linux-toradex.git/Documentation, branch v3.12.25

mm, pcp: allow restoring percpu_pagelist_fraction default

2014-07-18T13:51:01+00:00

commit 7cd2b0a34ab8e4db971920eef8982f985441adfb upstream.

Oleg reports a division by zero error on zero-length write() to the
percpu_pagelist_fraction sysctl:

    divide error: 0000 [#1] SMP DEBUG_PAGEALLOC
    CPU: 1 PID: 9142 Comm: badarea_io Not tainted 3.15.0-rc2-vm-nfs+ #19
    Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
    task: ffff8800d5aeb6e0 ti: ffff8800d87a2000 task.ti: ffff8800d87a2000
    RIP: 0010: percpu_pagelist_fraction_sysctl_handler+0x84/0x120
    RSP: 0018:ffff8800d87a3e78  EFLAGS: 00010246
    RAX: 0000000000000f89 RBX: ffff88011f7fd000 RCX: 0000000000000000
    RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000010
    RBP: ffff8800d87a3e98 R08: ffffffff81d002c8 R09: ffff8800d87a3f50
    R10: 000000000000000b R11: 0000000000000246 R12: 0000000000000060
    R13: ffffffff81c3c3e0 R14: ffffffff81cfddf8 R15: ffff8801193b0800
    FS:  00007f614f1e9740(0000) GS:ffff88011f440000(0000) knlGS:0000000000000000
    CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
    CR2: 00007f614f1fa000 CR3: 00000000d9291000 CR4: 00000000000006e0
    Call Trace:
      proc_sys_call_handler+0xb3/0xc0
      proc_sys_write+0x14/0x20
      vfs_write+0xba/0x1e0
      SyS_write+0x46/0xb0
      tracesys+0xe1/0xe6

However, if the percpu_pagelist_fraction sysctl is set by the user, it
is also impossible to restore it to the kernel default since the user
cannot write 0 to the sysctl.

This patch allows the user to write 0 to restore the default behavior.
It still requires a fraction equal to or larger than 8, however, as
stated by the documentation for sanity.  If a value in the range [1, 7]
is written, the sysctl will return EINVAL.

This successfully solves the divide by zero issue at the same time.

Signed-off-by: David Rientjes 
Reported-by: Oleg Drokin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Jiri Slaby

Documentation/SubmittingPatches: describe the Fixes: tag

2014-07-17T11:43:20+00:00

commit 8401aa1f59975c03eeebd3ac6d264cbdfe9af5de upstream.

Update the SubmittingPatches process to include howto about the new
'Fixes:' tag to be used when a patch fixes an issue in a previous commit
(found by git-bisect for example).

Signed-off-by: Jacob Keller 
Tested-by: Aaron Brown 
Signed-off-by: Jeff Kirsher 
Cc: Randy Dunlap 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Jiri Slaby

mm/memory-failure.c: support use of a dedicated thread to handle SIGBUS(BUS_MCEERR_AO)

2014-07-02T10:06:11+00:00

commit 3ba08129e38437561df44c36b7ea9081185d5333 upstream.

Currently memory error handler handles action optional errors in the
deferred manner by default.  And if a recovery aware application wants
to handle it immediately, it can do it by setting PF_MCE_EARLY flag.
However, such signal can be sent only to the main thread, so it's
problematic if the application wants to have a dedicated thread to
handler such signals.

So this patch adds dedicated thread support to memory error handler.  We
have PF_MCE_EARLY flags for each thread separately, so with this patch
AO signal is sent to the thread with PF_MCE_EARLY flag set, not the main
thread.  If you want to implement a dedicated thread, you call prctl()
to set PF_MCE_EARLY on the thread.

Memory error handler collects processes to be killed, so this patch lets
it check PF_MCE_EARLY flag on each thread in the collecting routines.

No behavioral change for all non-early kill cases.

Tony said:

: The old behavior was crazy - someone with a multithreaded process might
: well expect that if they call prctl(PF_MCE_EARLY) in just one thread, then
: that thread would see the SIGBUS with si_code = BUS_MCEERR_A0 - even if
: that thread wasn't the main thread for the process.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Naoya Horiguchi 
Reviewed-by: Tony Luck 
Cc: Kamil Iskra 
Cc: Andi Kleen 
Cc: Borislav Petkov 
Cc: Chen Gong 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Jiri Slaby

ACPI / memhotplug: add parameter to disable memory hotplug

2014-06-27T08:25:16+00:00

commit 00159a2013269bc0a617de885e4b921349192bd0 upstream.

