Commit Graph

502 Commits

Author SHA1 Message Date
Eric B Munson
5bbe3547aa mm: allow compaction of unevictable pages
Currently, pages which are marked as unevictable are protected from
compaction, but not from other types of migration.  The POSIX real time
extension explicitly states that mlock() will prevent a major page
fault, but the spirit of this is that mlock() should give a process the
ability to control sources of latency, including minor page faults.
However, the mlock manpage only explicitly says that a locked page will
not be written to swap and this can cause some confusion.  The
compaction code today does not give a developer who wants to avoid swap
but wants to have large contiguous areas available any method to achieve
this state.  This patch introduces a sysctl for controlling compaction
behavior with respect to the unevictable lru.  Users who demand no page
faults after a page is present can set compact_unevictable_allowed to 0
and users who need the large contiguous areas can enable compaction on
locked memory by leaving the default value of 1.

To illustrate this problem I wrote a quick test program that mmaps a
large number of 1MB files filled with random data.  These maps are
created locked and read only.  Then every other mmap is unmapped and I
attempt to allocate huge pages to the static huge page pool.  When the
compact_unevictable_allowed sysctl is 0, I cannot allocate hugepages
after fragmenting memory.  When the value is set to 1, allocations
succeed.

Signed-off-by: Eric B Munson <emunson@akamai.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Christoph Lameter <cl@linux.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-15 16:35:17 -07:00
Linus Torvalds
1dcf58d6e6 Merge branch 'akpm' (patches from Andrew)
Merge first patchbomb from Andrew Morton:

 - arch/sh updates

 - ocfs2 updates

 - kernel/watchdog feature

 - about half of mm/

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (122 commits)
  Documentation: update arch list in the 'memtest' entry
  Kconfig: memtest: update number of test patterns up to 17
  arm: add support for memtest
  arm64: add support for memtest
  memtest: use phys_addr_t for physical addresses
  mm: move memtest under mm
  mm, hugetlb: abort __get_user_pages if current has been oom killed
  mm, mempool: do not allow atomic resizing
  memcg: print cgroup information when system panics due to panic_on_oom
  mm: numa: remove migrate_ratelimited
  mm: fold arch_randomize_brk into ARCH_HAS_ELF_RANDOMIZE
  mm: split ET_DYN ASLR from mmap ASLR
  s390: redefine randomize_et_dyn for ELF_ET_DYN_BASE
  mm: expose arch_mmap_rnd when available
  s390: standardize mmap_rnd() usage
  powerpc: standardize mmap_rnd() usage
  mips: extract logic for mmap_rnd()
  arm64: standardize mmap_rnd() usage
  x86: standardize mmap_rnd() usage
  arm: factor out mmap ASLR into mmap_rnd
  ...
2015-04-14 16:49:17 -07:00
Ulrich Obergfell
195daf665a watchdog: enable the new user interface of the watchdog mechanism
With the current user interface of the watchdog mechanism it is only
possible to disable or enable both lockup detectors at the same time.
This series introduces new kernel parameters and changes the semantics of
some existing kernel parameters, so that the hard lockup detector and the
soft lockup detector can be disabled or enabled individually.  With this
series applied, the user interface is as follows.

- parameters in /proc/sys/kernel

  . soft_watchdog
    This is a new parameter to control and examine the run state of
    the soft lockup detector.

  . nmi_watchdog
    The semantics of this parameter have changed. It can now be used
    to control and examine the run state of the hard lockup detector.

  . watchdog
    This parameter is still available to control the run state of both
    lockup detectors at the same time. If this parameter is examined,
    it shows the logical OR of soft_watchdog and nmi_watchdog.

  . watchdog_thresh
    The semantics of this parameter are not affected by the patch.

- kernel command line parameters

  . nosoftlockup
    The semantics of this parameter have changed. It can now be used
    to disable the soft lockup detector at boot time.

  . nmi_watchdog=0 or nmi_watchdog=1
    Disable or enable the hard lockup detector at boot time. The patch
    introduces '=1' as a new option.

  . nowatchdog
    The semantics of this parameter are not affected by the patch. It
    is still available to disable both lockup detectors at boot time.

Also, remove the proc_dowatchdog() function which is no longer needed.

[dzickus@redhat.com: wrote changelog]
[dzickus@redhat.com: update documentation for kernel params and sysctl]
Signed-off-by: Ulrich Obergfell <uobergfe@redhat.com>
Signed-off-by: Don Zickus <dzickus@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-14 16:48:59 -07:00
Linus Torvalds
ca2ec32658 Merge branch 'for-linus-1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs update from Al Viro:
 "Part one:

   - struct filename-related cleanups

   - saner iov_iter_init() replacements (and switching the syscalls to
     use of those)

   - ntfs switch to ->write_iter() (Anton)

   - aio cleanups and splitting iocb into common and async parts
     (Christoph)

   - assorted fixes (me, bfields, Andrew Elble)

  There's a lot more, including the completion of switchover to
  ->{read,write}_iter(), d_inode/d_backing_inode annotations, f_flags
  race fixes, etc, but that goes after #for-davem merge.  David has
  pulled it, and once it's in I'll send the next vfs pull request"

* 'for-linus-1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (35 commits)
  sg_start_req(): use import_iovec()
  sg_start_req(): make sure that there's not too many elements in iovec
  blk_rq_map_user(): use import_single_range()
  sg_io(): use import_iovec()
  process_vm_access: switch to {compat_,}import_iovec()
  switch keyctl_instantiate_key_common() to iov_iter
  switch {compat_,}do_readv_writev() to {compat_,}import_iovec()
  aio_setup_vectored_rw(): switch to {compat_,}import_iovec()
  vmsplice_to_user(): switch to import_iovec()
  kill aio_setup_single_vector()
  aio: simplify arguments of aio_setup_..._rw()
  aio: lift iov_iter_init() into aio_setup_..._rw()
  lift iov_iter into {compat_,}do_readv_writev()
  NFS: fix BUG() crash in notify_change() with patch to chown_common()
  dcache: return -ESTALE not -EBUSY on distributed fs race
  NTFS: Version 2.1.32 - Update file write from aio_write to write_iter.
  VFS: Add iov_iter_fault_in_multipages_readable()
  drop bogus check in file_open_root()
  switch security_inode_getattr() to struct path *
  constify tomoyo_realpath_from_path()
  ...
2015-04-14 15:31:03 -07:00
Christoph Hellwig
e2e40f2c1e fs: move struct kiocb to fs.h
struct kiocb now is a generic I/O container, so move it to fs.h.
Also do a #include diet for aio.h while we're at it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-03-25 20:28:11 -04:00
Theodore Ts'o
1efff914af fs: add dirtytime_expire_seconds sysctl
Add a tuning knob so we can adjust the dirtytime expiration timeout,
which is very useful for testing lazytime.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
2015-03-17 12:23:32 -04:00
Andrey Ryabinin
3cd7645de6 mm, hugetlb: remove unnecessary lower bound on sysctl handlers"?
Commit ed4d4902eb ("mm, hugetlb: remove hugetlb_zero and
hugetlb_infinity") replaced 'unsigned long hugetlb_zero' with 'int zero'
leading to out-of-bounds access in proc_doulongvec_minmax().  Use
'.extra1 = NULL' instead of '.extra1 = &zero'.  Passing NULL is
equivalent to passing minimal value, which is 0 for unsigned types.

