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Message-Id: <1588812129-8596-4-git-send-email-anthony.yznaga@oracle.com>
Date: Wed, 6 May 2020 17:41:29 -0700
From: Anthony Yznaga <anthony.yznaga@...cle.com>
To: linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc: willy@...radead.org, corbet@....net, tglx@...utronix.de,
mingo@...hat.com, bp@...en8.de, x86@...nel.org, hpa@...or.com,
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Subject: [RFC 03/43] mm: PKRAM: implement object load and save functions
PKRAM nodes are further divided into a list of objects. After a save
operation has been initiated for a node, a save operation for an object
associated with the node is initiated by calling pkram_prepare_save_obj().
A new object is created and linked to the node. The save operation for
the object is committed by calling pkram_finish_save_obj(). After a load
operation has been initiated, pkram_prepare_load_obj() is called to
delete the next object from the node and prepare the corresponding
stream for loading data from it. After the load of object has been
finished, pkram_finish_load_obj() is called to free the object. Objects
are also deleted when a save operation is discarded.
Signed-off-by: Anthony Yznaga <anthony.yznaga@...cle.com>
---
include/linux/pkram.h | 1 +
mm/pkram.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++++---
2 files changed, 74 insertions(+), 4 deletions(-)
diff --git a/include/linux/pkram.h b/include/linux/pkram.h
index 83a0579e4c1c..fabde2cd8203 100644
--- a/include/linux/pkram.h
+++ b/include/linux/pkram.h
@@ -11,6 +11,7 @@ struct pkram_node;
struct pkram_stream {
gfp_t gfp_mask;
struct pkram_node *node;
+ struct pkram_obj *obj;
};
#define PKRAM_NAME_MAX 256 /* including nul */
diff --git a/mm/pkram.c b/mm/pkram.c
index 5c57126353ff..4934ffd8b019 100644
--- a/mm/pkram.c
+++ b/mm/pkram.c
@@ -6,9 +6,14 @@
#include <linux/mm.h>
#include <linux/mutex.h>
#include <linux/pkram.h>
+#include <linux/sched.h>
#include <linux/string.h>
#include <linux/types.h>
+struct pkram_obj {
+ __u64 obj_pfn; /* points to the next object in the list */
+};
+
/*
* Preserved memory is divided into nodes that can be saved or loaded
* independently of each other. The nodes are identified by unique name
@@ -18,6 +23,7 @@
*/
struct pkram_node {
__u32 flags;
+ __u64 obj_pfn; /* points to the first obj of the node */
__u8 name[PKRAM_NAME_MAX];
};
@@ -62,6 +68,21 @@ static struct pkram_node *pkram_find_node(const char *name)
return NULL;
}
+static void pkram_truncate_node(struct pkram_node *node)
+{
+ unsigned long obj_pfn;
+ struct pkram_obj *obj;
+
+ obj_pfn = node->obj_pfn;
+ while (obj_pfn) {
+ obj = pfn_to_kaddr(obj_pfn);
+ obj_pfn = obj->obj_pfn;
+ pkram_free_page(obj);
+ cond_resched();
+ }
+ node->obj_pfn = 0;
+}
+
static void pkram_stream_init(struct pkram_stream *ps,
struct pkram_node *node, gfp_t gfp_mask)
{
@@ -70,6 +91,11 @@ static void pkram_stream_init(struct pkram_stream *ps,
ps->node = node;
}
+static void pkram_stream_init_obj(struct pkram_stream *ps, struct pkram_obj *obj)
+{
+ ps->obj = obj;
+}
+
/**
* Create a preserved memory node with name @name and initialize stream @ps
* for saving data to it.
@@ -124,12 +150,31 @@ int pkram_prepare_save(struct pkram_stream *ps, const char *name, gfp_t gfp_mask
*
* Returns 0 on success, -errno on failure.
*
+ * Error values:
+ * %ENOMEM: insufficient memory available
+ *
* After the save has finished, pkram_finish_save_obj() (or pkram_discard_save()
* in case of failure) is to be called.
*/
int pkram_prepare_save_obj(struct pkram_stream *ps)
{
- return -ENOSYS;
+ struct pkram_node *node = ps->node;
+ struct pkram_obj *obj;
+ struct page *page;
+
+ BUG_ON((node->flags & PKRAM_ACCMODE_MASK) != PKRAM_SAVE);
+
+ page = pkram_alloc_page(GFP_KERNEL | __GFP_ZERO);
+ if (!page)
+ return -ENOMEM;
+ obj = page_address(page);
+
+ if (node->obj_pfn)
+ obj->obj_pfn = node->obj_pfn;
+ node->obj_pfn = page_to_pfn(page);
+
+ pkram_stream_init_obj(ps, obj);
+ return 0;
}
/**
@@ -137,7 +182,9 @@ int pkram_prepare_save_obj(struct pkram_stream *ps)
*/
void pkram_finish_save_obj(struct pkram_stream *ps)
{
- BUG();
+ struct pkram_node *node = ps->node;
+
+ BUG_ON((node->flags & PKRAM_ACCMODE_MASK) != PKRAM_SAVE);
}
/**
@@ -169,6 +216,7 @@ void pkram_discard_save(struct pkram_stream *ps)
pkram_delete_node(node);
mutex_unlock(&pkram_mutex);
+ pkram_truncate_node(node);
pkram_free_page(node);
}
@@ -216,11 +264,26 @@ int pkram_prepare_load(struct pkram_stream *ps, const char *name)
*
* Returns 0 on success, -errno on failure.
*
+ * Error values:
+ * %ENODATA: Stream @ps has no preserved memory objects
+ *
* After the load has finished, pkram_finish_load_obj() is to be called.
*/
int pkram_prepare_load_obj(struct pkram_stream *ps)
{
- return -ENOSYS;
+ struct pkram_node *node = ps->node;
+ struct pkram_obj *obj;
+
+ BUG_ON((node->flags & PKRAM_ACCMODE_MASK) != PKRAM_LOAD);
+
+ if (!node->obj_pfn)
+ return -ENODATA;
+
+ obj = pfn_to_kaddr(node->obj_pfn);
+ node->obj_pfn = obj->obj_pfn;
+
+ pkram_stream_init_obj(ps, obj);
+ return 0;
}
/**
@@ -230,7 +293,12 @@ int pkram_prepare_load_obj(struct pkram_stream *ps)
*/
void pkram_finish_load_obj(struct pkram_stream *ps)
{
- BUG();
+ struct pkram_node *node = ps->node;
+ struct pkram_obj *obj = ps->obj;
+
+ BUG_ON((node->flags & PKRAM_ACCMODE_MASK) != PKRAM_LOAD);
+
+ pkram_free_page(obj);
}
/**
@@ -244,6 +312,7 @@ void pkram_finish_load(struct pkram_stream *ps)
BUG_ON((node->flags & PKRAM_ACCMODE_MASK) != PKRAM_LOAD);
+ pkram_truncate_node(node);
pkram_free_page(node);
}
--
2.13.3
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