linux-stable.git/include/linux, branch v3.16.40

rose: limit sk_filter trim to payload

2017-02-23T03:54:46+00:00

commit f4979fcea7fd36d8e2f556abef86f80e0d5af1ba upstream.

Sockets can have a filter program attached that drops or trims
incoming packets based on the filter program return value.

Rose requires data packets to have at least ROSE_MIN_LEN bytes. It
verifies this on arrival in rose_route_frame and unconditionally pulls
the bytes in rose_recvmsg. The filter can trim packets to below this
value in-between, causing pull to fail, leaving the partial header at
the time of skb_copy_datagram_msg.

Place a lower bound on the size to which sk_filter may trim packets
by introducing sk_filter_trim_cap and call this for rose packets.

Signed-off-by: Willem de Bruijn 
Acked-by: Daniel Borkmann 
Signed-off-by: David S. Miller 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

ipc/sem.c: fix complex_count vs. simple op race

2017-02-23T03:54:12+00:00

commit 5864a2fd3088db73d47942370d0f7210a807b9bc upstream.

Commit 6d07b68ce16a ("ipc/sem.c: optimize sem_lock()") introduced a
race:

sem_lock has a fast path that allows parallel simple operations.
There are two reasons why a simple operation cannot run in parallel:
 - a non-simple operations is ongoing (sma->sem_perm.lock held)
 - a complex operation is sleeping (sma->complex_count != 0)

As both facts are stored independently, a thread can bypass the current
checks by sleeping in the right positions.  See below for more details
(or kernel bugzilla 105651).

The patch fixes that by creating one variable (complex_mode)
that tracks both reasons why parallel operations are not possible.

The patch also updates stale documentation regarding the locking.

With regards to stable kernels:
The patch is required for all kernels that include the
commit 6d07b68ce16a ("ipc/sem.c: optimize sem_lock()") (3.10?)

The alternative is to revert the patch that introduced the race.

The patch is safe for backporting, i.e. it makes no assumptions
about memory barriers in spin_unlock_wait().

Background:
Here is the race of the current implementation:

Thread A: (simple op)
- does the first "sma->complex_count == 0" test

Thread B: (complex op)
- does sem_lock(): This includes an array scan. But the scan can't
  find Thread A, because Thread A does not own sem->lock yet.
- the thread does the operation, increases complex_count,
  drops sem_lock, sleeps

Thread A:
- spin_lock(&sem->lock), spin_is_locked(sma->sem_perm.lock)
- sleeps before the complex_count test

Thread C: (complex op)
- does sem_lock (no array scan, complex_count==1)
- wakes up Thread B.
- decrements complex_count

Thread A:
- does the complex_count test

Bug:
Now both thread A and thread C operate on the same array, without
any synchronization.

Fixes: 6d07b68ce16a ("ipc/sem.c: optimize sem_lock()")
Link: http://lkml.kernel.org/r/1469123695-5661-1-git-send-email-manfred@colorfullife.com
Reported-by: 
Cc: "H. Peter Anvin" 
Cc: Peter Zijlstra 
Cc: Davidlohr Bueso 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: <1vier1@web.de>
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
[bwh: Backported to 3.16:
 - We missed out on some earlier memory barrier changes
 - Use set_mb instead of smp_store_mb]
Signed-off-by: Ben Hutchings

compiler: Allow 1- and 2-byte smp_load_acquire() and smp_store_release()

2017-02-23T03:54:11+00:00

commit 536fa402221f09633e7c5801b327055ab716a363 upstream.

CPUs without single-byte and double-byte loads and stores place some
"interesting" requirements on concurrent code.  For example (adapted
from Peter Hurley's test code), suppose we have the following structure:

	struct foo {
		spinlock_t lock1;
		spinlock_t lock2;
		char a; /* Protected by lock1. */
		char b; /* Protected by lock2. */
	};
	struct foo *foop;

Of course, it is common (and good) practice to place data protected
by different locks in separate cache lines.  However, if the locks are
rarely acquired (for example, only in rare error cases), and there are
a great many instances of the data structure, then memory footprint can
trump false-sharing concerns, so that it can be better to place them in
the same cache cache line as above.

But if the CPU does not support single-byte loads and stores, a store
to foop->a will do a non-atomic read-modify-write operation on foop->b,
which will come as a nasty surprise to someone holding foop->lock2.  So we
now require CPUs to support single-byte and double-byte loads and stores.
Therefore, this commit adjusts the definition of __native_word() to allow
these sizes to be used by smp_load_acquire() and smp_store_release().

Signed-off-by: Paul E. McKenney 
Cc: Peter Zijlstra 
Signed-off-by: Ben Hutchings

mm/hugetlb: check for reserved hugepages during memory offline

2017-02-23T03:54:10+00:00

commit 082d5b6b60e9f25e1511557fcfcb21eedd267446 upstream.

In dissolve_free_huge_pages(), free hugepages will be dissolved without
making sure that there are enough of them left to satisfy hugepage
reservations.

Fix this by adding a return value to dissolve_free_huge_pages() and
checking h->free_huge_pages vs.  h->resv_huge_pages.  Note that this may
lead to the situation where dissolve_free_huge_page() returns an error
and all free hugepages that were dissolved before that error are lost,
while the memory block still cannot be set offline.

