This patch adds the necessary changes so min_links would use
the new bonding option API.
Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch adds the necessary changes so lacp_rate would use
the new bonding option API. Also some trivial/style error fixes.
Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch adds the necessary changes so updelay would use
the new bonding option API. Also some trivial style fixes.
Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch adds the necessary changes so downdelay would use
the new bonding option API. Also some trivial style fixes.
Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch adds the necessary changes so arp_ip_target would use
the new bonding option API. This option is an exception because of
the way it's currently implemented that's why its netlink code is
a bit different from the other options to keep the functionality as
before and at the same time to have a single set function.
This patch also fixes a few stylistic errors.
Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch adds the necessary changes so arp_interval would use
the new bonding option API. The "default" definition has been removed as
it was 0.
Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch adds the necessary changes so fail_over_mac would use
the new bonding option API. Also fixes a trivial copy/paste error in
bond_check_params where the wrong variable was used for the error msg.
Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch adds the necessary changes so arp_all_targets would use the
new bonding option API.
Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch adds the necessary changes so arp_validate would use the
new bonding option API. Also fix some trivial/style errors.
Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch adds the necessary changes so xmit_hash_policy would use the
new bonding option API. Also fix some trivial/style errors.
Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch adds the necessary changes so packets_per_slave would use the
new bonding option API.
Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch makes the bond's mode setting use the new option API and
adds support for dependency printing which relies on having an entry for
the mode option in the bond_opts[] array.
Also add the ability to print the mode name when mode dependency fails
and fix some trivial/style errors.
Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch adds the necessary basic infrastructure to support
centralized and unified option manipulation API for the bonding. The new
structure bond_option will be used to describe each option with its
dependencies on modes which will be checked automatically thus removing a
lot of duplicated code. Also automatic range checking is added for
some options. Currently the option setting function requires RTNL to
be acquired prior to calling it, since many options already rely on RTNL
it seemed like the best choice to protect all against common race
conditions.
In order to add an option the following steps need to be done:
1. Add an entry BOND_OPT_<option> to bond_options.h so it gets a unique id
and a bit corresponding to the id
2. Add a bond_option entry to the bond_opts[] array in bond_options.c which
describes the option, its dependencies and its manipulation function
3. Add code to export the option through sysfs and/or as a module parameter
(the sysfs export will be made automatically in the future)
The options can have different flags set, currently the following are
supported:
BOND_OPTFLAG_NOSLAVES - require that the bond device has no slaves prior
to setting the option
BOND_OPTFLAG_IFDOWN - require that the bond device is down prior to
setting the option
BOND_OPTFLAG_RAWVAL - don't parse the value but return it raw for the
option to parse
There's a new value structure to describe different types of values
which can have the following flags:
BOND_VALFLAG_DEFAULT - marks the default option (permanent string alias
to this option is "default")
BOND_VALFLAG_MIN - the minimum value that this option can have
BOND_VALFLAG_MAX - the maximum value that this option can have
An example would be nice here, so if we have an option which can have
the values "off"(2), "special"(4, default) and supports a range, say
16 - 32, it should be defined as follows:
"off", 2,
"special", 4, BOND_VALFLAG_DEFAULT,
"rangemin", 16, BOND_VALFLAG_MIN,
"rangemax", 32, BOND_VALFLAG_MAX
So we have the valid intervals: [2, 2], [4, 4], [16, 32]
Also the valid strings: "off" = 2, "special" and "default" = 4
"rangemin" = 16, "rangemax" = 32
BOND_VALFLAG_(MIN|MAX) can be used to specify a valid range for an
option, if MIN is omitted then 0 is considered as a minimum. If an
exact match is found in the values[] table it will be returned,
otherwise the range is tried (if available).
