When the machine doesn't well handle the e820 persistent when hibernate
resuming, then it may cause page fault when writing image to snapshot
buffer:

[   17.929495] BUG: unable to handle kernel paging request at ffff880069d4f000
[   17.933469] IP: [<ffffffff810a1cf0>] load_image_lzo+0x810/0xe40
[   17.933469] PGD 2194067 PUD 77ffff067 PMD 2197067 PTE 0
[   17.933469] Oops: 0002 [#1] SMP
...

The ffff880069d4f000 page is in e820 reserved region of resume boot
kernel:

[    0.000000] BIOS-e820: [mem 0x0000000069d4f000-0x0000000069e12fff] reserved
...
[    0.000000] PM: Registered nosave memory: [mem 0x69d4f000-0x69e12fff]

So snapshot.c mark the pfn to forbidden pages map. But, this
page is also in the memory bitmap in snapshot image because it's an
original page used by image kernel, so it will also mark as an
unsafe(free) page in prepare_image().

That means the page in e820 when resuming mark as "forbidden" and
"free", it causes get_buffer() treat it as an allocated unsafe page.
Then snapshot_write_next() return this page to load_image, load_image
writing content to this address, but this page didn't really allocated
. So, we got page fault.

Although the root cause is from BIOS, I think aggressive check and
significant message in kernel will better then a page fault for
issue tracking, especially when serial console unavailable.

This patch adds code in mark_unsafe_pages() for check does free pages in
nosave region. If so, then it print message and return fault to stop whole
S4 resume process:

[    8.166004] PM: Image loading progress:   0%
[    8.658717] PM: 0x6796c000 in e820 nosave region: [mem 0x6796c000-0x6796cfff]
[    8.918737] PM: Read 2511940 kbytes in 1.04 seconds (2415.32 MB/s)
[    8.926633] PM: Error -14 resuming
[    8.933534] PM: Failed to load hibernation image, recovering.

Reviewed-by: Takashi Iwai <tiwai@suse.de>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Lee, Chun-Yi <jlee@suse.com>
[rjw: Subject]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

When a memory bitmap is fully populated on a large memory
machine (several TB of RAM) it can take more than a minute
to walk through all bits. This causes the soft lockup
detector on these machine to report warnings.

Avoid this by touching the soft lockup watchdog in the
memory bitmap walking code.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

The radix tree implementatio is proved to work the same as
the old implementation now. So the old implementation can be
removed to finish the switch to the radix tree for the
memory bitmaps.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

The existing implementation of swsusp_free iterates over all
pfns in the system and checks every bit in the two memory
bitmaps.

This doesn't scale very well with large numbers of pfns,
especially when the bitmaps are not populated very densly.
Change the algorithm to iterate over the set bits in the
bitmaps instead to make it scale better in large memory
configurations.

Also add a memory_bm_clear_current() helper function that
clears the bit for the last position returned from the
memory bitmap.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Add code to remember the last position that was requested in
the radix tree. Use it as a cache for faster linear walking
of the bitmap in the memory_bm_rtree_next_pfn() function
which is also added with this patch.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Add a function to find a bit in the radix tree for a given
pfn. Also add code to the memory bitmap wrapper functions to
use the radix tree together with the existing memory bitmap
implementation.

On read accesses compare the results of both bitmaps to make
sure the radix tree behaves the same way.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

This patch adds the code to allocate and build the radix
tree to store the memory bitmap. The old data structure is
left in place until the radix tree implementation is
finished.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

As requested by Linus add explicit __visible to the asmlinkage users.
This marks functions visible to assembler.

Tree sweep for rest of tree.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Link: http://lkml.kernel.org/r/1398984278-29319-4-git-send-email-andi@firstfloor.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

To increase compiler portability there is <linux/compiler.h> which
provides convenience macros for various gcc constructs.  Eg: __weak for
__attribute__((weak)).  I've replaced all instances of gcc attributes
with the right macro in the kernel subsystem.

Signed-off-by: Gideon Israel Dsouza <gidisrael@gmail.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Spelling fix.

Signed-off-by: Geert Uytterhoeven <geert+renesas@linux-m68k.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>