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Date: Wed, 26 Apr 2023 17:08:47 -0700
From: Anthony Yznaga <anthony.yznaga@...cle.com>
To: linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc: tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, x86@...nel.org,
hpa@...or.com, dave.hansen@...ux.intel.com, luto@...nel.org,
peterz@...radead.org, rppt@...nel.org, akpm@...ux-foundation.org,
ebiederm@...ssion.com, keescook@...omium.org, graf@...zon.com,
jason.zeng@...el.com, lei.l.li@...el.com,
steven.sistare@...cle.com, fam.zheng@...edance.com,
mgalaxy@...mai.com, kexec@...ts.infradead.org
Subject: [RFC v3 11/21] mm: PKRAM: reserve preserved memory at boot
Keep preserved pages from being recycled during boot by adding them
to the memblock reserved list during early boot. If memory reservation
fails (e.g. a region has already been reserved), all preserved pages
are dropped.
Signed-off-by: Anthony Yznaga <anthony.yznaga@...cle.com>
---
arch/x86/kernel/setup.c | 3 ++
arch/x86/mm/init_64.c | 2 ++
include/linux/pkram.h | 8 +++++
mm/pkram.c | 84 ++++++++++++++++++++++++++++++++++++++++++++++---
4 files changed, 92 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 16babff771bd..2806b21236d0 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -18,6 +18,7 @@
#include <linux/memblock.h>
#include <linux/panic_notifier.h>
#include <linux/pci.h>
+#include <linux/pkram.h>
#include <linux/root_dev.h>
#include <linux/hugetlb.h>
#include <linux/tboot.h>
@@ -1221,6 +1222,8 @@ void __init setup_arch(char **cmdline_p)
initmem_init();
dma_contiguous_reserve(max_pfn_mapped << PAGE_SHIFT);
+ pkram_reserve();
+
if (boot_cpu_has(X86_FEATURE_GBPAGES))
hugetlb_cma_reserve(PUD_SHIFT - PAGE_SHIFT);
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index a190aae8ceaf..a46ffb434f39 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -34,6 +34,7 @@
#include <linux/gfp.h>
#include <linux/kcore.h>
#include <linux/bootmem_info.h>
+#include <linux/pkram.h>
#include <asm/processor.h>
#include <asm/bios_ebda.h>
@@ -1339,6 +1340,7 @@ void __init mem_init(void)
after_bootmem = 1;
x86_init.hyper.init_after_bootmem();
+ totalram_pages_add(pkram_reserved_pages);
/*
* Must be done after boot memory is put on freelist, because here we
* might set fields in deferred struct pages that have not yet been
diff --git a/include/linux/pkram.h b/include/linux/pkram.h
index b614e9059bba..53d5a1ec42ff 100644
--- a/include/linux/pkram.h
+++ b/include/linux/pkram.h
@@ -99,4 +99,12 @@ int pkram_prepare_save(struct pkram_stream *ps, const char *name,
ssize_t pkram_write(struct pkram_access *pa, const void *buf, size_t count);
size_t pkram_read(struct pkram_access *pa, void *buf, size_t count);
+#ifdef CONFIG_PKRAM
+extern unsigned long pkram_reserved_pages;
+void pkram_reserve(void);
+#else
+#define pkram_reserved_pages 0UL
+static inline void pkram_reserve(void) { }
+#endif
+
#endif /* _LINUX_PKRAM_H */
diff --git a/mm/pkram.c b/mm/pkram.c
index c649504fa1fa..b711f94dbef4 100644
--- a/mm/pkram.c
+++ b/mm/pkram.c
@@ -134,6 +134,8 @@ extern void pkram_find_preserved(unsigned long start, unsigned long end, void *p
static LIST_HEAD(pkram_nodes); /* linked through page::lru */
static DEFINE_MUTEX(pkram_mutex); /* serializes open/close */
+unsigned long __initdata pkram_reserved_pages;
+
/*
* The PKRAM super block pfn, see above.
*/
@@ -143,6 +145,59 @@ static int __init parse_pkram_sb_pfn(char *arg)
}
early_param("pkram", parse_pkram_sb_pfn);
+static void * __init pkram_map_meta(unsigned long pfn)
+{
+ if (pfn >= max_low_pfn)
+ return ERR_PTR(-EINVAL);
+ return pfn_to_kaddr(pfn);
+}
+
+int pkram_merge_with_reserved(void);
+/*
+ * Reserve pages that belong to preserved memory.