When booting a kexec/kdump kernel on a system that has specific memory
hotplug regions the boot will fail with warnings like:

 swapper/0: page allocation failure: order:9, mode:0x84d0
 CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.10.0-65.el7.x86_64 #1
 Hardware name: QCI QSSC-S4R/QSSC-S4R, BIOS QSSC-S4R.QCI.01.00.S013.032920111005 03/29/2011
  0000000000000000 ffff8800341bd8c8 ffffffff815bcc67 ffff8800341bd950
  ffffffff8113b1a0 ffff880036339b00 0000000000000009 00000000000084d0
  ffff8800341bd950 ffffffff815b87ee 0000000000000000 0000000000000200
 Call Trace:
  [] dump_stack+0x19/0x1b
  [] warn_alloc_failed+0xf0/0x160
  [] ?  __alloc_pages_direct_compact+0xac/0x196
  [] __alloc_pages_nodemask+0x7ff/0xa00
  [] vmemmap_alloc_block+0x62/0xba
  [] vmemmap_alloc_block_buf+0x15/0x3b
  [] vmemmap_populate+0xb4/0x21b
  [] sparse_mem_map_populate+0x27/0x35
  [] sparse_add_one_section+0x7a/0x185
  [] __add_pages+0xaf/0x240
  [] arch_add_memory+0x59/0xd0
  [] add_memory+0xb9/0x1b0
  [] acpi_memory_device_add+0x18d/0x26d
  [] acpi_bus_device_attach+0x7d/0xcd
  [] acpi_ns_walk_namespace+0xc8/0x17f
  [] ? acpi_bus_type_and_status+0x90/0x90
  [] ? acpi_bus_type_and_status+0x90/0x90
  [] acpi_walk_namespace+0x95/0xc5
  [] acpi_bus_scan+0x8b/0x9d
  [] acpi_scan_init+0x63/0x160
  [] acpi_init+0x25d/0x2a6
  [] ? acpi_sleep_proc_init+0x2a/0x2a
  [] do_one_initcall+0xe2/0x190
  [] kernel_init_freeable+0x17c/0x207
  [] ? do_early_param+0x88/0x88
  [] ? rest_init+0x80/0x80
  [] kernel_init+0xe/0x180
  [] ret_from_fork+0x7c/0xb0
  [] ? rest_init+0x80/0x80
 Mem-Info:
 Node 0 DMA per-cpu:
 CPU    0: hi:    0, btch:   1 usd:   0
 Node 0 DMA32 per-cpu:
 CPU    0: hi:   42, btch:   7 usd:   0
 active_anon:0 inactive_anon:0 isolated_anon:0
  active_file:0 inactive_file:0 isolated_file:0
  unevictable:0 dirty:0 writeback:0 unstable:0
  free:872 slab_reclaimable:13 slab_unreclaimable:1880
  mapped:0 shmem:0 pagetables:0 bounce:0
  free_cma:0

because the system has run out of memory at boot time.  This occurs
because of the following sequence in the boot:

Main kernel boots and sets E820 map.  The second kernel is booted with a
map generated by the kdump service using memmap= and memmap=exactmap.
These parameters are added to the kernel parameters of the kexec/kdump
kernel.   The kexec/kdump kernel has limited memory resources so as not
to severely impact the main kernel.

The system then panics and the kdump/kexec kernel boots (which is a
completely new kernel boot).  During this boot ACPI is initialized and the
kernel (as can be seen above) traverses the ACPI namespace and finds an
entry for a memory device to be hotadded.

ie)

  [] __add_pages+0xaf/0x240
  [] arch_add_memory+0x59/0xd0
  [] add_memory+0xb9/0x1b0
  [] acpi_memory_device_add+0x18d/0x26d
  [] acpi_bus_device_attach+0x7d/0xcd
  [] acpi_ns_walk_namespace+0xc8/0x17f
  [] ? acpi_bus_type_and_status+0x90/0x90
  [] ? acpi_bus_type_and_status+0x90/0x90
  [] acpi_walk_namespace+0x95/0xc5
  [] acpi_bus_scan+0x8b/0x9d
  [] acpi_scan_init+0x63/0x160
  [] acpi_init+0x25d/0x2a6

At this point the kernel adds page table information and the the kexec/kdump
kernel runs out of memory.

This can also be reproduced by using the memmap=exactmap and mem=X
parameters on the main kernel and booting.

This patchset resolves the problem by adding a kernel parameter,
acpi_no_memhotplug, to disable ACPI memory hotplug.

Signed-off-by: Prarit Bhargava 
Acked-by: Vivek Goyal 
Acked-by: Toshi Kani 
Acked-by: David Rientjes 
Signed-off-by: Rafael J. Wysocki 
Signed-off-by: Jiri Slaby

ima: audit log files opened with O_DIRECT flag

2014-06-20T15:34:22+00:00

commit f9b2a735bdddf836214b5dca74f6ca7712e5a08c upstream.

