PM / Hibernate: Add sysfs knob to control size of memory for drivers

Martin reports that on his system hibernation occasionally fails due
to the lack of memory, because the radeon driver apparently allocates
too much of it during the device freeze stage.  It turns out that the
amount of memory allocated by radeon during hibernation (and
presumably during system suspend too) depends on the utilization of
the GPU (e.g. hibernating while there are two KDE 4 sessions with
compositing enabled causes radeon to allocate more memory than for
one KDE 4 session).

In principle it should be possible to use image_size to make the
memory preallocation mechanism free enough memory for the radeon
driver, but in practice it is not easy to guess the right value
because of the way the preallocation code uses image_size.  For this
reason, it seems reasonable to allow users to control the amount of
memory reserved for driver allocations made after the hibernate
preallocation, which currently is constant and amounts to 1 MB.

Introduce a new sysfs file, /sys/power/reserved_size, whose value
will be used as the amount of memory to reserve for the
post-preallocation reservations made by device drivers, in bytes.
For backwards compatibility, set its default (and initial) value to
the currently used number (1 MB).

References: https://bugzilla.kernel.org/show_bug.cgi?id=34102
Reported-and-tested-by: Martin Steigerwald <Martin@Lichtvoll.de>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

diff --git a/Documentation/ABI/testing/sysfs-power b/Documentation/ABI/testing/sysfs-power
index 194ca446ac287692333040ca76235503af8738a9..b464d12761baf81023bb35da2e3aba01049fc81a 100644 (file)
--- a/Documentation/ABI/testing/sysfs-power
+++ b/Documentation/ABI/testing/sysfs-power
@@ -158,3 +158,17 @@ Description:
                successful, will make the kernel abort a subsequent transition
                to a sleep state if any wakeup events are reported after the
                write has returned.
+
+What:          /sys/power/reserved_size
+Date:          May 2011
+Contact:       Rafael J. Wysocki <rjw@sisk.pl>
+Description:
+               The /sys/power/reserved_size file allows user space to control
+               the amount of memory reserved for allocations made by device
+               drivers during the "device freeze" stage of hibernation.  It can
+               be written a string representing a non-negative integer that
+               will be used as the amount of memory to reserve for allocations
+               made by device drivers' "freeze" callbacks, in bytes.
+
+               Reading from this file will display the current value, which is
+               set to 1 MB by default.

diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index 50aae660174d6bd0b0697b6a70e4e31b2e1535f3..431721313b71fa44bbbbc7b6c291562076252c1e 100644 (file)
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -982,10 +982,33 @@ static ssize_t image_size_store(struct kobject *kobj, struct kobj_attribute *att
 
 power_attr(image_size);
 
+static ssize_t reserved_size_show(struct kobject *kobj,
+                                 struct kobj_attribute *attr, char *buf)
+{
+       return sprintf(buf, "%lu\n", reserved_size);
+}
+
+static ssize_t reserved_size_store(struct kobject *kobj,
+                                  struct kobj_attribute *attr,
+                                  const char *buf, size_t n)
+{
+       unsigned long size;
+
+       if (sscanf(buf, "%lu", &size) == 1) {
+               reserved_size = size;
+               return n;
+       }
+
+       return -EINVAL;
+}
+
+power_attr(reserved_size);
+
 static struct attribute * g[] = {
        &disk_attr.attr,
        &resume_attr.attr,
        &image_size_attr.attr,
+       &reserved_size_attr.attr,
        NULL,
 };
 

diff --git a/kernel/power/main.c b/kernel/power/main.c
index de9aef8742f400df8f8cd696e6c977565fe21917..2981af4ce7cbbce49314e2fb2fef9fa13496f41e 100644 (file)
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -337,6 +337,7 @@ static int __init pm_init(void)
        if (error)
                return error;
        hibernate_image_size_init();
+       hibernate_reserved_size_init();
        power_kobj = kobject_create_and_add("power", NULL);
        if (!power_kobj)
                return -ENOMEM;

diff --git a/kernel/power/power.h b/kernel/power/power.h
index 03634be55f62aabb407b8797d6a5a74ca6feef96..9a00a0a262806b11905a84fb85c5a26c7e99592b 100644 (file)
--- a/kernel/power/power.h
+++ b/kernel/power/power.h
@@ -15,6 +15,7 @@ struct swsusp_info {
 
