tcp: fix tcp_shift_skb_data() to not shift SACKed data below snd_una

[ Upstream commit 4648dc97af9d496218a05353b0e442b3dfa6aaab ]

This commit fixes tcp_shift_skb_data() so that it does not shift
SACKed data below snd_una.

This fixes an issue whose symptoms exactly match reports showing
tp->sacked_out going negative since 3.3.0-rc4 (see "WARNING: at
net/ipv4/tcp_input.c:3418" thread on netdev).

Since 2008 (832d11c5cd076abc0aa1eaf7be96c81d1a59ce41)
tcp_shift_skb_data() had been shifting SACKed ranges that were below
snd_una. It checked that the *end* of the skb it was about to shift
from was above snd_una, but did not check that the end of the actual
shifted range was above snd_una; this commit adds that check.

Shifting SACKed ranges below snd_una is problematic because for such
ranges tcp_sacktag_one() short-circuits: it does not declare anything
as SACKed and does not increase sacked_out.

Before the fixes in commits cc9a672ee522d4805495b98680f4a3db5d0a0af9
and daef52bab1fd26e24e8e9578f8fb33ba1d0cb412, shifting SACKed ranges
below snd_una happened to work because tcp_shifted_skb() was always
(incorrectly) passing in to tcp_sacktag_one() an skb whose end_seq
tcp_shift_skb_data() had already guaranteed was beyond snd_una. Hence
tcp_sacktag_one() never short-circuited and always increased
tp->sacked_out in this case.

After those two fixes, my testing has verified that shifting SACKed
ranges below snd_una could cause tp->sacked_out to go negative with
the following sequence of events:

(1) tcp_shift_skb_data() sees an skb whose end_seq is beyond snd_una,
    then shifts a prefix of that skb that is below snd_una

(2) tcp_shifted_skb() increments the packet count of the
    already-SACKed prev sk_buff

(3) tcp_sacktag_one() sees the end of the new SACKed range is below
    snd_una, so it short-circuits and doesn't increase tp->sacked_out

(5) tcp_clean_rtx_queue() sees the SACKed skb has been ACKed,
    decrements tp->sacked_out by this "inflated" pcount that was
    missing a matching increase in tp->sacked_out, and hence
    tp->sacked_out underflows to a u32 like 0xFFFFFFFF, which casted
    to s32 is negative.

(6) this leads to the warnings seen in the recent "WARNING: at
    net/ipv4/tcp_input.c:3418" thread on the netdev list; e.g.:
    tcp_input.c:3418  WARN_ON((int)tp->sacked_out < 0);

More generally, I think this bug can be tickled in some cases where
two or more ACKs from the receiver are lost and then a DSACK arrives
that is immediately above an existing SACKed skb in the write queue.

This fix changes tcp_shift_skb_data() to abort this sequence at step
(1) in the scenario above by noticing that the bytes are below snd_una
and not shifting them.

Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
IPv6: Fix not join all-router mcast group when forwarding set.

[ Upstream commit d6ddef9e641d1229d4ec841dc75ae703171c3e92 ]

When forwarding was set and a new net device is register,
we need add this device to the all-router mcast group.

Signed-off-by: Li Wei <lw@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
regulator: Fix setting selector in tps6524x set_voltage function

commit f03570cf1709397ebe656608266b44ec772960c2 upstream.

Don't assign the voltage to selector.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
block: Fix NULL pointer dereference in sd_revalidate_disk

commit fe316bf2d5847bc5dd975668671a7b1067603bc7 upstream.

Since 2.6.39 (1196f8b), when a driver returns -ENOMEDIUM for open(),
__blkdev_get() calls rescan_partitions() to remove
in-kernel partition structures and raise KOBJ_CHANGE uevent.

However it ends up calling driver's revalidate_disk without open
and could cause oops.

