* [PATCH] kernfs: Move faulting copy_user operations outside of the mutex
@ 2016-03-31 10:45 Chris Wilson
2016-03-31 16:49 ` Tejun Heo
0 siblings, 1 reply; 5+ messages in thread
From: Chris Wilson @ 2016-03-31 10:45 UTC (permalink / raw)
To: intel-gfx
Cc: Chris Wilson, Ville Syrjälä,
Joonas Lahtinen, Tejun Heo, Greg Kroah-Hartman, NeilBrown,
linux-kernel
A fault in a user provided buffer may lead anywhere, and lockdep warns
that we have a potential deadlock between the mm->mmap_sem and the
kernfs file mutex:
[ 82.811702] ======================================================
[ 82.811705] [ INFO: possible circular locking dependency detected ]
[ 82.811709] 4.5.0-rc4-gfxbench+ #1 Not tainted
[ 82.811711] -------------------------------------------------------
[ 82.811714] kms_setmode/5859 is trying to acquire lock:
[ 82.811717] (&dev->struct_mutex){+.+.+.}, at: [<ffffffff8150d9c1>] drm_gem_mmap+0x1a1/0x270
[ 82.811731]
but task is already holding lock:
[ 82.811734] (&mm->mmap_sem){++++++}, at: [<ffffffff8117b364>] vm_mmap_pgoff+0x44/0xa0
[ 82.811745]
which lock already depends on the new lock.
[ 82.811749]
the existing dependency chain (in reverse order) is:
[ 82.811752]
-> #3 (&mm->mmap_sem){++++++}:
[ 82.811761] [<ffffffff810cc883>] lock_acquire+0xc3/0x1d0
[ 82.811766] [<ffffffff8118bc65>] __might_fault+0x75/0xa0
[ 82.811771] [<ffffffff8124da4a>] kernfs_fop_write+0x8a/0x180
[ 82.811787] [<ffffffff811d1023>] __vfs_write+0x23/0xe0
[ 82.811792] [<ffffffff811d1d74>] vfs_write+0xa4/0x190
[ 82.811797] [<ffffffff811d2c14>] SyS_write+0x44/0xb0
[ 82.811801] [<ffffffff817bb81b>] entry_SYSCALL_64_fastpath+0x16/0x73
[ 82.811807]
-> #2 (s_active#6){++++.+}:
[ 82.811814] [<ffffffff810cc883>] lock_acquire+0xc3/0x1d0
[ 82.811819] [<ffffffff8124c070>] __kernfs_remove+0x210/0x2f0
[ 82.811823] [<ffffffff8124d040>] kernfs_remove_by_name_ns+0x40/0xa0
[ 82.811828] [<ffffffff8124e9e0>] sysfs_remove_file_ns+0x10/0x20
[ 82.811832] [<ffffffff815318d4>] device_del+0x124/0x250
[ 82.811837] [<ffffffff81531a19>] device_unregister+0x19/0x60
[ 82.811841] [<ffffffff8153c051>] cpu_cache_sysfs_exit+0x51/0xb0
[ 82.811846] [<ffffffff8153c628>] cacheinfo_cpu_callback+0x38/0x70
[ 82.811851] [<ffffffff8109ae89>] notifier_call_chain+0x39/0xa0
[ 82.811856] [<ffffffff8109aef9>] __raw_notifier_call_chain+0x9/0x10
[ 82.811860] [<ffffffff810786de>] cpu_notify+0x1e/0x40
[ 82.811865] [<ffffffff81078779>] cpu_notify_nofail+0x9/0x20
[ 82.811869] [<ffffffff81078ac3>] _cpu_down+0x233/0x340
[ 82.811874] [<ffffffff81079019>] disable_nonboot_cpus+0xc9/0x350
[ 82.811878] [<ffffffff810d2e11>] suspend_devices_and_enter+0x5a1/0xb50