The option parameter passing is done by using a special structure called
bond_opt_value which can take either a string or a value to parse. One
of the bond_opt_init(val|str) macros should be used depending on which
one does the user want to parse (string or value). Then a call to
__bond_opt_set should be done under RTNL.
Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The linux build-bot recently reported a build error in arch/mips/kernel/vpe.c
tree: git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace.git for-linus
head: 261000a56b
commit: 261000a56b [4/4] userns: userns: Remove UIDGID_STRICT_TYPE_CHECKS
config: make ARCH=mips maltaaprp_defconfig
All error/warnings:
arch/mips/kernel/vpe.c: In function 'vpe_open':
>> arch/mips/kernel/vpe.c:1086:9: error: incompatible types when assigning to type 'unsigned int' from type 'kuid_t'
>> arch/mips/kernel/vpe.c:1087:9: error: incompatible types when assigning to type 'unsigned int' from type 'kgid_t'
vim +1086 arch/mips/kernel/vpe.c
863abad4 Jesper Juhl 2010-10-30 1080 return -ENOMEM;
863abad4 Jesper Juhl 2010-10-30 1081 }
e01402b1 Ralf Baechle 2005-07-14 1082 v->plen = P_SIZE;
e01402b1 Ralf Baechle 2005-07-14 1083 v->load_addr = NULL;
e01402b1 Ralf Baechle 2005-07-14 1084 v->len = 0;
e01402b1 Ralf Baechle 2005-07-14 1085
d76b0d9b David Howells 2008-11-14 @1086 v->uid = filp->f_cred->fsuid;
d76b0d9b David Howells 2008-11-14 @1087 v->gid = filp->f_cred->fsgid;
2600990e Ralf Baechle 2006-04-05 1088
2600990e Ralf Baechle 2006-04-05 1089 v->cwd[0] = 0;
2600990e Ralf Baechle 2006-04-05 1090 ret = getcwd(v->cwd, VPE_PATH_MAX);
When examining the code to see what v->uid and v->gid were used for I
discovered that the only users in the kernel are vpe_getuid and
vpe_getgid, and that vpe_getuid and vpe_getgid are never called.
So instead of proposing a conversion to use kuid_t and kgid_t instead
of unsigned int/int as I normally would let's just kill this dead code
so no one has to worry about it further.
Deng-Cheng Zhu said:
This is a good catch. vpe_get[u|g]id was originally used by KSPD which
has been removed.
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Reviewed-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
If a node page is trucated, we'd better drop the page in the node_inode's page
cache for better memory footprint.
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Commit bc20aa48bb ("x86, intel-mid:
Add Merrifield platform support") added new instances of __cpuinit
usage. We removed this a couple versions ago; we now want to remove
the compat no-op stubs. Introducing new users is not what we want to
see at this point in time, as it will break once the stubs are gone.
This also fixes an out of sync __init vs. __cpuinit -- as the former
is real, and the latter is a no-op; hence it would have been a section
mismatch.
Cc: Fei Yang <fei.yang@intel.com>
Cc: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Acked-by: David Cohen <david.a.cohen@linux.intel.com>
Link: http://lkml.kernel.org/r/1390412125-19439-1-git-send-email-paul.gortmaker@windriver.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Commit 85611e3feb ("x86, intel-mid:
Add Clovertrail platform support") added new instances of __cpuinit
usage. We removed this a couple versions ago; we now want to remove
the compat no-op stubs. Introducing new users is not what we want to
see at this point in time, as it will break once the stubs are gone.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Cc: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Cc: Fei Yang <fei.yang@intel.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Acked-by: David Cohen <david.a.cohen@linux.intel.com>
Link: http://lkml.kernel.org/r/1390412055-19341-1-git-send-email-paul.gortmaker@windriver.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This was a "forgotten" branch of tty fixes that somehow didn't make it
into my "main" branches, my fault.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
open/release operations require userspace transitions to keep track
of the open count and to perform any FS-specific setup. However,
for some purely read-only FSs which don't need to perform any setup
at open/release time, we can avoid the performance overhead of
calling into userspace for open/release calls.
This patch adds the necessary support to the fuse kernel modules to prevent
open/release operations from hitting in userspace. When the client returns
ENOSYS, we avoid sending the subsequent release to userspace, and also
remember this so that future opens also don't trigger a userspace
operation.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Various read operations (e.g. readlink, readdir) invalidate the cached
attrs for atime changes. This patch adds a new function
'fuse_invalidate_atime', which checks for a read-only super block and
avoids the attr invalidation in that case.
Signed-off-by: Andrew Gallagher <andrewjcg@fb.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
As noticed by Coverity the "num != 0" condition never triggers. Instead it
should check for a complete page.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Having this struct in module memory could Oops when if the module is
unloaded while the buffer still persists in a pipe.
Since sock_pipe_buf_ops is essentially the same as fuse_dev_pipe_buf_steal
merge them into nosteal_pipe_buf_ops (this is the same as
default_pipe_buf_ops except stealing the page from the buffer is not
allowed).
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Cc: stable@vger.kernel.org
With b8668fd0a7 "s390/uapi: change struct statfs[64] member types
to unsigned values" the size of a couple of struct statfs64 member got
incorrectly changed from 64 to 32 bit for 32 bit builds.
Fix this by changing the type of couple of struct statfs64 members from
unsigned long to unsigned long long.
The definition of struct compat_statfs64 was correct however.