Fixes: ed4d4902eb ("mm, hugetlb: remove hugetlb_zero and hugetlb_infinity")
Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Suggested-by: Manfred Spraul <manfred@colorfullife.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-10 14:30:34 -08:00
Linus Torvalds
a7c180aa7e As the merge window is still open, and this code was not as complex
as I thought it might be. I'm pushing this in now.
 
 This will allow Thomas to debug his irq work for 3.20.
 
 This adds two new features:
 
 1) Allow traceopoints to be enabled right after mm_init(). By passing
 in the trace_event= kernel command line parameter, tracepoints can be
 enabled at boot up. For debugging things like the initialization of
 interrupts, it is needed to have tracepoints enabled very early. People
 have asked about this before and this has been on my todo list. As it
 can be helpful for Thomas to debug his upcoming 3.20 IRQ work, I'm
 pushing this now. This way he can add tracepoints into the IRQ set up
 and have users enable them when things go wrong.
 
 2) Have the tracepoints printed via printk() (the console) when they
 are triggered. If the irq code locks up or reboots the box, having the
 tracepoint output go into the kernel ring buffer is useless for
 debugging. But being able to add the tp_printk kernel command line
 option along with the trace_event= option will have these tracepoints
 printed as they occur, and that can be really useful for debugging
 early lock up or reboot problems.
 
 This code is not that intrusive and it passed all my tests. Thomas tried
 them out too and it works for his needs.
 
  Link: http://lkml.kernel.org/r/20141214201609.126831471@goodmis.org
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Merge tag 'trace-3.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:
 "As the merge window is still open, and this code was not as complex as
  I thought it might be.  I'm pushing this in now.

  This will allow Thomas to debug his irq work for 3.20.

  This adds two new features:

  1) Allow traceopoints to be enabled right after mm_init().

     By passing in the trace_event= kernel command line parameter,
     tracepoints can be enabled at boot up.  For debugging things like
     the initialization of interrupts, it is needed to have tracepoints
     enabled very early.  People have asked about this before and this
     has been on my todo list.  As it can be helpful for Thomas to debug
     his upcoming 3.20 IRQ work, I'm pushing this now.  This way he can
     add tracepoints into the IRQ set up and have users enable them when
     things go wrong.

  2) Have the tracepoints printed via printk() (the console) when they
     are triggered.

     If the irq code locks up or reboots the box, having the tracepoint
     output go into the kernel ring buffer is useless for debugging.
     But being able to add the tp_printk kernel command line option
     along with the trace_event= option will have these tracepoints
     printed as they occur, and that can be really useful for debugging
     early lock up or reboot problems.

  This code is not that intrusive and it passed all my tests.  Thomas
  tried them out too and it works for his needs.

   Link: http://lkml.kernel.org/r/20141214201609.126831471@goodmis.org"

* tag 'trace-3.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Add tp_printk cmdline to have tracepoints go to printk()
  tracing: Move enabling tracepoints to just after rcu_init()
2014-12-16 12:53:59 -08:00
Steven Rostedt (Red Hat)
0daa230296 tracing: Add tp_printk cmdline to have tracepoints go to printk()
Add the kernel command line tp_printk option that will have tracepoints
that are active sent to printk() as well as to the trace buffer.

Passing "tp_printk" will activate this. To turn it off, the sysctl
/proc/sys/kernel/tracepoint_printk can have '0' echoed into it. Note,
this only works if the cmdline option is used. Echoing 1 into the sysctl
file without the cmdline option will have no affect.

Note, this is a dangerous option. Having high frequency tracepoints send
their data to printk() can possibly cause a live lock. This is another
reason why this is only active if the command line option is used.

Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1412121539300.16494@nanos

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-12-15 10:17:38 -05:00
Prarit Bhargava
9e3961a097 kernel: add panic_on_warn
There have been several times where I have had to rebuild a kernel to
cause a panic when hitting a WARN() in the code in order to get a crash
dump from a system.  Sometimes this is easy to do, other times (such as
in the case of a remote admin) it is not trivial to send new images to
the user.

A much easier method would be a switch to change the WARN() over to a
panic.  This makes debugging easier in that I can now test the actual
image the WARN() was seen on and I do not have to engage in remote
debugging.

This patch adds a panic_on_warn kernel parameter and
/proc/sys/kernel/panic_on_warn calls panic() in the
warn_slowpath_common() path.  The function will still print out the
location of the warning.

An example of the panic_on_warn output:

The first line below is from the WARN_ON() to output the WARN_ON()'s
location.  After that the panic() output is displayed.

    WARNING: CPU: 30 PID: 11698 at /home/prarit/dummy_module/dummy-module.c:25 init_dummy+0x1f/0x30 [dummy_module]()
    Kernel panic - not syncing: panic_on_warn set ...

    CPU: 30 PID: 11698 Comm: insmod Tainted: G        W  OE  3.17.0+ #57
    Hardware name: Intel Corporation S2600CP/S2600CP, BIOS RMLSDP.86I.00.29.D696.1311111329 11/11/2013
     0000000000000000 000000008e3f87df ffff88080f093c38 ffffffff81665190
     0000000000000000 ffffffff818aea3d ffff88080f093cb8 ffffffff8165e2ec
     ffffffff00000008 ffff88080f093cc8 ffff88080f093c68 000000008e3f87df
    Call Trace:
     [<ffffffff81665190>] dump_stack+0x46/0x58
     [<ffffffff8165e2ec>] panic+0xd0/0x204
     [<ffffffffa038e05f>] ? init_dummy+0x1f/0x30 [dummy_module]
     [<ffffffff81076b90>] warn_slowpath_common+0xd0/0xd0
     [<ffffffffa038e040>] ? dummy_greetings+0x40/0x40 [dummy_module]
     [<ffffffff81076c8a>] warn_slowpath_null+0x1a/0x20
     [<ffffffffa038e05f>] init_dummy+0x1f/0x30 [dummy_module]
     [<ffffffff81002144>] do_one_initcall+0xd4/0x210
     [<ffffffff811b52c2>] ? __vunmap+0xc2/0x110
     [<ffffffff810f8889>] load_module+0x16a9/0x1b30
     [<ffffffff810f3d30>] ? store_uevent+0x70/0x70
     [<ffffffff810f49b9>] ? copy_module_from_fd.isra.44+0x129/0x180
     [<ffffffff810f8ec6>] SyS_finit_module+0xa6/0xd0
     [<ffffffff8166cf29>] system_call_fastpath+0x12/0x17

Successfully tested by me.

hpa said: There is another very valid use for this: many operators would
rather a machine shuts down than being potentially compromised either
functionally or security-wise.

Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Acked-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-12-10 17:41:10 -08:00
Kirill Tkhai
6419265899 sched/fair: Fix division by zero sysctl_numa_balancing_scan_size
File /proc/sys/kernel/numa_balancing_scan_size_mb allows writing of zero.