[ 82.811883] [<ffffffff810d3903>] pm_suspend+0x543/0x8d0
[ 82.811888] [<ffffffff810d1b77>] state_store+0x77/0xe0
[ 82.811892] [<ffffffff813fa68f>] kobj_attr_store+0xf/0x20
[ 82.811897] [<ffffffff8124e740>] sysfs_kf_write+0x40/0x50
[ 82.811902] [<ffffffff8124dafc>] kernfs_fop_write+0x13c/0x180
[ 82.811906] [<ffffffff811d1023>] __vfs_write+0x23/0xe0
[ 82.811910] [<ffffffff811d1d74>] vfs_write+0xa4/0x190
[ 82.811914] [<ffffffff811d2c14>] SyS_write+0x44/0xb0
[ 82.811918] [<ffffffff817bb81b>] entry_SYSCALL_64_fastpath+0x16/0x73
[ 82.811923]
-> #1 (cpu_hotplug.lock){+.+.+.}:
[ 82.811929] [<ffffffff810cc883>] lock_acquire+0xc3/0x1d0
[ 82.811933] [<ffffffff817b6f72>] mutex_lock_nested+0x62/0x3b0
[ 82.811940] [<ffffffff810784c1>] get_online_cpus+0x61/0x80
[ 82.811944] [<ffffffff811170eb>] stop_machine+0x1b/0xe0
[ 82.811949] [<ffffffffa0178edd>] gen8_ggtt_insert_entries__BKL+0x2d/0x30 [i915]
[ 82.812009] [<ffffffffa017d3a6>] ggtt_bind_vma+0x46/0x70 [i915]
[ 82.812045] [<ffffffffa017eb70>] i915_vma_bind+0x140/0x290 [i915]
[ 82.812081] [<ffffffffa01862b9>] i915_gem_object_do_pin+0x899/0xb00 [i915]
[ 82.812117] [<ffffffffa0186555>] i915_gem_object_pin+0x35/0x40 [i915]
[ 82.812154] [<ffffffffa019a23e>] intel_init_pipe_control+0xbe/0x210 [i915]
[ 82.812192] [<ffffffffa0197312>] intel_logical_rings_init+0xe2/0xde0 [i915]
[ 82.812232] [<ffffffffa0186fe3>] i915_gem_init+0xf3/0x130 [i915]
[ 82.812278] [<ffffffffa02097ed>] i915_driver_load+0xf2d/0x1770 [i915]
[ 82.812318] [<ffffffff81512474>] drm_dev_register+0xa4/0xb0
[ 82.812323] [<ffffffff8151467e>] drm_get_pci_dev+0xce/0x1e0
[ 82.812328] [<ffffffffa01472cf>] i915_pci_probe+0x2f/0x50 [i915]
[ 82.812360] [<ffffffff8143f907>] pci_device_probe+0x87/0xf0
[ 82.812366] [<ffffffff81535f89>] driver_probe_device+0x229/0x450
[ 82.812371] [<ffffffff81536233>] __driver_attach+0x83/0x90
[ 82.812375] [<ffffffff81533c61>] bus_for_each_dev+0x61/0xa0
[ 82.812380] [<ffffffff81535879>] driver_attach+0x19/0x20
[ 82.812384] [<ffffffff8153535f>] bus_add_driver+0x1ef/0x290
[ 82.812388] [<ffffffff81536e9b>] driver_register+0x5b/0xe0
[ 82.812393] [<ffffffff8143e83b>] __pci_register_driver+0x5b/0x60
[ 82.812398] [<ffffffff81514866>] drm_pci_init+0xd6/0x100
[ 82.812402] [<ffffffffa027c094>] 0xffffffffa027c094
[ 82.812406] [<ffffffff810003de>] do_one_initcall+0xae/0x1d0
[ 82.812412] [<ffffffff811595a0>] do_init_module+0x5b/0x1cb
[ 82.812417] [<ffffffff81106160>] load_module+0x1c20/0x2480
[ 82.812422] [<ffffffff81106bae>] SyS_finit_module+0x7e/0xa0
[ 82.812428] [<ffffffff817bb81b>] entry_SYSCALL_64_fastpath+0x16/0x73
[ 82.812433]
-> #0 (&dev->struct_mutex){+.+.+.}:
