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From: Anthony Yznaga <anthony.yznaga@oracle.com>
To: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: willy@infradead.org, corbet@lwn.net, tglx@linutronix.de,
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	kexec@lists.infradead.org
Subject: [RFC 07/43] mm: PKRAM: link nodes by pfn before reboot
Date: Wed,  6 May 2020 17:41:33 -0700	[thread overview]
Message-ID: <1588812129-8596-8-git-send-email-anthony.yznaga@oracle.com> (raw)
In-Reply-To: <1588812129-8596-1-git-send-email-anthony.yznaga@oracle.com>

Since page structs are used for linking PKRAM nodes and cleared
on boot, organize all PKRAM nodes into a list singly-linked by pfns
before reboot to facilitate the node list restore in the new kernel.

Originally-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
---
 mm/pkram.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)

diff --git a/mm/pkram.c b/mm/pkram.c
index 06b471eea0b0..44fadb70acf6 100644
--- a/mm/pkram.c
+++ b/mm/pkram.c
@@ -2,12 +2,16 @@
 #include <linux/err.h>
 #include <linux/gfp.h>
 #include <linux/highmem.h>
+#include <linux/init.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
 #include <linux/list.h>
 #include <linux/mm.h>
+#include <linux/module.h>
 #include <linux/mutex.h>
+#include <linux/notifier.h>
 #include <linux/pkram.h>
+#include <linux/reboot.h>
 #include <linux/sched.h>
 #include <linux/string.h>
 #include <linux/types.h>
@@ -58,11 +62,15 @@ struct pkram_obj {
  * singly-linked list of PKRAM link structures (see above), the node has a
  * pointer to the head of.
  *
+ * To facilitate data restore in the new kernel, before reboot all PKRAM nodes
+ * are organized into a list singly-linked by pfn's (see pkram_reboot()).
+ *
  * The structure occupies a memory page.
  */
 struct pkram_node {
 	__u32	flags;
 	__u64	obj_pfn;	/* points to the first obj of the node */
+	__u64	node_pfn;	/* points to the next node in the node list */
 
 	__u8	name[PKRAM_NAME_MAX];
 };
@@ -71,6 +79,10 @@ struct pkram_node {
 #define PKRAM_LOAD		2
 #define PKRAM_ACCMODE_MASK	3
 
+/*
+ * For convenience sake PKRAM nodes are kept in an auxiliary doubly-linked list
+ * connected through the lru field of the page struct.
+ */
 static LIST_HEAD(pkram_nodes);			/* linked through page::lru */
 static DEFINE_MUTEX(pkram_mutex);		/* serializes open/close */
 
@@ -679,3 +691,41 @@ size_t pkram_read(struct pkram_stream *ps, void *buf, size_t count)
 
 	return copy_count;
 }
+
+/*
+ * Build the list of PKRAM nodes.
+ */
+static void __pkram_reboot(void)
+{
+	struct page *page;
+	struct pkram_node *node;
+	unsigned long node_pfn = 0;
+
+	list_for_each_entry_reverse(page, &pkram_nodes, lru) {
+		node = page_address(page);
+		if (WARN_ON(node->flags & PKRAM_ACCMODE_MASK))
+			continue;
+		node->node_pfn = node_pfn;
+		node_pfn = page_to_pfn(page);
+	}
+}
+
+static int pkram_reboot(struct notifier_block *notifier,
+		       unsigned long val, void *v)
+{
+	if (val != SYS_RESTART)
+		return NOTIFY_DONE;
+	__pkram_reboot();
+	return NOTIFY_OK;
+}
+
+static struct notifier_block pkram_reboot_notifier = {
+	.notifier_call = pkram_reboot,
+};
+
+static int __init pkram_init(void)
+{
+	register_reboot_notifier(&pkram_reboot_notifier);
+	return 0;
+}
+module_init(pkram_init);
-- 
2.13.3