This bash command reproduces problem:

$ while :; do echo 0 > /proc/sys/kernel/numa_balancing_scan_size_mb; \
	   echo 256 > /proc/sys/kernel/numa_balancing_scan_size_mb; done

	divide error: 0000 [#1] SMP
	Modules linked in:
	CPU: 0 PID: 24112 Comm: bash Not tainted 3.17.0+ #8
	Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
	task: ffff88013c852600 ti: ffff880037a68000 task.ti: ffff880037a68000
	RIP: 0010:[<ffffffff81074191>]  [<ffffffff81074191>] task_scan_min+0x21/0x50
	RSP: 0000:ffff880037a6bce0  EFLAGS: 00010246
	RAX: 0000000000000a00 RBX: 00000000000003e8 RCX: 0000000000000000
	RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88013c852600
	RBP: ffff880037a6bcf0 R08: 0000000000000001 R09: 0000000000015c90
	R10: ffff880239bf6c00 R11: 0000000000000016 R12: 0000000000003fff
	R13: ffff88013c852600 R14: ffffea0008d1b000 R15: 0000000000000003
	FS:  00007f12bb048700(0000) GS:ffff88007da00000(0000) knlGS:0000000000000000
	CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
	CR2: 0000000001505678 CR3: 0000000234770000 CR4: 00000000000006f0
	Stack:
	 ffff88013c852600 0000000000003fff ffff880037a6bd18 ffffffff810741d1
	 ffff88013c852600 0000000000003fff 000000000002bfff ffff880037a6bda8
	 ffffffff81077ef7 ffffea0008a56d40 0000000000000001 0000000000000001
	Call Trace:
	 [<ffffffff810741d1>] task_scan_max+0x11/0x40
	 [<ffffffff81077ef7>] task_numa_fault+0x1f7/0xae0
	 [<ffffffff8115a896>] ? migrate_misplaced_page+0x276/0x300
	 [<ffffffff81134a4d>] handle_mm_fault+0x62d/0xba0
	 [<ffffffff8103e2f1>] __do_page_fault+0x191/0x510
	 [<ffffffff81030122>] ? native_smp_send_reschedule+0x42/0x60
	 [<ffffffff8106dc00>] ? check_preempt_curr+0x80/0xa0
	 [<ffffffff8107092c>] ? wake_up_new_task+0x11c/0x1a0
	 [<ffffffff8104887d>] ? do_fork+0x14d/0x340
	 [<ffffffff811799bb>] ? get_unused_fd_flags+0x2b/0x30
	 [<ffffffff811799df>] ? __fd_install+0x1f/0x60
	 [<ffffffff8103e67c>] do_page_fault+0xc/0x10
	 [<ffffffff8150d322>] page_fault+0x22/0x30
	RIP  [<ffffffff81074191>] task_scan_min+0x21/0x50
	RSP <ffff880037a6bce0>
	---[ end trace 9a826d16936c04de ]---

Also fix race in task_scan_min (it depends on compiler behaviour).

Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Aaron Tomlin <atomlin@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dario Faggioli <raistlin@linux.it>
Cc: David Rientjes <rientjes@google.com>
Cc: Jens Axboe <axboe@fb.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Link: http://lkml.kernel.org/r/1413455977.24793.78.camel@tkhai
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 10:46:04 +01:00
Linus Torvalds
d6dd50e07c Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU updates from Ingo Molnar:
 "The main changes in this cycle were:

   - changes related to No-CBs CPUs and NO_HZ_FULL

   - RCU-tasks implementation

   - torture-test updates

   - miscellaneous fixes

   - locktorture updates

   - RCU documentation updates"

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (81 commits)
  workqueue: Use cond_resched_rcu_qs macro
  workqueue: Add quiescent state between work items
  locktorture: Cleanup header usage
  locktorture: Cannot hold read and write lock
  locktorture: Fix __acquire annotation for spinlock irq
  locktorture: Support rwlocks
  rcu: Eliminate deadlock between CPU hotplug and expedited grace periods
  locktorture: Document boot/module parameters
  rcutorture: Rename rcutorture_runnable parameter
  locktorture: Add test scenario for rwsem_lock
  locktorture: Add test scenario for mutex_lock
  locktorture: Make torture scripting account for new _runnable name
  locktorture: Introduce torture context
  locktorture: Support rwsems
  locktorture: Add infrastructure for torturing read locks
  torture: Address race in module cleanup
  locktorture: Make statistics generic
  locktorture: Teach about lock debugging
  locktorture: Support mutexes
  locktorture: Add documentation
  ...
2014-10-13 15:44:12 +02:00
Johannes Weiner
1f13ae399c mm: remove noisy remainder of the scan_unevictable interface
The deprecation warnings for the scan_unevictable interface triggers by
scripts doing `sysctl -a | grep something else'.  This is annoying and not
helpful.

The interface has been defunct since 264e56d824 ("mm: disable user
interface to manually rescue unevictable pages"), which was in 2011, and
there haven't been any reports of usecases for it, only reports that the
deprecation warnings are annying.  It's unlikely that anybody is using
this interface specifically at this point, so remove it.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-10-09 22:25:55 -04:00
Paul E. McKenney
59da22a020 rcutorture: Rename rcutorture_runnable parameter
This commit changes rcutorture_runnable to torture_runnable, which is
consistent with the names of the other parameters and is a bit shorter
as well.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-16 13:41:44 -07:00
David Rientjes
ed4d4902eb mm, hugetlb: remove hugetlb_zero and hugetlb_infinity
They are unnecessary: "zero" can be used in place of "hugetlb_zero" and
passing extra2 == NULL is equivalent to infinity.

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reviewed-by: Luiz Capitulino <lcapitulino@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-08-06 18:01:19 -07:00
Aaron Tomlin
ed235875e2 kernel/watchdog.c: print traces for all cpus on lockup detection
A 'softlockup' is defined as a bug that causes the kernel to loop in
kernel mode for more than a predefined period to time, without giving
other tasks a chance to run.

Currently, upon detection of this condition by the per-cpu watchdog
task, debug information (including a stack trace) is sent to the system
log.

On some occasions, we have observed that the "victim" rather than the
actual "culprit" (i.e.  the owner/holder of the contended resource) is
reported to the user.  Often this information has proven to be
insufficient to assist debugging efforts.

To avoid loss of useful debug information, for architectures which
support NMI, this patch makes it possible to improve soft lockup
reporting.  This is accomplished by issuing an NMI to each cpu to obtain
a stack trace.

If NMI is not supported we just revert back to the old method.  A sysctl
and boot-time parameter is available to toggle this feature.

[dzickus@redhat.com: add CONFIG_SMP in certain areas]
[akpm@linux-foundation.org: additional CONFIG_SMP=n optimisations]
[mq@suse.cz: fix warning]
Signed-off-by: Aaron Tomlin <atomlin@redhat.com>
Signed-off-by: Don Zickus <dzickus@redhat.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Mateusz Guzik <mguzik@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Jan Moskyto Matejka <mq@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-23 16:47:44 -07:00
David Rientjes
7cd2b0a34a mm, pcp: allow restoring percpu_pagelist_fraction default
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 <rientjes@google.com>
Reported-by: Oleg Drokin <green@linuxhacker.ru>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-23 16:47:43 -07:00
Linus Torvalds
c4222e4635 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-next
Pull sparc fixes from David Miller:
 "Sparc sparse fixes from Sam Ravnborg"

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-next: (67 commits)
  sparc64: fix sparse warnings in int_64.c
  sparc64: fix sparse warning in ftrace.c
  sparc64: fix sparse warning in kprobes.c
  sparc64: fix sparse warning in kgdb_64.c
  sparc64: fix sparse warnings in compat_audit.c
  sparc64: fix sparse warnings in init_64.c
  sparc64: fix sparse warnings in aes_glue.c
  sparc: fix sparse warnings in smp_32.c + smp_64.c
  sparc64: fix sparse warnings in perf_event.c
  sparc64: fix sparse warnings in kprobes.c
  sparc64: fix sparse warning in tsb.c
  sparc64: clean up compat_sigset_t.seta handling
  sparc64: fix sparse "Should it be static?" warnings in signal32.c
  sparc64: fix sparse warnings in sys_sparc32.c
  sparc64: fix sparse warning in pci.c
  sparc64: fix sparse warnings in smp_64.c
  sparc64: fix sparse warning in prom_64.c
  sparc64: fix sparse warning in btext.c
  sparc64: fix sparse warnings in sys_sparc_64.c + unaligned_64.c
  sparc64: fix sparse warning in process_64.c
  ...