Cc: stable@vger.kernel.org # v3.10+
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Remove some dead uaccess extern declarations and also make some functions
static, since they are only used locally.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
If get_fs() == USER_DS we better test if current->mm is not zero before
walking page tables.
The page table walk code would try to lock mm->page_table_lock, however
if mm is zero this might crash.
Now it is arguably incorrect trying to access userspace if current->mm
is zero, however we have seen that and s390 would be the only architecture
which would crash in such a case.
So we better make the page table walk code a bit more robust and report
always a fault instead.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Get rid of this link error:
arch/s390/built-in.o: In function `smp_prepare_cpus':
(.init.text+0x301e): undefined reference to `dump_save_area_create'
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
During parsing of the sizes array the pointer to the particular
string is lost. Keep it by using an extra pointer to store the end
position of the parsed string. Keeping these parameters accessible
can be helpful for debugging purposes and for userspace reading
the parameters at runtime via sysfs. Also this will ensure that the
memory is freed at module unload time.
Reported-by: Michael Veigel <veigel@de.ibm.com>
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This part of the ep11 patch should not have been merged.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Add the generic "lnxhvc" terminal ID to automatically assign a HVC terminal when
connecting to the HVC IUCV terminal device driver. The terminal device driver
tries to find a free (not connected) HVC terminal to satisfy the incoming
connection request.
With this improvement, you do not longer need to guess which HVC terminal is
free, that is, not connected. Also you can still connect to a particular HVC
terminal by using its associated terminal ID.
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Add device attributes to display details about the connection status
of HVC IUCV terminals.
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
drivers/tty/hvc/hvc_iucv.c:131:25: warning: symbol 'hvc_iucv_get_private' was not
declared. Should it be static?
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
When creating the virtual unit record (UR) device, specify the parent
CCW device.
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Nothing's changed here; we just need to bump the generation check.
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This patch adds NODE_MAPPING which is similar as META_MAPPING introduced by
Gu Zheng.
Cc: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
As the orphan_blocks may be max to 504, so it is not security
and rigorous to store such a large array in the kernel stack
as Dan Carpenter said.
In fact, grab_meta_page has locked the page in the page cache,
and we can use find_get_page() to fetch the page safely in the
downstream, so we can remove the page array directly.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Introduce help function META_MAPPING() to get the cache meta blocks'
address space.
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
If a dentry page is updated, we should call mark_inode_dirty to add the inode
into the dirty list, so that its dentry pages are flushed to the disk.
Otherwise, the inode can be evicted without flush.
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Since an old pageflip will keep its scanout buffer object pinned until
it has executed its unpin task on the common workqueue, we can clog up
our GGTT with stale pinned objects. As we cannot flush those workqueues
without dropping our locks, we have to resort to falling back to
userspace and telling them to repeat the operation in order to have a
chance to run our workqueues and free up the required memory. If we
fail, then we are forced to report ENOSPC back to userspace causing the
operation to fail and best-case scenario is that it introduces temporary
corruption.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Jon Bloomfield <jon.bloomfield@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
On older generations (gen2, gen3) the GPU requires fences for many
operations, such as blits. The display hardware also requires fences for
scanouts and this leads to a situation where an arbitrary number of
fences may be pinned by old scanouts following a pageflip but before we
have executed the unpin workqueue. This is unpredictable by userspace
and leads to random EDEADLK when submitting an otherwise benign
execbuffer. However, we can detect when we have an outstanding flip and
so cause userspace to wait upon their completion before finally
declaring that the system is starved of fences. This is really no worse
than forcing the GPU to stall waiting for older execbuffer to retire and
release their fences before we can reallocate them for the next
execbuffer.
v2: move the test for a pending fb unpin to a common routine for
later reuse during eviction
Reported-and-tested-by: dimon@gmx.net
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=73696
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Jon Bloomfield <jon.bloomfield@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Atm after a failed link training we disable the DP port. This can happen
during a modeset-enable or a DP link re-establishment. The latter can be
a problem and we shouldn't disable the DP port, see the previous patch for
the reasoning. In the former case the right thing would be to disable
the DP port, but also the rest of the pipe.
As a stop-gap solution leave the DP port enabled in both cases. It is an
improvement on its own (avoiding HW lock ups) and the proper solution
for the first case requires a bigger change, so let's keep that on the
TODO list.
v2:
- fix explanation of change impact (Chris)
Suggested-by: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Currently if the DP link is lost (either because of a hot unplug, or
failed link status check) we disable the DP port, but leave the rest
of the pipe running. This is incompatible with the modeset disabling
sequence of some platforms/configurations. At least this is the case for
DP ports on the CPU as opposed to PCH.