Fixes: c8721bbb ("mm: memory-hotplug: enable memory hotplug to handle hugepage")
Link: http://lkml.kernel.org/r/20160926172811.94033-3-gerald.schaefer@de.ibm.com
Signed-off-by: Gerald Schaefer 
Acked-by: Michal Hocko 
Acked-by: Naoya Horiguchi 
Cc: "Kirill A . Shutemov" 
Cc: Vlastimil Babka 
Cc: Mike Kravetz 
Cc: "Aneesh Kumar K . V" 
Cc: Martin Schwidefsky 
Cc: Heiko Carstens 
Cc: Rui Teng 
Cc: Dave Hansen 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

mfd: 88pm80x: Double shifting bug in suspend/resume

2017-02-23T03:54:09+00:00

commit 9a6dc644512fd083400a96ac4a035ac154fe6b8d upstream.

set_bit() and clear_bit() take the bit number so this code is really
doing "1 << (1 << irq)" which is a double shift bug.  It's done
consistently so it won't cause a problem unless "irq" is more than 4.

Fixes: 70c6cce04066 ('mfd: Support 88pm80x in 80x driver')
Signed-off-by: Dan Carpenter 
Signed-off-by: Lee Jones 
Signed-off-by: Ben Hutchings

svcrdma: Tail iovec leaves an orphaned DMA mapping

2017-02-23T03:54:03+00:00

commit cace564f8b6260e806f5e28d7f192fd0e0c603ed upstream.

The ctxt's count field is overloaded to mean the number of pages in
the ctxt->page array and the number of SGEs in the ctxt->sge array.
Typically these two numbers are the same.

However, when an inline RPC reply is constructed from an xdr_buf
with a tail iovec, the head and tail often occupy the same page,
but each are DMA mapped independently. In that case, ->count equals
the number of pages, but it does not equal the number of SGEs.
There's one more SGE, for the tail iovec. Hence there is one more
DMA mapping than there are pages in the ctxt->page array.

This isn't a real problem until the server's iommu is enabled. Then
each RPC reply that has content in that iovec orphans a DMA mapping
that consists of real resources.

krb5i and krb5p always populate that tail iovec. After a couple
million sent krb5i/p RPC replies, the NFS server starts behaving
erratically. Reboot is needed to clear the problem.

Fixes: 9d11b51ce7c1 ("svcrdma: Fix send_reply() scatter/gather set-up")
Signed-off-by: Chuck Lever 
Signed-off-by: J. Bruce Fields 
[bwh: Backported to 3.16:
 - Adjust context
 - Drop changes to svc_rdma_bc_sendto()
 - s/xprt->sc_pd->local_dma_lkey/xprt->sc_dma_lkey/
Signed-off-by: Ben Hutchings

pwm: Unexport children before chip removal

2017-02-23T03:53:57+00:00

commit 0733424c9ba9f42242409d1ece780777272f7ea1 upstream.

Exported pwm channels aren't removed before the pwmchip and are
leaked. This results in invalid sysfs files. This fix removes
all exported pwm channels before chip removal.

Signed-off-by: David Hsu 
Fixes: 76abbdde2d95 ("pwm: Add sysfs interface")
Signed-off-by: Thierry Reding 
Signed-off-by: Ben Hutchings

fs: Give dentry to inode_change_ok() instead of inode

2017-02-23T03:53:52+00:00

commit 31051c85b5e2aaaf6315f74c72a732673632a905 upstream.

inode_change_ok() will be resposible for clearing capabilities and IMA
extended attributes and as such will need dentry. Give it as an argument
to inode_change_ok() instead of an inode. Also rename inode_change_ok()
to setattr_prepare() to better relect that it does also some
modifications in addition to checks.

Reviewed-by: Christoph Hellwig 
Signed-off-by: Jan Kara 
[bwh: Backported to 3.16:
 - Drop changes to orangefs, overlayfs
 - Adjust filenames, context
 - In nfsd, pass dentry to nfsd_sanitize_attrs()
 - Update ext3 as well]
Signed-off-by: Ben Hutchings

Revert "fs: Give dentry to inode_change_ok() instead of inode"

2017-02-23T03:53:52+00:00

This reverts commit be9df699432235753c3824b0f5a27d46de7fdc9e, which was
commit 31051c85b5e2aaaf6315f74c72a732673632a905 upstream.  The backport
breaks fuse and makes a mess of xfs, which can be improved by picking
further upstream commits as I should have done in the first place.

Signed-off-by: Ben Hutchings

Using BUG_ON() as an assert() is _never_ acceptable

2016-11-20T01:17:40+00:00

commit 21f54ddae449f4bdd9f1498124901d67202243d9 upstream.

That just generally kills the machine, and makes debugging only much
harder, since the traces may long be gone.

Debugging by assert() is a disease.  Don't do it.  If you can continue,
you're much better off doing so with a live machine where you have a
much higher chance that the report actually makes it to the system logs,
rather than result in a machine that is just completely dead.

The only valid situation for BUG_ON() is when continuing is not an
option, because there is massive corruption.  But if you are just
verifying that something is true, you warn about your broken assumptions
(preferably just once), and limp on.

Fixes: 22f2ac51b6d6 ("mm: workingset: fix crash in shadow node shrinker caused by replace_page_cache_page()")
Cc: Johannes Weiner 
Cc: Miklos Szeredi 
Cc: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Ben Hutchings