On Wed, Jun 08, 2016 at 02:55:01PM -0700, a...@linux-foundation.org wrote:
>
> The patch titled
> Subject: thp-extract-khugepaged-from-mm-huge_memoryc-fix
> has been added to the -mm tree. Its filename is
> thp-extract-khugepaged-from-mm-huge_memoryc-fix.patch
>
> This patch should soon appear at
>
> http://ozlabs.org/~akpm/mmots/broken-out/thp-extract-khugepaged-from-mm-huge_memoryc-fix.patch
> and later at
>
> http://ozlabs.org/~akpm/mmotm/broken-out/thp-extract-khugepaged-from-mm-huge_memoryc-fix.patch
>
> Before you just go and hit "reply", please:
> a) Consider who else should be cc'ed
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>
> *** Remember to use Documentation/SubmitChecklist when testing your code ***
>
> The -mm tree is included into linux-next and is updated
> there every 3-4 working days
>
> ------------------------------------------------------
> From: Andrew Morton <a...@linux-foundation.org>
> Subject: thp-extract-khugepaged-from-mm-huge_memoryc-fix
>
> khugepaged_mutex can be static to mm/huge_memory.c:enabled_store()
>
> Makes me wonder what it actually does...
IIUC, it protects khugepaged_thread.
What about something like this:
diff --git a/include/linux/khugepaged.h b/include/linux/khugepaged.h
index f7b4b7dc97bc..1e032a1ddb3e 100644
--- a/include/linux/khugepaged.h
+++ b/include/linux/khugepaged.h
@@ -4,7 +4,6 @@
#include <linux/sched.h> /* MMF_VM_HUGEPAGE */
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-extern struct mutex khugepaged_mutex;
extern struct attribute_group khugepaged_attr_group;
extern int khugepaged_init(void);
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index eaf3a4a655a6..522cf178f118 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -181,12 +181,7 @@ static ssize_t enabled_store(struct kobject *kobj,
TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
if (ret > 0) {
- int err;
-
- mutex_lock(&khugepaged_mutex);
- err = start_stop_khugepaged();
- mutex_unlock(&khugepaged_mutex);
-
+ int err = start_stop_khugepaged();
if (err)
ret = err;
}
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 71a6f9bedfdc..6f5815488c6c 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -58,8 +58,6 @@ static unsigned int khugepaged_scan_sleep_millisecs
__read_mostly = 10000;
/* during fragmentation poll the hugepage allocator once every minute */
static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000;
static unsigned long khugepaged_sleep_expire;
-static struct task_struct *khugepaged_thread __read_mostly;
-DEFINE_MUTEX(khugepaged_mutex);
static DEFINE_SPINLOCK(khugepaged_mm_lock);
static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait);
/*
@@ -1885,7 +1883,11 @@ static void set_recommended_min_free_kbytes(void)
int start_stop_khugepaged(void)
{
+ static struct task_struct *khugepaged_thread __read_mostly;
+ static DEFINE_MUTEX(khugepaged_mutex);
int err = 0;
+
+ mutex_lock(&khugepaged_mutex);
if (khugepaged_enabled()) {
if (!khugepaged_thread)
khugepaged_thread = kthread_run(khugepaged, NULL,
@@ -1906,5 +1908,6 @@ int start_stop_khugepaged(void)
khugepaged_thread = NULL;
}
fail:
+ mutex_unlock(&khugepaged_mutex);
return err;
}
--
Kirill A. Shutemov