[ 82.812439] [<ffffffff810cbe59>] __lock_acquire+0x1fc9/0x20f0
[ 82.812443] [<ffffffff810cc883>] lock_acquire+0xc3/0x1d0
[ 82.812456] [<ffffffff8150d9e7>] drm_gem_mmap+0x1c7/0x270
[ 82.812460] [<ffffffff81196a14>] mmap_region+0x334/0x580
[ 82.812466] [<ffffffff81196fc4>] do_mmap+0x364/0x410
[ 82.812470] [<ffffffff8117b38d>] vm_mmap_pgoff+0x6d/0xa0
[ 82.812474] [<ffffffff811950f4>] SyS_mmap_pgoff+0x184/0x220
[ 82.812479] [<ffffffff8100a0fd>] SyS_mmap+0x1d/0x20
[ 82.812484] [<ffffffff817bb81b>] entry_SYSCALL_64_fastpath+0x16/0x73
[ 82.812489]
other info that might help us debug this:
[ 82.812493] Chain exists of:
&dev->struct_mutex --> s_active#6 --> &mm->mmap_sem
[ 82.812502] Possible unsafe locking scenario:
[ 82.812506] CPU0 CPU1
[ 82.812508] ---- ----
[ 82.812510] lock(&mm->mmap_sem);
[ 82.812514] lock(s_active#6);
[ 82.812519] lock(&mm->mmap_sem);
[ 82.812522] lock(&dev->struct_mutex);
[ 82.812526]
*** DEADLOCK ***
[ 82.812531] 1 lock held by kms_setmode/5859:
[ 82.812533] #0: (&mm->mmap_sem){++++++}, at: [<ffffffff8117b364>] vm_mmap_pgoff+0x44/0xa0
[ 82.812541]
stack backtrace:
[ 82.812547] CPU: 0 PID: 5859 Comm: kms_setmode Not tainted 4.5.0-rc4-gfxbench+ #1
[ 82.812550] Hardware name: /NUC5CPYB, BIOS PYBSWCEL.86A.0040.2015.0814.1353 08/14/2015
[ 82.812553] 0000000000000000 ffff880079407bf0 ffffffff813f8505 ffffffff825fb270
[ 82.812560] ffffffff825c4190 ffff880079407c30 ffffffff810c84ac ffff880079407c90
[ 82.812566] ffff8800797ed328 ffff8800797ecb00 0000000000000001 ffff8800797ed350
[ 82.812573] Call Trace:
[ 82.812578] [<ffffffff813f8505>] dump_stack+0x67/0x92
[ 82.812582] [<ffffffff810c84ac>] print_circular_bug+0x1fc/0x310
[ 82.812586] [<ffffffff810cbe59>] __lock_acquire+0x1fc9/0x20f0
[ 82.812590] [<ffffffff810cc883>] lock_acquire+0xc3/0x1d0
[ 82.812594] [<ffffffff8150d9c1>] ? drm_gem_mmap+0x1a1/0x270
[ 82.812599] [<ffffffff8150d9e7>] drm_gem_mmap+0x1c7/0x270
[ 82.812603] [<ffffffff8150d9c1>] ? drm_gem_mmap+0x1a1/0x270
[ 82.812608] [<ffffffff81196a14>] mmap_region+0x334/0x580
[ 82.812612] [<ffffffff81196fc4>] do_mmap+0x364/0x410
[ 82.812616] [<ffffffff8117b38d>] vm_mmap_pgoff+0x6d/0xa0
[ 82.812629] [<ffffffff811950f4>] SyS_mmap_pgoff+0x184/0x220
[ 82.812633] [<ffffffff8100a0fd>] SyS_mmap+0x1d/0x20
[ 82.812637] [<ffffffff817bb81b>] entry_SYSCALL_64_fastpath+0x16/0x73
Highly unlikely though this scenario is, we can avoid the issue entirely
by moving the copy operation from out under the kernfs_get_active()
tracking by assigning the preallocated buffer its own mutex. The
temporary buffer allocation doesn't require mutex locking as it is
entirely local.
