[PATCH] PM / hibernate: Simplify mark_unsafe_pages()

From: Rafael J. Wysocki
Date: Tue Jun 21 2016 - 21:17:59 EST


From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

Rework mark_unsafe_pages() to use a simpler method to clear
all bits in free_pages_map and to set the bits for the "unsafe"
pages (ie. pages that were used by the image kernel before
hibernation) with the help of duplicate_memory_bitmap().

For this purpose, move the pfn_valid() check from mark_unsafe_pages()
to unpack_orig_pfns() where the "unsafe" pages are discovered.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
---
kernel/power/snapshot.c | 53 +++++++++++++++++++-----------------------------
1 file changed, 22 insertions(+), 31 deletions(-)

Index: linux-pm/kernel/power/snapshot.c
===================================================================
--- linux-pm.orig/kernel/power/snapshot.c
+++ linux-pm/kernel/power/snapshot.c
@@ -2049,6 +2049,19 @@ int snapshot_read_next(struct snapshot_h
return PAGE_SIZE;
}

+static void duplicate_memory_bitmap(struct memory_bitmap *dst,
+ struct memory_bitmap *src)
+{
+ unsigned long pfn;
+
+ memory_bm_position_reset(src);
+ pfn = memory_bm_next_pfn(src);
+ while (pfn != BM_END_OF_MAP) {
+ memory_bm_set_bit(dst, pfn);
+ pfn = memory_bm_next_pfn(src);
+ }
+}
+
/**
* mark_unsafe_pages - mark the pages that cannot be used for storing
* the image during resume, because they conflict with the pages that
@@ -2060,44 +2073,22 @@ static int mark_unsafe_pages(struct memo
struct zone *zone;
unsigned long pfn, max_zone_pfn;

- /* Clear page flags */
- for_each_populated_zone(zone) {
- max_zone_pfn = zone_end_pfn(zone);
- for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
- if (pfn_valid(pfn))
- swsusp_unset_page_free(pfn_to_page(pfn));
+ /* Clear the "free"/"unsafe" bit for all PFNs */
+ memory_bm_position_reset(free_pages_map);
+ pfn = memory_bm_next_pfn(free_pages_map);
+ while (pfn != BM_END_OF_MAP) {
+ memory_bm_clear_current(free_pages_map);
+ pfn = memory_bm_next_pfn(free_pages_map);
}

- /* Mark pages that correspond to the "original" pfns as "unsafe" */
- memory_bm_position_reset(bm);
- do {
- pfn = memory_bm_next_pfn(bm);
- if (likely(pfn != BM_END_OF_MAP)) {
- if (likely(pfn_valid(pfn)))
- swsusp_set_page_free(pfn_to_page(pfn));
- else
- return -EFAULT;
- }
- } while (pfn != BM_END_OF_MAP);
+ /* Mark pages that correspond to the "original" PFNs as "unsafe" */
+ duplicate_memory_bitmap(free_pages_map, bm);

allocated_unsafe_pages = 0;

return 0;
}

-static void
-duplicate_memory_bitmap(struct memory_bitmap *dst, struct memory_bitmap *src)
-{
- unsigned long pfn;
-
- memory_bm_position_reset(src);
- pfn = memory_bm_next_pfn(src);
- while (pfn != BM_END_OF_MAP) {
- memory_bm_set_bit(dst, pfn);
- pfn = memory_bm_next_pfn(src);
- }
-}
-
static int check_header(struct swsusp_info *info)
{
char *reason;
@@ -2145,7 +2136,7 @@ static int unpack_orig_pfns(unsigned lon
/* Extract and buffer page key for data page (s390 only). */
page_key_memorize(buf + j);

- if (memory_bm_pfn_present(bm, buf[j]))
+ if (pfn_valid(buf[j]) && memory_bm_pfn_present(bm, buf[j]))
memory_bm_set_bit(bm, buf[j]);
else
return -EFAULT;