  parent reply	other threads:[~2020-05-07  0:44 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-07  0:41 [RFC 00/43] PKRAM: Preserved-over-Kexec RAM Anthony Yznaga
2020-05-07  0:41 ` [RFC 01/43] mm: add PKRAM API stubs and Kconfig Anthony Yznaga
2020-05-07  0:41 ` [RFC 02/43] mm: PKRAM: implement node load and save functions Anthony Yznaga
2020-05-07  0:41 ` [RFC 03/43] mm: PKRAM: implement object " Anthony Yznaga
2020-05-07  0:41 ` [RFC 04/43] mm: PKRAM: implement page stream operations Anthony Yznaga
2020-05-07  0:41 ` [RFC 05/43] mm: PKRAM: support preserving transparent hugepages Anthony Yznaga
2020-05-07  0:41 ` [RFC 06/43] mm: PKRAM: implement byte stream operations Anthony Yznaga
2020-05-07  0:41 ` Anthony Yznaga [this message]
2020-05-07  0:41 ` [RFC 08/43] mm: PKRAM: introduce super block Anthony Yznaga
2020-05-07  0:41 ` [RFC 09/43] PKRAM: build a physical mapping pagetable of pages to be preserved Anthony Yznaga
2020-05-07  0:41 ` [RFC 10/43] PKRAM: add code for walking the preserved pages pagetable Anthony Yznaga
2020-05-07  0:41 ` [RFC 11/43] PKRAM: pass the preserved pages pagetable to the next kernel Anthony Yznaga
2020-05-07  0:41 ` [RFC 12/43] mm: PKRAM: reserve preserved memory at boot Anthony Yznaga
2020-05-07  0:41 ` [RFC 13/43] mm: PKRAM: free preserved pages pagetable Anthony Yznaga
2020-05-07  0:41 ` [RFC 14/43] mm: memblock: PKRAM: prevent memblock resize from clobbering preserved pages Anthony Yznaga
2020-05-11 13:57   ` Mike Rapoport
2020-05-11 23:29     ` Anthony Yznaga
2020-05-07  0:41 ` [RFC 15/43] PKRAM: provide a way to ban pages from use by PKRAM Anthony Yznaga
2020-05-07  0:41 ` [RFC 16/43] kexec: PKRAM: prevent kexec clobbering preserved pages in some cases Anthony Yznaga
2020-05-07  0:41 ` [RFC 17/43] PKRAM: provide a way to check if a memory range has preserved pages Anthony Yznaga
2020-05-07  0:41 ` [RFC 18/43] kexec: PKRAM: avoid clobbering already " Anthony Yznaga
2020-05-07  0:41 ` [RFC 19/43] mm: PKRAM: allow preserved memory to be freed from userspace Anthony Yznaga
2020-05-07  0:41 ` [RFC 20/43] PKRAM: disable feature when running the kdump kernel Anthony Yznaga
2020-05-07  0:41 ` [RFC 21/43] x86/KASLR: PKRAM: support physical kaslr Anthony Yznaga
2020-05-07 17:51   ` Kees Cook
2020-05-07 18:41     ` Anthony Yznaga
2020-05-07  0:41 ` [RFC 22/43] mm: shmem: introduce shmem_insert_page Anthony Yznaga
2020-05-07  0:41 ` [RFC 23/43] mm: shmem: enable saving to PKRAM Anthony Yznaga
2020-05-07  0:41 ` [RFC 24/43] mm: shmem: prevent swapping of PKRAM-enabled tmpfs pages Anthony Yznaga
2020-05-07  0:41 ` [RFC 25/43] mm: shmem: specify the mm to use when inserting pages Anthony Yznaga
2020-05-07  0:41 ` [RFC 26/43] mm: shmem: when inserting, handle pages already charged to a memcg Anthony Yznaga
2020-05-07  0:41 ` [RFC 27/43] x86/mm/numa: add numa_isolate_memblocks() Anthony Yznaga
2020-05-07  0:41 ` [RFC 28/43] PKRAM: ensure memblocks with preserved pages init'd for numa Anthony Yznaga
2020-05-07  0:41 ` [RFC 29/43] memblock: PKRAM: mark memblocks that contain preserved pages Anthony Yznaga
2020-05-07  0:41 ` [RFC 30/43] memblock: add for_each_reserved_mem_range() Anthony Yznaga
2020-05-07  0:41 ` [RFC 31/43] memblock, mm: defer initialization of preserved pages Anthony Yznaga
2020-05-07  0:41 ` [RFC 32/43] shmem: PKRAM: preserve shmem files a chunk at a time Anthony Yznaga
2020-05-07  0:41 ` [RFC 33/43] PKRAM: atomically add and remove link pages Anthony Yznaga
2020-05-07  0:42 ` [RFC 34/43] shmem: PKRAM: multithread preserving and restoring shmem pages Anthony Yznaga
2020-05-07 16:30   ` Randy Dunlap
2020-05-07 17:59     ` Anthony Yznaga
2020-05-07  0:42 ` [RFC 35/43] shmem: introduce shmem_insert_pages() Anthony Yznaga
2020-05-07  0:42 ` [RFC 36/43] PKRAM: add support for loading pages in bulk Anthony Yznaga
2020-05-07  0:42 ` [RFC 37/43] shmem: PKRAM: enable bulk loading of preserved pages into shmem Anthony Yznaga
2020-05-07  0:42 ` [RFC 38/43] mm: implement splicing a list of pages to the LRU Anthony Yznaga
2020-05-07  0:42 ` [RFC 39/43] shmem: optimize adding pages to the LRU in shmem_insert_pages() Anthony Yznaga
2020-05-07  0:42 ` [RFC 40/43] shmem: initial support for adding multiple pages to pagecache Anthony Yznaga
2020-05-07  0:42 ` [RFC 41/43] XArray: add xas_export_node() and xas_import_node() Anthony Yznaga
2020-05-07  0:42 ` [RFC 42/43] shmem: reduce time holding xa_lock when inserting pages Anthony Yznaga
2020-05-07  0:42 ` [RFC 43/43] PKRAM: improve index alignment of pkram_link entries Anthony Yznaga

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