Commit 1ef2f06b authored by David Hildenbrand's avatar David Hildenbrand Committed by Michael Ellerman
Browse files

powerpc/pseries/cmm: Convert loaned_pages to an atomic_long_t 



When switching to balloon compaction, we want to drop the cmm_lock and
completely rely on the balloon compaction list lock internally.
loaned_pages is currently protected under the cmm_lock.

Note: Right now cmm_alloc_pages() and cmm_free_pages() can be called
at the same time, e.g., via the thread and a concurrent OOM notifier.

Signed-off-by: default avatarDavid Hildenbrand <david@redhat.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191031142933.10779-8-david@redhat.com
parent 7659f5d6

arch/powerpc/platforms/pseries/cmm.c

+19 −16
Original line number Diff line number Diff line
@@ -73,7 +73,7 @@ MODULE_PARM_DESC(debug, "Enable module debugging logging. Set to 1 to enable. " 


#define cmm_dbg(...) if (cmm_debug) { printk(KERN_INFO "cmm: "__VA_ARGS__); }



static unsigned long loaned_pages;

static atomic_long_t loaned_pages;

static unsigned long loaned_pages_target;

static unsigned long oom_freed_pages;
@@ -159,7 +159,7 @@ static long cmm_alloc_pages(long nr) 
		}



		list_add(&page->lru, &cmm_page_list);

		loaned_pages++;

		atomic_long_inc(&loaned_pages);

		adjust_managed_page_count(page, -1);

		spin_unlock(&cmm_lock);

		nr--;
@@ -189,7 +189,7 @@ static long cmm_free_pages(long nr) 
		list_del(&page->lru);

		adjust_managed_page_count(page, 1);

		__free_page(page);

		loaned_pages--;

		atomic_long_dec(&loaned_pages);

		nr--;

	}

	spin_unlock(&cmm_lock);
@@ -214,7 +214,7 @@ static int cmm_oom_notify(struct notifier_block *self, 


	cmm_dbg("OOM processing started\n");

	nr = cmm_free_pages(nr);

	loaned_pages_target = loaned_pages;

	loaned_pages_target = atomic_long_read(&loaned_pages);

	*freed += KB2PAGES(oom_kb) - nr;

	oom_freed_pages += KB2PAGES(oom_kb) - nr;

	cmm_dbg("OOM processing complete\n");
@@ -231,10 +231,11 @@ static int cmm_oom_notify(struct notifier_block *self, 
 **/

static void cmm_get_mpp(void)

{

	const long __loaned_pages = atomic_long_read(&loaned_pages);

	const long total_pages = totalram_pages() + __loaned_pages;

	int rc;

	struct hvcall_mpp_data mpp_data;

	signed long active_pages_target, page_loan_request, target;

	signed long total_pages = totalram_pages() + loaned_pages;

	signed long min_mem_pages = (min_mem_mb * 1024 * 1024) / PAGE_SIZE;



	rc = h_get_mpp(&mpp_data);
@@ -243,7 +244,7 @@ static void cmm_get_mpp(void) 
		return;



	page_loan_request = div_s64((s64)mpp_data.loan_request, PAGE_SIZE);

	target = page_loan_request + (signed long)loaned_pages;

	target = page_loan_request + __loaned_pages;



	if (target < 0 || total_pages < min_mem_pages)

		target = 0;
@@ -264,7 +265,7 @@ static void cmm_get_mpp(void) 
	loaned_pages_target = target;



	cmm_dbg("delta = %ld, loaned = %lu, target = %lu, oom = %lu, totalram = %lu\n",

		page_loan_request, loaned_pages, loaned_pages_target,

		page_loan_request, __loaned_pages, loaned_pages_target,

		oom_freed_pages, totalram_pages());

}
@@ -282,6 +283,7 @@ static struct notifier_block cmm_oom_nb = { 
static int cmm_thread(void *dummy)

{

	unsigned long timeleft;

	long __loaned_pages;



	while (1) {

		timeleft = msleep_interruptible(delay * 1000);
@@ -312,11 +314,12 @@ static int cmm_thread(void *dummy) 


		cmm_get_mpp();



		if (loaned_pages_target > loaned_pages) {

			if (cmm_alloc_pages(loaned_pages_target - loaned_pages))

				loaned_pages_target = loaned_pages;

		} else if (loaned_pages_target < loaned_pages)

			cmm_free_pages(loaned_pages - loaned_pages_target);

		__loaned_pages = atomic_long_read(&loaned_pages);

		if (loaned_pages_target > __loaned_pages) {

			if (cmm_alloc_pages(loaned_pages_target - __loaned_pages))

				loaned_pages_target = __loaned_pages;

		} else if (loaned_pages_target < __loaned_pages)

			cmm_free_pages(__loaned_pages - loaned_pages_target);

	}

	return 0;

}
@@ -330,7 +333,7 @@ static int cmm_thread(void *dummy) 
	}							\

	static DEVICE_ATTR(name, 0444, show_##name, NULL)



CMM_SHOW(loaned_kb, "%lu\n", PAGES2KB(loaned_pages));

CMM_SHOW(loaned_kb, "%lu\n", PAGES2KB(atomic_long_read(&loaned_pages)));

CMM_SHOW(loaned_target_kb, "%lu\n", PAGES2KB(loaned_pages_target));



static ssize_t show_oom_pages(struct device *dev,
@@ -433,7 +436,7 @@ static int cmm_reboot_notifier(struct notifier_block *nb, 
		if (cmm_thread_ptr)

			kthread_stop(cmm_thread_ptr);

		cmm_thread_ptr = NULL;

		cmm_free_pages(loaned_pages);

		cmm_free_pages(atomic_long_read(&loaned_pages));

	}

	return NOTIFY_DONE;

}
@@ -540,7 +543,7 @@ static void cmm_exit(void) 
	unregister_oom_notifier(&cmm_oom_nb);

	unregister_reboot_notifier(&cmm_reboot_nb);

	unregister_memory_notifier(&cmm_mem_nb);

	cmm_free_pages(loaned_pages);

	cmm_free_pages(atomic_long_read(&loaned_pages));

	cmm_unregister_sysfs(&cmm_dev);

}
@@ -561,7 +564,7 @@ static int cmm_set_disable(const char *val, const struct kernel_param *kp) 
		if (cmm_thread_ptr)

			kthread_stop(cmm_thread_ptr);

		cmm_thread_ptr = NULL;

		cmm_free_pages(loaned_pages);

		cmm_free_pages(atomic_long_read(&loaned_pages));

	} else if (!disable && cmm_disabled) {

		cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread");

		if (IS_ERR(cmm_thread_ptr))

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