Pull timer fix from Ingo Molnar:
"Fix a sporadic missed timer hw reprogramming bug that can result in
random delays"
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
tick/nohz: Fix possible missing clock reprog after tick soft restart
ts->next_tick keeps track of the next tick deadline in order to optimize
clock programmation on irq exit and avoid redundant clock device writes.
Now if ts->next_tick missed an update, we may spuriously miss a clock
reprog later as the nohz code is fooled by an obsolete next_tick value.
This is what happens here on a specific path: when we observe an
expired timer from the nohz update code on irq exit, we perform a soft
tick restart which simply fires the closest possible tick without
actually exiting the nohz mode and restoring a periodic state. But we
forget to update ts->next_tick accordingly.
As a result, after the next tick resulting from such soft tick restart,
the nohz code sees a stale value on ts->next_tick which doesn't match
the clock deadline that just expired. If that obsolete ts->next_tick
value happens to collide with the actual next tick deadline to be
scheduled, we may spuriously bypass the clock reprogramming. In the
worst case, the tick may never fire again.
Fix this with a ts->next_tick reset on soft tick restart.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed: Wanpeng Li <wanpeng.li@hotmail.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1486485894-29173-1-git-send-email-fweisbec@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Alexei had his box explode because doing read() on a package
(rapl/uncore) event that isn't currently scheduled in ends up doing an
out-of-bounds load.
Rework the code to more explicitly deal with event->oncpu being -1.
Reported-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Tested-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: David Carrillo-Cisneros <davidcc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: eranian@google.com
Fixes: d6a2f9035b ("perf/core: Introduce PMU_EV_CAP_READ_ACTIVE_PKG")
Link: http://lkml.kernel.org/r/20170131102710.GL6515@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The user_header gets caught by kmemleak with the following splat as
missing a free:
unreferenced object 0xffff99667a733d80 (size 96):
comm "swapper/0", pid 1, jiffies 4294892317 (age 62191.468s)
hex dump (first 32 bytes):
a0 b6 92 b4 ff ff ff ff 00 00 00 00 01 00 00 00 ................
01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
kmemleak_alloc+0x4a/0xa0
__kmalloc+0x144/0x260
__register_sysctl_table+0x54/0x5e0
register_sysctl+0x1b/0x20
user_namespace_sysctl_init+0x17/0x34
do_one_initcall+0x52/0x1a0
kernel_init_freeable+0x173/0x200
kernel_init+0xe/0x100
ret_from_fork+0x2c/0x40
The BUG_ON()s are intended to crash so no need to clean up after
ourselves on error there. This is also a kernel/ subsys_init() we don't
need a respective exit call here as this is never modular, so just white
list it.
Link: http://lkml.kernel.org/r/20170203211404.31458-1-mcgrof@kernel.org
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Nikolay Borisov <n.borisov.lkml@gmail.com>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since KERN_CONT became meaningful again, lockdep stack traces have had
annoying extra newlines, like this:
[ 5.561122] -> #1 (B){+.+...}:
[ 5.561528]
[ 5.561532] [<ffffffff810d8873>] lock_acquire+0xc3/0x210
[ 5.562178]
[ 5.562181] [<ffffffff816f6414>] mutex_lock_nested+0x74/0x6d0
[ 5.562861]
[ 5.562880] [<ffffffffa01aa3c3>] init_btrfs_fs+0x21/0x196 [btrfs]
[ 5.563717]
[ 5.563721] [<ffffffff81000472>] do_one_initcall+0x52/0x1b0
[ 5.564554]
[ 5.564559] [<ffffffff811a3af6>] do_init_module+0x5f/0x209
[ 5.565357]
[ 5.565361] [<ffffffff81122f4d>] load_module+0x218d/0x2b80
[ 5.566020]
[ 5.566021] [<ffffffff81123beb>] SyS_finit_module+0xeb/0x120
[ 5.566694]
[ 5.566696] [<ffffffff816fd241>] entry_SYSCALL_64_fastpath+0x1f/0xc2
That's happening because each printk() call now gets printed on its own
line, and we do a separate call to print the spaces before the symbol.
Fix it by doing the printk() directly instead of using the
print_ip_sym() helper.
Additionally, the symbol address isn't very helpful, so let's get rid of
that, too. The final result looks like this:
[ 5.194518] -> #1 (B){+.+...}:
[ 5.195002] lock_acquire+0xc3/0x210
[ 5.195439] mutex_lock_nested+0x74/0x6d0
[ 5.196491] do_one_initcall+0x52/0x1b0
[ 5.196939] do_init_module+0x5f/0x209
[ 5.197355] load_module+0x218d/0x2b80
[ 5.197792] SyS_finit_module+0xeb/0x120
[ 5.198251] entry_SYSCALL_64_fastpath+0x1f/0xc2
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kernel-team@fb.com
Fixes: 4bcc595ccd ("printk: reinstate KERN_CONT for printing continuation lines")
Link: http://lkml.kernel.org/r/43b4e114724b2bdb0308fa86cb33aa07d3d67fad.1486510315.git.osandov@fb.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull irq fixes from Thomas Gleixner:
- Prevent double activation of interrupt lines, which causes problems
on certain interrupt controllers
- Handle the fallout of the above because x86 (ab)uses the activation
function to reconfigure interrupts under the hood.
* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/irq: Make irq activate operations symmetric
irqdomain: Avoid activating interrupts more than once
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 d4703aefdb ("module: handle ppc64
relocating kcrctabs when CONFIG_RELOCATABLE=y")
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull perf fixes from Ingo Molnar:
"Five kernel fixes:
- an mmap tracing ABI fix for certain mappings
- a use-after-free fix, found via KASAN
- three CPU hotplug related x86 PMU driver fixes"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/x86/intel/uncore: Make package handling more robust
perf/x86/intel/uncore: Clean up hotplug conversion fallout
perf/x86/intel/rapl: Make package handling more robust
perf/core: Fix PERF_RECORD_MMAP2 prot/flags for anonymous memory
perf/core: Fix use-after-free bug
clang complains about "__init" being attached to a struct name:
kernel/trace/trace_kprobe.c:1375:15: error: '__section__' attribute only applies to functions and global variables
The intention must have been to mark the function as __init instead of
the type, so move the attribute there.
Link: http://lkml.kernel.org/r/20170201165826.2625888-1-arnd@arndb.de
Fixes: f18f97ac43 ("tracing/kprobes: Add a helper method to return number of probe hits")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
not migrate after the first instance. I found that there was as small
bug in the logic, and fixed it. It's minor, but should be fixed regardless.
There's not much impact outside the hwlat tracer.
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Merge tag 'trace-4.10-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fix from Steven Rostedt:
"It was reported to me that the thread created by the hwlat tracer does
not migrate after the first instance. I found that there was as small
bug in the logic, and fixed it. It's minor, but should be fixed
regardless. There's not much impact outside the hwlat tracer"
* tag 'trace-4.10-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing: Fix hwlat kthread migration
Pull cgroup fix from Tejun Heo:
"The cgroup creation path was getting the order of operations wrong and
exposing cgroups which don't have their names set yet to controllers
which can lead to NULL derefs.
This contains the fix for the bug"
* 'for-4.10-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: don't online subsystems before cgroup_name/path() are operational
The hwlat tracer creates a kernel thread at start of the tracer. It is
pinned to a single CPU and will move to the next CPU after each period of
running. If the user modifies the migration thread's affinity, it will not
change after that happens.
The original code created the thread at the first instance it was called,
but later was changed to destroy the thread after the tracer was finished,
and would not be created until the next instance of the tracer was
established. The code that initialized the affinity was only called on the
initial instantiation of the tracer. After that, it was not initialized, and
the previous affinity did not match the current newly created one, making
it appear that the user modified the thread's affinity when it did not, and
the thread failed to migrate again.
Cc: stable@vger.kernel.org
Fixes: 0330f7aa8e ("tracing: Have hwlat trace migrate across tracing_cpumask CPUs")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Since commit f3b0946d62 ("genirq/msi: Make sure PCI MSIs are
activated early"), we can end-up activating a PCI/MSI twice (once
at allocation time, and once at startup time).
This is normally of no consequences, except that there is some
HW out there that may misbehave if activate is used more than once
(the GICv3 ITS, for example, uses the activate callback
to issue the MAPVI command, and the architecture spec says that
"If there is an existing mapping for the EventID-DeviceID
combination, behavior is UNPREDICTABLE").
While this could be worked around in each individual driver, it may
make more sense to tackle the issue at the core level. In order to
avoid getting in that situation, let's have a per-interrupt flag
to remember if we have already activated that interrupt or not.
Fixes: f3b0946d62 ("genirq/msi: Make sure PCI MSIs are activated early")
Reported-and-tested-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1484668848-24361-1-git-send-email-marc.zyngier@arm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Andres reported that MMAP2 records for anonymous memory always have
their protection field 0.
Turns out, someone daft put the prot/flags generation code in the file
branch, leaving them unset for anonymous memory.
Reported-by: Andres Freund <andres@anarazel.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Don Zickus <dzickus@redhat.com
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@gmail.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: acme@kernel.org
Cc: anton@ozlabs.org
Cc: namhyung@kernel.org
Cc: stable@vger.kernel.org # v3.16+
Fixes: f972eb63b1 ("perf: Pass protection and flags bits through mmap2 interface")
Link: http://lkml.kernel.org/r/20170126221508.GF6536@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Dmitry reported a KASAN use-after-free on event->group_leader.
It turns out there's a hole in perf_remove_from_context() due to
event_function_call() not calling its function when the task
associated with the event is already dead.
In this case the event will have been detached from the task, but the
grouping will have been retained, such that group operations might
still work properly while there are live child events etc.
This does however mean that we can miss a perf_group_detach() call
when the group decomposes, this in turn can then lead to
use-after-free.
Fix it by explicitly doing the group detach if its still required.
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Tested-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org # v4.5+
Cc: syzkaller <syzkaller@googlegroups.com>
Fixes: 63b6da39bb ("perf: Fix perf_event_exit_task() race")
Link: http://lkml.kernel.org/r/20170126153955.GD6515@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull networking fixes from David Miller:
1) GTP fixes from Andreas Schultz (missing genl module alias, clear IP
DF on transmit).