+ *
+ * This function should be called at boot time as early as possible to prevent
+ * preserved memory from being recycled.
+ */
+void __init pkram_reserve(void)
+{
+ int err = 0;
+
+ if (!pkram_sb_pfn)
+ return;
+
+ pr_info("PKRAM: Examining preserved memory...\n");
+
+ /* Verify that nothing else has reserved the pkram_sb page */
+ if (memblock_is_region_reserved(PFN_PHYS(pkram_sb_pfn), PAGE_SIZE)) {
+ err = -EBUSY;
+ goto out;
+ }
+
+ pkram_sb = pkram_map_meta(pkram_sb_pfn);
+ if (IS_ERR(pkram_sb)) {
+ err = PTR_ERR(pkram_sb);
+ goto out;
+ }
+ /* An empty pkram_sb is not an error */
+ if (!pkram_sb->node_pfn) {
+ pkram_sb = NULL;
+ goto done;
+ }
+
+ err = pkram_merge_with_reserved();
+out:
+ if (err) {
+ pr_err("PKRAM: Reservation failed: %d\n", err);
+ WARN_ON(pkram_reserved_pages > 0);
+ pkram_sb = NULL;
+ return;
+ }
+
+done:
+ pr_info("PKRAM: %lu pages reserved\n", pkram_reserved_pages);
+}
+
static inline struct page *pkram_alloc_page(gfp_t gfp_mask)
{
struct page *page;
@@ -162,6 +217,7 @@ static inline struct page *pkram_alloc_page(gfp_t gfp_mask)
static inline void pkram_free_page(void *addr)
{
+ __ClearPageReserved(virt_to_page(addr));
pkram_remove_identity_map(virt_to_page(addr));
free_page((unsigned long)addr);
}
@@ -193,13 +249,23 @@ static void pkram_truncate_link(struct pkram_link *link)
{
struct page *page;
pkram_entry_t p;
- int i;
+ int i, j, order;
for (i = 0; i < PKRAM_LINK_ENTRIES_MAX; i++) {
p = link->entry[i];
if (!p)
continue;
+ order = p & PKRAM_ENTRY_ORDER_MASK;
+ if (order >= MAX_ORDER) {
+ pr_err("PKRAM: attempted truncate of invalid page\n");
+ return;
+ }
page = pfn_to_page(PHYS_PFN(p));
+ for (j = 0; j < (1 << order); j++) {
+ struct page *pg = page + j;
+
+ __ClearPageReserved(pg);
+ }
pkram_remove_identity_map(page);
put_page(page);
}
@@ -680,7 +746,7 @@ static int __pkram_bytes_save_page(struct pkram_access *pa, struct page *page)
static struct page *__pkram_prep_load_page(pkram_entry_t p)
{
struct page *page;
- int order;
+ int i, order;
short flags;
flags = (p >> PKRAM_ENTRY_FLAGS_SHIFT) & PKRAM_ENTRY_FLAGS_MASK;
@@ -690,9 +756,16 @@ static struct page *__pkram_prep_load_page(pkram_entry_t p)
page = pfn_to_page(PHYS_PFN(p));
- if (!page_ref_freeze(pg, 1)) {
- pr_err("PKRAM preserved page has unexpected inflated ref count\n");
- goto out_error;
+ for (i = 0; i < (1 << order); i++) {
+ struct page *pg = page + i;
+ int was_rsvd;
+
+ was_rsvd = PageReserved(pg);
+ __ClearPageReserved(pg);
+ if ((was_rsvd || i == 0) && !page_ref_freeze(pg, 1)) {
+ pr_err("PKRAM preserved page has unexpected inflated ref count\n");
+ goto out_error;
+ }
}
if (order) {
@@ -1331,6 +1404,7 @@ int __init pkram_create_merged_reserved(struct memblock_type *new)
}
WARN_ON(cnt_a + cnt_b != k);
+ pkram_reserved_pages = nr_preserved;
new->cnt = cnt_a + cnt_b;
new->total_size = total_size;
--
1.9.4
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