In the case of SCSI:

  process A                  process B
  ----------------------------------------------
  sys_open
    __blkdev_get
      sd_open
        returns -ENOMEDIUM
                             scsi_remove_device
                               <scsi_device torn down>
      rescan_partitions
        sd_revalidate_disk
          <oops>
Oopses are reported here:
http://marc.info/?l=linux-scsi&m=132388619710052

This patch separates the partition invalidation from rescan_partitions()
and use it for -ENOMEDIUM case.

Reported-by: Huajun Li <huajun.li.lee@gmail.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
block, sx8: fix pointer math issue getting fw version

commit ea5f4db8ece896c2ab9eafa0924148a2596c52e4 upstream.

"mem" is type u8.  We need parenthesis here or it screws up the pointer
math probably leading to an oops.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
block: fix __blkdev_get and add_disk race condition

commit 9f53d2fe815b4011ff930a7b6db98385d45faa68 upstream.

The following situation might occur:

__blkdev_get:			add_disk:

				register_disk()
get_gendisk()

disk_block_events()
	disk->ev == NULL

				disk_add_events()

__disk_unblock_events()
	disk->ev != NULL
	--ev->block

Then we unblock events, when they are suppose to be blocked. This can
trigger events related block/genhd.c warnings, but also can crash in
sd_check_events() or other places.

I'm able to reproduce crashes with the following scripts (with
connected usb dongle as sdb disk).

<snip>
DEV=/dev/sdb
ENABLE=/sys/bus/usb/devices/1-2/bConfigurationValue

function stop_me()
{
	for i in `jobs -p` ; do kill $i 2> /dev/null ; done
	exit
}

trap stop_me SIGHUP SIGINT SIGTERM

for ((i = 0; i < 10; i++)) ; do
	while true; do fdisk -l $DEV  2>&1 > /dev/null ; done &
done

while true ; do
echo 1 > $ENABLE
sleep 1
echo 0 > $ENABLE
done
</snip>

I use the script to verify patch fixing oops in sd_revalidate_disk
http://marc.info/?l=linux-scsi&m=132935572512352&w=2
Without Jun'ichi Nomura patch titled "Fix NULL pointer dereference in
sd_revalidate_disk" or this one, script easily crash kernel within
a few seconds. With both patches applied I do not observe crash.
Unfortunately after some time (dozen of minutes), script will hung in:

[ 1563.906432]  [<c08354f5>] schedule_timeout_uninterruptible+0x15/0x20
[ 1563.906437]  [<c04532d5>] msleep+0x15/0x20
[ 1563.906443]  [<c05d60b2>] blk_drain_queue+0x32/0xd0
[ 1563.906447]  [<c05d6e00>] blk_cleanup_queue+0xd0/0x170
[ 1563.906454]  [<c06d278f>] scsi_free_queue+0x3f/0x60
[ 1563.906459]  [<c06d7e6e>] __scsi_remove_device+0x6e/0xb0
[ 1563.906463]  [<c06d4aff>] scsi_forget_host+0x4f/0x60
[ 1563.906468]  [<c06cd84a>] scsi_remove_host+0x5a/0xf0
[ 1563.906482]  [<f7f030fb>] quiesce_and_remove_host+0x5b/0xa0 [usb_storage]
[ 1563.906490]  [<f7f03203>] usb_stor_disconnect+0x13/0x20 [usb_storage]

Anyway I think this patch is some step forward.

As drawback, I do not teardown on sysfs file create error, because I do
not know how to nullify disk->ev (since it can be used). However add_disk
error handling practically does not exist too, and things will work
without this sysfs file, except events will not be exported to user
space.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Block: use a freezable workqueue for disk-event polling

commit 62d3c5439c534b0e6c653fc63e6d8c67be3a57b1 upstream.

This patch (as1519) fixes a bug in the block layer's disk-events
polling.  The polling is done by a work routine queued on the
system_nrt_wq workqueue.  Since that workqueue isn't freezable, the
polling continues even in the middle of a system sleep transition.

