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Date: Sat, 16 May 2015 02:28:22 +0200 From: "Rafael J. Wysocki" <rjw@...ysocki.net> To: Anisse Astier <anisse@...ier.eu> Cc: Andrew Morton <akpm@...ux-foundation.org>, Mel Gorman <mgorman@...e.de>, "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>, David Rientjes <rientjes@...gle.com>, Alan Cox <gnomes@...rguk.ukuu.org.uk>, Linus Torvalds <torvalds@...ux-foundation.org>, Peter Zijlstra <peterz@...radead.org>, PaX Team <pageexec@...email.hu>, Brad Spengler <spender@...ecurity.net>, Kees Cook <keescook@...omium.org>, Andi Kleen <andi@...stfloor.org>, Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>, linux-mm@...ck.org, linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH v4 1/3] PM / Hibernate: prepare for SANITIZE_FREED_PAGES 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@...ier.eu> > --- > 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. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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