On Tue, Nov 3, 2020 at 4:24 PM Vlastimil Babka <vbabka@xxxxxxx> wrote:
>
> Page poisoning used to be incompatible with hibernation, as the state of
> poisoned pages was lost after resume, thus enabling CONFIG_HIBERNATION forces
> CONFIG_PAGE_POISONING_NO_SANITY. For the same reason, the poisoning with zeroes
> variant CONFIG_PAGE_POISONING_ZERO used to disable hibernation. The latter
> restriction was removed by commit 1ad1410f632d ("PM / Hibernate: allow
> hibernation with PAGE_POISONING_ZERO") and similarly for init_on_free by commit
> 18451f9f9e58 ("PM: hibernate: fix crashes with init_on_free=1") by making sure
> free pages are cleared after resume.
>
> We can use the same mechanism to instead poison free pages with PAGE_POISON
> after resume. This covers both zero and 0xAA patterns. Thus we can remove the
> Kconfig restriction that disables page poison sanity checking when hibernation
> is enabled.
>
> Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
> Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
> Cc: Len Brown <len.brown@xxxxxxxxx>
> Cc: Pavel Machek <pavel@xxxxxx>
> Cc: <linux-pm@xxxxxxxxxxxxxxx>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
for the hibernation part and I'm assuming that this patch will be
routed through the mm tree.
> ---
> kernel/power/hibernate.c | 2 +-
> kernel/power/power.h | 2 +-
> kernel/power/snapshot.c | 14 ++++++++++----
> mm/Kconfig.debug | 1 -
> 4 files changed, 12 insertions(+), 7 deletions(-)
>
> diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
> index 2fc7d509a34f..da0b41914177 100644
> --- a/kernel/power/hibernate.c
> +++ b/kernel/power/hibernate.c
> @@ -326,7 +326,7 @@ static int create_image(int platform_mode)
>
> if (!in_suspend) {
> events_check_enabled = false;
> - clear_free_pages();
> + clear_or_poison_free_pages();
> }
>
> platform_leave(platform_mode);
> diff --git a/kernel/power/power.h b/kernel/power/power.h
> index 24f12d534515..778bf431ec02 100644
> --- a/kernel/power/power.h
> +++ b/kernel/power/power.h
> @@ -106,7 +106,7 @@ extern int create_basic_memory_bitmaps(void);
> extern void free_basic_memory_bitmaps(void);
> extern int hibernate_preallocate_memory(void);
>
> -extern void clear_free_pages(void);
> +extern void clear_or_poison_free_pages(void);
>
> /**
> * Auxiliary structure used for reading the snapshot image data and
> diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
> index 46b1804c1ddf..6b1c84afa891 100644
> --- a/kernel/power/snapshot.c
> +++ b/kernel/power/snapshot.c
> @@ -1144,7 +1144,7 @@ void free_basic_memory_bitmaps(void)
> pr_debug("Basic memory bitmaps freed\n");
> }
>
> -void clear_free_pages(void)
> +void clear_or_poison_free_pages(void)
> {
> struct memory_bitmap *bm = free_pages_map;
> unsigned long pfn;
> @@ -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);
> + if (page_poisoning_enabled_static())
> + kernel_poison_pages(page, 1);
> + else if (want_init_on_free())
> + clear_highpage(page);
> +
> + }
>
> pfn = memory_bm_next_pfn(bm);
> }
> diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug
> index 864f129f1937..c57786ad5be9 100644
> --- a/mm/Kconfig.debug
> +++ b/mm/Kconfig.debug
> @@ -64,7 +64,6 @@ config PAGE_OWNER
>
> config PAGE_POISONING
> bool "Poison pages after freeing"
> - select PAGE_POISONING_NO_SANITY if HIBERNATION
> help
> Fill the pages with poison patterns after free_pages() and verify
> the patterns before alloc_pages. The filling of the memory helps
> --
> 2.29.1
>