Obviously, polling a suspended drive for media changes and such isn't
a good thing to do; in the case of USB mass-storage devices it can
lead to real problems requiring device resets and even re-enumeration.

The patch fixes things by creating a new system-wide, non-reentrant,
freezable workqueue and using it for disk-events polling.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
nilfs2: fix NULL pointer dereference in nilfs_load_super_block()

commit d7178c79d9b7c5518f9943188091a75fc6ce0675 upstream.

According to the report from Slicky Devil, nilfs caused kernel oops at
nilfs_load_super_block function during mount after he shrank the
partition without resizing the filesystem:

 BUG: unable to handle kernel NULL pointer dereference at 00000048
 IP: [<d0d7a08e>] nilfs_load_super_block+0x17e/0x280 [nilfs2]
 *pde = 00000000
 Oops: 0000 [#1] PREEMPT SMP
 ...
 Call Trace:
  [<d0d7a87b>] init_nilfs+0x4b/0x2e0 [nilfs2]
  [<d0d6f707>] nilfs_mount+0x447/0x5b0 [nilfs2]
  [<c0226636>] mount_fs+0x36/0x180
  [<c023d961>] vfs_kern_mount+0x51/0xa0
  [<c023ddae>] do_kern_mount+0x3e/0xe0
  [<c023f189>] do_mount+0x169/0x700
  [<c023fa9b>] sys_mount+0x6b/0xa0
  [<c04abd1f>] sysenter_do_call+0x12/0x28
 Code: 53 18 8b 43 20 89 4b 18 8b 4b 24 89 53 1c 89 43 24 89 4b 20 8b 43
 20 c7 43 2c 00 00 00 00 23 75 e8 8b 50 68 89 53 28 8b 54 b3 20 <8b> 72
 48 8b 7a 4c 8b 55 08 89 b3 84 00 00 00 89 bb 88 00 00 00
 EIP: [<d0d7a08e>] nilfs_load_super_block+0x17e/0x280 [nilfs2] SS:ESP 0068:ca9bbdcc
 CR2: 0000000000000048

This turned out due to a defect in an error path which runs if the
calculated location of the secondary super block was invalid.

This patch fixes it and eliminates the reported oops.

Reported-by: Slicky Devil <slicky.dvl@gmail.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Tested-by: Slicky Devil <slicky.dvl@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tcp: fix syncookie regression

[ Upstream commit dfd25ffffc132c00070eed64200e8950da5d7e9d ]

commit ea4fc0d619 (ipv4: Don't use rt->rt_{src,dst} in ip_queue_xmit())
added a serious regression on synflood handling.

Simon Kirby discovered a successful connection was delayed by 20 seconds
before being responsive.

In my tests, I discovered that xmit frames were lost, and needed ~4
retransmits and a socket dst rebuild before being really sent.

In case of syncookie initiated connection, we use a different path to
initialize the socket dst, and inet->cork.fl.u.ip4 is left cleared.

As ip_queue_xmit() now depends on inet flow being setup, fix this by
copying the temp flowi4 we use in cookie_v4_check().

Reported-by: Simon Kirby <sim@netnation.com>
Bisected-by: Simon Kirby <sim@netnation.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Tested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
staging: zcache: avoid AB-BA deadlock condition

commit cfbc6a92212e74b07aa76c9e2f20c542e36077fb upstream.

Commit 9256a47 fixed a deadlock condition, being sure that the buddy
list spinlock is always taken before the page spinlock.

However in zbud_free_and_delist() locking order is the opposite
(page lock -> list lock).

Possible unsafe locking scenario (reported by lockdep):

        CPU0                    CPU1
        ----                    ----
   lock(&(&zbpg->lock)->rlock);
                                lock(zbud_budlists_spinlock);
                                lock(&(&zbpg->lock)->rlock);
   lock(zbud_budlists_spinlock);

Fix by grabbing the locks in opposite order in zbud_free_and_delist().

