Add platform hooks for custom suspend() and resume() functions. The
generic suspend/resume code in drivers/ata/ahci_platform.c is adapted
from the PCI version in drivers/ata/ahci.c.
Signed-off-by: NBrian Norris <computersforpeace@gmail.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Commit b3a70601 (libata: Add a
drivers/ide style DMA disable) neglected to remove the line in
ata_do_set_mode() it has obviously made useless/duplicated.  Do this
now, and make a line added back then wrapped properly...
Signed-off-by: NSergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

CONFIG_OF_IRQ is not available on some platforms and using of_irq_*
breaks the build. Since resources are already populated in the platform
device, get the irq from there instead.
Reported-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NRob Herring <rob.herring@calxeda.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

This patch converts the drivers in drivers/ata/* to use the
module_platform_driver() macro which makes the code smaller and a bit
simpler.

Cc: Viresh Kumar <viresh.kumar@st.com>
Cc: Jeff Garzik <jgarzik@pobox.com>
Cc: Arnaud Patard <arnaud.patard@rtp-net.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Sylvain Munaut <tnt@246tNt.com>
Cc: Anton Vorontsov <avorontsov@ru.mvista.com>
Cc: Marek Vasut <marek.vasut@gmail.com>
Cc: Florian Fainelli <florian@openwrt.org>
Cc: Mark Miesfeld <mmiesfeld@amcc.com>
Cc: Ashish Kalra <ashish.kalra@freescale.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: NAxel Lin <axel.lin@gmail.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

* Fix cable detection to also account for the slave device cable bit.

* Disable UDMA when programming MWDMA in cs5536_set_dmamode().

* Don't change UDMA settings in cs5536_set_piomode().

* Add cs5536_program_dtc() helper.

* Cleanup and uninline cs5536_[read,write]() methods.

Cc: Martin K. Petersen <mkp@mkp.net>
Signed-off-by: NBartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

atapi_pio_bytes() uses bare numbers for the ATAPI interrupt reason bits despite
these are #define'd in <linux/ata.h>.
Signed-off-by: NSergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Add ata port runtime suspend/resume/idle callbacks.
Set ->eh_noresume to skip the runtime PM calls on scsi host
in the error handler to avoid dead lock.
Acked-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NLin Ming <ming.m.lin@intel.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Change ata_host_request_pm to ata_port_request_pm which performs
port suspend/resume.

Add ata port type driver which implements port PM callbacks.
Signed-off-by: NLin Ming <ming.m.lin@intel.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

sd_shutdown is called during reboot/poweroff.
It may fail if parent device, for example, ata port, was runtime suspended.

Fix it by checking runtime PM status of sd.
Exit immediately if sd was runtime suspended already.
Acked-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NLin Ming <ming.m.lin@intel.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

The only high-level SCSI driver that currently implements runtime PM is
sd, and sd treats runtime suspend exactly the same as the SUSPEND and
HIBERNATE stages of system sleep, but not the same as the FREEZE stage.

Therefore, when entering the SUSPEND or HIBERNATE stages of system
sleep, we can skip the callback to the driver if the device is already
in runtime suspend.  When entering the FREEZE stage, however, we should
first issue a runtime resume.  The overhead of doing this is
negligible, because a suspended drive would be spun up during the THAW
stage of hibernation anyway.
Signed-off-by: NLin Ming <ming.m.lin@intel.com>
Signed-off-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

With previous change, now the ata port runtime suspend will happen as:

disk suspend --> scsi target suspend --> scsi host suspend --> ata port
suspend

ata port(parent device) suspend need to schedule scsi EH which will resume
scsi host(child device). Then the child device resume will in turn make
parent device resume first. This is kind of recursive.

This patch adds a new flag Scsi_Host::eh_noresume.
ata port will set this flag to skip the runtime PM calls on scsi host.
Acked-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NLin Ming <ming.m.lin@intel.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Currently, the device tree of ata port and scsi host looks as below,

        /sys/devices/pci0000:00/0000:00:1f.2    (ahci controller)
        |-- ata1                                (ata port)
        |-- host0                               (scsi host)
           |-- target0:0:0                      (scsi target)
               |-- 0:0:0:0                      (disk)

This patch makes ata port as parent device of scsi host, then it becomes

        /sys/devices/pci0000:00/0000:00:1f.2    (ahci controller)
        |-- ata1                                (ata port)
            |-- host0                           (scsi host)
                |-- target0:0:0                 (scsi target)
                    |-- 0:0:0:0                 (disk)

With this change, the ata port runtime PM is easier.
For example, the ata port runtime suspend will happen as,

disk suspend --> scsi target suspend --> scsi host suspend --> ata port
suspend.
Acked-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NLin Ming <ming.m.lin@intel.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

This is another attempt at fixing the same problem that 270dac35
(libata: ahci_start_engine compliant to AHCI spec) tried to solve.
Unfortunately, 270dac35 created regressions for a lot more common
controllers and got reverted.

