linux.git/include/linux, branch v4.13.13

mm, swap: fix race between swap count continuation operations

2017-11-08T09:17:18+00:00

commit 2628bd6fc052bd85e9864dae4de494d8a6313391 upstream.

One page may store a set of entries of the sis->swap_map
(swap_info_struct->swap_map) in multiple swap clusters.

If some of the entries has sis->swap_map[offset] > SWAP_MAP_MAX,
multiple pages will be used to store the set of entries of the
sis->swap_map.  And the pages are linked with page->lru.  This is called
swap count continuation.  To access the pages which store the set of
entries of the sis->swap_map simultaneously, previously, sis->lock is
used.  But to improve the scalability of __swap_duplicate(), swap
cluster lock may be used in swap_count_continued() now.  This may race
with add_swap_count_continuation() which operates on a nearby swap
cluster, in which the sis->swap_map entries are stored in the same page.

The race can cause wrong swap count in practice, thus cause unfreeable
swap entries or software lockup, etc.

To fix the race, a new spin lock called cont_lock is added to struct
swap_info_struct to protect the swap count continuation page list.  This
is a lock at the swap device level, so the scalability isn't very well.
But it is still much better than the original sis->lock, because it is
only acquired/released when swap count continuation is used.  Which is
considered rare in practice.  If it turns out that the scalability
becomes an issue for some workloads, we can split the lock into some
more fine grained locks.

Link: http://lkml.kernel.org/r/20171017081320.28133-1-ying.huang@intel.com
Fixes: 235b62176712 ("mm/swap: add cluster lock")
Signed-off-by: "Huang, Ying" 
Cc: Johannes Weiner 
Cc: Shaohua Li 
Cc: Tim Chen 
Cc: Michal Hocko 
Cc: Aaron Lu 
Cc: Dave Hansen 
Cc: Andi Kleen 
Cc: Minchan Kim 
Cc: Hugh Dickins 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

KEYS: Fix race between updating and finding a negative key

2017-10-27T08:39:15+00:00

commit 363b02dab09b3226f3bd1420dad9c72b79a42a76 upstream.

Consolidate KEY_FLAG_INSTANTIATED, KEY_FLAG_NEGATIVE and the rejection
error into one field such that:

 (1) The instantiation state can be modified/read atomically.

 (2) The error can be accessed atomically with the state.

 (3) The error isn't stored unioned with the payload pointers.

This deals with the problem that the state is spread over three different
objects (two bits and a separate variable) and reading or updating them
atomically isn't practical, given that not only can uninstantiated keys
change into instantiated or rejected keys, but rejected keys can also turn
into instantiated keys - and someone accessing the key might not be using
any locking.

The main side effect of this problem is that what was held in the payload
may change, depending on the state.  For instance, you might observe the
key to be in the rejected state.  You then read the cached error, but if
the key semaphore wasn't locked, the key might've become instantiated
between the two reads - and you might now have something in hand that isn't
actually an error code.

The state is now KEY_IS_UNINSTANTIATED, KEY_IS_POSITIVE or a negative error
code if the key is negatively instantiated.  The key_is_instantiated()
function is replaced with key_is_positive() to avoid confusion as negative
keys are also 'instantiated'.

Additionally, barriering is included:

 (1) Order payload-set before state-set during instantiation.

 (2) Order state-read before payload-read when using the key.

Further separate barriering is necessary if RCU is being used to access the
payload content after reading the payload pointers.

Fixes: 146aa8b1453b ("KEYS: Merge the type-specific data with the payload data")
Reported-by: Eric Biggers 
Signed-off-by: David Howells 
Reviewed-by: Eric Biggers 
Signed-off-by: Greg Kroah-Hartman

bus: mbus: fix window size calculation for 4GB windows

2017-10-27T08:39:14+00:00

commit 2bbbd96357ce76cc45ec722c00f654aa7b189112 upstream.

At least the Armada XP SoC supports 4GB on a single DRAM window. Because
the size register values contain the actual size - 1, the MSB is set in
that case. For example, the SDRAM window's control register's value is
0xffffffe1 for 4GB (bits 31 to 24 contain the size).

The MBUS driver reads back each window's size from registers and
calculates the actual size as (control_reg | ~DDR_SIZE_MASK) + 1, which
overflows for 32 bit values, resulting in other miscalculations further
on (a bad RAM window for the CESA crypto engine calculated by
mvebu_mbus_setup_cpu_target_nooverlap() in my case).

This patch changes the type in 'struct mbus_dram_window' from u32 to
u64, which allows us to keep using the same register calculation code in
most MBUS-using drivers (which calculate ->size - 1 again).

Fixes: fddddb52a6c4 ("bus: introduce an Marvell EBU MBus driver")
Signed-off-by: Jan Luebbe 
Signed-off-by: Gregory CLEMENT 
Signed-off-by: Greg Kroah-Hartman

vmbus: eliminate duplicate cached index

2017-10-21T15:55:07+00:00

commit 05d00bc94ac27d220d8a78e365d7fa3a26dcca17 upstream.

Don't need cached read index anymore now that packet iterator
is used. The iterator has the original read index until the
visible read_index is updated.

Signed-off-by: Stephen Hemminger 
Signed-off-by: K. Y. Srinivasan 
Signed-off-by: Greg Kroah-Hartman

vmbus: refactor hv_signal_on_read

2017-10-21T15:55:07+00:00

commit 8dd45f2ab005a1f3301296059b23b03ec3dbf79b upstream.