Atm we'll also get a warning when we do a modeset disable after the
above link lost event, since we expect the DP port to be enabled at this
point (see the bugzilla ticket for the related dmesg).
Note that with this patch we'll still end up disabling the port, thanks
to the HPD uevent and subsequent modeset disable.
See also the next patch fixing the other half of this issue.
Solution suggested by Ville.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=70570
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
My 855gm doesn't register the intel backlight but it still ends up
calling the backlight code to enable/disable the backlight via the
LVDS code. This leads to some WARNs due to backlight.max being 0.
Let's have intel_panel_enable_backlight() and intel_panel_disable_backlight()
check whether there's a backlight present or not.
Also move the backlight.present check from asle_set_backlight() into
intel_panel_set_backlight() for some extra symmetry.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Fix typo possibly leading to timed out DP aux transactions on ports C,D.
Introduced in:
Commmit 4aeebd7443
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date: Thu Oct 31 09:53:36 2013 +0100
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=72210
Signed off-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
We need to defer the free request until the object/vma is capable of
being freed - or else we have a problem when we try to destroy the
context.
The exact same issue is described and fixed here:
commit e20780439b
Author: Ben Widawsky <ben@bwidawsk.net>
Date: Fri Dec 6 14:11:22 2013 -0800
drm/i915: Defer request freeing
I had this fix previously, but decided not to keep it for some reason I
can no longer remember.
gem_reset_stats is a really good test at hitting the problem.
For the inquisitive:
[ 170.516392] ------------[ cut here ]------------
[ 170.517227] WARNING: CPU: 1 PID: 105 at drivers/gpu/drm/drm_mm.c:578 drm_mm_takedown+0x2e/0x30 [drm]()
[ 170.518064] Memory manager not clean during takedown.
[ 170.518941] CPU: 1 PID: 105 Comm: kworker/1:1 Not tainted 3.13.0-rc4-BEN+ #28
[ 170.519787] Hardware name: Hewlett-Packard HP EliteBook 8470p/179B, BIOS 68ICF Ver. F.02 04/27/2012
[ 170.520662] Call Trace:
[ 170.521517] [<ffffffff814f0589>] dump_stack+0x4e/0x7a
[ 170.522373] [<ffffffff81049e6d>] warn_slowpath_common+0x7d/0xa0
[ 170.523227] [<ffffffff81049edc>] warn_slowpath_fmt+0x4c/0x50
[ 170.524079] [<ffffffffa06c414e>] drm_mm_takedown+0x2e/0x30 [drm]
[ 170.524934] [<ffffffffa07213f3>] gen6_ppgtt_cleanup+0x23/0x110
[i915]
[ 170.525777] [<ffffffffa07837ed>] ppgtt_release.part.5+0x24/0x29
[i915]
[ 170.526603] [<ffffffffa071aaa5>] i915_gem_context_free+0x195/0x1a0
[i915]
[ 170.527423] [<ffffffffa071189d>] i915_gem_free_request+0x9d/0xb0
[i915]
[ 170.528247] [<ffffffffa0718af9>] i915_gem_reset+0x1f9/0x3f0 [i915]
[ 170.529065] [<ffffffffa0700cce>] i915_reset+0x4e/0x180 [i915]
[ 170.529870] [<ffffffffa070829d>] i915_error_work_func+0xcd/0x120
[i915]
[ 170.530666] [<ffffffff8106c13a>] process_one_work+0x1fa/0x6d0
[ 170.531453] [<ffffffff8106c0d8>] ? process_one_work+0x198/0x6d0
[ 170.532230] [<ffffffff8106c72b>] worker_thread+0x11b/0x3a0
[ 170.532996] [<ffffffff8106c610>] ? process_one_work+0x6d0/0x6d0
[ 170.533771] [<ffffffff810743ef>] kthread+0xff/0x120
[ 170.534548] [<ffffffff810742f0>] ? insert_kthread_work+0x80/0x80
[ 170.535322] [<ffffffff814f97ac>] ret_from_fork+0x7c/0xb0
[ 170.536089] [<ffffffff810742f0>] ? insert_kthread_work+0x80/0x80
[ 170.536847] ---[ end trace 3d4c12892e42d58f ]---
v2: Whitespace fix. (Chris)
Note: This is a bug that only hits the ppgtt topic branch but I've
figured that doing the request cleanup in this order is generally the
right thing to do.
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
[danvet: Add a code comment to clarify what's actually going on since
the lifetime rules aroung ppgtt cleanup are ... fuzzy a best atm. Also
add a note about why we need this.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