This specific AHCI IP block becomes a brick if the DMA engine is
started while DRQ is set.  It is not possible to avoid the condition
completely but the most common occurrence is caused by spurious use of
ahci_start_engine() from ahci_start_port() during init sequence.

DMA engine is started after both soft and hard resets and
ahci_start_port() is always followed by resets, so there is no reason
to start DMA engine from ahci_start_port().

This patch removes ahci_start_engine() invocation from
ahci_start_port().  This change makes failure path of
ahci_port_suspend() leave engine stopped without following resets.
This is resolved by replacing ahci_start_port() call with
ata_port_freeze() which forces resets afterwards, which is the better
behavior anyway.
Signed-off-by: NTejun Heo <tj@kernel.org>
Reported-by: NBrian Norris <computersforpeace@gmail.com>
Reported-by: NJian Peng <jipeng2005@gmail.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net:
  fix CAN MAINTAINERS SCM tree type
  mwifiex: fix crash during simultaneous scan and connect
  b43: fix regression in PIO case
  ath9k: Fix kernel panic in AR2427 in AP mode
  CAN MAINTAINERS update
  net: fsl: fec: fix build for mx23-only kernel
  sch_qfq: fix overflow in qfq_update_start()
  Revert "Bluetooth: Increase HCI reset timeout in hci_dev_do_close"

bitmap size sanity checks should be done *before* allocating ->s_root;
there their cleanup on failure would be correct.  As it is, we do iput()
on root inode, but leak the root dentry...
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Acked-by: NJosh Boyer <jwboyer@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This is the temporary simple fix for 3.2, we need more changes in this
area.

1. do_signal_stop() assumes that the running untraced thread in the
   stopped thread group is not possible. This was our goal but it is
   not yet achieved: a stopped-but-resumed tracee can clone the running
   thread which can initiate another group-stop.

   Remove WARN_ON_ONCE(!current->ptrace).

2. A new thread always starts with ->jobctl = 0. If it is auto-attached
   and this group is stopped, __ptrace_unlink() sets JOBCTL_STOP_PENDING
   but JOBCTL_STOP_SIGMASK part is zero, this triggers WANR_ON(!signr)
   in do_jobctl_trap() if another debugger attaches.

   Change __ptrace_unlink() to set the artificial SIGSTOP for report.

   Alternatively we could change ptrace_init_task() to copy signr from
   current, but this means we can copy it for no reason and hide the
   possible similar problems.
Acked-by: NTejun Heo <tj@kernel.org>
Cc: <stable@kernel.org>		[3.1]
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Test-case:

	int main(void)
	{
		int pid, status;

		pid = fork();
		if (!pid) {
			for (;;) {
				if (!fork())
					return 0;
				if (waitpid(-1, &status, 0) < 0) {
					printf("ERR!! wait: %m\n");
					return 0;
				}
			}
		}

		assert(ptrace(PTRACE_ATTACH, pid, 0,0) == 0);
		assert(waitpid(-1, NULL, 0) == pid);

		assert(ptrace(PTRACE_SETOPTIONS, pid, 0,
					PTRACE_O_TRACEFORK) == 0);

		do {
			ptrace(PTRACE_CONT, pid, 0, 0);
			pid = waitpid(-1, NULL, 0);
		} while (pid > 0);

		return 1;
	}

It fails because ->real_parent sees its child in EXIT_DEAD state
while the tracer is going to change the state back to EXIT_ZOMBIE
in wait_task_zombie().

The offending commit is 823b018e which moved the EXIT_DEAD check,
but in fact we should not blame it. The original code was not
correct as well because it didn't take ptrace_reparented() into
account and because we can't really trust ->ptrace.

This patch adds the additional check to close this particular
race but it doesn't solve the whole problem. We simply can't
rely on ->ptrace in this case, it can be cleared if the tracer
is multithreaded by the exiting ->parent.

I think we should kill EXIT_DEAD altogether, we should always
remove the soon-to-be-reaped child from ->children or at least
we should never do the DEAD->ZOMBIE transition. But this is too
complex for 3.2.
Reported-and-tested-by: NDenys Vlasenko <vda.linux@googlemail.com>
Tested-by: NLukasz Michalik <lmi@ift.uni.wroc.pl>
Acked-by: NTejun Heo <tj@kernel.org>
Cc: <stable@kernel.org>		[3.0+]
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

* git://git.samba.org/sfrench/cifs-2.6:
  [CIFS] default ntlmv2 for cifs mount delayed to 3.3
  cifs: fix bad buffer length check in coalesce_t2

Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless into for-davem

This reverts commit 93b2ec01.

The call to "schedule_work()" in rtc_initialize_alarm() happens too
early, and can cause oopses at bootup

Neil Brown explains why we do it:

  "If you set an alarm in the future, then shutdown and boot again after
   that time, then you will end up with a timer_queue node which is in
   the past.

   When this happens the queue gets stuck.  That entry-in-the-past won't
   get removed until and interrupt happens and an interrupt won't happen
   because the RTC only triggers an interrupt when the alarm is "now".

   So you'll find that e.g.  "hwclock" will always tell you that
   'select' timed out.

   So we force the interrupt work to happen at the start just in case."

and has a patch that convert it to do things in-process rather than with
the worker thread, but right now it's too late to play around with this,
so we just revert the patch that caused problems for now.
Reported-by: NSander Eikelenboom <linux@eikelenboom.it>
Requested-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Requested-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Turned out the ntlmv2 (default security authentication)
upgrade was harder to test than expected, and we ran
out of time to test against Apple and a few other servers
that we wanted to.  Delay upgrade of default security
from ntlm to ntlmv2 (on mount) to 3.3.  Still works
fine to specify it explicitly via "sec=ntlmv2" so this
should be fine.
Acked-by: NJeff Layton <jlayton@samba.org>
Signed-off-by: NSteve French <smfrench@gmail.com>

The current check looks to see if the RFC1002 length is larger than
CIFSMaxBufSize, and fails if it is. The buffer is actually larger than
that by MAX_CIFS_HDR_SIZE.

This bug has been around for a long time, but the fact that we used to
cap the clients MaxBufferSize at the same level as the server tended
to paper over it. Commit c974befa changed that however and caused this
bug to bite in more cases.
Reported-and-Tested-by: NKonstantinos Skarlatos <k.skarlatos@gmail.com>
Tested-by: NShirish Pargaonkar <shirishpargaonkar@gmail.com>
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NSteve French <smfrench@gmail.com>

This reverts commit c0afabd3.

It causes failures on Toshiba laptops - instead of disabling the alarm,
it actually seems to enable it on the affected laptops, resulting in
(for example) the laptop powering on automatically five minutes after
shutdown.

There's a patch for it that appears to work for at least some people,
but it's too late to play around with this, so revert for now and try
again in the next merge window.

See for example

	http://bugs.debian.org/652869

Reported-and-bisected-by: Andreas Friedrich <afrie@gmx.net> (Toshiba Tecra)
Reported-by: Antonio-M. Corbi Bellot <antonio.corbi@ua.es> (Toshiba Portege R500)
Reported-by: Marco Santos <marco.santos@waynext.com> (Toshiba Portege Z830)
Reported-by: Christophe Vu-Brugier <cvubrugier@yahoo.fr>  (Toshiba Portege R830)
Cc: Jonathan Nieder <jrnieder@gmail.com>
Requested-by: NJohn Stultz <john.stultz@linaro.org>
Cc: stable@kernel.org  # for the versions that applied this
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

vfork parent uninterruptibly and unkillably waits for its child to
exec/exit. This wait is of unbounded length. Ignore such waits
in the hung_task detector.
Signed-off-by: NMandeep Singh Baines <msb@chromium.org>
Reported-by: NSasha Levin <levinsasha928@gmail.com>
LKML-Reference: <1325344394.28904.43.camel@lappy>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: John Kacur <jkacur@redhat.com>
Cc: stable@kernel.org
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Commit 1e39f384 ("evm: fix build problems") makes the stub version
of security_old_inode_init_security() return 0 when CONFIG_SECURITY is
not set.

But that makes callers such as reiserfs_security_init() assume that
security_old_inode_init_security() has set name, value, and len
arguments properly - but security_old_inode_init_security() left them
uninitialized which then results in interesting failures.

Revert security_old_inode_init_security() to the old behavior of
returning EOPNOTSUPP since both callers (reiserfs and ocfs2) handle this
just fine.