Conflicts:
	arch/sparc/include/asm/pgtable_64.h
2014-06-19 07:50:07 -10:00
Linus Torvalds
f9da455b93 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next
Pull networking updates from David Miller:

 1) Seccomp BPF filters can now be JIT'd, from Alexei Starovoitov.

 2) Multiqueue support in xen-netback and xen-netfront, from Andrew J
    Benniston.

 3) Allow tweaking of aggregation settings in cdc_ncm driver, from Bjørn
    Mork.

 4) BPF now has a "random" opcode, from Chema Gonzalez.

 5) Add more BPF documentation and improve test framework, from Daniel
    Borkmann.

 6) Support TCP fastopen over ipv6, from Daniel Lee.

 7) Add software TSO helper functions and use them to support software
    TSO in mvneta and mv643xx_eth drivers.  From Ezequiel Garcia.

 8) Support software TSO in fec driver too, from Nimrod Andy.

 9) Add Broadcom SYSTEMPORT driver, from Florian Fainelli.

10) Handle broadcasts more gracefully over macvlan when there are large
    numbers of interfaces configured, from Herbert Xu.

11) Allow more control over fwmark used for non-socket based responses,
    from Lorenzo Colitti.

12) Do TCP congestion window limiting based upon measurements, from Neal
    Cardwell.

13) Support busy polling in SCTP, from Neal Horman.

14) Allow RSS key to be configured via ethtool, from Venkata Duvvuru.

15) Bridge promisc mode handling improvements from Vlad Yasevich.

16) Don't use inetpeer entries to implement ID generation any more, it
    performs poorly, from Eric Dumazet.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1522 commits)
  rtnetlink: fix userspace API breakage for iproute2 < v3.9.0
  tcp: fixing TLP's FIN recovery
  net: fec: Add software TSO support
  net: fec: Add Scatter/gather support
  net: fec: Increase buffer descriptor entry number
  net: fec: Factorize feature setting
  net: fec: Enable IP header hardware checksum
  net: fec: Factorize the .xmit transmit function
  bridge: fix compile error when compiling without IPv6 support
  bridge: fix smatch warning / potential null pointer dereference
  via-rhine: fix full-duplex with autoneg disable
  bnx2x: Enlarge the dorq threshold for VFs
  bnx2x: Check for UNDI in uncommon branch
  bnx2x: Fix 1G-baseT link
  bnx2x: Fix link for KR with swapped polarity lane
  sctp: Fix sk_ack_backlog wrap-around problem
  net/core: Add VF link state control policy
  net/fsl: xgmac_mdio is dependent on OF_MDIO
  net/fsl: Make xgmac_mdio read error message useful
  net_sched: drr: warn when qdisc is not work conserving
  ...
2014-06-12 14:27:40 -07:00
Joe Perches
6f8fd1d77e sysctl: convert use of typedef ctl_table to struct ctl_table
This typedef is unnecessary and should just be removed.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-06 16:08:16 -07:00
Kees Cook
f4aacea2f5 sysctl: allow for strict write position handling
When writing to a sysctl string, each write, regardless of VFS position,
begins writing the string from the start.  This means the contents of
the last write to the sysctl controls the string contents instead of the
first:

  open("/proc/sys/kernel/modprobe", O_WRONLY)   = 1
  write(1, "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"..., 4096) = 4096
  write(1, "/bin/true", 9)                = 9
  close(1)                                = 0

  $ cat /proc/sys/kernel/modprobe
  /bin/true

Expected behaviour would be to have the sysctl be "AAAA..." capped at
maxlen (in this case KMOD_PATH_LEN: 256), instead of truncating to the
contents of the second write.  Similarly, multiple short writes would
not append to the sysctl.

The old behavior is unlike regular POSIX files enough that doing audits
of software that interact with sysctls can end up in unexpected or
dangerous situations.  For example, "as long as the input starts with a
trusted path" turns out to be an insufficient filter, as what must also
happen is for the input to be entirely contained in a single write
syscall -- not a common consideration, especially for high level tools.

This provides kernel.sysctl_writes_strict as a way to make this behavior
act in a less surprising manner for strings, and disallows non-zero file
position when writing numeric sysctls (similar to what is already done
when reading from non-zero file positions).  For now, the default (0) is
to warn about non-zero file position use, but retain the legacy
behavior.  Setting this to -1 disables the warning, and setting this to
1 enables the file position respecting behavior.

[akpm@linux-foundation.org: fix build]
[akpm@linux-foundation.org: move misplaced hunk, per Randy]
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-06 16:08:13 -07:00
Kees Cook
2ca9bb456a sysctl: refactor sysctl string writing logic
Consolidate buffer length checking with new-line/end-of-line checking.
Additionally, instead of reading user memory twice, just do the
assignment during the loop.

This change doesn't affect the potential races here.  It was already
possible to read a sysctl that was in the middle of a write.  In both
cases, the string will always be NULL terminated.  The pre-existing race
remains a problem to be solved.

Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-06 16:08:13 -07:00
Kees Cook
f88083005a sysctl: clean up char buffer arguments
When writing to a sysctl string, each write, regardless of VFS position,
began writing the string from the start.  This meant the contents of the
last write to the sysctl controlled the string contents instead of the
first.

This misbehavior was featured in an exploit against Chrome OS.  While
it's not in itself a vulnerability, it's a weirdness that isn't on the
mind of most auditors: "This filter looks correct, the first line
written would not be meaningful to sysctl" doesn't apply here, since the
size of the write and the contents of the final write are what matter
when writing to sysctls.

This adds the sysctl kernel.sysctl_writes_strict to control the write
behavior.  The default (0) reports when VFS position is non-0 on a
write, but retains legacy behavior, -1 disables the warning, and 1
enables the position-respecting behavior.

The long-term plan here is to wait for userspace to be fixed in response
to the new warning and to then switch the default kernel behavior to the
new position-respecting behavior.

This patch (of 4):

The char buffer arguments are needlessly cast in weird places.  Clean it
up so things are easier to read.

Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-06 16:08:13 -07:00
Linus Torvalds
a0abcf2e8f Merge branch 'x86/vdso' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into next
Pull x86 cdso updates from Peter Anvin:
 "Vdso cleanups and improvements largely from Andy Lutomirski.  This
  makes the vdso a lot less ''special''"

* 'x86/vdso' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/vdso, build: Make LE access macros clearer, host-safe
  x86/vdso, build: Fix cross-compilation from big-endian architectures
  x86/vdso, build: When vdso2c fails, unlink the output
  x86, vdso: Fix an OOPS accessing the HPET mapping w/o an HPET
  x86, mm: Replace arch_vma_name with vm_ops->name for vsyscalls
  x86, mm: Improve _install_special_mapping and fix x86 vdso naming
  mm, fs: Add vm_ops->name as an alternative to arch_vma_name
  x86, vdso: Fix an OOPS accessing the HPET mapping w/o an HPET
  x86, vdso: Remove vestiges of VDSO_PRELINK and some outdated comments
  x86, vdso: Move the vvar and hpet mappings next to the 64-bit vDSO
  x86, vdso: Move the 32-bit vdso special pages after the text
  x86, vdso: Reimplement vdso.so preparation in build-time C
  x86, vdso: Move syscall and sysenter setup into kernel/cpu/common.c
  x86, vdso: Clean up 32-bit vs 64-bit vdso params
  x86, mm: Ensure correct alignment of the fixmap
2014-06-05 08:05:29 -07:00
Sam Ravnborg
8c7260c0d9 sparc64: fix sparse warning in tsb.c
Fix following warning:
tsb.c:290:5: warning: symbol 'sysctl_tsb_ratio' was not declared. Should it be static?