The locked section was extended by the addition of the preallocated buf
to speed up md user operations in
commit 2b75869bba676c248d8d25ae6d2bd9221dfffdb6
Author: NeilBrown <neilb@suse.de>
Date: Mon Oct 13 16:41:28 2014 +1100
sysfs/kernfs: allow attributes to request write buffer be pre-allocated.
Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94350
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: NeilBrown <neilb@suse.de>
Cc: linux-kernel@vger.kernel.org
---
fs/kernfs/file.c | 51 ++++++++++++++++++++++++++++----------------------
include/linux/kernfs.h | 1 +
2 files changed, 30 insertions(+), 22 deletions(-)
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index 7247252ee9b1..e1574008adc9 100644
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -190,15 +190,16 @@ static ssize_t kernfs_file_direct_read(struct kernfs_open_file *of,
char *buf;
buf = of->prealloc_buf;
- if (!buf)
+ if (buf)
+ mutex_lock(&of->prealloc_mutex);
+ else
buf = kmalloc(len, GFP_KERNEL);
if (!buf)
return -ENOMEM;
/*
* @of->mutex nests outside active ref and is used both to ensure that
- * the ops aren't called concurrently for the same open file, and
- * to provide exclusive access to ->prealloc_buf (when that exists).
+ * the ops aren't called concurrently for the same open file.
*/
mutex_lock(&of->mutex);
if (!kernfs_get_active(of->kn)) {
@@ -214,21 +215,23 @@ static ssize_t kernfs_file_direct_read(struct kernfs_open_file *of,
else
len = -EINVAL;
+ kernfs_put_active(of->kn);
+ mutex_unlock(&of->mutex);
+
if (len < 0)
- goto out_unlock;
+ goto out_free;
if (copy_to_user(user_buf, buf, len)) {
len = -EFAULT;
- goto out_unlock;
+ goto out_free;
}
*ppos += len;
- out_unlock:
- kernfs_put_active(of->kn);
- mutex_unlock(&of->mutex);
out_free:
- if (buf != of->prealloc_buf)
+ if (buf == of->prealloc_buf)
+ mutex_unlock(&of->prealloc_mutex);
+ else
kfree(buf);
return len;
}
@@ -284,15 +287,22 @@ static ssize_t kernfs_fop_write(struct file *file, const char __user *user_buf,
}
buf = of->prealloc_buf;
- if (!buf)
+ if (buf)
+ mutex_lock(&of->prealloc_mutex);
+ else
buf = kmalloc(len + 1, GFP_KERNEL);
if (!buf)
return -ENOMEM;
+ if (copy_from_user(buf, user_buf, len)) {
+ len = -EFAULT;
+ goto out_free;
+ }
+ buf[len] = '\0'; /* guarantee string termination */
+
/*
* @of->mutex nests outside active ref and is used both to ensure that
- * the ops aren't called concurrently for the same open file, and
- * to provide exclusive access to ->prealloc_buf (when that exists).
+ * the ops aren't called concurrently for the same open file.