[ Also fixed the S_PRIVATE(inode) case of the actual non-stub
  security_old_inode_init_security() function to return EOPNOTSUPP
  for the same reason, as pointed out by Mimi Zohar.

  It got incorrectly changed to match the new function in commit
  fb88c2b6: "evm: fix security/security_old_init_security return
  code".   - Linus ]
Reported-by: NJorge Bastos <mysql.jorge@decimal.pt>
Acked-by: NJames Morris <jmorris@namei.org>
Acked-by: NMimi Zohar <zohar@us.ibm.com>
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

As pointed out by Joe Perches the SCM tree type was missing in my patch.
Signed-off-by: NOliver Hartkopp <socketcan@hartkopp.net>

CC: Oliver Hartkopp <oliver.hartkopp@volkswagen.de>
CC: Urs Thuermann <urs.thuermann@volkswagen.de>
CC: Wolfgang Grandegger <wg@grandegger.com>
CC: Marc Kleine-Budde <mkl@pengutronix.de>
CC: linux-can@vger.kernel.org

If 'iw connect' command is fired when driver is already busy in
serving 'iw scan' command, ssid specific scan operation for connect
is skipped. In this case cmd wait queue handler gets called with no
command in queue (i.e. adapter->cmd_queued = NULL).

This patch adds a NULL check in mwifiex_wait_queue_complete()
routine to fix crash observed during simultaneous scan and assoc
operations.
Signed-off-by: NAmitkumar Karwar <akarwar@marvell.com>
Signed-off-by: NBing Zhao <bzhao@marvell.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

This patch fixes the regression, introduced by

commit 17030f48
From: Rafał Miłecki <zajec5@gmail.com>
Date: Thu, 11 Aug 2011 17:16:27 +0200
Subject: [PATCH] b43: support new RX header, noticed to be used in 598.314+ fw

in PIO case.
Signed-off-by: NGuennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

don't do aggregation related stuff for 'AP mode client power save
handling' if aggregation is not enabled in the driver, otherwise it
will lead to panic because those data structures won't be never
intialized in 'ath_tx_node_init' if aggregation is disabled

	EIP is at ath_tx_aggr_wakeup+0x37/0x80 [ath9k]
	EAX: e8c09a20 EBX: f2a304e8 ECX: 00000001 EDX: 00000000
	ESI: e8c085e0 EDI: f2a304ac EBP: f40e1ca4 ESP: f40e1c8c
	DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
	Process swapper/1 (pid: 0, ti=f40e0000 task=f408e860
	task.ti=f40dc000)
	Stack:
	0001e966 e8c09a20 00000000 f2a304ac e8c085e0 f2a304ac
	f40e1cb0 f8186741
	f8186700 f40e1d2c f922988d f2a304ac 00000202 00000001
	c0b4ba43 00000000
	0000000f e8eb75c0 e8c085e0 205b0001 34383220 f2a304ac
	f2a30000 00010020
	Call Trace:
	[<f8186741>] ath9k_sta_notify+0x41/0x50 [ath9k]
	[<f8186700>] ? ath9k_get_survey+0x110/0x110 [ath9k]
	[<f922988d>] ieee80211_sta_ps_deliver_wakeup+0x9d/0x350
	[mac80211]
	[<c018dc75>] ? __module_address+0x95/0xb0
	[<f92465b3>] ap_sta_ps_end+0x63/0xa0 [mac80211]
	[<f9246746>] ieee80211_rx_h_sta_process+0x156/0x2b0
	[mac80211]
	[<f9247d1e>] ieee80211_rx_handlers+0xce/0x510 [mac80211]
	[<c018440b>] ? trace_hardirqs_on+0xb/0x10
	[<c056936e>] ? skb_queue_tail+0x3e/0x50
	[<f9248271>] ieee80211_prepare_and_rx_handle+0x111/0x750
	[mac80211]
	[<f9248bf9>] ieee80211_rx+0x349/0xb20 [mac80211]
	[<f9248949>] ? ieee80211_rx+0x99/0xb20 [mac80211]
	[<f818b0b8>] ath_rx_tasklet+0x818/0x1d00 [ath9k]
	[<f8187a75>] ? ath9k_tasklet+0x35/0x1c0 [ath9k]
	[<f8187a75>] ? ath9k_tasklet+0x35/0x1c0 [ath9k]
	[<f8187b33>] ath9k_tasklet+0xf3/0x1c0 [ath9k]
	[<c0151b7e>] tasklet_action+0xbe/0x180