2) Netfilter needs to reflect the fwmark when sending resets, from Pau
Espin Pedrol.
3) nftable dump OOPS fix from Liping Zhang.
4) Fix erroneous setting of VIRTIO_NET_HDR_F_DATA_VALID on transmit,
from Rolf Neugebauer.
5) Fix build error of ipt_CLUSTERIP when procfs is disabled, from Arnd
Bergmann.
6) Fix regression in handling of NETIF_F_SG in harmonize_features(),
from Eric Dumazet.
7) Fix RTNL deadlock wrt. lwtunnel module loading, from David Ahern.
8) tcp_fastopen_create_child() needs to setup tp->max_window, from
Alexey Kodanev.
9) Missing kmemdup() failure check in ipv6 segment routing code, from
Eric Dumazet.
10) Don't execute unix_bind() under the bindlock, otherwise we deadlock
with splice. From WANG Cong.
11) ip6_tnl_parse_tlv_enc_lim() potentially reallocates the skb buffer,
therefore callers must reload cached header pointers into that skb.
Fix from Eric Dumazet.
12) Fix various bugs in legacy IRQ fallback handling in alx driver, from
Tobias Regnery.
13) Do not allow lwtunnel drivers to be unloaded while they are
referenced by active instances, from Robert Shearman.
14) Fix truncated PHY LED trigger names, from Geert Uytterhoeven.
15) Fix a few regressions from virtio_net XDP support, from John
Fastabend and Jakub Kicinski.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (102 commits)
ISDN: eicon: silence misleading array-bounds warning
net: phy: micrel: add support for KSZ8795
gtp: fix cross netns recv on gtp socket
gtp: clear DF bit on GTP packet tx
gtp: add genl family modules alias
tcp: don't annotate mark on control socket from tcp_v6_send_response()
ravb: unmap descriptors when freeing rings
virtio_net: reject XDP programs using header adjustment
virtio_net: use dev_kfree_skb for small buffer XDP receive
r8152: check rx after napi is enabled
r8152: re-schedule napi for tx
r8152: avoid start_xmit to schedule napi when napi is disabled
r8152: avoid start_xmit to call napi_schedule during autosuspend
net: dsa: Bring back device detaching in dsa_slave_suspend()
net: phy: leds: Fix truncated LED trigger names
net: phy: leds: Break dependency of phy.h on phy_led_triggers.h
net: phy: leds: Clear phy_num_led_triggers on failure to avoid crash
net-next: ethernet: mediatek: change the compatible string
Documentation: devicetree: change the mediatek ethernet compatible string
bnxt_en: Fix RTNL lock usage on bnxt_get_port_module_status().
...
- Revert the recent change that caused suspend-to-idle to be used
as the default suspend method on systems where it is indicated to
be efficient by the ACPI tables, as that turned out to be premature
and introduced suspend regressions on some systems with missing
power management support in device drivers (Rafael Wysocki).
- Fix up the intel_pstate driver to take changes of the global
limits via sysfs correctly when the performance policy is used
which has been broken by a recent change in it (Srinivas Pandruvada).
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Merge tag 'pm-4.10-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management fixes from Rafael Wysocki:
"These fix two regressions introduced recently, one by reverting the
problematic commit and one by fixing up the behavior in an overlooked
case.
Specifics:
- Revert the recent change that caused suspend-to-idle to be used as
the default suspend method on systems where it is indicated to be
efficient by the ACPI tables, as that turned out to be premature
and introduced suspend regressions on some systems with missing
power management support in device drivers (Rafael Wysocki).
- Fix up the intel_pstate driver to take changes of the global limits
via sysfs correctly when the performance policy is used which has
been broken by a recent change in it (Srinivas Pandruvada)"
* tag 'pm-4.10-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
cpufreq: intel_pstate: Fix sysfs limits enforcement for performance policy
Revert "PM / sleep / ACPI: Use the ACPI_FADT_LOW_POWER_S0 flag"
While refactoring cgroup creation, a5bca21520 ("cgroup: factor out
cgroup_create() out of cgroup_mkdir()") incorrectly onlined subsystems
before the new cgroup is associated with it kernfs_node. This is fine
for cgroup proper but cgroup_name/path() depend on the associated
kernfs_node and if a subsystem makes the new cgroup_subsys_state
visible, which they're allowed to after onlining, it can lead to NULL
dereference.
The current code performs cgroup creation and subsystem onlining in
cgroup_create() and cgroup_mkdir() makes the cgroup and subsystems
visible afterwards. There's no reason to online the subsystems early
and we can simply drop cgroup_apply_control_enable() call from
cgroup_create() so that the subsystems are onlined and made visible at
the same time.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Fixes: a5bca21520 ("cgroup: factor out cgroup_create() out of cgroup_mkdir()")
Cc: stable@vger.kernel.org # v4.6+
We perform the conversion between kernel jiffies and ms only when
exporting kernel value to user space.
We need to do the opposite operation when value is written by user.