Signed-off-by: Andrea Righi <andrea@betterlinux.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
futex: Cover all PI opcodes with cmpxchg enabled check

commit 59263b513c11398cd66a52d4c5b2b118ce1e0359 upstream.

Some of the newer futex PI opcodes do not check the cmpxchg enabled
variable and call unconditionally into the handling functions. Cover
all PI opcodes in a separate check.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Darren Hart <dvhart@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
sysfs: Fix memory leak in sysfs_sd_setsecdata().

commit 93518dd2ebafcc761a8637b2877008cfd748c202 upstream.

This patch fixies follwing two memory leak patterns that reported by kmemleak.
sysfs_sd_setsecdata() is called during sys_lsetxattr() operation.
It checks sd->s_iattr is NULL or not. Then if it is NULL, it calls
sysfs_init_inode_attrs() to allocate memory.
That code is this.

iattrs = sd->s_iattr;
if (!iattrs)
                iattrs = sysfs_init_inode_attrs(sd);

The iattrs recieves sysfs_init_inode_attrs()'s result,  but sd->s_iattr
doesn't know the address. so it needs to set correct address to
sd->s_iattr to free memory in other function.

unreferenced object 0xffff880250b73e60 (size 32):
  comm "systemd", pid 1, jiffies 4294683888 (age 94.553s)
  hex dump (first 32 bytes):
    73 79 73 74 65 6d 5f 75 3a 6f 62 6a 65 63 74 5f  system_u:object_
    72 3a 73 79 73 66 73 5f 74 3a 73 30 00 00 00 00  r:sysfs_t:s0....
  backtrace:
    [<ffffffff814cb1d0>] kmemleak_alloc+0x73/0x98
    [<ffffffff811270ab>] __kmalloc+0x100/0x12c
    [<ffffffff8120775a>] context_struct_to_string+0x106/0x210
    [<ffffffff81207cc1>] security_sid_to_context_core+0x10b/0x129
    [<ffffffff812090ef>] security_sid_to_context+0x10/0x12
    [<ffffffff811fb0da>] selinux_inode_getsecurity+0x7d/0xa8
    [<ffffffff811fb127>] selinux_inode_getsecctx+0x22/0x2e
    [<ffffffff811f4d62>] security_inode_getsecctx+0x16/0x18
    [<ffffffff81191dad>] sysfs_setxattr+0x96/0x117
    [<ffffffff811542f0>] __vfs_setxattr_noperm+0x73/0xd9
    [<ffffffff811543d9>] vfs_setxattr+0x83/0xa1
    [<ffffffff811544c6>] setxattr+0xcf/0x101
    [<ffffffff81154745>] sys_lsetxattr+0x6a/0x8f
    [<ffffffff814efda9>] system_call_fastpath+0x16/0x1b
    [<ffffffffffffffff>] 0xffffffffffffffff
unreferenced object 0xffff88024163c5a0 (size 96):
  comm "systemd", pid 1, jiffies 4294683888 (age 94.553s)
  hex dump (first 32 bytes):
    00 00 00 00 ed 41 00 00 00 00 00 00 00 00 00 00  .....A..........
    00 00 00 00 00 00 00 00 0c 64 42 4f 00 00 00 00  .........dBO....
  backtrace:
    [<ffffffff814cb1d0>] kmemleak_alloc+0x73/0x98
    [<ffffffff81127402>] kmem_cache_alloc_trace+0xc4/0xee
    [<ffffffff81191cbe>] sysfs_init_inode_attrs+0x2a/0x83
    [<ffffffff81191dd6>] sysfs_setxattr+0xbf/0x117
    [<ffffffff811542f0>] __vfs_setxattr_noperm+0x73/0xd9
    [<ffffffff811543d9>] vfs_setxattr+0x83/0xa1
    [<ffffffff811544c6>] setxattr+0xcf/0x101
    [<ffffffff81154745>] sys_lsetxattr+0x6a/0x8f
    [<ffffffff814efda9>] system_call_fastpath+0x16/0x1b
    [<ffffffffffffffff>] 0xffffffffffffffff
`

Signed-off-by: Masami Ichikawa <masami256@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
math: Introduce div64_long

commit f910381a55cdaa097030291f272f6e6e4380c39a upstream.