Add extern declaration in asm/setup.h and remove local declaration
in kernel/sysctl.c

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-05-18 19:01:32 -07:00
WANG Cong
122ff243f5 ipv4: make ip_local_reserved_ports per netns
ip_local_port_range is already per netns, so should ip_local_reserved_ports
be. And since it is none by default we don't actually need it when we don't
enable CONFIG_SYSCTL.

By the way, rename inet_is_reserved_local_port() to inet_is_local_reserved_port()

Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-05-14 15:31:45 -04:00
Andy Lutomirski
3d7ee969bf x86, vdso: Clean up 32-bit vs 64-bit vdso params
Rather than using 'vdso_enabled' and an awful #define, just call the
parameters vdso32_enabled and vdso64_enabled.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Link: http://lkml.kernel.org/r/87913de56bdcbae3d93917938302fc369b05caee.1399317206.git.luto@amacapital.net
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-05 13:18:40 -07:00
Michael Marineau
86d56134f1 kobject: Make support for uevent_helper optional.
Support for uevent_helper, aka hotplug, is not required on many systems
these days but it can still be enabled via sysfs or sysctl.

Reported-by: Darren Shepherd <darren.s.shepherd@gmail.com>
Signed-off-by: Michael Marineau <mike@marineau.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-04-25 12:00:49 -07:00
Liu Hua
80df284765 hung_task: check the value of "sysctl_hung_task_timeout_sec"
As sysctl_hung_task_timeout_sec is unsigned long, when this value is
larger then LONG_MAX/HZ, the function schedule_timeout_interruptible in
watchdog will return immediately without sleep and with print :

  schedule_timeout: wrong timeout value ffffffffffffff83

and then the funtion watchdog will call schedule_timeout_interruptible
again and again.  The screen will be filled with

	"schedule_timeout: wrong timeout value ffffffffffffff83"

This patch does some check and correction in sysctl, to let the function
schedule_timeout_interruptible allways get the valid parameter.

Signed-off-by: Liu Hua <sdu.liu@huawei.com>
Tested-by: Satoru Takeuchi <satoru.takeuchi@gmail.com>
Cc: <stable@vger.kernel.org>	[3.4+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-07 16:36:07 -07:00
Dave Hansen
5509a5d27b drop_caches: add some documentation and info message
There is plenty of anecdotal evidence and a load of blog posts
suggesting that using "drop_caches" periodically keeps your system
running in "tip top shape".  Perhaps adding some kernel documentation
will increase the amount of accurate data on its use.

If we are not shrinking caches effectively, then we have real bugs.
Using drop_caches will simply mask the bugs and make them harder to
find, but certainly does not fix them, nor is it an appropriate
"workaround" to limit the size of the caches.  On the contrary, there
have been bug reports on issues that turned out to be misguided use of
cache dropping.

Dropping caches is a very drastic and disruptive operation that is good
for debugging and running tests, but if it creates bug reports from
production use, kernel developers should be aware of its use.

Add a bit more documentation about it, a syslog message to track down
abusers, and vmstat drop counters to help analyze problem reports.

[akpm@linux-foundation.org: checkpatch fixes]
[hannes@cmpxchg.org: add runtime suppression control]
Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-03 16:21:04 -07:00
Linus Torvalds
7a48837732 Merge branch 'for-3.15/core' of git://git.kernel.dk/linux-block
Pull core block layer updates from Jens Axboe:
 "This is the pull request for the core block IO bits for the 3.15
  kernel.  It's a smaller round this time, it contains:

   - Various little blk-mq fixes and additions from Christoph and
     myself.

   - Cleanup of the IPI usage from the block layer, and associated
     helper code.  From Frederic Weisbecker and Jan Kara.

   - Duplicate code cleanup in bio-integrity from Gu Zheng.  This will
     give you a merge conflict, but that should be easy to resolve.

   - blk-mq notify spinlock fix for RT from Mike Galbraith.

   - A blktrace partial accounting bug fix from Roman Pen.

   - Missing REQ_SYNC detection fix for blk-mq from Shaohua Li"

* 'for-3.15/core' of git://git.kernel.dk/linux-block: (25 commits)
  blk-mq: add REQ_SYNC early
  rt,blk,mq: Make blk_mq_cpu_notify_lock a raw spinlock
  blk-mq: support partial I/O completions
  blk-mq: merge blk_mq_insert_request and blk_mq_run_request
  blk-mq: remove blk_mq_alloc_rq
  blk-mq: don't dump CPU -> hw queue map on driver load
  blk-mq: fix wrong usage of hctx->state vs hctx->flags
  blk-mq: allow blk_mq_init_commands() to return failure
  block: remove old blk_iopoll_enabled variable
  blktrace: fix accounting of partially completed requests
  smp: Rename __smp_call_function_single() to smp_call_function_single_async()
  smp: Remove wait argument from __smp_call_function_single()
  watchdog: Simplify a little the IPI call
  smp: Move __smp_call_function_single() below its safe version
  smp: Consolidate the various smp_call_function_single() declensions
  smp: Teach __smp_call_function_single() to check for offline cpus
  smp: Remove unused list_head from csd
  smp: Iterate functions through llist_for_each_entry_safe()
  block: Stop abusing rq->csd.list in blk-softirq
  block: Remove useless IPI struct initialization
  ...
2014-04-01 19:19:15 -07:00
Jens Axboe
89f8b33ca1 block: remove old blk_iopoll_enabled variable
This was a debugging measure to toggle enabled/disabled
when testing. But for real production setups, it's not
safe to toggle this setting without either reloading
drivers of quiescing IO first. Neither of which the toggle
enforces.

Additionally, it makes drivers deal with the conditional
state.

Remove it completely. It's up to the driver whether iopoll
is enabled or not.

Signed-off-by: Jens Axboe <axboe@fb.com>
2014-03-13 09:38:42 -06:00
Ingo Molnar
eaa4e4fcf1 Merge branch 'linus' into sched/core, to resolve conflicts
Conflicts:
	kernel/sysctl.c

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-02-02 09:45:39 +01:00
Linus Torvalds
ab5318788c Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull core debug changes from Ingo Molnar:
 "This contains mostly kernel debugging related updates:

   - make hung_task detection more configurable to distros
   - add final bits for x86 UV NMI debugging, with related KGDB changes
   - update the mailing-list of MAINTAINERS entries I'm involved with"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  hung_task: Display every hung task warning
  sysctl: Add neg_one as a standard constraint
  x86/uv/nmi, kgdb/kdb: Fix UV NMI handler when KDB not configured
  x86/uv/nmi: Fix Sparse warnings
  kgdb/kdb: Fix no KDB config problem
  MAINTAINERS: Restore "L: linux-kernel@vger.kernel.org" entries
2014-01-31 08:59:46 -08:00
Rik van Riel
52bf84aa20 sched/numa, mm: Remove p->numa_migrate_deferred
Excessive migration of pages can hurt the performance of workloads
that span multiple NUMA nodes.  However, it turns out that the
p->numa_migrate_deferred knob is a really big hammer, which does
reduce migration rates, but does not actually help performance.