Only matters when HZ != 1000
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge fixes from Andrew Morton:
"26 fixes"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (26 commits)
MAINTAINERS: add Dan Streetman to zbud maintainers
MAINTAINERS: add Dan Streetman to zswap maintainers
mm: do not export ioremap_page_range symbol for external module
mn10300: fix build error of missing fpu_save()
romfs: use different way to generate fsid for BLOCK or MTD
frv: add missing atomic64 operations
mm, page_alloc: fix premature OOM when racing with cpuset mems update
mm, page_alloc: move cpuset seqcount checking to slowpath
mm, page_alloc: fix fast-path race with cpuset update or removal
mm, page_alloc: fix check for NULL preferred_zone
kernel/panic.c: add missing \n
fbdev: color map copying bounds checking
frv: add atomic64_add_unless()
mm/mempolicy.c: do not put mempolicy before using its nodemask
radix-tree: fix private list warnings
Documentation/filesystems/proc.txt: add VmPin
mm, memcg: do not retry precharge charges
proc: add a schedule point in proc_pid_readdir()
mm: alloc_contig: re-allow CMA to compact FS pages
mm/slub.c: trace free objects at KERN_INFO
...
When a system panics, the "Rebooting in X seconds.." message is never
printed because it lacks a new line. Fix it.
Link: http://lkml.kernel.org/r/20170119114751.2724-1-jslaby@suse.cz
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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.com
Signed-off-by: Don Zickus <dzickus@redhat.com>
Reviewed-by: Aaron Tomlin <atomlin@redhat.com>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull namespace fix from Eric Biederman:
"This has a single brown bag fix.
The possible deadlock with dec_pid_namespaces that I had thought was
fixed earlier turned out only to have been moved. So instead of being
cleaver this change takes ucounts_lock with irqs disabled. So
dec_ucount can be used from any context without fear of deadlock.
The items accounted for dec_ucount and inc_ucount are all
comparatively heavy weight objects so I don't exepct this will have
any measurable performance impact"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
userns: Make ucounts lock irq-safe
Pull smp/hotplug fix from Thomas Gleixner:
"Remove an unused variable which is a leftover from the notifier
removal"
* 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
cpu/hotplug: Remove unused but set variable in _cpu_down()
Revert commit 08b98d3291 (PM / sleep / ACPI: Use the ACPI_FADT_LOW_POWER_S0
flag) as it caused system suspend (in the default configuration) to fail
on Dell XPS13 (9360) with the Kaby Lake processor.
Fixes: 08b98d3291 (PM / sleep / ACPI: Use the ACPI_FADT_LOW_POWER_S0 flag)
Reported-by: Paul Menzel <pmenzel@molgen.mpg.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This patch adds two helpers, bpf_map_area_alloc() and bpf_map_area_free(),
that are to be used for map allocations. Using kmalloc() for very large
allocations can cause excessive work within the page allocator, so i) fall
back earlier to vmalloc() when the attempt is considered costly anyway,
and even more importantly ii) don't trigger OOM killer with any of the
allocators.
Since this is based on a user space request, for example, when creating
maps with element pre-allocation, we really want such requests to fail
instead of killing other user space processes.
Also, don't spam the kernel log with warnings should any of the allocations
fail under pressure. Given that, we can make backend selection in
bpf_map_area_alloc() generic, and convert all maps over to use this API
for spots with potentially large allocation requests.
Note, replacing the one kmalloc_array() is fine as overflow checks happen
earlier in htab_map_alloc(), since it must also protect the multiplication
for vmalloc() should kmalloc_array() fail.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull SMP hotplug update from Thomas Gleixner:
"This contains a trivial typo fix and an extension to the core code for
dynamically allocating states in the prepare stage.
The extension is necessary right now because we need a proper way to
unbreak LTTNG, which iscurrently non functional due to the removal of
the notifiers. Surely it's out of tree, but it's widely used by
distros.
The simple solution would have been to reserve a state for LTTNG, but
I'm not fond about unused crap in the kernel and the dynamic range,
which we admittedly should have done right away, allows us to remove
quite some of the hardcoded states, i.e. those which have no ordering
requirements. So doing the right thing now is better than having an
smaller intermediate solution which needs to be reworked anyway"
* 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
cpu/hotplug: Provide dynamic range for prepare stage
perf/x86/amd/ibs: Fix typo after cleanup state names in cpu/hotplug
Pull RCU fixes from Ingo Molnar:
"This fixes sporadic ACPI related hangs in synchronize_rcu() that were
caused by the ACPI code mistakenly relying on an aspect of RCU that
was neither promised to work nor reliable but which happened to work -
until in v4.9 we changed the RCU implementation, which made the hangs
more prominent.
Since the mis-use of the RCU facility wasn't properly detected and
prevented either, these fixes make the RCU side work reliably instead
of working around the problem in the ACPI code.
Hence the slightly larger diffstat that goes beyond the normal scope
of RCU fixes in -rc kernels"
* 'rcu-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
rcu: Narrow early boot window of illegal synchronous grace periods
rcu: Remove cond_resched() from Tiny synchronize_sched()
After the recent removal of the hotplug notifiers the variable 'hasdied' in
_cpu_down() is set but no longer read, leading to the following GCC warning
when building with 'make W=1':
kernel/cpu.c:767:7: warning: variable ‘hasdied’ set but not used [-Wunused-but-set-variable]
Fix it by removing the variable.