Add a div64_long macro which is used to devide a 64bit number by a long (which
can be 4 bytes on 32bit systems and 8 bytes on 64bit systems).

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Cc: johnstul@us.ibm.com
Link: http://lkml.kernel.org/r/1331829374-31543-1-git-send-email-levinsasha928@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ntp: Fix integer overflow when setting time

commit a078c6d0e6288fad6d83fb6d5edd91ddb7b6ab33 upstream.

'long secs' is passed as divisor to div_s64, which accepts a 32bit
divisor. On 64bit machines that value is trimmed back from 8 bytes
back to 4, causing a divide by zero when the number is bigger than
(1 << 32) - 1 and all 32 lower bits are 0.

Use div64_long() instead.

Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Cc: johnstul@us.ibm.com
Link: http://lkml.kernel.org/r/1331829374-31543-2-git-send-email-levinsasha928@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
uevent: send events in correct order according to seqnum (v3)

commit 7b60a18da393ed70db043a777fd9e6d5363077c4 upstream.

The queue handling in the udev daemon assumes that the events are
ordered.

Before this patch uevent_seqnum is incremented under sequence_lock,
than an event is send uner uevent_sock_mutex. I want to say that code
contained a window between incrementing seqnum and sending an event.

This patch locks uevent_sock_mutex before incrementing uevent_seqnum.

v2: delete sequence_lock, uevent_seqnum is protected by uevent_sock_mutex
v3: unlock the mutex before the goto exit

Thanks for Kay for the comments.

Signed-off-by: Andrew Vagin <avagin@openvz.org>
Tested-By: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
mm: thp: fix pmd_bad() triggering in code paths holding mmap_sem read mode

commit 1a5a9906d4e8d1976b701f889d8f35d54b928f25 upstream.

In some cases it may happen that pmd_none_or_clear_bad() is called with
the mmap_sem hold in read mode.  In those cases the huge page faults can
allocate hugepmds under pmd_none_or_clear_bad() and that can trigger a
false positive from pmd_bad() that will not like to see a pmd
materializing as trans huge.

It's not khugepaged causing the problem, khugepaged holds the mmap_sem
in write mode (and all those sites must hold the mmap_sem in read mode
to prevent pagetables to go away from under them, during code review it
seems vm86 mode on 32bit kernels requires that too unless it's
restricted to 1 thread per process or UP builds).  The race is only with
the huge pagefaults that can convert a pmd_none() into a
pmd_trans_huge().

Effectively all these pmd_none_or_clear_bad() sites running with
mmap_sem in read mode are somewhat speculative with the page faults, and
the result is always undefined when they run simultaneously.  This is
probably why it wasn't common to run into this.  For example if the
madvise(MADV_DONTNEED) runs zap_page_range() shortly before the page
fault, the hugepage will not be zapped, if the page fault runs first it
will be zapped.

Altering pmd_bad() not to error out if it finds hugepmds won't be enough
to fix this, because zap_pmd_range would then proceed to call
zap_pte_range (which would be incorrect if the pmd become a
pmd_trans_huge()).

The simplest way to fix this is to read the pmd in the local stack
(regardless of what we read, no need of actual CPU barriers, only
compiler barrier needed), and be sure it is not changing under the code
that computes its value.  Even if the real pmd is changing under the
value we hold on the stack, we don't care.  If we actually end up in
zap_pte_range it means the pmd was not none already and it was not huge,
and it can't become huge from under us (khugepaged locking explained
above).

