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Subject[PATCH 1/2] mem-hotplug: Introduce {un}lock_memory_hotplug()
Date
Now, hwpoison are using lock_system_sleep() for prevent a race
with memory hotplug. However lock_system_sleep() is no-op if
CONFIG_HIBERNATION=n. Therefore we need new lock.

Cc: Andi Kleen <andi@firstfloor.org>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Suggested-by: Hugh Dickins <hughd@google.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
---
include/linux/memory_hotplug.h | 6 ++++++
mm/memory-failure.c | 8 ++++----
mm/memory_hotplug.c | 31 ++++++++++++++++++++++++-------
3 files changed, 34 insertions(+), 11 deletions(-)

diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 4307231..31c237a 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -161,6 +161,9 @@ extern void register_page_bootmem_info_node(struct pglist_data *pgdat);
extern void put_page_bootmem(struct page *page);
#endif

+void lock_memory_hotplug(void);
+void unlock_memory_hotplug(void);
+
#else /* ! CONFIG_MEMORY_HOTPLUG */
/*
* Stub functions for when hotplug is off
@@ -192,6 +195,9 @@ static inline void register_page_bootmem_info_node(struct pglist_data *pgdat)
{
}

+static inline void lock_memory_hotplug(void) {}
+static inline void unlock_memory_hotplug(void) {}
+
#endif /* ! CONFIG_MEMORY_HOTPLUG */

#ifdef CONFIG_MEMORY_HOTREMOVE
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 1243241..46ab2c0 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -51,6 +51,7 @@
#include <linux/slab.h>
#include <linux/swapops.h>
#include <linux/hugetlb.h>
+#include <linux/memory_hotplug.h>
#include "internal.h"

int sysctl_memory_failure_early_kill __read_mostly = 0;
@@ -1230,11 +1231,10 @@ static int get_any_page(struct page *p, unsigned long pfn, int flags)
return 1;

/*
- * The lock_system_sleep prevents a race with memory hotplug,
- * because the isolation assumes there's only a single user.
+ * The lock_memory_hotplug prevents a race with memory hotplug.
* This is a big hammer, a better would be nicer.
*/
- lock_system_sleep();
+ lock_memory_hotplug();

/*
* Isolate the page, so that it doesn't get reallocated if it
@@ -1264,7 +1264,7 @@ static int get_any_page(struct page *p, unsigned long pfn, int flags)
ret = 1;
}
unset_migratetype_isolate(p);
- unlock_system_sleep();
+ unlock_memory_hotplug();
return ret;
}

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 833e286..7549a01 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -34,6 +34,23 @@

#include "internal.h"

+DEFINE_MUTEX(mem_hotplug_mutex);
+
+void lock_memory_hotplug(void)
+{
+ mutex_lock(&mem_hotplug_mutex);
+
+ /* for exclusive hibernation if CONFIG_HIBERNATION=y */
+ lock_system_sleep();
+}
+
+void unlock_memory_hotplug(void)
+{
+ unlock_system_sleep();
+ mutex_unlock(&mem_hotplug_mutex);
+}
+
+
/* add this memory to iomem resource */
static struct resource *register_memory_resource(u64 start, u64 size)
{
@@ -491,7 +508,7 @@ int mem_online_node(int nid)
pg_data_t *pgdat;
int ret;

- lock_system_sleep();
+ lock_memory_hotplug();
pgdat = hotadd_new_pgdat(nid, 0);
if (pgdat) {
ret = -ENOMEM;
@@ -502,7 +519,7 @@ int mem_online_node(int nid)
BUG_ON(ret);

out:
- unlock_system_sleep();
+ unlock_memory_hotplug();
return ret;
}

@@ -514,7 +531,7 @@ int __ref add_memory(int nid, u64 start, u64 size)
struct resource *res;
int ret;

- lock_system_sleep();
+ lock_memory_hotplug();

res = register_memory_resource(start, size);
ret = -EEXIST;
@@ -561,7 +578,7 @@ error:
release_memory_resource(res);

out:
- unlock_system_sleep();
+ unlock_memory_hotplug();
return ret;
}
EXPORT_SYMBOL_GPL(add_memory);
@@ -789,7 +806,7 @@ static int offline_pages(unsigned long start_pfn,
if (!test_pages_in_a_zone(start_pfn, end_pfn))
return -EINVAL;

- lock_system_sleep();
+ lock_memory_hotplug();

zone = page_zone(pfn_to_page(start_pfn));
node = zone_to_nid(zone);
@@ -877,7 +894,7 @@ repeat:
vm_total_pages = nr_free_pagecache_pages();

memory_notify(MEM_OFFLINE, &arg);
- unlock_system_sleep();
+ unlock_memory_hotplug();
return 0;

failed_removal:
@@ -888,7 +905,7 @@ failed_removal:
undo_isolate_page_range(start_pfn, end_pfn);

out:
- unlock_system_sleep();
+ unlock_memory_hotplug();
return ret;
}

--
1.6.5.2




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