat = !p;
> }
> +
> + lock_memory_hotplug();
> +
> new_node = !node_online(nid);
> if (new_node) {
> pgdat = hotadd_new_pgdat(nid, start);
>
--
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^ permalink raw reply [flat|nested] 6+ messages in thread