All we need is to enforce that there is no way anymore that in a code
path like below, pmd_trans_huge can be false, but pmd_none_or_clear_bad
can run into a hugepmd.  The overhead of a barrier() is just a compiler
tweak and should not be measurable (I only added it for THP builds).  I
don't exclude different compiler versions may have prevented the race
too by caching the value of *pmd on the stack (that hasn't been
verified, but it wouldn't be impossible considering
pmd_none_or_clear_bad, pmd_bad, pmd_trans_huge, pmd_none are all inlines
and there's no external function called in between pmd_trans_huge and
pmd_none_or_clear_bad).

		if (pmd_trans_huge(*pmd)) {
			if (next-addr != HPAGE_PMD_SIZE) {
				VM_BUG_ON(!rwsem_is_locked(&tlb->mm->mmap_sem));
				split_huge_page_pmd(vma->vm_mm, pmd);
			} else if (zap_huge_pmd(tlb, vma, pmd, addr))
				continue;
			/* fall through */
		}
		if (pmd_none_or_clear_bad(pmd))

Because this race condition could be exercised without special
privileges this was reported in CVE-2012-1179.

The race was identified and fully explained by Ulrich who debugged it.
I'm quoting his accurate explanation below, for reference.

====== start quote =======
      mapcount 0 page_mapcount 1
      kernel BUG at mm/huge_memory.c:1384!

    At some point prior to the panic, a "bad pmd ..." message similar to the
    following is logged on the console:

      mm/memory.c:145: bad pmd ffff8800376e1f98(80000000314000e7).

    The "bad pmd ..." message is logged by pmd_clear_bad() before it clears
    the page's PMD table entry.

        143 void pmd_clear_bad(pmd_t *pmd)
        144 {
    ->  145         pmd_ERROR(*pmd);
        146         pmd_clear(pmd);
        147 }

    After the PMD table entry has been cleared, there is an inconsistency
    between the actual number of PMD table entries that are mapping the page
    and the page's map count (_mapcount field in struct page). When the page
    is subsequently reclaimed, __split_huge_page() detects this inconsistency.

       1381         if (mapcount != page_mapcount(page))
       1382                 printk(KERN_ERR "mapcount %d page_mapcount %d\n",
       1383                        mapcount, page_mapcount(page));
    -> 1384         BUG_ON(mapcount != page_mapcount(page));

    The root cause of the problem is a race of two threads in a multithreaded
    process. Thread B incurs a page fault on a virtual address that has never
    been accessed (PMD entry is zero) while Thread A is executing an madvise()
    system call on a virtual address within the same 2 MB (huge page) range.

               virtual address space
              .---------------------.
              |                     |
              |                     |
            .-|---------------------|
            | |                     |
            | |                     |<-- B(fault)
            | |                     |
      2 MB  | |/////////////////////|-.
      huge <  |/////////////////////|  > A(range)
      page  | |/////////////////////|-'
            | |                     |
            | |                     |
            '-|---------------------|
              |                     |
              |                     |
              '---------------------'

    - Thread A is executing an madvise(..., MADV_DONTNEED) system call
      on the virtual address range "A(range)" shown in the picture.

    sys_madvise
      // Acquire the semaphore in shared mode.
      down_read(&current->mm->mmap_sem)
      ...
      madvise_vma
        switch (behavior)
        case MADV_DONTNEED:
             madvise_dontneed
               zap_page_range
                 unmap_vmas
                   unmap_page_range
                     zap_pud_range
                       zap_pmd_range
                         //
                         // Assume that this huge page has never been accessed.
                         // I.e. content of the PMD entry is zero (not mapped).
                         //
                         if (pmd_trans_huge(*pmd)) {
                             // We don't get here due to the above assumption.
                         }
                         //
                         // Assume that Thread B incurred a page fault and
             .---------> // sneaks in here as shown below.
             |           //
             |           if (pmd_none_or_clear_bad(pmd))
             |               {
             |                 if (unlikely(pmd_bad(*pmd)))
             |                     pmd_clear_bad
             |                     {
             |                       pmd_ERROR
             |                         // Log "bad pmd ..." message here.
             |                       pmd_clear
             |                         // Clear the page's PMD entry.
             |                         // Thread B incremented the map count
             |                         // in page_add_new_anon_rmap(), but
             |                         // now the page is no longer mapped
             |                         // by a PMD entry (-> inconsistency).
             |                     }
             |               }
             |
             v
    - Thread B is handling a page fault on virtual address "B(fault)" shown
      in the picture.