Now that the second stage of the automatic numa balancing code
has stabilized, it is time to replace the simplistic migration
deferral code with something smarter.

Signed-off-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Chegu Vinod <chegu_vinod@hp.com>
Link: http://lkml.kernel.org/r/1390860228-21539-2-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-01-28 13:17:04 +01:00
Aaron Tomlin
270750dbc1 hung_task: Display every hung task warning
When khungtaskd detects hung tasks, it prints out
backtraces from a number of those tasks.

Limiting the number of backtraces being printed
out can result in the user not seeing the information
necessary to debug the issue. The hung_task_warnings
sysctl controls this feature.

This patch makes it possible for hung_task_warnings
to accept a special value to print an unlimited
number of backtraces when khungtaskd detects hung
tasks.

The special value is -1. To use this value it is
necessary to change types from ulong to int.

Signed-off-by: Aaron Tomlin <atomlin@redhat.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: oleg@redhat.com
Link: http://lkml.kernel.org/r/1390239253-24030-3-git-send-email-atomlin@redhat.com
[ Build warning fix. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-01-25 12:13:33 +01:00
Aaron Tomlin
2397efb1bb sysctl: Add neg_one as a standard constraint
Add neg_one to the list of standard constraints - will be used by the next patch.

Signed-off-by: Aaron Tomlin <atomlin@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: oleg@redhat.com
Link: http://lkml.kernel.org/r/1390239253-24030-2-git-send-email-atomlin@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-01-25 08:59:53 +01:00
Kees Cook
7984754b99 kexec: add sysctl to disable kexec_load
For general-purpose (i.e.  distro) kernel builds it makes sense to build
with CONFIG_KEXEC to allow end users to choose what kind of things they
want to do with kexec.  However, in the face of trying to lock down a
system with such a kernel, there needs to be a way to disable kexec_load
(much like module loading can be disabled).  Without this, it is too easy
for the root user to modify kernel memory even when CONFIG_STRICT_DEVMEM
and modules_disabled are set.  With this change, it is still possible to
load an image for use later, then disable kexec_load so the image (or lack
of image) can't be altered.

The intention is for using this in environments where "perfect"
enforcement is hard.  Without a verified boot, along with verified
modules, and along with verified kexec, this is trying to give a system a
better chance to defend itself (or at least grow the window of
discoverability) against attack in the face of a privilege escalation.

In my mind, I consider several boot scenarios:

1) Verified boot of read-only verified root fs loading fd-based
   verification of kexec images.
2) Secure boot of writable root fs loading signed kexec images.
3) Regular boot loading kexec (e.g. kcrash) image early and locking it.
4) Regular boot with no control of kexec image at all.

1 and 2 don't exist yet, but will soon once the verified kexec series has
landed.  4 is the state of things now.  The gap between 2 and 4 is too
large, so this change creates scenario 3, a middle-ground above 4 when 2
and 1 are not possible for a system.

Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-01-23 16:37:03 -08:00
Andi Kleen
54a43d5498 numa: add a sysctl for numa_balancing
Add a working sysctl to enable/disable automatic numa memory balancing
at runtime.

This allows us to track down performance problems with this feature and
is generally a good idea.

This was possible earlier through debugfs, but only with special
debugging options set.  Also fix the boot message.

[akpm@linux-foundation.org: s/sched_numa_balancing/sysctl_numa_balancing/]
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-01-23 16:36:51 -08:00
Jerome Marchand
49f0ce5f92 mm: add overcommit_kbytes sysctl variable
Some applications that run on HPC clusters are designed around the
availability of RAM and the overcommit ratio is fine tuned to get the
maximum usage of memory without swapping.  With growing memory, the
1%-of-all-RAM grain provided by overcommit_ratio has become too coarse
for these workload (on a 2TB machine it represents no less than 20GB).

This patch adds the new overcommit_kbytes sysctl variable that allow a
much finer grain.

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix nommu build]
Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-01-21 16:19:44 -08:00
Peter Zijlstra
1724813d9f sched/deadline: Remove the sysctl_sched_dl knobs
Remove the deadline specific sysctls for now. The problem with them is
that the interaction with the exisiting rt knobs is nearly impossible
to get right.

The current (as per before this patch) situation is that the rt and dl
bandwidth is completely separate and we enforce rt+dl < 100%. This is
undesirable because this means that the rt default of 95% leaves us
hardly any room, even though dl tasks are saver than rt tasks.

Another proposed solution was (a discarted patch) to have the dl
bandwidth be a fraction of the rt bandwidth. This is highly
confusing imo.

Furthermore neither proposal is consistent with the situation we
actually want; which is rt tasks ran from a dl server. In which case
the rt bandwidth is a direct subset of dl.

So whichever way we go, the introduction of dl controls at this point
is painful. Therefore remove them and instead share the rt budget.

This means that for now the rt knobs are used for dl admission control
and the dl runtime is accounted against the rt runtime. I realise that
this isn't entirely desirable either; but whatever we do we appear to
need to change the interface later, so better have a small interface
for now.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-zpyqbqds1r0vyxtxza1e7rdc@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-01-13 13:47:23 +01:00
Dario Faggioli
332ac17ef5 sched/deadline: Add bandwidth management for SCHED_DEADLINE tasks
In order of deadline scheduling to be effective and useful, it is
important that some method of having the allocation of the available
CPU bandwidth to tasks and task groups under control.
This is usually called "admission control" and if it is not performed
at all, no guarantee can be given on the actual scheduling of the
-deadline tasks.

Since when RT-throttling has been introduced each task group have a
bandwidth associated to itself, calculated as a certain amount of
runtime over a period. Moreover, to make it possible to manipulate
such bandwidth, readable/writable controls have been added to both
procfs (for system wide settings) and cgroupfs (for per-group
settings).

Therefore, the same interface is being used for controlling the
bandwidth distrubution to -deadline tasks and task groups, i.e.,
new controls but with similar names, equivalent meaning and with
the same usage paradigm are added.

However, more discussion is needed in order to figure out how
we want to manage SCHED_DEADLINE bandwidth at the task group level.
Therefore, this patch adds a less sophisticated, but actually
very sensible, mechanism to ensure that a certain utilization
cap is not overcome per each root_domain (the single rq for !SMP
configurations).

Another main difference between deadline bandwidth management and
RT-throttling is that -deadline tasks have bandwidth on their own
(while -rt ones doesn't!), and thus we don't need an higher level
throttling mechanism to enforce the desired bandwidth.

This patch, therefore:

 - adds system wide deadline bandwidth management by means of:
    * /proc/sys/kernel/sched_dl_runtime_us,
    * /proc/sys/kernel/sched_dl_period_us,
   that determine (i.e., runtime / period) the total bandwidth
   available on each CPU of each root_domain for -deadline tasks;

 - couples the RT and deadline bandwidth management, i.e., enforces
   that the sum of how much bandwidth is being devoted to -rt
   -deadline tasks to stay below 100%.

This means that, for a root_domain comprising M CPUs, -deadline tasks
can be created until the sum of their bandwidths stay below:

    M * (sched_dl_runtime_us / sched_dl_period_us)

It is also possible to disable this bandwidth management logic, and
be thus free of oversubscribing the system up to any arbitrary level.