Files are measured or appraised based on the IMA policy.  When a
file, in policy, is opened with the O_DIRECT flag, a deadlock
occurs.

The first attempt at resolving this lockdep temporarily removed the
O_DIRECT flag and restored it, after calculating the hash.  The
second attempt introduced the O_DIRECT_HAVELOCK flag. Based on this
flag, do_blockdev_direct_IO() would skip taking the i_mutex a second
time.  The third attempt, by Dmitry Kasatkin, resolves the i_mutex
locking issue, by re-introducing the IMA mutex, but uncovered
another problem.  Reading a file with O_DIRECT flag set, writes
directly to userspace pages.  A second patch allocates a user-space
like memory.  This works for all IMA hooks, except ima_file_free(),
which is called on __fput() to recalculate the file hash.

Until this last issue is addressed, do not 'collect' the
measurement for measuring, appraising, or auditing files opened
with the O_DIRECT flag set.  Based on policy, permit or deny file
access.  This patch defines a new IMA policy rule option named
'permit_directio'.  Policy rules could be defined, based on LSM
or other criteria, to permit specific applications to open files
with the O_DIRECT flag set.

Changelog v1:
- permit or deny file access based IMA policy rules

Signed-off-by: Mimi Zohar 
Acked-by: Dmitry Kasatkin 
Signed-off-by: Jiri Slaby

Documentation: fix DOCBOOKS=... building

2014-06-20T15:33:53+00:00

commit e60cbeedc48d80689c249ab5dcc3c31ad0452dea upstream.

Prior to commit 4266129964b8 ("[media] DocBook: Move all media docbook
stuff into its own directory") it was possible to build only a single
(or more) book(s) by calling, for example

    make htmldocs DOCBOOKS=80211.xml

This now fails:

    cp: target `.../Documentation/DocBook//media_api' is not a directory

Ignore errors from that copy to make this possible again.

Fixes: 4266129964b8 ("[media] DocBook: Move all media docbook stuff into its own directory")
Signed-off-by: Johannes Berg 
Acked-by: Randy Dunlap 
Cc: Mauro Carvalho Chehab 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Jiri Slaby

Input: elantech - fix touchpad initialization on Gigabyte U2442

2014-06-09T13:53:29+00:00

commit 36189cc3cd57ab0f1cd75241f93fe01de928ac06 upstream.

The hw_version 3 Elantech touchpad on the Gigabyte U2442 does not accept
0x0b as initialization value for r10, this stand-alone version of the
driver: http://planet76.com/drivers/elantech/psmouse-elantech-v6.tar.bz2

Uses 0x03 which does work, so this means not setting bit 3 of r10 which
sets: "Enable Real H/W Resolution In Absolute mode"

Which will result in half the x and y resolution we get with that bit set,
so simply not setting it everywhere is not a solution. We've been unable to
find a way to identify touchpads where setting the bit will fail, so this
patch uses a dmi based blacklist for this.

https://bugzilla.kernel.org/show_bug.cgi?id=61151

Reported-by: Philipp Wolfer 
Tested-by: Philipp Wolfer 
Signed-off-by: Hans de Goede 
Signed-off-by: Dmitry Torokhov 
Signed-off-by: Jiri Slaby

Documentation: Update stable address in Chinese and Japanese translations

2014-06-09T13:53:23+00:00

commit 98b0f811aade1b7c6e7806c86aa0befd5919d65f upstream.

The English and Korean translations were updated, the Chinese and Japanese
weren't.

Signed-off-by: Geert Uytterhoeven 
Signed-off-by: Jiri Slaby 
Signed-off-by: Jiri Slaby

media: media: gspca: sn9c20x: add ID for Genius Look 1320 V2

2014-05-15T07:55:30+00:00

commit 61f0319193c44adbbada920162d880b1fdb3aeb3 upstream.

Signed-off-by: Wolfram Sang 
Signed-off-by: Hans de Goede 
Signed-off-by: Mauro Carvalho Chehab 
Signed-off-by: Jiri Slaby

spi: efm32: use $vendor,$device scheme for compatible string

2014-05-15T07:54:49+00:00

commit 12f6dd860cf8bf036c0bec38c00a53da71bcd43a upstream.

Wolfram Sang pointed out that "efm32,$device" is non-standard. So use the
common scheme and prefix device with "efm32-". The old compatible string
is left in place until arch/arm/boot/dts/efm32* is fixed.

Signed-off-by: Uwe Kleine-König 
Acked-by: Wolfram Sang 
Signed-off-by: Mark Brown 
Signed-off-by: Jiri Slaby