    ...
    do_page_fault
      __do_page_fault
        // Acquire the semaphore in shared mode.
        down_read_trylock(&mm->mmap_sem)
        ...
        handle_mm_fault
          if (pmd_none(*pmd) && transparent_hugepage_enabled(vma))
              // We get here due to the above assumption (PMD entry is zero).
              do_huge_pmd_anonymous_page
                alloc_hugepage_vma
                  // Allocate a new transparent huge page here.
                ...
                __do_huge_pmd_anonymous_page
                  ...
                  spin_lock(&mm->page_table_lock)
                  ...
                  page_add_new_anon_rmap
                    // Here we increment the page's map count (starts at -1).
                    atomic_set(&page->_mapcount, 0)
                  set_pmd_at
                    // Here we set the page's PMD entry which will be cleared
                    // when Thread A calls pmd_clear_bad().
                  ...
                  spin_unlock(&mm->page_table_lock)

    The mmap_sem does not prevent the race because both threads are acquiring
    it in shared mode (down_read).  Thread B holds the page_table_lock while
    the page's map count and PMD table entry are updated.  However, Thread A
    does not synchronize on that lock.

====== end quote =======

[akpm@linux-foundation.org: checkpatch fixes]
Reported-by: Ulrich Obergfell <uobergfe@redhat.com>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Jones <davej@redhat.com>
Acked-by: Larry Woodman <lwoodman@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Mark Salter <msalter@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
PM / Domains: Fix handling of wakeup devices during system resume

commit cc85b20780562d404e18a47b9b55b4a5102ae53e upstream.

During system suspend pm_genpd_suspend_noirq() checks if the given
device is in a wakeup path (i.e. it appears to be needed for one or
more wakeup devices to work or is a wakeup device itself) and if it
needs to be "active" for wakeup to work.  If that is the case, the
function returns 0 without incrementing the device domain's counter
of suspended devices and without executing genpd_stop_dev() for the
device.  In consequence, the device is not stopped (e.g. its clock
isn't disabled) and power is always supplied to its domain in the
resulting system sleep state.

However, pm_genpd_resume_noirq() doesn't repeat that check and it
runs genpd_start_dev() and decrements the domain's counter of
suspended devices even for the wakeup device that weren't stopped by
pm_genpd_suspend_noirq().  As a result, the start callback may be run
unnecessarily for them and their domains' counters of suspended
devices may become negative.  Both outcomes aren't desirable, so fix
pm_genpd_resume_noirq() to look for wakeup devices that might not be
stopped by during system suspend.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Tested-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
bootmem/sparsemem: remove limit constraint in alloc_bootmem_section

commit f5bf18fa22f8c41a13eb8762c7373eb3a93a7333 upstream.

While testing AMS (Active Memory Sharing) / CMO (Cooperative Memory
Overcommit) on powerpc, we tripped the following:

  kernel BUG at mm/bootmem.c:483!
  cpu 0x0: Vector: 700 (Program Check) at [c000000000c03940]
      pc: c000000000a62bd8: .alloc_bootmem_core+0x90/0x39c
      lr: c000000000a64bcc: .sparse_early_usemaps_alloc_node+0x84/0x29c
      sp: c000000000c03bc0
     msr: 8000000000021032
    current = 0xc000000000b0cce0
    paca    = 0xc000000001d80000
      pid   = 0, comm = swapper
  kernel BUG at mm/bootmem.c:483!
  enter ? for help
  [c000000000c03c80] c000000000a64bcc
  .sparse_early_usemaps_alloc_node+0x84/0x29c
  [c000000000c03d50] c000000000a64f10 .sparse_init+0x12c/0x28c
  [c000000000c03e20] c000000000a474f4 .setup_arch+0x20c/0x294
  [c000000000c03ee0] c000000000a4079c .start_kernel+0xb4/0x460
  [c000000000c03f90] c000000000009670 .start_here_common+0x1c/0x2c

