linux-stable.git, branch v4.16.4

Linux 4.16.4

2018-04-24T07:43:11+00:00

writeback: safer lock nesting

2018-04-24T07:43:11+00:00

commit 2e898e4c0a3897ccd434adac5abb8330194f527b upstream.

lock_page_memcg()/unlock_page_memcg() use spin_lock_irqsave/restore() if
the page's memcg is undergoing move accounting, which occurs when a
process leaves its memcg for a new one that has
memory.move_charge_at_immigrate set.

unlocked_inode_to_wb_begin,end() use spin_lock_irq/spin_unlock_irq() if
the given inode is switching writeback domains.  Switches occur when
enough writes are issued from a new domain.

This existing pattern is thus suspicious:
    lock_page_memcg(page);
    unlocked_inode_to_wb_begin(inode, &locked);
    ...
    unlocked_inode_to_wb_end(inode, locked);
    unlock_page_memcg(page);

If both inode switch and process memcg migration are both in-flight then
unlocked_inode_to_wb_end() will unconditionally enable interrupts while
still holding the lock_page_memcg() irq spinlock.  This suggests the
possibility of deadlock if an interrupt occurs before unlock_page_memcg().

    truncate
    __cancel_dirty_page
    lock_page_memcg
    unlocked_inode_to_wb_begin
    unlocked_inode_to_wb_end
    
                                    
                                    end_page_writeback
                                    test_clear_page_writeback
                                    lock_page_memcg
                                    
    unlock_page_memcg

Due to configuration limitations this deadlock is not currently possible
because we don't mix cgroup writeback (a cgroupv2 feature) and
memory.move_charge_at_immigrate (a cgroupv1 feature).

If the kernel is hacked to always claim inode switching and memcg
moving_account, then this script triggers lockup in less than a minute:

  cd /mnt/cgroup/memory
  mkdir a b
  echo 1 > a/memory.move_charge_at_immigrate
  echo 1 > b/memory.move_charge_at_immigrate
  (
    echo $BASHPID > a/cgroup.procs
    while true; do
      dd if=/dev/zero of=/mnt/big bs=1M count=256
    done
  ) &
  while true; do
    sync
  done &
  sleep 1h &
  SLEEP=$!
  while true; do
    echo $SLEEP > a/cgroup.procs
    echo $SLEEP > b/cgroup.procs
  done

The deadlock does not seem possible, so it's debatable if there's any
reason to modify the kernel.  I suggest we should to prevent future
surprises.  And Wang Long said "this deadlock occurs three times in our
environment", so there's more reason to apply this, even to stable.
Stable 4.4 has minor conflicts applying this patch.  For a clean 4.4 patch
see "[PATCH for-4.4] writeback: safer lock nesting"
https://lkml.org/lkml/2018/4/11/146

Wang Long said "this deadlock occurs three times in our environment"

[gthelen@google.com: v4]
  Link: http://lkml.kernel.org/r/20180411084653.254724-1-gthelen@google.com
[akpm@linux-foundation.org: comment tweaks, struct initialization simplification]
Change-Id: Ibb773e8045852978f6207074491d262f1b3fb613
Link: http://lkml.kernel.org/r/20180410005908.167976-1-gthelen@google.com
Fixes: 682aa8e1a6a1 ("writeback: implement unlocked_inode_to_wb transaction and use it for stat updates")
Signed-off-by: Greg Thelen 
Reported-by: Wang Long 
Acked-by: Wang Long 
Acked-by: Michal Hocko 
Reviewed-by: Andrew Morton 
Cc: Johannes Weiner 
Cc: Tejun Heo 
Cc: Nicholas Piggin 
Cc: 	[v4.2+]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
[natechancellor: Adjust context due to lack of b93b016313b3b]
Signed-off-by: Nathan Chancellor 
Signed-off-by: Greg Kroah-Hartman

HID: i2c-hid: fix inverted return value from i2c_hid_command()

2018-04-24T07:43:10+00:00

commit b658912cb023cd6f8e46963d29779903d3c10538 upstream.

i2c_hid_command() returns non-zero in error cases (the actual
errno). Error handling in for I2C_HID_QUIRK_RESEND_REPORT_DESCR
case in i2c_hid_resume() had the check inverted; fix that.

Fixes: 3e83eda467 ("HID: i2c-hid: Fix resume issue on Raydium touchscreen device")
Reported-by: Dan Carpenter 
Signed-off-by: Jiri Kosina 
Cc: Aaron Ma 
Signed-off-by: Greg Kroah-Hartman

drm/i915/gvt: init mmio by lri command in vgpu inhibit context

2018-04-24T07:43:10+00:00

commit cd7e61b93d068a80bfe6cb55bf00f17332d831a1 upstream.

There is one issue relates to Coarse Power Gating(CPG) on KBL NUC in GVT-g,
vgpu can't get the correct default context by updating the registers before
inhibit context submission. It always get back the hardware default value
unless the inhibit context submission happened before the 1st time
forcewake put. With this wrong default context, vgpu will run with
incorrect state and meet unknown issues.