Fixes: 530e9b76ae ("cpu/hotplug: Remove obsolete cpu hotplug register/unregister functions")
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20170117143501.20893-1-tklauser@distanz.ch
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
- Fix out-of-tree module breakage when it supplies its own
definitions of true and false
Signed-off-by: Jessica Yu <jeyu@redhat.com>
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Merge tag 'modules-for-v4.10-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux
Pull modules fix from Jessica Yu:
- fix out-of-tree module breakage when it supplies its own definitions
of true and false
* tag 'modules-for-v4.10-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux:
taint/module: Fix problems when out-of-kernel driver defines true or false
Commit 7fd8329ba5 ("taint/module: Clean up global and module taint
flags handling") used the key words true and false as character members
of a new struct. These names cause problems when out-of-kernel modules
such as VirtualBox include their own definitions of true and false.
Fixes: 7fd8329ba5 ("taint/module: Clean up global and module taint flags handling")
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Jessica Yu <jeyu@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Reported-by: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Jessica Yu <jeyu@redhat.com>
Pull networking fixes from David Miller:
1) Handle multicast packets properly in fast-RX path of mac80211, from
Johannes Berg.
2) Because of a logic bug, the user can't actually force SW
checksumming on r8152 devices. This makes diagnosis of hw
checksumming bugs really annoying. Fix from Hayes Wang.
3) VXLAN route lookup does not take the source and destination ports
into account, which means IPSEC policies cannot be matched properly.
Fix from Martynas Pumputis.
4) Do proper RCU locking in netvsc callbacks, from Stephen Hemminger.
5) Fix SKB leaks in mlxsw driver, from Arkadi Sharshevsky.
6) If lwtunnel_fill_encap() fails, we do not abort the netlink message
construction properly in fib_dump_info(), from David Ahern.
7) Do not use kernel stack for DMA buffers in atusb driver, from Stefan
Schmidt.
8) Openvswitch conntack actions need to maintain a correct checksum,
fix from Lance Richardson.
9) ax25_disconnect() is missing a check for ax25->sk being NULL, in
fact it already checks this, but not in all of the necessary spots.
Fix from Basil Gunn.
10) Action GET operations in the packet scheduler can erroneously bump
the reference count of the entry, making it unreleasable. Fix from
Jamal Hadi Salim. Jamal gives a great set of example command lines
that trigger this in the commit message.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (46 commits)
net sched actions: fix refcnt when GETing of action after bind
net/mlx4_core: Eliminate warning messages for SRQ_LIMIT under SRIOV
net/mlx4_core: Fix when to save some qp context flags for dynamic VST to VGT transitions
net/mlx4_core: Fix racy CQ (Completion Queue) free
net: stmmac: don't use netdev_[dbg, info, ..] before net_device is registered
net/mlx5e: Fix a -Wmaybe-uninitialized warning
ax25: Fix segfault after sock connection timeout
bpf: rework prog_digest into prog_tag
tipc: allocate user memory with GFP_KERNEL flag
net: phy: dp83867: allow RGMII_TXID/RGMII_RXID interface types
ip6_tunnel: Account for tunnel header in tunnel MTU
mld: do not remove mld souce list info when set link down
be2net: fix MAC addr setting on privileged BE3 VFs
be2net: don't delete MAC on close on unprivileged BE3 VFs
be2net: fix status check in be_cmd_pmac_add()
cpmac: remove hopeless #warning
ravb: do not use zero-length alignment DMA descriptor
mlx4: do not call napi_schedule() without care
openvswitch: maintain correct checksum state in conntrack actions
tcp: fix tcp_fastopen unaligned access complaints on sparc
...
Commit 7bd509e311 ("bpf: add prog_digest and expose it via
fdinfo/netlink") was recently discussed, partially due to
admittedly suboptimal name of "prog_digest" in combination
with sha1 hash usage, thus inevitably and rightfully concerns
about its security in terms of collision resistance were
raised with regards to use-cases.
The intended use cases are for debugging resp. introspection
only for providing a stable "tag" over the instruction sequence
that both kernel and user space can calculate independently.
It's not usable at all for making a security relevant decision.
So collisions where two different instruction sequences generate
the same tag can happen, but ideally at a rather low rate. The
"tag" will be dumped in hex and is short enough to introspect
in tracepoints or kallsyms output along with other data such
as stack trace, etc. Thus, this patch performs a rename into
prog_tag and truncates the tag to a short output (64 bits) to
make it obvious it's not collision-free.
Should in future a hash or facility be needed with a security
relevant focus, then we can think about requirements, constraints,
etc that would fit to that situation. For now, rework the exposed
parts for the current use cases as long as nothing has been
released yet. Tested on x86_64 and s390x.
Fixes: 7bd509e311 ("bpf: add prog_digest and expose it via fdinfo/netlink")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Mathieu reported that the LTTNG modules are broken as of 4.10-rc1 due to
the removal of the cpu hotplug notifiers.
Usually I don't care much about out of tree modules, but LTTNG is widely
used in distros. There are two ways to solve that:
1) Reserve a hotplug state for LTTNG
2) Add a dynamic range for the prepare states.
