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Brewmaster 3.18 #24

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merged 6 commits into from
Jul 28, 2015
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xpad changes from Pavel's and Pierre-Loup's patches

vivek added 6 commits July 24, 2015 01:32
From original patch by Pavel rojtberg at

  http://www.spinics.net/lists/linux-input/msg39706.html

Introduces xpad_identify_controller
From Pavel Rojtberg

  http://www.spinics.net/lists/linux-input/msg39706.html

this code is now redundand with xpad_send_led_command which does the
same thing using irq_out.
Furthermore it was probably wrong from the start as setting the LEDs did
not work before completing the xbox360 wireless package in
xpad_send_led_command.
Note that this change only affects the two supported wireless
controllers. Tested using the xbox360 wireless controller (PC).
From: "Pierre-Loup A. Griffais"

To allow us to later create / destroy the input device from the urb
callback, we need to initialize/ deinitialize the input device from a
separate function.  So pull that logic out now to make later patches
more "obvious" as to what they do.
From: Pavel Rojtberg

We initializing the driver/device, we really don't know how many
controllers are connected.  So send a "query presence" command to the
base-station. (Command discovered by Zachary Lund)

Note, this means we now do not "preallocate" all 4 devices when a single
wireless base station is seen, but require the device to be properly
connected to the base station before that can happen.  The allocation of
the device happens in the next patch, not here, so in a way, this patch
breaks all wireless devices...

based on patch by
"Pierre-Loup A. Griffais"

presence packet taken from:
https://github.com/computerquip/xpad5
From: "Pierre-Loup A. Griffais"

Handle the "a new device is present" message properly by dynamically
creating the input device at this point in time.  This requires a
workqueue as we are in interrupt context when we learn about this.

Also properly disconnect any devices that we are told are removed.
From: Pavel Rojtberg

The pad_nr should be consistent after disconnecting/ reconnecting a
xbox360 controllers.
Use a bitmask to track connected pads - this way we can re-assign freed
up pad numbers.

Consider the following case:
1. pad A is connected and gets pad_nr = 0
2. pad B is connected and gets pad_nr = 1
3. pad A is disconnected
4. pad A is connected again

using the bitmask controller A now correctly gets pad_nr = 0 again.

Note: this sets a limit of 32 simultaneous connected xbox360
controllers. However this should be tolerable.
Plagman added a commit that referenced this pull request Jul 28, 2015
@Plagman Plagman merged commit 7b3ca85 into ValveSoftware:brewmaster-3.18 Jul 28, 2015
Plagman pushed a commit that referenced this pull request Sep 16, 2015
[ Upstream commit ecf5fc6 ]

Nikolay has reported a hang when a memcg reclaim got stuck with the
following backtrace:

PID: 18308  TASK: ffff883d7c9b0a30  CPU: 1   COMMAND: "rsync"
  #0 __schedule at ffffffff815ab152
  #1 schedule at ffffffff815ab76e
  #2 schedule_timeout at ffffffff815ae5e5
  #3 io_schedule_timeout at ffffffff815aad6a
  #4 bit_wait_io at ffffffff815abfc6
  #5 __wait_on_bit at ffffffff815abda5
  #6 wait_on_page_bit at ffffffff8111fd4f
  #7 shrink_page_list at ffffffff81135445
  #8 shrink_inactive_list at ffffffff81135845
  #9 shrink_lruvec at ffffffff81135ead
 #10 shrink_zone at ffffffff811360c3
 #11 shrink_zones at ffffffff81136eff
 #12 do_try_to_free_pages at ffffffff8113712f
 #13 try_to_free_mem_cgroup_pages at ffffffff811372be
 #14 try_charge at ffffffff81189423
 #15 mem_cgroup_try_charge at ffffffff8118c6f5
 #16 __add_to_page_cache_locked at ffffffff8112137d
 #17 add_to_page_cache_lru at ffffffff81121618
 #18 pagecache_get_page at ffffffff8112170b
 #19 grow_dev_page at ffffffff811c8297
 #20 __getblk_slow at ffffffff811c91d6
 #21 __getblk_gfp at ffffffff811c92c1
 #22 ext4_ext_grow_indepth at ffffffff8124565c
 #23 ext4_ext_create_new_leaf at ffffffff81246ca8
 #24 ext4_ext_insert_extent at ffffffff81246f09
 #25 ext4_ext_map_blocks at ffffffff8124a848
 #26 ext4_map_blocks at ffffffff8121a5b7
 #27 mpage_map_one_extent at ffffffff8121b1fa
 #28 mpage_map_and_submit_extent at ffffffff8121f07b
 #29 ext4_writepages at ffffffff8121f6d5
 #30 do_writepages at ffffffff8112c490
 #31 __filemap_fdatawrite_range at ffffffff81120199
 #32 filemap_flush at ffffffff8112041c
 #33 ext4_alloc_da_blocks at ffffffff81219da1
 #34 ext4_rename at ffffffff81229b91
 #35 ext4_rename2 at ffffffff81229e32
 #36 vfs_rename at ffffffff811a08a5
 #37 SYSC_renameat2 at ffffffff811a3ffc
 #38 sys_renameat2 at ffffffff811a408e
 #39 sys_rename at ffffffff8119e51e
 #40 system_call_fastpath at ffffffff815afa89

Dave Chinner has properly pointed out that this is a deadlock in the
reclaim code because ext4 doesn't submit pages which are marked by
PG_writeback right away.

The heuristic was introduced by commit e62e384 ("memcg: prevent OOM
with too many dirty pages") and it was applied only when may_enter_fs
was specified.  The code has been changed by c3b94f4 ("memcg:
further prevent OOM with too many dirty pages") which has removed the
__GFP_FS restriction with a reasoning that we do not get into the fs
code.  But this is not sufficient apparently because the fs doesn't
necessarily submit pages marked PG_writeback for IO right away.

ext4_bio_write_page calls io_submit_add_bh but that doesn't necessarily
submit the bio.  Instead it tries to map more pages into the bio and
mpage_map_one_extent might trigger memcg charge which might end up
waiting on a page which is marked PG_writeback but hasn't been submitted
yet so we would end up waiting for something that never finishes.

Fix this issue by replacing __GFP_IO by may_enter_fs check (for case 2)
before we go to wait on the writeback.  The page fault path, which is
the only path that triggers memcg oom killer since 3.12, shouldn't
require GFP_NOFS and so we shouldn't reintroduce the premature OOM
killer issue which was originally addressed by the heuristic.

As per David Chinner the xfs is doing similar thing since 2.6.15 already
so ext4 is not the only affected filesystem.  Moreover he notes:

: For example: IO completion might require unwritten extent conversion
: which executes filesystem transactions and GFP_NOFS allocations. The
: writeback flag on the pages can not be cleared until unwritten
: extent conversion completes. Hence memory reclaim cannot wait on
: page writeback to complete in GFP_NOFS context because it is not
: safe to do so, memcg reclaim or otherwise.

Cc: stable@vger.kernel.org # 3.9+
[tytso@mit.edu: corrected the control flow]
Fixes: c3b94f4 ("memcg: further prevent OOM with too many dirty pages")
Reported-by: Nikolay Borisov <kernel@kyup.com>
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
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