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The rcutree.kthread_prio kernel-boot parameter is used to set the
priority for boost (rcub), per-CPU (rcuc), and grace-period (rcu_preempt
or rcu_sched) kthreads. It is also used by rcutorture to check whether
it is possible to meaningfully test RCU priority boosting. However,
all of these cases will either ignore or be confused by any post-boot
changes to rcutree.kthread_prio.
Note that the user really can change the priorities of all of these
kthreads using chrt, given sufficient privileges. Therefore, the
read-write nature of sysfs access to rcutree.kthread_prio is thus at
best an attractive nuisance.
This commit therefore changes sysfs access to rcutree.kthread_prio to
be read-only.
Signed-off-by: Liu Song <liu.song11@zte.com.cn>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
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The purpose of exit_rcu() is to handle cases where buggy code causes a
task to exit within an RCU read-side critical section. It currently
does that in the case where said RCU read-side critical section was
preempted at least once, but fails to handle cases where preemption did
not occur. This case needs to be handled because otherwise the final
context switch away from the exiting task will incorrectly behave as if
task exit were instead a preemption of an RCU read-side critical section,
and will therefore queue the exiting task. The exiting task will have
exited, and thus won't ever execute rcu_read_unlock(), which means that
it will remain queued forever, blocking all subsequent grace periods,
and eventually resulting in OOM.
Although this is arguably better than letting grace periods proceed
and having a later rcu_read_unlock() access the now-freed task
structure that once belonged to the exiting tasks, it would obviously
be better to correctly handle this case. This commit therefore sets
->rcu_read_lock_nesting to 1 in that case, so that the subsequence call
to __rcu_read_unlock() causes the exiting task to exit its dangling RCU
read-side critical section.
Note that deferred quiescent states need not be considered. The reason
is that removing the task from the ->blkd_tasks[] list in the call to
rcu_preempt_deferred_qs() handles the per-task component of any deferred
quiescent state, and all other components of any deferred quiescent state
are associated with the CPU, which isn't going anywhere until some later
CPU-hotplug operation, which will report any remaining deferred quiescent
states from within the rcu_report_dead() function.
Note also that negative values of ->rcu_read_lock_nesting need not be
considered. First, these won't show up in exit_rcu() unless there is
a serious bug in RCU, and second, setting ->rcu_read_lock_nesting sets
the state so that the RCU read-side critical section will be exited
normally.
Again, this code has no effect unless there has been some prior bug
that prevents a task from leaving an RCU read-side critical section
before exiting. Furthermore, there have been no reports of the bug
fixed by this commit appearing in production. This commit is therefore
absolutely -not- recommended for backporting to -stable.
Reported-by: ABHISHEK DUBEY <dabhishek@iisc.ac.in>
Reported-by: BHARATH Y MOURYA <bharathm@iisc.ac.in>
Reported-by: Aravinda Prasad <aravinda@iisc.ac.in>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Tested-by: ABHISHEK DUBEY <dabhishek@iisc.ac.in>
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The rcu_qs is disabling IRQs by self so no need to do the same in raise_softirq
but instead we can save some cycles using raise_softirq_irqoff directly.
CC: Paul E. McKenney <paulmck@linux.ibm.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
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When there are no callbacks pending on an idle system, I noticed that
RCU softirq is continuously firing. During this the cpu_no_qs is set to
false, and core_needs_qs is set to true indefinitely. This causes
rcu_process_callbacks to be repeatedly called, even though the node
corresponding to the CPU has that CPU's mask bit cleared and the system
is idle. I believe the race is when such mask clearing is done during
idle CPU scan of the quiescent state forcing stage in the kthread
instead of the softirq. Since the rnp mask is cleared, but the flags on
the CPU's rdp are not cleared, the CPU thinks it still needs to report
to core RCU.
Cure this by clearing the core_needs_qs flag when the CPU detects that
its node is already updated which will avoid the unwanted softirq raises
to the benefit of real-time systems.
Test: Ran rcutorture for various tree RCU configs.
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
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The rcu_pm_notify() function refuses to switch to/from expedited grace
periods on systems with more than 256 CPUs due to the serialized
initialization of expedited grace periods. However, expedited grace
periods are now initialized in parallel, removing this concern.
This commit therefore removes the checks from rcu_pm_notify(), so that
expedited grace periods are used unconditionally during suspend/resume
and hibernate/wake operations.