While #1 is the simplest solution, #2 is the proper one as we can convert
in tree users, which do not care about ordering, to the dynamic range as
well.
Add a dynamic range which allows LTTNG to request states in the prepare
stage.
Reported-and-tested-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Sewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1701101353010.3401@nanos
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Pull an urgent RCU fix from Paul E. McKenney:
"This series contains a pair of commits that permit RCU synchronous grace
periods (synchronize_rcu() and friends) to work correctly throughout boot.
This eliminates the current "dead time" starting when the scheduler spawns
its first taks and ending when the last of RCU's kthreads is spawned
(this last happens during early_initcall() time). Although RCU's
synchronous grace periods have long been documented as not working
during this time, prior to 4.9, the expedited grace periods worked by
accident, and some ACPI code came to rely on this unintentional behavior.
(Note that this unintentional behavior was -not- reliable. For example,
failures from ACPI could occur on !SMP systems and on systems booting
with the rcu_normal kernel boot parameter.)
Either way, there is a bug that needs fixing, and the 4.9 switch of RCU's
expedited grace periods to workqueues could be considered to have caused
a regression. This series therefore makes RCU's expedited grace periods
operate correctly throughout the boot process. This has been demonstrated
to fix the problems ACPI was encountering, and has the added longer-term
benefit of simplifying RCU's behavior."
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull namespace fixes from Eric Biederman:
"This tree contains 4 fixes.
The first is a fix for a race that can causes oopses under the right
circumstances, and that someone just recently encountered.
Past that are several small trivial correct fixes. A real issue that
was blocking development of an out of tree driver, but does not appear
to have caused any actual problems for in-tree code. A potential
deadlock that was reported by lockdep. And a deadlock people have
experienced and took the time to track down caused by a cleanup that
removed the code to drop a reference count"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
sysctl: Drop reference added by grab_header in proc_sys_readdir
pid: fix lockdep deadlock warning due to ucount_lock
libfs: Modify mount_pseudo_xattr to be clear it is not a userspace mount
mnt: Protect the mountpoint hashtable with mount_lock
Pull NOHZ fix from Ingo Molnar:
"This fixes an old NOHZ race where we incorrectly calculate the next
timer interrupt in certain circumstances where hrtimers are pending,
that can cause hard to reproduce stalled-values artifacts in
/proc/stat"
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
nohz: Fix collision between tick and other hrtimers
Pull perf fixes from Ingo Molnar:
"Misc race fixes uncovered by fuzzing efforts, a Sparse fix, two PMU
driver fixes, plus miscellanous tooling fixes"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/x86: Reject non sampling events with precise_ip
perf/x86/intel: Account interrupts for PEBS errors
perf/core: Fix concurrent sys_perf_event_open() vs. 'move_group' race
perf/core: Fix sys_perf_event_open() vs. hotplug
perf/x86/intel: Use ULL constant to prevent undefined shift behaviour
perf/x86/intel/uncore: Fix hardcoded socket 0 assumption in the Haswell init code
perf/x86: Set pmu->module in Intel PMU modules
perf probe: Fix to probe on gcc generated symbols for offline kernel
perf probe: Fix --funcs to show correct symbols for offline module
perf symbols: Robustify reading of build-id from sysfs
perf tools: Install tools/lib/traceevent plugins with install-bin
tools lib traceevent: Fix prev/next_prio for deadline tasks
perf record: Fix --switch-output documentation and comment
perf record: Make __record_options static
tools lib subcmd: Add OPT_STRING_OPTARG_SET option
perf probe: Fix to get correct modname from elf header
samples/bpf trace_output_user: Remove duplicate sys/ioctl.h include
samples/bpf sock_example: Avoid getting ethhdr from two includes
perf sched timehist: Show total scheduling time
The current preemptible RCU implementation goes through three phases
during bootup. In the first phase, there is only one CPU that is running
with preemption disabled, so that a no-op is a synchronous grace period.
In the second mid-boot phase, the scheduler is running, but RCU has
not yet gotten its kthreads spawned (and, for expedited grace periods,
workqueues are not yet running. During this time, any attempt to do
a synchronous grace period will hang the system (or complain bitterly,
depending). In the third and final phase, RCU is fully operational and
everything works normally.
This has been OK for some time, but there has recently been some
synchronous grace periods showing up during the second mid-boot phase.
This code worked "by accident" for awhile, but started failing as soon
as expedited RCU grace periods switched over to workqueues in commit
8b355e3bc1 ("rcu: Drive expedited grace periods from workqueue").
Note that the code was buggy even before this commit, as it was subject
to failure on real-time systems that forced all expedited grace periods
to run as normal grace periods (for example, using the rcu_normal ksysfs
parameter). The callchain from the failure case is as follows:
early_amd_iommu_init()
|-> acpi_put_table(ivrs_base);
|-> acpi_tb_put_table(table_desc);
|-> acpi_tb_invalidate_table(table_desc);
|-> acpi_tb_release_table(...)
|-> acpi_os_unmap_memory
|-> acpi_os_unmap_iomem
|-> acpi_os_map_cleanup
|-> synchronize_rcu_expedited
The kernel showing this callchain was built with CONFIG_PREEMPT_RCU=y,
which caused the code to try using workqueues before they were
initialized, which did not go well.