The solution is initialize these mmios by adding lri command in ring buffer
of the inhibit context, then gpu hardware has no chance to go down RC6 when
lri commands are right being executed, and then vgpu can get correct
default context for further use.

v3:
- fix code fault, use 'for' to loop through mmio render list(Zhenyu)

v4:
- save the count of engine mmio need to be restored for inhibit context and
  refine some comments. (Kevin)

v5:
- code rebase

Cc: Kevin Tian 
Cc: Zhenyu Wang 
Signed-off-by: Weinan Li 
Signed-off-by: Zhenyu Wang 
Signed-off-by: Changbin Du 
Signed-off-by: Greg Kroah-Hartman

mm/filemap.c: fix NULL pointer in page_cache_tree_insert()

2018-04-24T07:43:10+00:00

commit abc1be13fd113ddef5e2d807a466286b864caed3 upstream.

f2fs specifies the __GFP_ZERO flag for allocating some of its pages.
Unfortunately, the page cache also uses the mapping's GFP flags for
allocating radix tree nodes.  It always masked off the __GFP_HIGHMEM
flag, and masks off __GFP_ZERO in some paths, but not all.  That causes
radix tree nodes to be allocated with a NULL list_head, which causes
backtraces like:

  __list_del_entry+0x30/0xd0
  list_lru_del+0xac/0x1ac
  page_cache_tree_insert+0xd8/0x110

The __GFP_DMA and __GFP_DMA32 flags would also be able to sneak through
if they are ever used.  Fix them all by using GFP_RECLAIM_MASK at the
innermost location, and remove it from earlier in the callchain.

Link: http://lkml.kernel.org/r/20180411060320.14458-2-willy@infradead.org
Fixes: 449dd6984d0e ("mm: keep page cache radix tree nodes in check")
Signed-off-by: Matthew Wilcox 
Reported-by: Chris Fries 
Debugged-by: Minchan Kim 
Acked-by: Johannes Weiner 
Acked-by: Michal Hocko 
Reviewed-by: Jan Kara 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

autofs: mount point create should honour passed in mode

2018-04-24T07:43:10+00:00

commit 1e6306652ba18723015d1b4967fe9de55f042499 upstream.

The autofs file system mkdir inode operation blindly sets the created
directory mode to S_IFDIR | 0555, ingoring the passed in mode, which can
cause selinux dac_override denials.

But the function also checks if the caller is the daemon (as no-one else
should be able to do anything here) so there's no point in not honouring
the passed in mode, allowing the daemon to set appropriate mode when
required.

Link: http://lkml.kernel.org/r/152361593601.8051.14014139124905996173.stgit@pluto.themaw.net
Signed-off-by: Ian Kent 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

device-dax: allow MAP_SYNC to succeed

2018-04-24T07:43:10+00:00

commit ef8423022324cf79bd1b41d8707c766461e7e555 upstream.

MAP_SYNC is a nop for device-dax. Allow MAP_SYNC to succeed on device-dax
to eliminate special casing between device-dax and fs-dax as to when the
flag can be specified. Device-dax users already implicitly assume that they do
not need to call fsync(), and this enables them to explicitly check for this
capability.

Cc: 
Fixes: b6fb293f2497 ("mm: Define MAP_SYNC and VM_SYNC flags")
Signed-off-by: Dave Jiang 
Reviewed-by: Dan Williams 
Signed-off-by: Dan Williams 
Signed-off-by: Greg Kroah-Hartman

libnvdimm, dimm: handle EACCES failures from label reads

2018-04-24T07:43:10+00:00

commit e7c5a571a8d6a266aee9ca3f3f26e5afe3717eca upstream.

The new support for the standard _LSR and _LSW methods neglected to also
update the nvdimm_init_config_data() and nvdimm_set_config_data() to
return the translated error code from failed commands. This precision is
necessary because the locked status that was previously returned on
ND_CMD_GET_CONFIG_SIZE commands is now returned on
ND_CMD_{GET,SET}_CONFIG_DATA commands.

If the kernel misses this indication it can inadvertently fall back to
label-less mode when it should otherwise avoid all access to locked
regions.

Cc: 
Fixes: 4b27db7e26cd ("acpi, nfit: add support for the _LSI, _LSR, and...")
Signed-off-by: Dan Williams 
Signed-off-by: Greg Kroah-Hartman

Don't leak MNT_INTERNAL away from internal mounts

2018-04-24T07:43:10+00:00

commit 16a34adb9392b2fe4195267475ab5b472e55292c upstream.

We want it only for the stuff created by SB_KERNMOUNT mounts, *not* for
their copies.  As it is, creating a deep stack of bindings of /proc/*/ns/*
somewhere in a new namespace and exiting yields a stack overflow.

Cc: stable@kernel.org
Reported-by: Alexander Aring 
Bisected-by: Kirill Tkhai 
Tested-by: Kirill Tkhai 
Tested-by: Alexander Aring 
Signed-off-by: Al Viro 
Signed-off-by: Greg Kroah-Hartman

rpc_pipefs: fix double-dput()

2018-04-24T07:43:10+00:00

commit 4a3877c4cedd95543f8726b0a98743ed8db0c0fb upstream.

if we ever hit rpc_gssd_dummy_depopulate() dentry passed to
it has refcount equal to 1.  __rpc_rmpipe() drops it and
dput() done after that hits an already freed dentry.

Cc: stable@kernel.org
Signed-off-by: Al Viro 
Signed-off-by: Greg Kroah-Hartman