This is a note to let you know that I've just added the patch titled
memory hotplug: one more lock on memory hotplug
to the 2.6.37-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
memory-hotplug-one-more-lock-on-memory-hotplug.patch
and it can be found in the queue-2.6.37 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 925268a06dc2b1ff7bfcc37419a6827a0e739639 Mon Sep 17 00:00:00 2001
From: KAMEZAWA Hiroyuki <[email protected]>
Date: Tue, 11 Jan 2011 16:44:01 +0900
Subject: memory hotplug: one more lock on memory hotplug
From: KAMEZAWA Hiroyuki <[email protected]>
commit 925268a06dc2b1ff7bfcc37419a6827a0e739639 upstream.
Now, memory_hotplug_(un)lock() is used for add/remove/offline pages
for avoiding races with hibernation. But this should be held in
online_pages(), too. It seems asymmetric.
There are cases where one has to avoid a race with memory hotplug
notifier and his own local code, and hotplug v.s. hotplug.
This will add a generic solution for avoiding races. In other view,
having lock here has no big impacts. online pages is tend to be
done by udev script at el against each memory section one by one.
Then, it's better to have lock here, too.
Reviewed-by: Christoph Lameter <[email protected]>
Acked-by: David Rientjes <[email protected]>
Signed-off-by: KAMEZAWA Hiroyuki <[email protected]>
Signed-off-by: Pekka Enberg <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
include/linux/memory_hotplug.h | 6 ++++++
mm/memory_hotplug.c | 4 ++++
2 files changed, 10 insertions(+)
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -161,6 +161,12 @@ extern void register_page_bootmem_info_n
extern void put_page_bootmem(struct page *page);
#endif
+/*
+ * Lock for memory hotplug guarantees 1) all callbacks for memory hotplug
+ * notifier will be called under this. 2) offline/online/add/remove memory
+ * will not run simultaneously.
+ */
+
void lock_memory_hotplug(void);
void unlock_memory_hotplug(void);
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -407,6 +407,7 @@ int online_pages(unsigned long pfn, unsi
int ret;
struct memory_notify arg;
+ lock_memory_hotplug();
arg.start_pfn = pfn;
arg.nr_pages = nr_pages;
arg.status_change_nid = -1;
@@ -419,6 +420,7 @@ int online_pages(unsigned long pfn, unsi
ret = notifier_to_errno(ret);
if (ret) {
memory_notify(MEM_CANCEL_ONLINE, &arg);
+ unlock_memory_hotplug();
return ret;
}
/*
@@ -443,6 +445,7 @@ int online_pages(unsigned long pfn, unsi
printk(KERN_DEBUG "online_pages %lx at %lx failed\n",
nr_pages, pfn);
memory_notify(MEM_CANCEL_ONLINE, &arg);
+ unlock_memory_hotplug();
return ret;
}
@@ -467,6 +470,7 @@ int online_pages(unsigned long pfn, unsi
if (onlined_pages)
memory_notify(MEM_ONLINE, &arg);
+ unlock_memory_hotplug();
return 0;
}
Patches currently in stable-queue which might be from
[email protected] are
queue-2.6.37/memory-hotplug-one-more-lock-on-memory-hotplug.patch
queue-2.6.37/memcg-fix-account-leak-at-failure-of-memsw-acconting.patch
queue-2.6.37/memsw-handle-swapaccount-kernel-parameter-correctly.patch
queue-2.6.37/mm-migration-use-rcu_dereference_protected-when-dereferencing-the-radix-tree-slot-during-file-page-migration.patch
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