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* [PATCH 0/2] Configurable order free page reporting in hyper-v
@ 2022-09-29 10:24 Shradha Gupta
  2022-09-29 10:24 ` [PATCH 1/2] mm/page_reporting: Add checks for page_reporting_order param value Shradha Gupta
                   ` (2 more replies)
  0 siblings, 3 replies; 15+ messages in thread
From: Shradha Gupta @ 2022-09-29 10:24 UTC (permalink / raw)
  To: Andrew Morton, linux-mm, linux-hyperv, linux-kernel
  Cc: Shradha Gupta, K. Y. Srinivasan, Haiyang Zhang, Stephen Hemminger,
	Wei Liu, Dexuan Cui, Shradha Gupta, Michael Kelley

Configurable order free page reporting is enabled in page_reporting
driver in mm tree. However, changes need to be made in drivers like
hyper-v's hv_balloon to make it aware of the page order.
These patches add support for the same.
In the page_reporting driver we export the page_reporting_order module
parameter. Following precedence is added in setting the reporting order
        a. Value of page_reporting_order parameter
        b. Value of order passed while registering with the driver
        c. default value (pageblock_order)
Besides this, in the page_reporting module a check is added to ensure
that whenever the page_reporting_order value is changed, it is within
the prescribed limits.

The hv_balloon side changes include consuming the exported
page_reporting_order. Making changes in reporting these variable order
free pages as cold discard hints to hyper-v and dropping and refining
checks that restrict the order to a minimum of 9(default).

Shradha Gupta (2):
  mm/page_reporting: Add checks for page_reporting_order param value
  hv_balloon: Add support for configurable order free page reporting

 drivers/hv/hv_balloon.c | 94 ++++++++++++++++++++++++++++++++---------
 mm/page_reporting.c 	 | 50 ++++++++++++++++++++++++++++++++++++++++-----
 2 file changed, 118 insertions(+), 26 deletions(-)

-- 
2.37.2


^ permalink raw reply	[flat|nested] 15+ messages in thread
* [PATCH 1/2] mm/page_reporting: Add checks for page_reporting_order param value
@ 2022-09-29 10:32 Shradha Gupta
  0 siblings, 0 replies; 15+ messages in thread
From: Shradha Gupta @ 2022-09-29 10:32 UTC (permalink / raw)
  To: linux-hyperv
  Cc: Shradha Gupta, K. Y. Srinivasan, Haiyang Zhang, Stephen Hemminger,
	Wei Liu, Dexuan Cui, Shradha Gupta

Current code allows the page_reporting_order parameter to be changed
via sysfs to any integer value.  The new value is used immediately
in page reporting code with no validation, which could cause incorrect
behavior.  Fix this by adding validation of the new value.
Export this parameter for use in the driver that is calling the
page_reporting_register().
This is needed by drivers like hv_balloon to know the order of the
pages reported. Traditionally the values provided in the kernel boot
line or subsequently changed via sysfs take priority therefore, if
page_reporting_order parameter's value is set, it takes precedence
over the value passed while registering with the driver.

Signed-off-by: Shradha Gupta <shradhagupta@linux.microsoft.com>
---
 mm/page_reporting.c | 50 ++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 45 insertions(+), 5 deletions(-)

diff --git a/mm/page_reporting.c b/mm/page_reporting.c
index 382958eef8a9..29d67c824fd2 100644
--- a/mm/page_reporting.c
+++ b/mm/page_reporting.c
@@ -11,10 +11,42 @@
 #include "page_reporting.h"
 #include "internal.h"
 
-unsigned int page_reporting_order = MAX_ORDER;
-module_param(page_reporting_order, uint, 0644);
+/* Initialize to an unsupported value */
+unsigned int page_reporting_order = -1;
+
+int page_order_update_notify(const char *val, const struct kernel_param *kp)
+{
+	/*
+	 * If param is set beyond this limit, order is set to default
+	 * pageblock_order value
+	 */
+	return  param_set_uint_minmax(val, kp, 0, MAX_ORDER-1);
+}
+
+const struct kernel_param_ops page_reporting_param_ops = {
+	.set = &page_order_update_notify,
+	/*
+	 * For the get op, use param_get_int instead of param_get_uint.
+	 * This is to make sure that when unset the initialized value of
+	 * -1 is shown correctly
+	 */
+	.get = &param_get_int,
+};
+
+module_param_cb(page_reporting_order, &page_reporting_param_ops,
+			&page_reporting_order, 0644);
 MODULE_PARM_DESC(page_reporting_order, "Set page reporting order");
 
+/*
+ * This symbol is also a kernel parameter. Export the page_reporting_order
+ * symbol so that other drivers can access it to control order values without
+ * having to introduce another configurable parameter. Only one driver can
+ * register with the page_reporting driver for the service, so we have just
+ * one control parameter for the use case(which can be accessed in both
+ * drivers)
+ */
+EXPORT_SYMBOL_GPL(page_reporting_order);
+
 #define PAGE_REPORTING_DELAY	(2 * HZ)
 static struct page_reporting_dev_info __rcu *pr_dev_info __read_mostly;
 
@@ -330,10 +362,18 @@ int page_reporting_register(struct page_reporting_dev_info *prdev)
 	}
 
 	/*
-	 * Update the page reporting order if it's specified by driver.
-	 * Otherwise, it falls back to @pageblock_order.
+	 * If the page_reporting_order value is not set, we check if
+	 * an order is provided from the driver that is performing the
+	 * registration. If that is not provided either, we default to
+	 * pageblock_order.
 	 */
-	page_reporting_order = prdev->order ? : pageblock_order;
+
+	if (page_reporting_order == -1) {
+		if (prdev->order > 0 && prdev->order <= MAX_ORDER)
+			page_reporting_order = prdev->order;
+		else
+			page_reporting_order = pageblock_order;
+	}
 
 	/* initialize state and work structures */
 	atomic_set(&prdev->state, PAGE_REPORTING_IDLE);
-- 
2.37.2


^ permalink raw reply related	[flat|nested] 15+ messages in thread
end of thread, other threads:[~2022-10-28 10:43 UTC | newest]

Thread overview: 15+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2022-09-29 10:24 [PATCH 0/2] Configurable order free page reporting in hyper-v Shradha Gupta
2022-09-29 10:24 ` [PATCH 1/2] mm/page_reporting: Add checks for page_reporting_order param value Shradha Gupta
2022-10-01  8:00   ` kernel test robot
2022-10-01  9:49   ` kernel test robot
2022-09-29 10:24 ` [PATCH 2/2] hv_balloon: Add support for configurable order free page reporting Shradha Gupta
2022-09-30  6:01 ` [PATCH v2 0/2] Configurable order free page reporting in hyper-v Shradha Gupta
2022-09-30  6:01   ` [PATCH v2 1/2] mm/page_reporting: Add checks for page_reporting_order param Shradha Gupta
2022-10-17 15:49     ` Michael Kelley (LINUX)
2022-10-26 15:33     ` Wei Liu
2022-10-27 20:22       ` Andrew Morton
2022-10-28 10:38         ` Wei Liu
2022-09-30  6:01   ` [PATCH v2 2/2] hv_balloon: Add support for configurable order free page reporting Shradha Gupta
2022-10-17 15:53     ` Michael Kelley (LINUX)
2022-10-28 10:42   ` [PATCH v2 0/2] Configurable order free page reporting in hyper-v Wei Liu
  -- strict thread matches above, loose matches on Subject: below --
2022-09-29 10:32 [PATCH 1/2] mm/page_reporting: Add checks for page_reporting_order param value Shradha Gupta

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