Cc: stable@kernel.org
Cc: Senthil Balasubramanian <senthilb@qca.qualcomm.com>
Cc: Rajkumar Manoharan <rmanohar@qca.qualcomm.com>
Reported-by: NAshwin Mendonca <ashwinloyal@gmail.com>
Tested-by: NAshwin Mendonca <ashwinloyal@gmail.com>
Signed-off-by: NMohammed Shafi Shajakhan <mohammed@qca.qualcomm.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Update the CAN MAINTAINERS section:

- point out active maintainers
- pull the CAN driver discussion away from netdev ML
- point to the new CAN web site on gitorious.org
- add CAN development git repository URL to submit patches
Signed-off-by: NOliver Hartkopp <socketcan@hartkopp.net>

CC: Oliver Hartkopp <oliver.hartkopp@volkswagen.de>
CC: Urs Thuermann <urs.thuermann@volkswagen.de>
CC: Wolfgang Grandegger <wg@grandegger.com>
CC: Marc Kleine-Budde <mkl@pengutronix.de>
CC: linux-can@vger.kernel.org
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

If one only selects mx23-based boards, compile fails:

drivers/net/ethernet/freescale/fec.c:410:2: error: 'FEC_HASH_TABLE_HIGH' undeclared (first use in this function)
drivers/net/ethernet/freescale/fec.c:411:2: error: 'FEC_HASH_TABLE_LOW' undeclared (first use in this function)

This is because fec.h uses CONFIG_SOC_IMX28 to determine the register
layout of the core which makes sense since the MX23 does not have a fec.
However, Kconfig uses the broader ARCH_MXS symbol and this way even
makes the fec-driver default for MX23. Adapt Kconfig to use the more
precise SOC_IMX28 as well.
Signed-off-by: NWolfram Sang <w.sang@pengutronix.de>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Shawn Guo <shawn.guo@linaro.org>
Cc: David S. Miller <davem@davemloft.net>
Acked-by: NFabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

grp->slot_shift is between 22 and 41, so using 32bit wide variables is
probably a typo.

This could explain QFQ hangs Dave reported to me, after 2^23 packets ?

(23 = 64 - 41)
Reported-by: NDave Taht <dave.taht@gmail.com>
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
CC: Stephen Hemminger <shemminger@vyatta.com>
CC: Dave Taht <dave.taht@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

If we end up with no power states, don't look up
current vddc.

fixes:
https://bugs.freedesktop.org/show_bug.cgi?id=44130

agd5f: fix patch formatting
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: NDave Airlie <airlied@redhat.com>

* 'devicetree/merge' of git://git.secretlab.ca/git/linux-2.6:
  dt/device: Fix auxdata matching to handle entries without a name override

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net:
  netfilter: ctnetlink: fix timeout calculation
  ipvs: try also real server with port 0 in backup server
  skge: restore rx multicast filter on resume and after config changes
  mlx4_en: nullify cq->vector field when closing completion queue

* 'fix/asoc' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound:
  ASoC: wm8776: add missing break in sample size switch

The current gspca core code has a regression where it no longer properly
falls back to lower alt settings when there is not enough bandwidth.

This causes many iso based usb-1 cameras to not work when plugged into a
usb2 hub or a sandybridge chipset motherboard!

This patch fixes this.
Signed-off-by: NHans de Goede <hdegoede@redhat.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

It was found (by Sasha) that if you use a futex located in the gate
area we get stuck in an uninterruptible infinite loop, much like the
ZERO_PAGE issue.

While looking at this problem, PeterZ realized you'll get into similar
trouble when hitting any install_special_pages() mapping.  And are there
still drivers setting up their own special mmaps without page->mapping,
and without special VM or pte flags to make get_user_pages fail?

In most cases, if page->mapping is NULL, we do not need to retry at all:
Linus points out that even /proc/sys/vm/drop_caches poses no problem,
because it ends up using remove_mapping(), which takes care not to
interfere when the page reference count is raised.

But there is still one case which does need a retry: if memory pressure
called shmem_writepage in between get_user_pages_fast dropping page
table lock and our acquiring page lock, then the page gets switched from
filecache to swapcache (and ->mapping set to NULL) whatever the refcount.
Fault it back in to get the page->mapping needed for key->shared.inode.
Reported-by: NSasha Levin <levinsasha928@gmail.com>
Signed-off-by: NHugh Dickins <hughd@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>