This is

        BUG_ON(limit && goal + size > limit);

and after some debugging, it seems that

	goal = 0x7ffff000000
	limit = 0x80000000000

and sparse_early_usemaps_alloc_node ->
sparse_early_usemaps_alloc_pgdat_section calls

	return alloc_bootmem_section(usemap_size() * count, section_nr);

This is on a system with 8TB available via the AMS pool, and as a quirk
of AMS in firmware, all of that memory shows up in node 0.  So, we end
up with an allocation that will fail the goal/limit constraints.

In theory, we could "fall-back" to alloc_bootmem_node() in
sparse_early_usemaps_alloc_node(), but since we actually have HOTREMOVE
defined, we'll BUG_ON() instead.  A simple solution appears to be to
unconditionally remove the limit condition in alloc_bootmem_section,
meaning allocations are allowed to cross section boundaries (necessary
for systems of this size).

Johannes Weiner pointed out that if alloc_bootmem_section() no longer
guarantees section-locality, we need check_usemap_section_nr() to print
possible cross-dependencies between node descriptors and the usemaps
allocated through it.  That makes the two loops in
sparse_early_usemaps_alloc_node() identical, so re-factor the code a
bit.

[akpm@linux-foundation.org: code simplification]
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Anton Blanchard <anton@au1.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ben Herrenschmidt <benh@kernel.crashing.org>
Cc: Robert Jennings <rcj@linux.vnet.ibm.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tcm_loop: Set residual field for SCSI commands

commit 6cf3fa6918baab0c447f1206f1cef9166ad04864 upstream.

If the target core signals an over- or under-run, tcm_loop should call
scsi_set_resid() to tell the SCSI midlayer about the residual data length.

The difference can be seen by doing something like

    strace -eioctl sg_raw -r 1024 /dev/sda 8 0 0 0 1 0 > /dev/null

and looking at the "resid=" part of the SG_IO ioctl -- after this patch,
the field is correctly reported as 512.

Signed-off-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
udlfb: remove sysfs framebuffer device with USB .disconnect()

commit ce880cb860f36694d2cdebfac9e6ae18176fe4c4 upstream.

The USB graphics card driver delays the unregistering of the framebuffer
device to a workqueue, which breaks the userspace visible remove uevent
sequence. Recent userspace tools started to support USB graphics card
hotplug out-of-the-box and rely on proper events sent by the kernel.

The framebuffer device is a direct child of the USB interface which is
removed immediately after the USB .disconnect() callback. But the fb device
in /sys stays around until its final cleanup, at a time where all the parent
devices have been removed already.

To work around that, we remove the sysfs fb device directly in the USB
.disconnect() callback and leave only the cleanup of the internal fb
data to the delayed work.

Before:
 add      /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2 (usb)
 add      /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2/2-1.2:1.0 (usb)
 add      /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2/2-1.2:1.0/graphics/fb0 (graphics)
 remove   /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2/2-1.2:1.0 (usb)
 remove   /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2 (usb)
 remove   /2-1.2:1.0/graphics/fb0 (graphics)

After:
 add      /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2 (usb)
 add      /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2/2-1.2:1.0 (usb)
 add      /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2/2-1.2:1.0/graphics/fb1 (graphics)
 remove   /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2/2-1.2:1.0/graphics/fb1 (graphics)
 remove   /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2/2-1.2:1.0 (usb)
 remove   /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2 (usb)

Tested-by: Bernie Thompson <bernie@plugable.com>
Acked-by: Bernie Thompson <bernie@plugable.com>
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>