On Thursday, May 14, 2015 04:19:46 PM Anisse Astier wrote:
> SANITIZE_FREED_PAGES feature relies on having all pages going through
> the free_pages_prepare path in order to be cleared before being used. In
> the hibernate use case, free pages will automagically appear in the
> system without being cleared, left there by the loading kernel.
>
> This patch will make sure free pages are cleared on resume; when we'll
> enable SANITIZE_FREED_PAGES. We free the pages just after resume because
> we can't do it later: going through any device resume code might
> allocate some memory and invalidate the free pages bitmap.
>
> Signed-off-by: Anisse Astier <anisse@xxxxxxxxx>
> ---
> kernel/power/hibernate.c | 4 +++-
> kernel/power/power.h | 2 ++
> kernel/power/snapshot.c | 22 ++++++++++++++++++++++
> 3 files changed, 27 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
> index 2329daa..0a73126 100644
> --- a/kernel/power/hibernate.c
> +++ b/kernel/power/hibernate.c
> @@ -305,9 +305,11 @@ static int create_image(int platform_mode)
> error);
> /* Restore control flow magically appears here */
> restore_processor_state();
> - if (!in_suspend)
> + if (!in_suspend) {
> events_check_enabled = false;
>
> + clear_free_pages();
Again, why don't you do that at the swsusp_free() time?
> + }
> platform_leave(platform_mode);
>
> Power_up:
> diff --git a/kernel/power/power.h b/kernel/power/power.h
> index ce9b832..6d2d7bf 100644
> --- a/kernel/power/power.h
> +++ b/kernel/power/power.h
> @@ -92,6 +92,8 @@ 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);
> +
> /**
> * Auxiliary structure used for reading the snapshot image data and
> * metadata from and writing them to the list of page backup entries
> diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
> index 5235dd4..2335130 100644
> --- a/kernel/power/snapshot.c
> +++ b/kernel/power/snapshot.c
> @@ -1032,6 +1032,28 @@ void free_basic_memory_bitmaps(void)
> pr_debug("PM: Basic memory bitmaps freed\n");
> }
>
> +void clear_free_pages(void)
> +{
> +#ifdef CONFIG_SANITIZE_FREED_PAGES
> + struct memory_bitmap *bm = free_pages_map;
> + unsigned long pfn;
> +
> + if (WARN_ON(!(free_pages_map)))
One paren too many.
> + return;
> +
> + 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));
Is clear_highpage() also fine for non-highmem pages?
> +
> + pfn = memory_bm_next_pfn(bm);
> + }
> + memory_bm_position_reset(bm);
> + printk(KERN_INFO "PM: free pages cleared after restore\n");
> +#endif /* SANITIZE_FREED_PAGES */
> +}
> +
> /**
> * snapshot_additional_pages - estimate the number of additional pages
> * be needed for setting up the suspend image data structures for given
>
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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