This commit therefore reworks RCU to permit synchronous grace periods
to proceed during this mid-boot phase. This commit is therefore a
fix to a regression introduced in v4.9, and is therefore being put
forward post-merge-window in v4.10.
This commit sets a flag from the existing rcu_scheduler_starting()
function which causes all synchronous grace periods to take the expedited
path. The expedited path now checks this flag, using the requesting task
to drive the expedited grace period forward during the mid-boot phase.
Finally, this flag is updated by a core_initcall() function named
rcu_exp_runtime_mode(), which causes the runtime codepaths to be used.
Note that this arrangement assumes that tasks are not sent POSIX signals
(or anything similar) from the time that the first task is spawned
through core_initcall() time.
Fixes: 8b355e3bc1 ("rcu: Drive expedited grace periods from workqueue")
Reported-by: "Zheng, Lv" <lv.zheng@intel.com>
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Stan Kain <stan.kain@gmail.com>
Tested-by: Ivan <waffolz@hotmail.com>
Tested-by: Emanuel Castelo <emanuel.castelo@gmail.com>
Tested-by: Bruno Pesavento <bpesavento@infinito.it>
Tested-by: Borislav Petkov <bp@suse.de>
Tested-by: Frederic Bezies <fredbezies@gmail.com>
Cc: <stable@vger.kernel.org> # 4.9.0-
It is now legal to invoke synchronize_sched() at early boot, which causes
Tiny RCU's synchronize_sched() to emit spurious splats. This commit
therefore removes the cond_resched() from Tiny RCU's synchronize_sched().
Fixes: 8b355e3bc1 ("rcu: Drive expedited grace periods from workqueue")
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: <stable@vger.kernel.org> # 4.9.0-
It's possible to set up PEBS events to get only errors and not
any data, like on SNB-X (model 45) and IVB-EP (model 62)
via 2 perf commands running simultaneously:
taskset -c 1 ./perf record -c 4 -e branches:pp -j any -C 10
This leads to a soft lock up, because the error path of the
intel_pmu_drain_pebs_nhm() does not account event->hw.interrupt
for error PEBS interrupts, so in case you're getting ONLY
errors you don't have a way to stop the event when it's over
the max_samples_per_tick limit:
NMI watchdog: BUG: soft lockup - CPU#22 stuck for 22s! [perf_fuzzer:5816]
...
RIP: 0010:[<ffffffff81159232>] [<ffffffff81159232>] smp_call_function_single+0xe2/0x140
...
Call Trace:
? trace_hardirqs_on_caller+0xf5/0x1b0
? perf_cgroup_attach+0x70/0x70
perf_install_in_context+0x199/0x1b0
? ctx_resched+0x90/0x90
SYSC_perf_event_open+0x641/0xf90
SyS_perf_event_open+0x9/0x10
do_syscall_64+0x6c/0x1f0
entry_SYSCALL64_slow_path+0x25/0x25
Add perf_event_account_interrupt() which does the interrupt
and frequency checks and call it from intel_pmu_drain_pebs_nhm()'s
error path.
We keep the pending_kill and pending_wakeup logic only in the
__perf_event_overflow() path, because they make sense only if
there's any data to deliver.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
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: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vince@deater.net>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/1482931866-6018-2-git-send-email-jolsa@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Di Shen reported a race between two concurrent sys_perf_event_open()
calls where both try and move the same pre-existing software group
into a hardware context.
The problem is exactly that described in commit:
f63a8daa58 ("perf: Fix event->ctx locking")
... where, while we wait for a ctx->mutex acquisition, the event->ctx
relation can have changed under us.
That very same commit failed to recognise sys_perf_event_context() as an
external access vector to the events and thereby didn't apply the
established locking rules correctly.
So while one sys_perf_event_open() call is stuck waiting on
mutex_lock_double(), the other (which owns said locks) moves the group
about. So by the time the former sys_perf_event_open() acquires the
locks, the context we've acquired is stale (and possibly dead).
Apply the established locking rules as per perf_event_ctx_lock_nested()
to the mutex_lock_double() for the 'move_group' case. This obviously means
we need to validate state after we acquire the locks.
Reported-by: Di Shen (Keen Lab)
Tested-by: John Dias <joaodias@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Min Chong <mchong@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Fixes: f63a8daa58 ("perf: Fix event->ctx locking")
Link: http://lkml.kernel.org/r/20170106131444.GZ3174@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There is problem with installing an event in a task that is 'stuck' on
an offline CPU.
Blocked tasks are not dis-assosciated from offlined CPUs, after all, a
blocked task doesn't run and doesn't require a CPU etc.. Only on
wakeup do we ammend the situation and place the task on a available
CPU.
If we hit such a task with perf_install_in_context() we'll loop until
either that task wakes up or the CPU comes back online, if the task
waking depends on the event being installed, we're stuck.
While looking into this issue, I also spotted another problem, if we
hit a task with perf_install_in_context() that is in the middle of
being migrated, that is we observe the old CPU before sending the IPI,
but run the IPI (on the old CPU) while the task is already running on
the new CPU, things also go sideways.