The function hv_signal_on_read was defined in hyperv.h and
only used in one place in ring_buffer code. Clearer to just
move it inline there.

Signed-off-by: Stephen Hemminger 
Signed-off-by: K. Y. Srinivasan 
Signed-off-by: Greg Kroah-Hartman

Drivers: hv: vmbus: Fix bugs in rescind handling

2017-10-21T15:55:06+00:00

commit 192b2d78722ffea188e5ec6ae5d55010dce05a4b upstream.

This patch addresses the following bugs in the current rescind handling code:

1. Fixes a race condition where we may be invoking hv_process_channel_removal()
on an already freed channel.

2. Prevents indefinite wait when rescinding sub-channels by correctly setting
the probe_complete state.

I would like to thank Dexuan for patiently reviewing earlier versions of this
patch and identifying many of the issues fixed here.

Greg, please apply this to 4.14-final.

Fixes: '54a66265d675 ("Drivers: hv: vmbus: Fix rescind handling")'

Signed-off-by: K. Y. Srinivasan 
Reviewed-by: Dexuan Cui 
Signed-off-by: Greg Kroah-Hartman

Drivers: hv: vmbus: Fix rescind handling issues

2017-10-21T15:55:06+00:00

commit 6f3d791f300618caf82a2be0c27456edd76d5164 upstream.

This patch handles the following issues that were observed when we are
handling racing channel offer message and rescind message for the same
offer:

1. Since the host does not respond to messages on a rescinded channel,
in the current code, we could be indefinitely blocked on the vmbus_open() call.

2. When a rescinded channel is being closed, if there is a pending interrupt on the
channel, we could end up freeing the channel that the interrupt handler would run on.

Signed-off-by: K. Y. Srinivasan 
Reviewed-by: Dexuan Cui 
Tested-by: Dexuan Cui 
Signed-off-by: Greg Kroah-Hartman

fs/mpage.c: fix mpage_writepage() for pages with buffers

2017-10-18T07:38:29+00:00

commit f892760aa66a2d657deaf59538fb69433036767c upstream.

When using FAT on a block device which supports rw_page, we can hit
BUG_ON(!PageLocked(page)) in try_to_free_buffers().  This is because we
call clean_buffers() after unlocking the page we've written.  Introduce
a new clean_page_buffers() which cleans all buffers associated with a
page and call it from within bdev_write_page().

[akpm@linux-foundation.org: s/PAGE_SIZE/~0U/ per Linus and Matthew]
Link: http://lkml.kernel.org/r/20171006211541.GA7409@bombadil.infradead.org
Signed-off-by: Matthew Wilcox 
Reported-by: Toshi Kani 
Reported-by: OGAWA Hirofumi 
Tested-by: Toshi Kani 
Acked-by: Johannes Thumshirn 
Cc: Ross Zwisler 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm, oom_reaper: skip mm structs with mmu notifiers

2017-10-12T09:56:13+00:00

commit 4d4bbd8526a8fbeb2c090ea360211fceff952383 upstream.

Andrea has noticed that the oom_reaper doesn't invalidate the range via
mmu notifiers (mmu_notifier_invalidate_range_start/end) and that can
corrupt the memory of the kvm guest for example.

tlb_flush_mmu_tlbonly already invokes mmu notifiers but that is not
sufficient as per Andrea:

 "mmu_notifier_invalidate_range cannot be used in replacement of
  mmu_notifier_invalidate_range_start/end. For KVM
  mmu_notifier_invalidate_range is a noop and rightfully so. A MMU
  notifier implementation has to implement either ->invalidate_range
  method or the invalidate_range_start/end methods, not both. And if you
  implement invalidate_range_start/end like KVM is forced to do, calling
  mmu_notifier_invalidate_range in common code is a noop for KVM.

  For those MMU notifiers that can get away only implementing
  ->invalidate_range, the ->invalidate_range is implicitly called by
  mmu_notifier_invalidate_range_end(). And only those secondary MMUs
  that share the same pagetable with the primary MMU (like AMD iommuv2)
  can get away only implementing ->invalidate_range"

As the callback is allowed to sleep and the implementation is out of
hand of the MM it is safer to simply bail out if there is an mmu
notifier registered.  In order to not fail too early make the
mm_has_notifiers check under the oom_lock and have a little nap before
failing to give the current oom victim some more time to exit.

[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20170913113427.2291-1-mhocko@kernel.org
Fixes: aac453635549 ("mm, oom: introduce oom reaper")
Signed-off-by: Michal Hocko 
Reported-by: Andrea Arcangeli 
Reviewed-by: Andrea Arcangeli 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

iio: ad_sigma_delta: Implement a dedicated reset function

2017-10-12T09:56:11+00:00

commit 7fc10de8d49a748c476532c9d8e8fe19e548dd67 upstream.

Since most of the SD ADCs have the option of reseting the serial
interface by sending a number of SCLKs with CS = 0 and DIN = 1,
a dedicated function that can do this is usefull.

Needed for the patch:  iio: ad7793: Fix the serial interface reset
Signed-off-by: Dragos Bogdan 
Acked-by: Lars-Peter Clausen 
Signed-off-by: Jonathan Cameron 
Signed-off-by: Greg Kroah-Hartman