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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Subject: [RFC 06/43] mm: PKRAM: implement byte stream operations
Date: Wed, 6 May 2020 17:41:32 -0700 [thread overview]
Message-ID: <1588812129-8596-7-git-send-email-anthony.yznaga@oracle.com> (raw)
In-Reply-To: <1588812129-8596-1-git-send-email-anthony.yznaga@oracle.com>
This patch adds the ability to save arbitrary byte streams up to a
total length of one page to a PKRAM object using pkram_write() to be
restored later using pkram_read().
Originally-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
---
include/linux/pkram.h | 4 +++
mm/pkram.c | 84 +++++++++++++++++++++++++++++++++++++++++++++++++--
2 files changed, 86 insertions(+), 2 deletions(-)
diff --git a/include/linux/pkram.h b/include/linux/pkram.h
index 584cadb662b4..a58dd2ea835a 100644
--- a/include/linux/pkram.h
+++ b/include/linux/pkram.h
@@ -17,6 +17,10 @@ struct pkram_stream {
unsigned int entry_idx; /* next entry in link */
unsigned long next_index;
+
+ /* byte data */
+ struct page *data_page;
+ unsigned int data_offset;
};
#define PKRAM_NAME_MAX 256 /* including nul */
diff --git a/mm/pkram.c b/mm/pkram.c
index 9164060e36f5..06b471eea0b0 100644
--- a/mm/pkram.c
+++ b/mm/pkram.c
@@ -1,6 +1,7 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/err.h>
#include <linux/gfp.h>
+#include <linux/highmem.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/list.h>
@@ -42,6 +43,8 @@ struct pkram_link {
((PAGE_SIZE-sizeof(struct pkram_link))/sizeof(pkram_entry_t))
struct pkram_obj {
+ __u64 data_pfn; /* points to the byte data */
+ __u64 data_len; /* byte data size */
__u64 link_pfn; /* points to the first link of the object */
__u64 obj_pfn; /* points to the next object in the list */
};
@@ -407,6 +410,9 @@ void pkram_finish_load_obj(struct pkram_stream *ps)
}
}
+ if (ps->data_page)
+ pkram_free_page(page_address(ps->data_page));
+
pkram_truncate_obj(obj);
pkram_free_page(obj);
}
@@ -422,6 +428,9 @@ void pkram_finish_load(struct pkram_stream *ps)
BUG_ON((node->flags & PKRAM_ACCMODE_MASK) != PKRAM_LOAD);
+ if (ps->data_page)
+ put_page(ps->data_page);
+
pkram_truncate_node(node);
pkram_free_page(node);
}
@@ -581,10 +590,41 @@ struct page *pkram_load_page(struct pkram_stream *ps, unsigned long *index, shor
*
* On success, returns the number of bytes written, which is always equal to
* @count. On failure, -errno is returned.
+ *
+ * Error values:
+ * %ENOMEM: insufficient amount of memory available
*/
ssize_t pkram_write(struct pkram_stream *ps, const void *buf, size_t count)
{
- return -ENOSYS;
+ struct pkram_node *node = ps->node;
+ struct pkram_obj *obj = ps->obj;
+ void *addr;
+
+ BUG_ON((node->flags & PKRAM_ACCMODE_MASK) != PKRAM_SAVE);
+
+ if (!ps->data_page) {
+ struct page *page;
+
+ page = pkram_alloc_page((ps->gfp_mask & GFP_RECLAIM_MASK) |
+ __GFP_HIGHMEM | __GFP_ZERO);
+ if (!page)
+ return -ENOMEM;
+
+ ps->data_page = page;
+ ps->data_offset = 0;
+ obj->data_pfn = page_to_pfn(page);
+ }
+
+ BUG_ON(count > PAGE_SIZE - ps->data_offset);
+
+ addr = kmap_atomic(ps->data_page);
+ memcpy(addr + ps->data_offset, buf, count);
+ kunmap_atomic(addr);
+
+ obj->data_len += count;
+ ps->data_offset += count;
+
+ return count;
}
/**
@@ -597,5 +637,45 @@ ssize_t pkram_write(struct pkram_stream *ps, const void *buf, size_t count)
*/
size_t pkram_read(struct pkram_stream *ps, void *buf, size_t count)
{
- return 0;
+ struct pkram_node *node = ps->node;
+ struct pkram_obj *obj = ps->obj;
+ size_t copy_count;
+ char *addr;
+
+ BUG_ON((node->flags & PKRAM_ACCMODE_MASK) != PKRAM_LOAD);
+
+ if (!count || !obj->data_len)
+ return 0;
+
+ if (!ps->data_page) {
+ struct page *page;
+
+ page = pfn_to_page(obj->data_pfn);
+ if (!page)
+ return 0;
+
+ ps->data_page = page;
+ ps->data_offset = 0;
+ obj->data_pfn = 0;
+ }
+
+ BUG_ON(count > PAGE_SIZE - ps->data_offset);
+
+ copy_count = min_t(size_t, count, PAGE_SIZE - ps->data_offset);
+ if (copy_count > obj->data_len)
+ copy_count = obj->data_len;
+
+ addr = kmap_atomic(ps->data_page);
+ memcpy(buf, addr + ps->data_offset, copy_count);
+ kunmap_atomic(addr);
+
+ obj->data_len -= copy_count;
+ ps->data_offset += copy_count;
+
+ if (!obj->data_len) {
+ pkram_free_page(page_address(ps->data_page));
+ ps->data_page = NULL;
+ }
+
+ return copy_count;
}
--
2.13.3
next prev 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 ` Anthony Yznaga [this message]
2020-05-07 0:41 ` [RFC 07/43] mm: PKRAM: link nodes by pfn before reboot Anthony Yznaga
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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