Signed-off-by: Dario Faggioli <raistlin@linux.it>
Signed-off-by: Juri Lelli <juri.lelli@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1383831828-15501-12-git-send-email-juri.lelli@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-01-13 13:46:42 +01:00
Wanpeng Li
1bd53a7efd sched/numa: Drop sysctl_numa_balancing_settle_count sysctl
commit 887c290e (sched/numa: Decide whether to favour task or group weights
based on swap candidate relationships) drop the check against
sysctl_numa_balancing_settle_count, this patch remove the sysctl.

Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Link: http://lkml.kernel.org/r/1386833006-6600-1-git-send-email-liwanp@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-12-17 15:24:38 +01:00
Linus Torvalds
5e30025a31 Merge branch 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull core locking changes from Ingo Molnar:
 "The biggest changes:

   - add lockdep support for seqcount/seqlocks structures, this
     unearthed both bugs and required extra annotation.

   - move the various kernel locking primitives to the new
     kernel/locking/ directory"

* 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (21 commits)
  block: Use u64_stats_init() to initialize seqcounts
  locking/lockdep: Mark __lockdep_count_forward_deps() as static
  lockdep/proc: Fix lock-time avg computation
  locking/doc: Update references to kernel/mutex.c
  ipv6: Fix possible ipv6 seqlock deadlock
  cpuset: Fix potential deadlock w/ set_mems_allowed
  seqcount: Add lockdep functionality to seqcount/seqlock structures
  net: Explicitly initialize u64_stats_sync structures for lockdep
  locking: Move the percpu-rwsem code to kernel/locking/
  locking: Move the lglocks code to kernel/locking/
  locking: Move the rwsem code to kernel/locking/
  locking: Move the rtmutex code to kernel/locking/
  locking: Move the semaphore core to kernel/locking/
  locking: Move the spinlock code to kernel/locking/
  locking: Move the lockdep code to kernel/locking/
  locking: Move the mutex code to kernel/locking/
  hung_task debugging: Add tracepoint to report the hang
  x86/locking/kconfig: Update paravirt spinlock Kconfig description
  lockstat: Report avg wait and hold times
  lockdep, x86/alternatives: Drop ancient lockdep fixup message
  ...
2013-11-14 16:30:30 +09:00
Chen Gang
7833819d2e kernel/sysctl.c: check return value after call proc_put_char() in __do_proc_doulongvec_minmax()
Need to check the return value of proc_put_char(), as was done in
__do_proc_doulongvec_minmax().

Signed-off-by: Chen Gang <gang.chen@asianux.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-11-13 12:09:33 +09:00
Linus Torvalds
39cf275a1a Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler changes from Ingo Molnar:
 "The main changes in this cycle are:

   - (much) improved CONFIG_NUMA_BALANCING support from Mel Gorman, Rik
     van Riel, Peter Zijlstra et al.  Yay!

   - optimize preemption counter handling: merge the NEED_RESCHED flag
     into the preempt_count variable, by Peter Zijlstra.

   - wait.h fixes and code reorganization from Peter Zijlstra

   - cfs_bandwidth fixes from Ben Segall

   - SMP load-balancer cleanups from Peter Zijstra

   - idle balancer improvements from Jason Low

   - other fixes and cleanups"

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (129 commits)
  ftrace, sched: Add TRACE_FLAG_PREEMPT_RESCHED
  stop_machine: Fix race between stop_two_cpus() and stop_cpus()
  sched: Remove unnecessary iteration over sched domains to update nr_busy_cpus
  sched: Fix asymmetric scheduling for POWER7
  sched: Move completion code from core.c to completion.c
  sched: Move wait code from core.c to wait.c
  sched: Move wait.c into kernel/sched/
  sched/wait: Fix __wait_event_interruptible_lock_irq_timeout()
  sched: Avoid throttle_cfs_rq() racing with period_timer stopping
  sched: Guarantee new group-entities always have weight
  sched: Fix hrtimer_cancel()/rq->lock deadlock
  sched: Fix cfs_bandwidth misuse of hrtimer_expires_remaining
  sched: Fix race on toggling cfs_bandwidth_used
  sched: Remove extra put_online_cpus() inside sched_setaffinity()
  sched/rt: Fix task_tick_rt() comment
  sched/wait: Fix build breakage
  sched/wait: Introduce prepare_to_wait_event()
  sched/wait: Add ___wait_cond_timeout() to wait_event*_timeout() too
  sched: Remove get_online_cpus() usage
  sched: Fix race in migrate_swap_stop()
  ...
2013-11-12 10:20:12 +09:00
Linus Torvalds
ad5d69899e Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf updates from Ingo Molnar:
 "As a first remark I'd like to note that the way to build perf tooling
  has been simplified and sped up, in the future it should be enough for
  you to build perf via:

        cd tools/perf/
        make install

  (ie without the -j option.) The build system will figure out the
  number of CPUs and will do a parallel build+install.

  The various build system inefficiencies and breakages Linus reported
  against the v3.12 pull request should now be resolved - please
  (re-)report any remaining annoyances or bugs.

  Main changes on the perf kernel side:

   * Performance optimizations:
      . perf ring-buffer code optimizations,          by Peter Zijlstra
      . perf ring-buffer code optimizations,          by Oleg Nesterov
      . x86 NMI call-stack processing optimizations,  by Peter Zijlstra
      . perf context-switch optimizations,            by Peter Zijlstra
      . perf sampling speedups,                       by Peter Zijlstra
      . x86 Intel PEBS processing speedups,           by Peter Zijlstra

   * Enhanced hardware support:
      . for Intel Ivy Bridge-EP uncore PMUs,          by Zheng Yan
      . for Haswell transactions,                     by Andi Kleen, Peter Zijlstra

   * Core perf events code enhancements and fixes by Oleg Nesterov:
      . for uprobes, if fork() is called with pending ret-probes
      . for uprobes platform support code

   * New ABI details by Andi Kleen:
      . Report x86 Haswell TSX transaction abort cost as weight

  Main changes on the perf tooling side (some of these tooling changes
  utilize the above kernel side changes):

   * 'perf report/top' enhancements:

      . Convert callchain children list to rbtree, greatly reducing the
        time taken for callchain processing, from Namhyung Kim.

      . Add new COMM infrastructure, further improving histogram
        processing, from Frédéric Weisbecker, one fix from Namhyung Kim.

      . Add /proc/kcore based live-annotation improvements, including
        build-id cache support, multi map 'call' instruction navigation
        fixes, kcore address validation, objdump workarounds.  From
        Adrian Hunter.

      . Show progress on histogram collapsing, that can take a long
        time, from Namhyung Kim.

      . Add --max-stack option to limit callchain stack scan in 'top'
        and 'report', improving callchain processing when reducing the
        stack depth is an option, from Waiman Long.

      . Add new option --ignore-vmlinux for perf top, from Willy
        Tarreau.

   * 'perf trace' enhancements:

      . 'perf trace' now can can use a 'perf probe' dynamic tracepoints
        to hook into the userspace -> kernel pathname copy so that it
        can map fds to pathnames without reading /proc/pid/fd/ symlinks.
        From Arnaldo Carvalho de Melo.

      . Show VFS path associated with fd in live sessions, using a
        'vfs_getname' 'perf probe' created dynamic tracepoint or by
        looking at /proc/pid/fd, from Arnaldo Carvalho de Melo.

      . Add 'trace' beautifiers for lots of syscall arguments, from
        Arnaldo Carvalho de Melo.

      . Implement more compact 'trace' output by suppressing zeroed
        args, from Arnaldo Carvalho de Melo.

      . Show thread COMM by default in 'trace', from Arnaldo Carvalho de
        Melo.

      . Add option to show full timestamp in 'trace', from David Ahern.

      . Add 'record' command in 'trace', to record raw_syscalls:*, from
        David Ahern.

      . Add summary option to dump syscall statistics in 'trace', from
        David Ahern.

      . Improve error messages in 'trace', providing hints about system
        configuration steps needed for using it, from Ramkumar
        Ramachandra.

      . 'perf trace' now emits hints as to why tracing is not possible,
        helping the user to setup the system to allow tracing in the
        desired permission granularity, telling if the problem is due to
        debugfs not being mounted or with not enough permission for
        !root, /proc/sys/kernel/perf_event_paranoit value, etc.  From
        Arnaldo Carvalho de Melo.

   * 'perf record' enhancements:

      . Check maximum frequency rate for record/top, emitting better
        error messages, from Jiri Olsa.

      . 'perf record' code cleanups, from David Ahern.

      . Improve write_output error message in 'perf record', from Adrian
        Hunter.

      . Allow specifying B/K/M/G unit to the --mmap-pages arguments,
        from Jiri Olsa.

      . Fix command line callchain attribute tests to handle the new
        -g/--call-chain semantics, from Arnaldo Carvalho de Melo.

   * 'perf kvm' enhancements:

      . Disable live kvm command if timerfd is not supported, from David
        Ahern.

      . Fix detection of non-core features, from David Ahern.

   * 'perf list' enhancements:

      . Add usage to 'perf list', from David Ahern.

      . Show error in 'perf list' if tracepoints not available, from
        Pekka Enberg.

   * 'perf probe' enhancements:

      . Support "$vars" meta argument syntax for local variables,
        allowing asking for all possible variables at a given probe
        point to be collected when it hits, from Masami Hiramatsu.

   * 'perf sched' enhancements:

      . Address the root cause of that 'perf sched' stack initialization
        build slowdown, by programmatically setting a big array after
        moving the global variable back to the stack.  Fix from Adrian
        Hunter.

   * 'perf script' enhancements:

      . Set up output options for in-stream attributes, from Adrian
        Hunter.

      . Print addr by default for BTS in 'perf script', from Adrian
        Juntmer

   * 'perf stat' enhancements:

      . Improved messages when doing profiling in all or a subset of
        CPUs using a workload as the session delimitator, as in:

         'perf stat --cpu 0,2 sleep 10s'

        from Arnaldo Carvalho de Melo.

      . Add units to nanosec-based counters in 'perf stat', from David
        Ahern.

      . Remove bogus info when using 'perf stat' -e cycles/instructions,
        from Ramkumar Ramachandra.

   * 'perf lock' enhancements:

      . 'perf lock' fixes and cleanups, from Davidlohr Bueso.

   * 'perf test' enhancements:

      . Fixup PERF_SAMPLE_TRANSACTION handling in sample synthesizing
        and 'perf test', from Adrian Hunter.

      . Clarify the "sample parsing" test entry, from Arnaldo Carvalho
        de Melo.

      . Consider PERF_SAMPLE_TRANSACTION in the "sample parsing" test,
        from Arnaldo Carvalho de Melo.

      . Memory leak fixes in 'perf test', from Felipe Pena.

   * 'perf bench' enhancements:

      . Change the procps visible command-name of invididual benchmark
        tests plus cleanups, from Ingo Molnar.

   * Generic perf tooling infrastructure/plumbing changes:

      . Separating data file properties from session, code
        reorganization from Jiri Olsa.

      . Fix version when building out of tree, as when using one of
        these:

        $ make help | grep perf
          perf-tar-src-pkg    - Build perf-3.12.0.tar source tarball
          perf-targz-src-pkg  - Build perf-3.12.0.tar.gz source tarball
          perf-tarbz2-src-pkg - Build perf-3.12.0.tar.bz2 source tarball
          perf-tarxz-src-pkg  - Build perf-3.12.0.tar.xz source tarball
        $

        from David Ahern.

      . Enhance option parse error message, showing just the help lines
        of the options affected, from Namhyung Kim.

      . libtraceevent updates from upstream trace-cmd repo, from Steven
        Rostedt.

      . Always use perf_evsel__set_sample_bit to set sample_type, from
        Adrian Hunter.

      . Memory and mmap leak fixes from Chenggang Qin.

      . Assorted build fixes for from David Ahern and Jiri Olsa.

      . Speed up and prettify the build system, from Ingo Molnar.

      . Implement addr2line directly using libbfd, from Roberto Vitillo.

      . Separate the GTK support in a separate libperf-gtk.so DSO, that
        is only loaded when --gtk is specified, from Namhyung Kim.

      . perf bash completion fixes and improvements from Ramkumar
        Ramachandra.

      . Support for Openembedded/Yocto -dbg packages, from Ricardo
        Ribalda Delgado.

  And lots and lots of other fixes and code reorganizations that did not
  make it into the list, see the shortlog, diffstat and the Git log for
  details!"

* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (300 commits)
  uprobes: Fix the memory out of bound overwrite in copy_insn()
  uprobes: Fix the wrong usage of current->utask in uprobe_copy_process()
  perf tools: Remove unneeded include
  perf record: Remove post_processing_offset variable
  perf record: Remove advance_output function
  perf record: Refactor feature handling into a separate function
  perf trace: Don't relookup fields by name in each sample
  perf tools: Fix version when building out of tree
  perf evsel: Ditch evsel->handler.data field
  uprobes: Export write_opcode() as uprobe_write_opcode()
  uprobes: Introduce arch_uprobe->ixol
  uprobes: Kill module_init() and module_exit()
  uprobes: Move function declarations out of arch
  perf/x86/intel: Add Ivy Bridge-EP uncore IRP box support
  perf/x86/intel/uncore: Add filter support for IvyBridge-EP QPI boxes
  perf: Factor out strncpy() in perf_event_mmap_event()
  tools/perf: Add required memory barriers
  perf: Fix arch_perf_out_copy_user default
  perf: Update a stale comment
  perf: Optimize perf_output_begin() -- address calculation
  ...
2013-11-12 10:06:34 +09:00
Ingo Molnar
c90423d1de Merge branch 'sched/core' into core/locking, to prepare the kernel/locking/ file move
Conflicts:
	kernel/Makefile

There are conflicts in kernel/Makefile due to file moving in the
scheduler tree - resolve them.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-11-06 07:50:37 +01:00
Ben Hutchings
8eaede49df sysrq: Allow magic SysRq key functions to be disabled through Kconfig
Turn the initial value of sysctl kernel.sysrq (SYSRQ_DEFAULT_ENABLE)
into a Kconfig variable.

Original version by Bastian Blank <waldi@debian.org>.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-16 13:01:44 -07:00
Rik van Riel
de1c9ce6f0 sched/numa: Skip some page migrations after a shared fault
Shared faults can lead to lots of unnecessary page migrations,
slowing down the system, and causing private faults to hit the
per-pgdat migration ratelimit.

This patch adds sysctl numa_balancing_migrate_deferred, which specifies
how many shared page migrations to skip unconditionally, after each page
migration that is skipped because it is a shared fault.

This reduces the number of page migrations back and forth in
shared fault situations. It also gives a strong preference to
the tasks that are already running where most of the memory is,
and to moving the other tasks to near the memory.

Testing this with a much higher scan rate than the default
still seems to result in fewer page migrations than before.

Memory seems to be somewhat better consolidated than previously,
with multi-instance specjbb runs on a 4 node system.

Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1381141781-10992-62-git-send-email-mgorman@suse.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-09 14:48:21 +02:00