Rework things to rely on task_curr() -- outside of rq->lock -- which
is rather tricky. Imagine the following scenario where we're trying to
install the first event into our task 't':
CPU0 CPU1 CPU2
(current == t)
t->perf_event_ctxp[] = ctx;
smp_mb();
cpu = task_cpu(t);
switch(t, n);
migrate(t, 2);
switch(p, t);
ctx = t->perf_event_ctxp[]; // must not be NULL
smp_function_call(cpu, ..);
generic_exec_single()
func();
spin_lock(ctx->lock);
if (task_curr(t)) // false
add_event_to_ctx();
spin_unlock(ctx->lock);
perf_event_context_sched_in();
spin_lock(ctx->lock);
// sees event
So its CPU0's store of t->perf_event_ctxp[] that must not go 'missing'.
Because if CPU2's load of that variable were to observe NULL, it would
not try to schedule the ctx and we'd have a task running without its
counter, which would be 'bad'.
As long as we observe !NULL, we'll acquire ctx->lock. If we acquire it
first and not see the event yet, then CPU0 must observe task_curr()
and retry. If the install happens first, then we must see the event on
sched-in and all is well.
I think we can translate the first part (until the 'must not be NULL')
of the scenario to a litmus test like:
C C-peterz
{
}
P0(int *x, int *y)
{
int r1;
WRITE_ONCE(*x, 1);
smp_mb();
r1 = READ_ONCE(*y);
}
P1(int *y, int *z)
{
WRITE_ONCE(*y, 1);
smp_store_release(z, 1);
}
P2(int *x, int *z)
{
int r1;
int r2;
r1 = smp_load_acquire(z);
smp_mb();
r2 = READ_ONCE(*x);
}
exists
(0:r1=0 /\ 2:r1=1 /\ 2:r2=0)
Where:
x is perf_event_ctxp[],
y is our tasks's CPU, and
z is our task being placed on the rq of CPU2.
The P0 smp_mb() is the one added by this patch, ordering the store to
perf_event_ctxp[] from find_get_context() and the load of task_cpu()
in task_function_call().
The smp_store_release/smp_load_acquire model the RCpc locking of the
rq->lock and the smp_mb() of P2 is the context switch switching from
whatever CPU2 was running to our task 't'.
This litmus test evaluates into:
Test C-peterz Allowed
States 7
0:r1=0; 2:r1=0; 2:r2=0;
0:r1=0; 2:r1=0; 2:r2=1;
0:r1=0; 2:r1=1; 2:r2=1;
0:r1=1; 2:r1=0; 2:r2=0;
0:r1=1; 2:r1=0; 2:r2=1;
0:r1=1; 2:r1=1; 2:r2=0;
0:r1=1; 2:r1=1; 2:r2=1;
No
Witnesses
Positive: 0 Negative: 7
Condition exists (0:r1=0 /\ 2:r1=1 /\ 2:r2=0)
Observation C-peterz Never 0 7
Hash=e427f41d9146b2a5445101d3e2fcaa34
And the strong and weak model agree.
Reported-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
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 Andrzej Siewior <bigeasy@linutronix.de>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: Will Deacon <will.deacon@arm.com>
Cc: jeremy.linton@arm.com
Link: http://lkml.kernel.org/r/20161209135900.GU3174@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
- Cleanups and bug fixes for the mtty sample driver (Dan Carpenter)
- Export and make use of has_capability() to fix incorrect use of
ns_capable() for testing task capabilities (Jike Song)
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Merge tag 'vfio-v4.10-rc4' of git://github.com/awilliam/linux-vfio
Pull VFIO fixes from Alex Williamson:
- Cleanups and bug fixes for the mtty sample driver (Dan Carpenter)
- Export and make use of has_capability() to fix incorrect use of
ns_capable() for testing task capabilities (Jike Song)
* tag 'vfio-v4.10-rc4' of git://github.com/awilliam/linux-vfio:
vfio/type1: Remove pid_namespace.h include
vfio iommu type1: fix the testing of capability for remote task
capability: export has_capability
vfio-mdev: remove some dead code
vfio-mdev: buffer overflow in ioctl()
vfio-mdev: return -EFAULT if copy_to_user() fails
other buggy modules!)
* two NULL pointer dereferences from syzkaller
* CVE from syzkaller, very serious on 4.10-rc, "just" kernel memory
leak on releases
* CVE from security@kernel.org, somewhat serious on AMD, less so on
Intel
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull KVM fixes from Paolo Bonzini:
- fix for module unload vs deferred jump labels (note: there might be
other buggy modules!)
- two NULL pointer dereferences from syzkaller
- also syzkaller: fix emulation of fxsave/fxrstor/sgdt/sidt, problem
made worse during this merge window, "just" kernel memory leak on
releases
- fix emulation of "mov ss" - somewhat serious on AMD, less so on Intel
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: x86: fix emulation of "MOV SS, null selector"
KVM: x86: fix NULL deref in vcpu_scan_ioapic
KVM: eventfd: fix NULL deref irqbypass consumer
KVM: x86: Introduce segmented_write_std
KVM: x86: flush pending lapic jump label updates on module unload
jump_labels: API for flushing deferred jump label updates