*/
mutex_lock(&of->mutex);
if (!kernfs_get_active(of->kn)) {
@@ -301,26 +311,22 @@ static ssize_t kernfs_fop_write(struct file *file, const char __user *user_buf,
goto out_free;
}
- if (copy_from_user(buf, user_buf, len)) {
- len = -EFAULT;
- goto out_unlock;
- }
- buf[len] = '\0'; /* guarantee string termination */
-
ops = kernfs_ops(of->kn);
if (ops->write)
len = ops->write(of, buf, len, *ppos);
else
len = -EINVAL;
+ kernfs_put_active(of->kn);
+ mutex_unlock(&of->mutex);
+
if (len > 0)
*ppos += len;
-out_unlock:
- kernfs_put_active(of->kn);
- mutex_unlock(&of->mutex);
out_free:
- if (buf != of->prealloc_buf)
+ if (buf == of->prealloc_buf)
+ mutex_unlock(&of->prealloc_mutex);
+ else
kfree(buf);
return len;
}
@@ -687,6 +693,7 @@ static int kernfs_fop_open(struct inode *inode, struct file *file)
error = -ENOMEM;
if (!of->prealloc_buf)
goto err_free;
+ mutex_init(&of->prealloc_mutex);
}
/*
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index c06c44242f39..d306e282bb1d 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -177,6 +177,7 @@ struct kernfs_open_file {
/* private fields, do not use outside kernfs proper */
struct mutex mutex;
+ struct mutex prealloc_mutex;
int event;
struct list_head list;
char *prealloc_buf;
--
2.8.0.rc3
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] kernfs: Move faulting copy_user operations outside of the mutex
2016-03-31 10:45 [PATCH] kernfs: Move faulting copy_user operations outside of the mutex Chris Wilson
@ 2016-03-31 16:49 ` Tejun Heo
2016-03-31 17:30 ` Joonas Lahtinen
0 siblings, 1 reply; 5+ messages in thread
From: Tejun Heo @ 2016-03-31 16:49 UTC (permalink / raw)
To: Chris Wilson
Cc: intel-gfx, Ville Syrjälä,
Joonas Lahtinen, Greg Kroah-Hartman, NeilBrown, linux-kernel
On Thu, Mar 31, 2016 at 11:45:06AM +0100, Chris Wilson wrote:
> A fault in a user provided buffer may lead anywhere, and lockdep warns
> that we have a potential deadlock between the mm->mmap_sem and the
> kernfs file mutex:
...
> Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94350
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> Cc: Tejun Heo <tj@kernel.org>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: NeilBrown <neilb@suse.de>
> Cc: linux-kernel@vger.kernel.org
Acked-by: Tejun Heo <tj@kernel.org>
Thanks!
--
tejun
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] kernfs: Move faulting copy_user operations outside of the mutex
2016-03-31 16:49 ` Tejun Heo
@ 2016-03-31 17:30 ` Joonas Lahtinen
2016-03-31 20:15 ` Greg Kroah-Hartman
0 siblings, 1 reply; 5+ messages in thread
From: Joonas Lahtinen @ 2016-03-31 17:30 UTC (permalink / raw)
To: Tejun Heo, Chris Wilson, Daniel Vetter
Cc: intel-gfx, Ville Syrjälä,
Greg Kroah-Hartman, NeilBrown, linux-kernel
On to, 2016-03-31 at 12:49 -0400, Tejun Heo wrote:
> On Thu, Mar 31, 2016 at 11:45:06AM +0100, Chris Wilson wrote:
> >
> > A fault in a user provided buffer may lead anywhere, and lockdep warns
> > that we have a potential deadlock between the mm->mmap_sem and the
> > kernfs file mutex:
> ...
> >
> > Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94350
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> > Cc: Tejun Heo <tj@kernel.org>
> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > Cc: NeilBrown <neilb@suse.de>
> > Cc: linux-kernel@vger.kernel.org
> Acked-by: Tejun Heo <tj@kernel.org>
>
Thanks.
I have applied this locally to our repo to be included into our CI
builds.
We will drop the local patch once this waterfalls from upstream to our
drm-intel-nightly repo.
