linux.git/lib, branch v4.9-rc3

lib/genalloc.c: start search from start of chunk

2016-10-28T01:43:43+00:00

gen_pool_alloc_algo() iterates over the chunks of a pool trying to find
a contiguous block of memory that satisfies the allocation request.

The shortcut

	if (size > atomic_read(&chunk->avail))
		continue;

makes the loop skip over chunks that do not have enough bytes left to
fulfill the request.  There are two situations, though, where an
allocation might still fail:

(1) The available memory is not contiguous, i.e.  the request cannot
    be fulfilled due to external fragmentation.

(2) A race condition.  Another thread runs the same code concurrently
    and is quicker to grab the available memory.

In those situations, the loop calls pool->algo() to search the entire
chunk, and pool->algo() returns some value that is >= end_bit to
indicate that the search failed.  This return value is then assigned to
start_bit.  The variables start_bit and end_bit describe the range that
should be searched, and this range should be reset for every chunk that
is searched.  Today, the code fails to reset start_bit to 0.  As a
result, prefixes of subsequent chunks are ignored.  Memory allocations
might fail even though there is plenty of room left in these prefixes of
those other chunks.

Fixes: 7f184275aa30 ("lib, Make gen_pool memory allocator lockless")
Link: http://lkml.kernel.org/r/1477420604-28918-1-git-send-email-danielmentz@google.com
Signed-off-by: Daniel Mentz 
Reviewed-by: Mathieu Desnoyers 
Acked-by: Will Deacon 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

lib/stackdepot.c: bump stackdepot capacity from 16MB to 128MB

2016-10-28T01:43:43+00:00

KASAN uses stackdepot to memorize stacks for all kmalloc/kfree calls.
Current stackdepot capacity is 16MB (1024 top level entries x 4 pages on
second level).  Size of each stack is (num_frames + 3) * sizeof(long).
Which gives us ~84K stacks.  This capacity was chosen empirically and it
is enough to run kernel normally.

However, when lots of configs are enabled and a fuzzer tries to maximize
code coverage, it easily hits the limit within tens of minutes.  I've
tested for long a time with number of top level entries bumped 4x
(4096).  And I think I've seen overflow only once.  But I don't have all
configs enabled and code coverage has not reached maximum yet.  So bump
it 8x to 8192.

Since we have two-level table, memory cost of this is very moderate --
currently the top-level table is 8KB, with this patch it is 64KB, which
is negligible under KASAN.

Here is some approx math.

128MB allows us to memorize ~670K stacks (assuming stack is ~200b).
I've grepped kernel for kmalloc|kfree|kmem_cache_alloc|kmem_cache_free|
kzalloc|kstrdup|kstrndup|kmemdup and it gives ~60K matches.  Most of
alloc/free call sites are reachable with only one stack.  But some
utility functions can have large fanout.  Assuming average fanout is 5x,
total number of alloc/free stacks is ~300K.

Link: http://lkml.kernel.org/r/1476458416-122131-1-git-send-email-dvyukov@google.com
Signed-off-by: Dmitry Vyukov 
Cc: Andrey Ryabinin 
Cc: Alexander Potapenko 
Cc: Joonsoo Kim 
Cc: Baozeng Ding 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

latent_entropy: raise CONFIG_FRAME_WARN by default

2016-10-28T01:43:43+00:00

When building with the latent_entropy plugin, set the default
CONFIG_FRAME_WARN to 2048, since some __init functions have many basic
blocks that, when instrumented by the latent_entropy plugin, grow beyond
1024 byte stack size on 32-bit builds.

Link: http://lkml.kernel.org/r/20161018211216.GA39687@beast
Signed-off-by: Kees Cook 
Reported-by: kbuild test robot 
Cc: Emese Revfy 
Cc: Ingo Molnar 
Cc: Michal Marek 
Cc: "Paul E. McKenney" 
Cc: Dan Williams 
Cc: Andrey Ryabinin 
Cc: Josh Poimboeuf 
Cc: Tejun Heo 
Cc: Nikolay Aleksandrov 
Cc: Dmitry Vyukov 
Cc: Shuah Khan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge tag 'gcc-plugins-v4.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

2016-10-15T17:03:15+00:00

Pull gcc plugins update from Kees Cook:
 "This adds a new gcc plugin named "latent_entropy". It is designed to
  extract as much possible uncertainty from a running system at boot
  time as possible, hoping to capitalize on any possible variation in
  CPU operation (due to runtime data differences, hardware differences,
  SMP ordering, thermal timing variation, cache behavior, etc).

  At the very least, this plugin is a much more comprehensive example
  for how to manipulate kernel code using the gcc plugin internals"

* tag 'gcc-plugins-v4.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  latent_entropy: Mark functions with __latent_entropy
  gcc-plugins: Add latent_entropy plugin

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2016-10-15T01:19:05+00:00

Pull more misc uaccess and vfs updates from Al Viro:
 "The rest of the stuff from -next (more uaccess work) + assorted fixes"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  score: traps: Add missing include file to fix build error
  fs/super.c: don't fool lockdep in freeze_super() and thaw_super() paths
  fs/super.c: fix race between freeze_super() and thaw_super()
  overlayfs: Fix setting IOP_XATTR flag
  iov_iter: kernel-doc import_iovec() and rw_copy_check_uvector()
  blackfin: no access_ok() for __copy_{to,from}_user()
  arm64: don't zero in __copy_from_user{,_inatomic}
  arm: don't zero in __copy_from_user_inatomic()/__copy_from_user()
  arc: don't leak bits of kernel stack into coredump
  alpha: get rid of tail-zeroing in __copy_user()

iov_iter: kernel-doc import_iovec() and rw_copy_check_uvector()

2016-10-15T00:00:34+00:00

Both import_iovec() and rw_copy_check_uvector() take an array
(typically small and on-stack) which is used to hold an iovec array copy
from userspace. This is to avoid an expensive memory allocation in the
fast path (i.e. few iovec elements).