 #ifdef CONFIG_HIBERNATION
 /* kernel/power/snapshot.c */
+extern void __init hibernate_reserved_size_init(void);
 extern void __init hibernate_image_size_init(void);
 
 #ifdef CONFIG_ARCH_HIBERNATION_HEADER
@@ -55,6 +56,7 @@ extern int hibernation_platform_enter(void);
 
 #else /* !CONFIG_HIBERNATION */
 
+static inline void hibernate_reserved_size_init(void) {}
 static inline void hibernate_image_size_init(void) {}
 #endif /* !CONFIG_HIBERNATION */
 
@@ -72,6 +74,8 @@ static struct kobj_attribute _name##_attr = { \
 
 /* Preferred image size in bytes (default 500 MB) */
 extern unsigned long image_size;
+/* Size of memory reserved for drivers (default SPARE_PAGES x PAGE_SIZE) */
+extern unsigned long reserved_size;
 extern int in_suspend;
 extern dev_t swsusp_resume_device;
 extern sector_t swsusp_resume_block;

diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index ca0aacc2487426522df9b9cf71297a61d9faa0b1..d69e3323a85dac1c15adf5d0a0a1ad4c9132aa76 100644 (file)
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -40,6 +40,18 @@ static int swsusp_page_is_free(struct page *);
 static void swsusp_set_page_forbidden(struct page *);
 static void swsusp_unset_page_forbidden(struct page *);
 
+/*
+ * Number of bytes to reserve for memory allocations made by device drivers
+ * from their ->freeze() and ->freeze_noirq() callbacks so that they don't
+ * cause image creation to fail (tunable via /sys/power/reserved_size).
+ */
+unsigned long reserved_size;
+
+void __init hibernate_reserved_size_init(void)
+{
+       reserved_size = SPARE_PAGES * PAGE_SIZE;
+}
+
 /*
  * Preferred image size in bytes (tunable via /sys/power/image_size).
  * When it is set to N, the image creating code will do its best to
@@ -1263,11 +1275,13 @@ static unsigned long minimum_image_size(unsigned long saveable)
  * frame in use.  We also need a number of page frames to be free during
  * hibernation for allocations made while saving the image and for device
  * drivers, in case they need to allocate memory from their hibernation
- * callbacks (these two numbers are given by PAGES_FOR_IO and SPARE_PAGES,
- * respectively, both of which are rough estimates).  To make this happen, we
- * compute the total number of available page frames and allocate at least
+ * callbacks (these two numbers are given by PAGES_FOR_IO (which is a rough
+ * estimate) and reserverd_size divided by PAGE_SIZE (which is tunable through
+ * /sys/power/reserved_size, respectively).  To make this happen, we compute the
+ * total number of available page frames and allocate at least
  *
- * ([page frames total] + PAGES_FOR_IO + [metadata pages]) / 2 + 2 * SPARE_PAGES
+ * ([page frames total] + PAGES_FOR_IO + [metadata pages]) / 2
+ *  + 2 * DIV_ROUND_UP(reserved_size, PAGE_SIZE)
  *
  * of them, which corresponds to the maximum size of a hibernation image.
  *
@@ -1322,7 +1336,8 @@ int hibernate_preallocate_memory(void)
        count -= totalreserve_pages;
 
        /* Compute the maximum number of saveable pages to leave in memory. */
-       max_size = (count - (size + PAGES_FOR_IO)) / 2 - 2 * SPARE_PAGES;
+       max_size = (count - (size + PAGES_FOR_IO)) / 2
+                       - 2 * DIV_ROUND_UP(reserved_size, PAGE_SIZE);
        /* Compute the desired number of image pages specified by image_size. */
        size = DIV_ROUND_UP(image_size, PAGE_SIZE);
        if (size > max_size)