Regards, Joonas
--
Joonas Lahtinen
Open Source Technology Center
Intel Corporation
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] kernfs: Move faulting copy_user operations outside of the mutex
2016-03-31 17:30 ` Joonas Lahtinen
@ 2016-03-31 20:15 ` Greg Kroah-Hartman
2016-04-01 6:11 ` Joonas Lahtinen
0 siblings, 1 reply; 5+ messages in thread
From: Greg Kroah-Hartman @ 2016-03-31 20:15 UTC (permalink / raw)
To: Joonas Lahtinen
Cc: Tejun Heo, Chris Wilson, Daniel Vetter, intel-gfx,
Ville Syrjälä,
NeilBrown, linux-kernel
On Thu, Mar 31, 2016 at 08:30:05PM +0300, Joonas Lahtinen wrote:
> On to, 2016-03-31 at 12:49 -0400, Tejun Heo wrote:
> > On Thu, Mar 31, 2016 at 11:45:06AM +0100, Chris Wilson wrote:
> > >
> > > A fault in a user provided buffer may lead anywhere, and lockdep warns
> > > that we have a potential deadlock between the mm->mmap_sem and the
> > > kernfs file mutex:
> > ...
> > >
> > > Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94350
> > > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > > Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> > > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> > > Cc: Tejun Heo <tj@kernel.org>
> > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > > Cc: NeilBrown <neilb@suse.de>
> > > Cc: linux-kernel@vger.kernel.org
> > Acked-by: Tejun Heo <tj@kernel.org>
> >
>
> Thanks.
>
> I have applied this locally to our repo to be included into our CI
> builds.
>
> We will drop the local patch once this waterfalls from upstream to our
> drm-intel-nightly repo.
So is this something that needs to get into 4.6-final because it
resolves a reported issue? Or can it wait for 4.7-rc1?
thanks,
greg k-h
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] kernfs: Move faulting copy_user operations outside of the mutex
2016-03-31 20:15 ` Greg Kroah-Hartman
@ 2016-04-01 6:11 ` Joonas Lahtinen
0 siblings, 0 replies; 5+ messages in thread
From: Joonas Lahtinen @ 2016-04-01 6:11 UTC (permalink / raw)
To: Greg Kroah-Hartman
Cc: Tejun Heo, Chris Wilson, Daniel Vetter, intel-gfx,
Ville Syrjälä,
NeilBrown, linux-kernel
On to, 2016-03-31 at 13:15 -0700, Greg Kroah-Hartman wrote:
> On Thu, Mar 31, 2016 at 08:30:05PM +0300, Joonas Lahtinen wrote:
> >
> > On to, 2016-03-31 at 12:49 -0400, Tejun Heo wrote:
> > >
> > > On Thu, Mar 31, 2016 at 11:45:06AM +0100, Chris Wilson wrote:
> > > >
> > > >
> > > > A fault in a user provided buffer may lead anywhere, and lockdep warns
> > > > that we have a potential deadlock between the mm->mmap_sem and the
> > > > kernfs file mutex:
> > > ...
> > > >
> > > >
> > > > Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94350
> > > > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > > > Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> > > > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > > Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> > > > Cc: Tejun Heo <tj@kernel.org>
> > > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > > > Cc: NeilBrown <neilb@suse.de>
> > > > Cc: linux-kernel@vger.kernel.org
> > > Acked-by: Tejun Heo <tj@kernel.org>
> > >
> > Thanks.
> >
> > I have applied this locally to our repo to be included into our CI
> > builds.
> >
> > We will drop the local patch once this waterfalls from upstream to our
> > drm-intel-nightly repo.
> So is this something that needs to get into 4.6-final because it
> resolves a reported issue? Or can it wait for 4.7-rc1?
>
It is only a getting rid of a lockdep splat describing a scenario very
unlikely to ever happen, so it can wait for 4.7-rc1.
Regards, Joonas
> thanks,
>
> greg k-h
--
Joonas Lahtinen
Open Source Technology Center
Intel Corporation
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2016-03-31 10:45 [PATCH] kernfs: Move faulting copy_user operations outside of the mutex Chris Wilson
2016-03-31 16:49 ` Tejun Heo
2016-03-31 17:30 ` Joonas Lahtinen
2016-03-31 20:15 ` Greg Kroah-Hartman
2016-04-01 6:11 ` Joonas Lahtinen
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