The caller may have to check whether these functions actually used
the provided buffer or allocated a new one -- but this differs between
the too. Let's just add a kernel doc to clarify what the semantics are
for each function.

Signed-off-by: Vegard Nossum 
Signed-off-by: Al Viro

Merge tag 'linux-kselftest-4.9-rc1-update' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest

2016-10-14T22:17:12+00:00

Pull kselftest updates from Shuah Khan:
 "This update consists of:

   - Fixes and improvements to existing tests

   - Moving code from Documentation to selftests, samples, and tools:

     * Moves dnotify_test, prctl, ptp, vDSO, ia64, watchdog, and
       networking tests from Documentation to selftests.

     * Moves mic/mpssd, misc-devices/mei, timers, watchdog, auxdisplay,
       and blackfin examples from Documentation to samples.

     * Moves accounting, laptops/dslm, and pcmcia/crc32hash tools from
       Documentation to tools.

     * Deletes BUILD_DOCSRC and its dependencies"

* tag 'linux-kselftest-4.9-rc1-update' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest: (21 commits)
  selftests/futex: Check ANSI terminal color support
  Doc: update 00-INDEX files to reflect the runnable code move
  samples: move blackfin gptimers-example from Documentation
  tools: move pcmcia crc32hash tool from Documentation
  tools: move laptops dslm tool from Documentation
  tools: move accounting tool from Documentation
  samples: move auxdisplay example code from Documentation
  samples: move watchdog example code from Documentation
  samples: move timers example code from Documentation
  samples: move misc-devices/mei example code from Documentation
  samples: move mic/mpssd example code from Documentation
  selftests: Move networking/timestamping from Documentation
  selftests: move watchdog tests from Documentation/watchdog
  selftests: move ia64 tests from Documentation/ia64
  selftests: move vDSO tests from Documentation/vDSO
  selftests: move ptp tests from Documentation/ptp
  selftests: move prctl tests from Documentation/prctl
  selftests: move dnotify_test from Documentation/filesystems
  selftests/timers: Add missing error code assignment before test
  selftests/zram: replace ZRAM_LZ4_COMPRESS
  ...

Merge branch 'for-4.9' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu

2016-10-14T18:46:25+00:00

Pull percpu updates from Tejun Heo:

 - Nick improved generic implementations of percpu operations which
   modify the variable and return so that they calculate the physical
   address only once.

 - percpu_ref percpu <-> atomic mode switching improvements. The
   patchset was originally posted about a year ago but fell through the
   crack.

 - misc non-critical fixes.

* 'for-4.9' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu:
  mm/percpu.c: fix potential memory leakage for pcpu_embed_first_chunk()
  mm/percpu.c: correct max_distance calculation for pcpu_embed_first_chunk()
  percpu: eliminate two sparse warnings
  percpu: improve generic percpu modify-return implementation
  percpu-refcount: init ->confirm_switch member properly
  percpu_ref: allow operation mode switching operations to be called concurrently
  percpu_ref: restructure operation mode switching
  percpu_ref: unify staggered atomic switching wait behavior
  percpu_ref: reorganize __percpu_ref_switch_to_atomic() and relocate percpu_ref_switch_to_atomic()
  percpu_ref: remove unnecessary RCU grace period for staggered atomic switching confirmation

kcov: do not instrument lib/stackdepot.c

2016-10-11T22:06:32+00:00

There's no point in collecting coverage from lib/stackdepot.c, as it is
not a function of syscall inputs.  Disabling kcov instrumentation for that
file will reduce the coverage noise level.

Link: http://lkml.kernel.org/r/1474640972-104131-1-git-send-email-glider@google.com
Signed-off-by: Alexander Potapenko 
Acked-by: Dmitry Vyukov 
Cc: Kostya Serebryany 
Cc: Andrey Konovalov 
Cc: syzkaller 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

lib/bitmap.c: enhance bitmap syntax

2016-10-11T22:06:30+00:00

Today there are platforms with many CPUs (up to 4K).  Trying to boot only
part of the CPUs may result in too long string.

For example lets take NPS platform that is part of arch/arc.  This
platform have SMP system with 256 cores each with 16 HW threads (SMT
machine) where HW thread appears as CPU to the kernel.  In this example
there is total of 4K CPUs.  When one tries to boot only part of the HW
threads from each core the string representing the map may be long...  For
example if for sake of performance we decided to boot only first half of
HW threads of each core the map will look like:
0-7,16-23,32-39,...,4080-4087

This patch introduce new syntax to accommodate with such use case.  I
added an optional postfix to a range of CPUs which will choose according
to given modulo the desired range of reminders i.e.:

    :sed_size/group_size

For example, above map can be described in new syntax like this:
0-4095:8/16

Note that this patch is backward compatible with current syntax.

[akpm@linux-foundation.org: rework documentation]
Link: http://lkml.kernel.org/r/1473579629-4283-1-git-send-email-noamca@mellanox.com
Signed-off-by: Noam Camus 
Cc: David Decotigny 
Cc: Ben Hutchings 
Cc: David S. Miller 
Cc: Pan Xinhui 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds