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  1. 15 2月, 2017 5 次提交
  3. 10 2月, 2017 9 次提交
  5. 04 2月, 2017 4 次提交
    • T
      base/memory, hotplug: fix a kernel oops in show_valid_zones() · a96dfddb
      由 Toshi Kani 提交于 
      Reading a sysfs "memoryN/valid_zones" file leads to the following oops
when the first page of a range is not backed by struct page.
show_valid_zones() assumes that 'start_pfn' is always valid for
page_zone().

 BUG: unable to handle kernel paging request at ffffea017a000000
 IP: show_valid_zones+0x6f/0x160

This issue may happen on x86-64 systems with 64GiB or more memory since
their memory block size is bumped up to 2GiB.  [1] An example of such
systems is desribed below.  0x3240000000 is only aligned by 1GiB and
this memory block starts from 0x3200000000, which is not backed by
struct page.

 BIOS-e820: [mem 0x0000003240000000-0x000000603fffffff] usable

Since test_pages_in_a_zone() already checks holes, fix this issue by
extending this function to return 'valid_start' and 'valid_end' for a
given range.  show_valid_zones() then proceeds with the valid range.

[1] 'Commit bdee237c ("x86: mm: Use 2GB memory block size on
    large-memory x86-64 systems")'

Link: http://lkml.kernel.org/r/20170127222149.30893-3-toshi.kani@hpe.comSigned-off-by: NToshi Kani <toshi.kani@hpe.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Zhang Zhen <zhenzhang.zhang@huawei.com>
Cc: Reza Arbab <arbab@linux.vnet.ibm.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: <stable@vger.kernel.org>	[4.4+]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      a96dfddb
    • A
      log2: make order_base_2() behave correctly on const input value zero · 29905b52
      由 Ard Biesheuvel 提交于 
      The function order_base_2() is defined (according to the comment block)
as returning zero on input zero, but subsequently passes the input into
roundup_pow_of_two(), which is explicitly undefined for input zero.

This has gone unnoticed until now, but optimization passes in GCC 7 may
produce constant folded function instances where a constant value of
zero is passed into order_base_2(), resulting in link errors against the
deliberately undefined '____ilog2_NaN'.

So update order_base_2() to adhere to its own documented interface.

[ See

     http://marc.info/?l=linux-kernel&m=147672952517795&w=2

  and follow-up discussion for more background. The gcc "optimization
  pass" is really just broken, but now the GCC trunk problem seems to
  have escaped out of just specially built daily images, so we need to
  work around it in mainline.    - Linus ]
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      29905b52
    • A
      module: unify absolute krctab definitions for 32-bit and 64-bit · 4b9eee96
      由 Ard Biesheuvel 提交于 
      The previous patch introduced a separate inline asm version of the
krcrctab declaration template for use with 64-bit architectures, which
cannot refer to ELF symbols using 32-bit quantities.

This declaration should be equivalent to the C one for 32-bit
architectures, but just in case - unify them in a separate patch, which
can simply be dropped if it turns out to break anything.
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      4b9eee96
    • A
      modversions: treat symbol CRCs as 32 bit quantities · 71810db2
      由 Ard Biesheuvel 提交于 
      The modversion symbol CRCs are emitted as ELF symbols, which allows us
to easily populate the kcrctab sections by relying on the linker to
associate each kcrctab slot with the correct value.

This has a couple of downsides:

 - Given that the CRCs are treated as memory addresses, we waste 4 bytes
   for each CRC on 64 bit architectures,

 - On architectures that support runtime relocation, a R_<arch>_RELATIVE
   relocation entry is emitted for each CRC value, which identifies it
   as a quantity that requires fixing up based on the actual runtime
   load offset of the kernel. This results in corrupted CRCs unless we
   explicitly undo the fixup (and this is currently being handled in the
   core module code)

 - Such runtime relocation entries take up 24 bytes of __init space
   each, resulting in a x8 overhead in [uncompressed] kernel size for
   CRCs.

Switching to explicit 32 bit values on 64 bit architectures fixes most
of these issues, given that 32 bit values are not treated as quantities
that require fixing up based on the actual runtime load offset.  Note
that on some ELF64 architectures [such as PPC64], these 32-bit values
are still emitted as [absolute] runtime relocatable quantities, even if
the value resolves to a build time constant.  Since relative relocations
are always resolved at build time, this patch enables MODULE_REL_CRCS on
powerpc when CONFIG_RELOCATABLE=y, which turns the absolute CRC
references into relative references into .rodata where the actual CRC
value is stored.

So redefine all CRC fields and variables as u32, and redefine the
__CRC_SYMBOL() macro for 64 bit builds to emit the CRC reference using
inline assembler (which is necessary since 64-bit C code cannot use
32-bit types to hold memory addresses, even if they are ultimately
resolved using values that do not exceed 0xffffffff).  To avoid
potential problems with legacy 32-bit architectures using legacy
toolchains, the equivalent C definition of the kcrctab entry is retained
for 32-bit architectures.

Note that this mostly reverts commit d4703aef ("module: handle ppc64
relocating kcrctabs when CONFIG_RELOCATABLE=y")
Acked-by: NRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      71810db2
  7. 03 2月, 2017 1 次提交
  9. 02 2月, 2017 1 次提交
  11. 01 2月, 2017 4 次提交
    • T
      perf/x86/intel/uncore: Make package handling more robust · fff4b87e
      由 Thomas Gleixner 提交于 
      The package management code in uncore relies on package mapping being
available before a CPU is started. This changed with:

  9d85eb91 ("x86/smpboot: Make logical package management more robust")

because the ACPI/BIOS information turned out to be unreliable, but that
left uncore in broken state. This was not noticed because on a regular boot
all CPUs are online before uncore is initialized.

Move the allocation to the CPU online callback and simplify the hotplug
handling. At this point the package mapping is established and correct.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: Yasuaki Ishimatsu <yasu.isimatu@gmail.com>
Fixes: 9d85eb91 ("x86/smpboot: Make logical package management more robust")
Link: http://lkml.kernel.org/r/20170131230141.377156255@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
      fff4b87e
    • T
      perf/x86/intel/rapl: Make package handling more robust · dd86e373
      由 Thomas Gleixner 提交于 
      The package management code in RAPL relies on package mapping being
available before a CPU is started. This changed with:

  9d85eb91 ("x86/smpboot: Make logical package management more robust")

because the ACPI/BIOS information turned out to be unreliable, but that
left RAPL in broken state. This was not noticed because on a regular boot
all CPUs are online before RAPL is initialized.

A possible fix would be to reintroduce the mess which allocates a package
data structure in CPU prepare and when it turns out to already exist in
starting throw it away later in the CPU online callback. But that's a
horrible hack and not required at all because RAPL becomes functional for
perf only in the CPU online callback. That's correct because user space is
not yet informed about the CPU being onlined, so nothing caan rely on RAPL
being available on that particular CPU.

Move the allocation to the CPU online callback and simplify the hotplug
handling. At this point the package mapping is established and correct.

This also adds a missing check for available package data in the
event_init() function.
Reported-by: NYasuaki Ishimatsu <yasu.isimatu@gmail.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Fixes: 9d85eb91 ("x86/smpboot: Make logical package management more robust")
Link: http://lkml.kernel.org/r/20170131230141.212593966@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
      dd86e373
    • D
      fscache: Fix dead object requeue · e26bfebd
      由 David Howells 提交于 
      Under some circumstances, an fscache object can become queued such that it
fscache_object_work_func() can be called once the object is in the
OBJECT_DEAD state.  This results in the kernel oopsing when it tries to
invoke the handler for the state (which is hard coded to 0x2).

The way this comes about is something like the following:

 (1) The object dispatcher is processing a work state for an object.  This
     is done in workqueue context.

 (2) An out-of-band event comes in that isn't masked, causing the object to
     be queued, say EV_KILL.

 (3) The object dispatcher finishes processing the current work state on
     that object and then sees there's another event to process, so,
     without returning to the workqueue core, it processes that event too.
     It then follows the chain of events that initiates until we reach
     OBJECT_DEAD without going through a wait state (such as
     WAIT_FOR_CLEARANCE).

     At this point, object->events may be 0, object->event_mask will be 0
     and oob_event_mask will be 0.

 (4) The object dispatcher returns to the workqueue processor, and in due
     course, this sees that the object's work item is still queued and
     invokes it again.

 (5) The current state is a work state (OBJECT_DEAD), so the dispatcher
     jumps to it - resulting in an OOPS.

When I'm seeing this, the work state in (1) appears to have been either
LOOK_UP_OBJECT or CREATE_OBJECT (object->oob_table is
fscache_osm_lookup_oob).

The window for (2) is very small:

 (A) object->event_mask is cleared whilst the event dispatch process is
     underway - though there's no memory barrier to force this to the top
     of the function.

     The window, therefore is from the time the object was selected by the
     workqueue processor and made requeueable to the time the mask was
     cleared.

 (B) fscache_raise_event() will only queue the object if it manages to set
     the event bit and the corresponding event_mask bit was set.

     The enqueuement is then deferred slightly whilst we get a ref on the
     object and get the per-CPU variable for workqueue congestion.  This
     slight deferral slightly increases the probability by allowing extra
     time for the workqueue to make the item requeueable.

Handle this by giving the dead state a processor function and checking the
for the dead state address rather than seeing if the processor function is
address 0x2.  The dead state processor function can then set a flag to
indicate that it's occurred and give a warning if it occurs more than once
per object.

If this race occurs, an oops similar to the following is seen (note the RIP
value):

BUG: unable to handle kernel NULL pointer dereference at 0000000000000002
IP: [<0000000000000002>] 0x1
PGD 0
Oops: 0010 [#1] SMP
Modules linked in: ...
CPU: 17 PID: 16077 Comm: kworker/u48:9 Not tainted 3.10.0-327.18.2.el7.x86_64 #1
Hardware name: HP ProLiant DL380 Gen9/ProLiant DL380 Gen9, BIOS P89 12/27/2015
Workqueue: fscache_object fscache_object_work_func [fscache]
task: ffff880302b63980 ti: ffff880717544000 task.ti: ffff880717544000
RIP: 0010:[<0000000000000002>]  [<0000000000000002>] 0x1
RSP: 0018:ffff880717547df8  EFLAGS: 00010202
RAX: ffffffffa0368640 RBX: ffff880edf7a4480 RCX: dead000000200200
RDX: 0000000000000002 RSI: 00000000ffffffff RDI: ffff880edf7a4480
RBP: ffff880717547e18 R08: 0000000000000000 R09: dfc40a25cb3a4510
R10: dfc40a25cb3a4510 R11: 0000000000000400 R12: 0000000000000000
R13: ffff880edf7a4510 R14: ffff8817f6153400 R15: 0000000000000600
FS:  0000000000000000(0000) GS:ffff88181f420000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000002 CR3: 000000000194a000 CR4: 00000000001407e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Stack:
 ffffffffa0363695 ffff880edf7a4510 ffff88093f16f900 ffff8817faa4ec00
 ffff880717547e60 ffffffff8109d5db 00000000faa4ec18 0000000000000000
 ffff8817faa4ec18 ffff88093f16f930 ffff880302b63980 ffff88093f16f900
Call Trace:
 [<ffffffffa0363695>] ? fscache_object_work_func+0xa5/0x200 [fscache]
 [<ffffffff8109d5db>] process_one_work+0x17b/0x470
 [<ffffffff8109e4ac>] worker_thread+0x21c/0x400
 [<ffffffff8109e290>] ? rescuer_thread+0x400/0x400
 [<ffffffff810a5acf>] kthread+0xcf/0xe0
 [<ffffffff810a5a00>] ? kthread_create_on_node+0x140/0x140
 [<ffffffff816460d8>] ret_from_fork+0x58/0x90
 [<ffffffff810a5a00>] ? kthread_create_on_node+0x140/0x140
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Acked-by: NJeremy McNicoll <jeremymc@redhat.com>
Tested-by: NFrank Sorenson <sorenson@redhat.com>
Tested-by: NBenjamin Coddington <bcodding@redhat.com>
Reviewed-by: NBenjamin Coddington <bcodding@redhat.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      e26bfebd
    • D
      ipv6: fix flow labels when the traffic class is non-0 · 90427ef5
      由 Dimitris Michailidis 提交于 
      ip6_make_flowlabel() determines the flow label for IPv6 packets. It's
supposed to be passed a flow label, which it returns as is if non-0 and
in some other cases, otherwise it calculates a new value.

The problem is callers often pass a flowi6.flowlabel, which may also
contain traffic class bits. If the traffic class is non-0
ip6_make_flowlabel() mistakes the non-0 it gets as a flow label and
returns the whole thing. Thus it can return a 'flow label' longer than
20b and the low 20b of that is typically 0 resulting in packets with 0
label. Moreover, different packets of a flow may be labeled differently.
For a TCP flow with ECN non-payload and payload packets get different
labels as exemplified by this pair of consecutive packets:

(pure ACK)
Internet Protocol Version 6, Src: 2002:af5:11a3::, Dst: 2002:af5:11a2::
    0110 .... = Version: 6
    .... 0000 0000 .... .... .... .... .... = Traffic Class: 0x00 (DSCP: CS0, ECN: Not-ECT)
        .... 0000 00.. .... .... .... .... .... = Differentiated Services Codepoint: Default (0)
        .... .... ..00 .... .... .... .... .... = Explicit Congestion Notification: Not ECN-Capable Transport (0)
    .... .... .... 0001 1100 1110 0100 1001 = Flow Label: 0x1ce49
    Payload Length: 32
    Next Header: TCP (6)

(payload)
Internet Protocol Version 6, Src: 2002:af5:11a3::, Dst: 2002:af5:11a2::
    0110 .... = Version: 6
    .... 0000 0010 .... .... .... .... .... = Traffic Class: 0x02 (DSCP: CS0, ECN: ECT(0))
        .... 0000 00.. .... .... .... .... .... = Differentiated Services Codepoint: Default (0)
        .... .... ..10 .... .... .... .... .... = Explicit Congestion Notification: ECN-Capable Transport codepoint '10' (2)
    .... .... .... 0000 0000 0000 0000 0000 = Flow Label: 0x00000
    Payload Length: 688
    Next Header: TCP (6)

This patch allows ip6_make_flowlabel() to be passed more than just a
flow label and has it extract the part it really wants. This was simpler
than modifying the callers. With this patch packets like the above become

Internet Protocol Version 6, Src: 2002:af5:11a3::, Dst: 2002:af5:11a2::
    0110 .... = Version: 6
    .... 0000 0000 .... .... .... .... .... = Traffic Class: 0x00 (DSCP: CS0, ECN: Not-ECT)
        .... 0000 00.. .... .... .... .... .... = Differentiated Services Codepoint: Default (0)
        .... .... ..00 .... .... .... .... .... = Explicit Congestion Notification: Not ECN-Capable Transport (0)
    .... .... .... 1010 1111 1010 0101 1110 = Flow Label: 0xafa5e
    Payload Length: 32
    Next Header: TCP (6)

Internet Protocol Version 6, Src: 2002:af5:11a3::, Dst: 2002:af5:11a2::
    0110 .... = Version: 6
    .... 0000 0010 .... .... .... .... .... = Traffic Class: 0x02 (DSCP: CS0, ECN: ECT(0))
        .... 0000 00.. .... .... .... .... .... = Differentiated Services Codepoint: Default (0)
        .... .... ..10 .... .... .... .... .... = Explicit Congestion Notification: ECN-Capable Transport codepoint '10' (2)
    .... .... .... 1010 1111 1010 0101 1110 = Flow Label: 0xafa5e
    Payload Length: 688
    Next Header: TCP (6)
Signed-off-by: NDimitris Michailidis <dmichail@google.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      90427ef5
  13. 31 1月, 2017 2 次提交
  15. 30 1月, 2017 5 次提交
  17. 28 1月, 2017 2 次提交
    • D
      percpu-refcount: fix reference leak during percpu-atomic transition · 966d2b04
      由 Douglas Miller 提交于 
      percpu_ref_tryget() and percpu_ref_tryget_live() should return
"true" IFF they acquire a reference. But the return value from
atomic_long_inc_not_zero() is a long and may have high bits set,
e.g. PERCPU_COUNT_BIAS, and the return value of the tryget routines
is bool so the reference may actually be acquired but the routines
return "false" which results in a reference leak since the caller
assumes it does not need to do a corresponding percpu_ref_put().

This was seen when performing CPU hotplug during I/O, as hangs in
blk_mq_freeze_queue_wait where percpu_ref_kill (blk_mq_freeze_queue_start)
raced with percpu_ref_tryget (blk_mq_timeout_work).
Sample stack trace:

__switch_to+0x2c0/0x450
__schedule+0x2f8/0x970
schedule+0x48/0xc0
blk_mq_freeze_queue_wait+0x94/0x120
blk_mq_queue_reinit_work+0xb8/0x180
blk_mq_queue_reinit_prepare+0x84/0xa0
cpuhp_invoke_callback+0x17c/0x600
cpuhp_up_callbacks+0x58/0x150
_cpu_up+0xf0/0x1c0
do_cpu_up+0x120/0x150
cpu_subsys_online+0x64/0xe0
device_online+0xb4/0x120
online_store+0xb4/0xc0
dev_attr_store+0x68/0xa0
sysfs_kf_write+0x80/0xb0
kernfs_fop_write+0x17c/0x250
__vfs_write+0x6c/0x1e0
vfs_write+0xd0/0x270
SyS_write+0x6c/0x110
system_call+0x38/0xe0

Examination of the queue showed a single reference (no PERCPU_COUNT_BIAS,
and __PERCPU_REF_DEAD, __PERCPU_REF_ATOMIC set) and no requests.
However, conditions at the time of the race are count of PERCPU_COUNT_BIAS + 0
and __PERCPU_REF_DEAD and __PERCPU_REF_ATOMIC set.

The fix is to make the tryget routines use an actual boolean internally instead
of the atomic long result truncated to a int.

Fixes: e625305b percpu-refcount: make percpu_ref based on longs instead of ints
Link: https://bugzilla.kernel.org/show_bug.cgi?id=190751Signed-off-by: NDouglas Miller <dougmill@linux.vnet.ibm.com>
Reviewed-by: NJens Axboe <axboe@fb.com>
Signed-off-by: NTejun Heo <tj@kernel.org>
Fixes: e625305b ("percpu-refcount: make percpu_ref based on longs instead of ints")
Cc: stable@vger.kernel.org # v3.18+
      966d2b04
    • S
      net: phy: micrel: add support for KSZ8795 · 9d162ed6
      由 Sean Nyekjaer 提交于 
      This is adds support for the PHYs in the KSZ8795 5port managed switch.

It will allow to detect the link between the switch and the soc
and uses the same read_status functions as the KSZ8873MLL switch.
Signed-off-by: NSean Nyekjaer <sean.nyekjaer@prevas.dk>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      9d162ed6
  19. 27 1月, 2017 1 次提交
  21. 26 1月, 2017 3 次提交
  23. 25 1月, 2017 3 次提交
    • D
      misc: sram: Introduce support code for protect-exec sram type · 728bbe75
      由 Dave Gerlach 提交于 
      Some platforms, like many ARM SoCs, require the ability to run code from
on-chip memory like SRAM for tasks like reconfiguring the SDRAM
controller or entering low-power sleep modes. In order to do this we
must be able to allocate memory that the code can be copied to but then
change the mapping to be read-only and executable so that no memory is
both writable and executable at the same time to avoid opening any
unneccesary security holes.

By using the existing "pool" partition type that the SRAM driver allows
we can create a memory space that will already be exposed by the
genalloc framework to allow for allocating memory but we must extend
this to meet the executable requirements. By making use of various
set_memory_* APIs we can change the attributes of pages to make them
writable for code upload but then read-only and executable when we want
to actually run code.  Because SRAM is a shared resource we need a
centralized manager of these set memory calls. Because the SRAM driver
itself is responsible for allocating the memory we can introduce a
sram_copy_exec API for the driver that works like memcpy but also
manages the page attributes and locking to allow multiple users of the
same SRAM space to all copy their code over independent of other each
before starting execution.

It is maintained in a separate file from the core SRAM driver to allow
it to be selectively built depending on whether or not a platform has
the appropriate set_memory_* APIs. A future patch will integrate it with
the core SRAM driver.
Signed-off-by: NDave Gerlach <d-gerlach@ti.com>
Acked-by: NTony Lindgren <tony@atomide.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      728bbe75
    • V
      mm, page_alloc: fix check for NULL preferred_zone · ea57485a
      由 Vlastimil Babka 提交于 
      Patch series "fix premature OOM regression in 4.7+ due to cpuset races".

This is v2 of my attempt to fix the recent report based on LTP cpuset
stress test [1].  The intention is to go to stable 4.9 LTSS with this,
as triggering repeated OOMs is not nice.  That's why the patches try to
be not too intrusive.

Unfortunately why investigating I found that modifying the testcase to
use per-VMA policies instead of per-task policies will bring the OOM's
back, but that seems to be much older and harder to fix problem.  I have
posted a RFC [2] but I believe that fixing the recent regressions has a
higher priority.

Longer-term we might try to think how to fix the cpuset mess in a better
and less error prone way.  I was for example very surprised to learn,
that cpuset updates change not only task->mems_allowed, but also
nodemask of mempolicies.  Until now I expected the parameter to
alloc_pages_nodemask() to be stable.  I wonder why do we then treat
cpusets specially in get_page_from_freelist() and distinguish HARDWALL
etc, when there's unconditional intersection between mempolicy and
cpuset.  I would expect the nodemask adjustment for saving overhead in
g_p_f(), but that clearly doesn't happen in the current form.  So we
have both crazy complexity and overhead, AFAICS.

[1] https://lkml.kernel.org/r/CAFpQJXUq-JuEP=QPidy4p_=FN0rkH5Z-kfB4qBvsf6jMS87Edg@mail.gmail.com
[2] https://lkml.kernel.org/r/7c459f26-13a6-a817-e508-b65b903a8378@suse.cz

This patch (of 4):

Since commit c33d6c06 ("mm, page_alloc: avoid looking up the first
zone in a zonelist twice") we have a wrong check for NULL preferred_zone,
which can theoretically happen due to concurrent cpuset modification.  We
check the zoneref pointer which is never NULL and we should check the zone
pointer.  Also document this in first_zones_zonelist() comment per Michal
Hocko.

Fixes: c33d6c06 ("mm, page_alloc: avoid looking up the first zone in a zonelist twice")
Link: http://lkml.kernel.org/r/20170120103843.24587-2-vbabka@suse.czSigned-off-by: NVlastimil Babka <vbabka@suse.cz>
Acked-by: NMel Gorman <mgorman@techsingularity.net>
Acked-by: NHillf Danton <hillf.zj@alibaba-inc.com>
Cc: Ganapatrao Kulkarni <gpkulkarni@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      ea57485a
    • D
      kernel/watchdog: prevent false hardlockup on overloaded system · b94f5118
      由 Don Zickus 提交于 
      On an overloaded system, it is possible that a change in the watchdog
threshold can be delayed long enough to trigger a false positive.

This can easily be achieved by having a cpu spinning indefinitely on a
task, while another cpu updates watchdog threshold.

What happens is while trying to park the watchdog threads, the hrtimers
on the other cpus trigger and reprogram themselves with the new slower
watchdog threshold.  Meanwhile, the nmi watchdog is still programmed
with the old faster threshold.

Because the one cpu is blocked, it prevents the thread parking on the
other cpus from completing, which is needed to shutdown the nmi watchdog
and reprogram it correctly.  As a result, a false positive from the nmi
watchdog is reported.

Fix this by setting a park_in_progress flag to block all lockups until
the parking is complete.

Fix provided by Ulrich Obergfell.

[akpm@linux-foundation.org: s/park_in_progress/watchdog_park_in_progress/]
Link: http://lkml.kernel.org/r/1481041033-192236-1-git-send-email-dzickus@redhat.comSigned-off-by: NDon Zickus <dzickus@redhat.com>
Reviewed-by: NAaron Tomlin <atomlin@redhat.com>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      b94f5118