From: David Hildenbrand <david@redhat.com>
To: Vlastimil Babka <vbabka@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Alexander Potapenko <glider@google.com>,
Kees Cook <keescook@chromium.org>,
Michal Hocko <mhocko@kernel.org>,
Mateusz Nosek <mateusznosek0@gmail.com>,
Laura Abbott <labbott@kernel.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Len Brown <len.brown@intel.com>, Pavel Machek <pavel@ucw.cz>,
linux-pm@vger.kernel.org
Subject: Re: [PATCH v2 3/5] kernel/power: allow hibernation with page_poison sanity checking
Date: Wed, 11 Nov 2020 16:42:45 +0100 [thread overview]
Message-ID: <eba10537-98c0-5363-8ff6-c0e71b823e50@redhat.com> (raw)
In-Reply-To: <20201103152237.9853-4-vbabka@suse.cz>
On 03.11.20 16:22, Vlastimil Babka 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@suse.cz>
> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> Cc: Len Brown <len.brown@intel.com>
> Cc: Pavel Machek <pavel@ucw.cz>
> Cc: <linux-pm@vger.kernel.org>
> ---
> 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);
^ 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)
> + 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
>
Unless I am missing something important, this should work! Thanks!
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2020-11-11 15:42 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-03 15:22 [PATCH v2 0/5] cleanup page poisoning Vlastimil Babka
2020-11-03 15:22 ` [PATCH v2 1/5] mm, page_alloc: do not rely on the order of page_poison and init_on_alloc/free parameters Vlastimil Babka
2020-11-03 15:22 ` [PATCH v2 2/5] mm, page_poison: use static key more efficiently Vlastimil Babka
2020-11-11 15:38 ` David Hildenbrand
2020-11-12 14:37 ` Vlastimil Babka
2020-11-12 16:06 ` David Hildenbrand
2020-11-03 15:22 ` [PATCH v2 3/5] kernel/power: allow hibernation with page_poison sanity checking Vlastimil Babka
2020-11-05 18:36 ` Rafael J. Wysocki
2020-11-11 15:42 ` David Hildenbrand [this message]
2020-11-12 14:39 ` Vlastimil Babka
2020-11-12 15:52 ` Rafael J. Wysocki
2020-11-12 16:07 ` David Hildenbrand
2020-11-03 15:22 ` [PATCH v2 4/5] mm, page_poison: remove CONFIG_PAGE_POISONING_NO_SANITY Vlastimil Babka
2020-11-11 15:43 ` David Hildenbrand
2020-11-03 15:22 ` [PATCH v2 5/5] mm, page_poison: remove CONFIG_PAGE_POISONING_ZERO Vlastimil Babka
2020-11-11 15:45 ` David Hildenbrand
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