Re: [PATCH v2 3/5] kernel/power: allow hibernation with page_poison sanity checking

[Vlastimil Babka]

On 11/11/20 4:42 PM, David Hildenbrand wrote:
...
> > @@ -1152,12 +1152,18 @@ void clear_free_pages(void)
> >   	if (WARN_ON(!(free_pages_map)))
> >   		return;
> >   
> > -	if (IS_ENABLED(CONFIG_PAGE_POISONING_ZERO) || want_init_on_free()) {
> > +	if (page_poisoning_enabled() || want_init_on_free()) {
> >   		memory_bm_position_reset(bm);
> >   		pfn = memory_bm_next_pfn(bm);
> >   		while (pfn != BM_END_OF_MAP) {
> > -			if (pfn_valid(pfn))
> > -				clear_highpage(pfn_to_page(pfn));
> > +			if (pfn_valid(pfn)) {
> > +				struct page *page = pfn_to_page(pfn);
>
> ^ empty line missing. And at least I prefer to declare all variables in
> the function header.
>
> I'd even suggest to move this into a separate function like
>
> clear_or_poison_free_page(struct page *page)

Ok, fixup below.

----8<----
From cae1e8ccfa57c28ed1b2f5f8a47319b86cbdcfbf Mon Sep 17 00:00:00 2001
From: Vlastimil Babka <vbabka@xxxxxxx>
Date: Thu, 12 Nov 2020 15:33:07 +0100
Subject: [PATCH] kernel/power: allow hibernation with page_poison sanity
 checking-fix

Adapt to __kernel_unpoison_pages fixup. Split out clear_or_poison_free_page()
per David Hildenbrand.

Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
---
 include/linux/mm.h      |  1 +
 kernel/power/snapshot.c | 18 ++++++++++--------
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 861b9392b5dc..d4cfb06a611e 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2896,6 +2896,7 @@ static inline void kernel_unpoison_pages(struct page *page, int numpages)
 #else
 static inline bool page_poisoning_enabled(void) { return false; }
 static inline bool page_poisoning_enabled_static(void) { return false; }
+static inline void __kernel_poison_pages(struct page *page, int nunmpages) { }
 static inline void kernel_poison_pages(struct page *page, int numpages) { }
 static inline void kernel_unpoison_pages(struct page *page, int numpages) { }
 #endif
diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index 6b1c84afa891..a3491b29c5cc 100644
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -1144,6 +1144,14 @@ void free_basic_memory_bitmaps(void)
 	pr_debug("Basic memory bitmaps freed\n");
 }
 
+static void clear_or_poison_free_page(struct page *page)
+{
+	if (page_poisoning_enabled_static())
+		__kernel_poison_pages(page, 1);
+	else if (want_init_on_free())
+		clear_highpage(page);
+}
+
 void clear_or_poison_free_pages(void)
 {
 	struct memory_bitmap *bm = free_pages_map;
@@ -1156,14 +1164,8 @@ void clear_or_poison_free_pages(void)
 		memory_bm_position_reset(bm);
 		pfn = memory_bm_next_pfn(bm);
 		while (pfn != BM_END_OF_MAP) {
-			if (pfn_valid(pfn)) {
-				struct page *page = pfn_to_page(pfn);
-				if (page_poisoning_enabled_static())
-					kernel_poison_pages(page, 1);
-				else if (want_init_on_free())
-					clear_highpage(page);
-
-			}
+			if (pfn_valid(pfn))
+				clear_or_poison_free_page(pfn_to_page(pfn));
 
 			pfn = memory_bm_next_pfn(bm);
 		}
--
2.29.1