partitions/efi: use lba-aware partition records

The kernel's GPT implementation currently uses the generic 'struct
partition' type for dealing with legacy MBR partition records.  While this
is is useful for disklabels that we designed for CHS addressing, such as
msdos, it doesn't adapt well to newer standards that use LBA instead, such
as GUID partition tables.  Furthermore, these generic partition structures
do not have all the required fields to properly follow the UEFI specs.

While a CHS address can be translated to LBA, it's much simpler and
cleaner to just replace the partition type.  This patch adds a new
'gpt_record' type that is fully compliant with EFI and will allow, in the
next patches, to add more checks to properly verify a protective MBR,
which is paramount to probing a device that makes use of GPT.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Reviewed-by: Karel Zak <kzak@redhat.com>
Acked-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
partitions/efi: check pmbr record's starting lba

Per the UEFI Specs 2.4, June 2013, the starting lba of the partition that
has the EFI GPT (0xEE) must be set to 0x00000001 - this is obviously the
LBA of the GPT Partition Header.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Reviewed-by: Karel Zak <kzak@redhat.com>
Acked-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
partitions/efi: do not require gpt partition to begin at sector 1

When detecting a valid protective MBR, the Linux kernel isn't picky about
the partition (1-4) the 0xEE is at, but, unlike other operating systems,
it does require it to begin at the second sector (sector 1).  This check,
apart from it not being enforced by UEFI, and causing Linux to potentially
fail to detect any *valid* partitions on the disk, can present problems
when dealing with hybrid MBRs[1].

For compatibility reasons, if the first partition is hybridized, the 0xEE
partition must be small enough to ensure that it only protects the GPT
data structures - as opposed to the the whole disk in a protective MBR.
This problem is very well described by Rod Smith[1]: where MBR-only
partitioning programs (such as older versions of fdisk) can see some of
the disk space as unallocated, thus loosing the purpose of the 0xEE
partition's protection of GPT data structures.

By dropping this check, this patch enables Linux to be more flexible when
probing for GPT disklabels.

[1] http://www.rodsbooks.com/gdisk/hybrid.html#reactions

Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Reviewed-by: Karel Zak <kzak@redhat.com>
Acked-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
partitions/efi: detect hybrid MBRs

One of the biggest problems with GPT is compatibility with older, non-GPT
systems.  The problem is addressed by creating hybrid mbrs, an extension,
or variant, of the traditional protective mbr.  This contains, apart from
the 0xEE partition, up three additional primary partitions that point to
the same space marked by up to three GPT partitions.  The result is that
legacy OSs can see the three required MBR partitions and at the same time
ignore the GPT-aware partitions that protect the GPT structures.

While hybrid MBRs are hacks, workarounds and simply not part of the GPT
standard, they do exist and we have no way around them.  For instance, by
default, OSX creates a hybrid scheme when using multi-OS booting.

In order for Linux to properly discover protective MBRs, it must be made
aware of devices that have hybrid MBRs.  No functionality is changed by
this patch, just a debug message informing the user of the MBR scheme that
is being used.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Reviewed-by: Karel Zak <kzak@redhat.com>
Acked-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
partitions/efi: account for pmbr size in lba

The partition that has the 0xEE (GPT protective), must have the size in
lba field set to the lesser of the size of the disk minus one or
0xFFFFFFFF for larger disks.

Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Reviewed-by: Karel Zak <kzak@redhat.com>
Acked-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
partitions/efi: compare first and last usable LBAs

When verifying GPT header integrity, make sure that first usable LBA is
smaller than last usable LBA.

Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Reviewed-by: Karel Zak <kzak@redhat.com>
Acked-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
partitions/efi: delete annoying emacs style comments

I love emacs, but these settings for coding style are annoying when trying
to open the efi.h file.  More important, we already have checkpatch for
that.

Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Reviewed-by: Karel Zak <kzak@redhat.com>
Acked-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
partitions/efi: some style cleanups

Trivial coding style cleanups - still plenty left.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Reviewed-by: Karel Zak <kzak@redhat.com>
Acked-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
block/partitions/efi.c: consistently use pr_foo()

Cc: Davidlohr Bueso <davidlohr@hp.com>
Cc: Karel Zak <kzak@redhat.com>
Cc: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
partitions/efi: loosen check fot pmbr size in lba

Matt found that commit 27a7c642174e ("partitions/efi: account for pmbr
size in lba") caused his GPT formatted eMMC device not to boot.  The
reason is that this commit enforced Linux to always check the lesser of
the whole disk or 2Tib for the pMBR size in LBA.  While most disk
partitioning tools out there create a pMBR with these characteristics,
Microsoft does not, as it always sets the entry to the maximum 32-bit
limitation - even though a drive may be smaller than that[1].

Loosen this check and only verify that the size is either the whole disk
or 0xFFFFFFFF.  No tool in its right mind would set it to any value
other than these.

[1] http://thestarman.pcministry.com/asm/mbr/GPT.htm#GPTPT

Reported-and-tested-by: Matt Porter <matt.porter@linaro.org>
Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
block/partitions/efi.c: treat size mismatch as a warning, not an error

In commit 27a7c642174e ("partitions/efi: account for pmbr size in lba")
we started treating bad sizes in lba field of the partition that has the
0xEE (GPT protective) as errors.

However, we may run into these "bad sizes" in the real world if someone
uses dd to copy an image from a smaller disk to a bigger disk.  Since
this case used to work (even without using force_gpt), keep it working
and treat the size mismatch as a warning instead of an error.

Reported-by: Josh Triplett <josh@joshtriplett.org>
Reported-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Doug Anderson <dianders@chromium.org>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Acked-by: Davidlohr Bueso <davidlohr@hp.com>
Tested-by: Artem Bityutskiy <dedekind1@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm, memcg: protect mem_cgroup_read_events for cpu hotplug

for_each_online_cpu() needs the protection of {get,put}_online_cpus() so
cpu_online_mask doesn't change during the iteration.

cpu_hotplug.lock is held while a cpu is going down, it's a coarse lock
that is used kernel-wide to synchronize cpu hotplug activity.  Memcg has
a cpu hotplug notifier, called while there may not be any cpu hotplug
refcounts, which drains per-cpu event counts to memcg->nocpu_base.events
to maintain a cumulative event count as cpus disappear.  Without
get_online_cpus() in mem_cgroup_read_events(), it's possible to account
for the event count on a dying cpu twice, and this value may be
significantly large.

In fact, all memcg->pcp_counter_lock use should be nested by
{get,put}_online_cpus().

This fixes that issue and ensures the reported statistics are not vastly
over-reported during cpu hotplug.

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
ipc: update locking scheme comments

The initial documentation was a bit incomplete, update accordingly.

[akpm@linux-foundation.org: make it more readable in 80 columns]
Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Acked-by: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
ipc/sem.c: synchronize semop and semctl with IPC_RMID

After acquiring the semlock spinlock, operations must test that the
array is still valid.

 - semctl() and exit_sem() would walk stale linked lists (ugly, but
   should be ok: all lists are empty)

 - semtimedop() would sleep forever - and if woken up due to a signal -
   access memory after free.

The patch also:
 - standardizes the tests for .deleted, so that all tests in one
   function leave the function with the same approach.
 - unconditionally tests for .deleted immediately after every call to
   sem_lock - even it it means that for semctl(GETALL), .deleted will be
   tested twice.

Both changes make the review simpler: After every sem_lock, there must
be a test of .deleted, followed by a goto to the cleanup code (if the
function uses "goto cleanup").

The only exception is semctl_down(): If sem_ids().rwsem is locked, then
the presence in ids->ipcs_idr is equivalent to !.deleted, thus no
additional test is required.

Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Mike Galbraith <efault@gmx.de>
Acked-by: Davidlohr Bueso <davidlohr@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/vmscan.c: don't forget to free shrinker->nr_deferred

This leak was added by commit 1d3d4437eae1 ("vmscan: per-node deferred
work").

unreferenced object 0xffff88006ada3bd0 (size 8):
  comm "criu", pid 14781, jiffies 4295238251 (age 105.641s)
  hex dump (first 8 bytes):
    00 00 00 00 00 00 00 00                          ........
  backtrace:
    [<ffffffff8170caee>] kmemleak_alloc+0x5e/0xc0
    [<ffffffff811c0527>] __kmalloc+0x247/0x310
    [<ffffffff8117848c>] register_shrinker+0x3c/0xa0
    [<ffffffff811e115b>] sget+0x5ab/0x670
    [<ffffffff812532f4>] proc_mount+0x54/0x170
    [<ffffffff811e1893>] mount_fs+0x43/0x1b0
    [<ffffffff81202dd2>] vfs_kern_mount+0x72/0x110
    [<ffffffff81202e89>] kern_mount_data+0x19/0x30
    [<ffffffff812530a0>] pid_ns_prepare_proc+0x20/0x40
    [<ffffffff81083c56>] alloc_pid+0x466/0x4a0
    [<ffffffff8105aeda>] copy_process+0xc6a/0x1860
    [<ffffffff8105beab>] do_fork+0x8b/0x370
    [<ffffffff8105c1a6>] SyS_clone+0x16/0x20
    [<ffffffff8171f739>] stub_clone+0x69/0x90
    [<ffffffffffffffff>] 0xffffffffffffffff

Signed-off-by: Andrew Vagin <avagin@openvz.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Glauber Costa <glommer@openvz.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/hugetlb.c: correct missing private flag clearing

We should clear the page's private flag when returing the page to the
hugepage pool.  Otherwise, marked hugepage can be allocated to the user
who tries to allocate the non-reserved hugepage.  If this user fail to
map this hugepage, he would try to return the page to the hugepage pool.
Since this page has a private flag, resv_huge_pages would mistakenly
increase.  This patch fixes this situation.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Davidlohr Bueso <davidlohr.bueso@hp.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Hillf Danton <dhillf@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
gcov: MAINTAINERS: Add an entry for gcov

Signed-off-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm: migration: do not lose soft dirty bit if page is in migration state

If page migration is turned on in config and the page is migrating, we
may lose the soft dirty bit.  If fork and mprotect are called on
migrating pages (once migration is complete) pages do not obtain the
soft dirty bit in the correspond pte entries.  Fix it adding an
appropriate test on swap entries.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm: /proc/pid/pagemap: inspect _PAGE_SOFT_DIRTY only on present pages

If a page we are inspecting is in swap we may occasionally report it as
having soft dirty bit (even if it is clean).  The pte_soft_dirty helper
should be called on present pte only.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/zswap: bugfix: memory leak when re-swapon

zswap_tree is not freed when swapoff, and it got re-kmalloced in swapon,
so a memory leak occurs.

Free the memory of zswap_tree in zswap_frontswap_invalidate_area().

Signed-off-by: Weijie Yang <weijie.yang@samsung.com>
Reviewed-by: Bob Liu <bob.liu@oracle.com>
Cc: Minchan Kim <minchan@kernel.org>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Cc: <stable@vger.kernel.org>
From: Weijie Yang <weijie.yang@samsung.com>
Subject: mm/zswap: bugfix: memory leak when invalidate and reclaim occur concurrently

Consider the following scenario:
thread 0: reclaim entry x (get refcount, but not call zswap_get_swap_cache_page)
thread 1: call zswap_frontswap_invalidate_page to invalidate entry x.
	finished, entry x and its zbud is not freed as its refcount != 0
	now, the swap_map[x] = 0
thread 0: now call zswap_get_swap_cache_page
	swapcache_prepare return -ENOENT because entry x is not used any more
	zswap_get_swap_cache_page return ZSWAP_SWAPCACHE_NOMEM
	zswap_writeback_entry do nothing except put refcount
Now, the memory of zswap_entry x and its zpage leak.

Modify:
 - check the refcount in fail path, free memory if it is not referenced.

 - use ZSWAP_SWAPCACHE_FAIL instead of ZSWAP_SWAPCACHE_NOMEM as the fail path
   can be not only caused by nomem but also by invalidate.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Weijie Yang <weijie.yang@samsung.com>
Reviewed-by: Bob Liu <bob.liu@oracle.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: <stable@vger.kernel.org>
Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com>

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>