As always, real-time workloads wishing to completely avoid expedited
grace periods can use the rcupdate.rcu_normal= kernel parameter.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull more Kbuild updates from Masahiro Yamada:
- add more Build-Depends to Debian source package
- prefix header search paths with $(srctree)/
- make modpost show verbose section mismatch warnings
- avoid hard-coded CROSS_COMPILE for h8300
- fix regression for Debian make-kpkg command
- add semantic patch to detect missing put_device()
- fix some warnings of 'make deb-pkg'
- optimize NOSTDINC_FLAGS evaluation
- add warnings about redundant generic-y
- clean up Makefiles and scripts
* tag 'kbuild-v5.1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
kconfig: remove stale lxdialog/.gitignore
kbuild: force all architectures except um to include mandatory-y
kbuild: warn redundant generic-y
Revert "modsign: Abort modules_install when signing fails"
kbuild: Make NOSTDINC_FLAGS a simply expanded variable
kbuild: deb-pkg: avoid implicit effects
coccinelle: semantic code search for missing put_device()
kbuild: pkg: grep include/config/auto.conf instead of $KCONFIG_CONFIG
kbuild: deb-pkg: introduce is_enabled and if_enabled_echo to builddeb
kbuild: deb-pkg: add CONFIG_ prefix to kernel config options
kbuild: add workaround for Debian make-kpkg
kbuild: source include/config/auto.conf instead of ${KCONFIG_CONFIG}
unicore32: simplify linker script generation for decompressor
h8300: use cc-cross-prefix instead of hardcoding h8300-unknown-linux-
kbuild: move archive command to scripts/Makefile.lib
modpost: always show verbose warning for section mismatch
ia64: prefix header search path with $(srctree)/
libfdt: prefix header search paths with $(srctree)/
deb-pkg: generate correct build dependencies
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 asm updates from Thomas Gleixner:
"Two cleanup patches removing dead conditionals and unused code"
* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/asm: Remove unused __constant_c_x_memset() macro and inlines
x86/asm: Remove dead __GNUC__ conditionals
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf fixes from Thomas Gleixner:
"Three fixes for the fallout from the TSX errata workaround:
- Prevent memory corruption caused by a unchecked out of bound array
index.
- Two trivial fixes to address compiler warnings"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/x86/intel: Make dev_attr_allow_tsx_force_abort static
perf/x86: Fixup typo in stub functions
perf/x86/intel: Fix memory corruption
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git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip
Pull xen fix from Juergen Gross:
"A fix for a Xen bug introduced by David's series for excluding
ballooned pages in vmcores"
* tag 'for-linus-5.1b-rc1b-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
xen/balloon: Fix mapping PG_offline pages to user space
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Pull 9p updates from Dominique Martinet:
"Here is a 9p update for 5.1; there honestly hasn't been much.
Two fixes (leak on invalid mount argument and possible deadlock on
i_size update on 32bit smp) and a fall-through warning cleanup"
* tag '9p-for-5.1' of git://github.com/martinetd/linux:
9p/net: fix memory leak in p9_client_create
9p: use inode->i_lock to protect i_size_write() under 32-bit
9p: mark expected switch fall-through
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Fixes: 400816f60c54 ("perf/x86/intel: Implement support for TSX Force Abort")
Signed-off-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: kbuild-all@01.org
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20190313184243.GA10820@lkp-sb-ep06
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When this .gitignore was added, lxdialog was an independent hostprogs-y.
Now that all objects in lxdialog/ are directly linked to mconf, the
lxdialog is no longer generated.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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Currently, every arch/*/include/uapi/asm/Kbuild explicitly includes
the common Kbuild.asm file. Factor out the duplicated include directives
to scripts/Makefile.asm-generic so that no architecture would opt out
of the mandatory-y mechanism.
um is not forced to include mandatory-y since it is a very exceptional
case which does not support UAPI.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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The generic-y is redundant under the following condition:
- arch has its own implementation
- the same header is added to generated-y
- the same header is added to mandatory-y
If a redundant generic-y is found, the warning like follows is displayed:
scripts/Makefile.asm-generic:20: redundant generic-y found in arch/arm/include/asm/Kbuild: timex.h
I fixed up arch Kbuild files found by this.
Suggested-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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This reverts commit caf6fe91ddf62a96401e21e9b7a07227440f4185.
The commit was fine but is no longer needed as of commit 3a2429e1faf4
("kbuild: change if_changed_rule for multi-line recipe"). Let's go
back to using ";" to be consistent.
For some discussion, see:
https://lkml.kernel.org/r/CAK7LNASde0Q9S5GKeQiWhArfER4S4wL1=R_FW8q0++_X3T5=hQ@mail.gmail.com
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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During a simple no-op (nothing changed) build I saw 39 invocations of
the C compiler with the argument "-print-file-name=include". We don't
need to call the C compiler 39 times for this--one time will suffice.
Let's change NOSTDINC_FLAGS to a simply expanded variable to avoid
this since there doesn't appear to be any reason it should be
recursively expanded.
On my build this shaved ~400 ms off my "no-op" build.
Note that the recursive expansion seems to date back to the (really
old) commit e8f5bdb02ce0 ("[PATCH] Makefile include path ordering").
It's a little unclear to me if the point of that patch was to switch
the variable to be recursively expanded (which it did) or to avoid
directly assigning to NOSTDINC_FLAGS (AKA to switch to +=) because
someone else (out of tree?) was setting it. I presume later since if
the only goal was to switch to recursive expansion the patch would
have just removed the ":".
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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* The man page for dpkg-source(1) notes:
> -b, --build directory [format-specific-parameters]
> Build a source package (--build since dpkg 1.17.14).
> <...>
>
> dpkg-source will build the source package with the first
> format found in this ordered list: the format indicated
> with the --format command line option, the format
> indicated in debian/source/format, “1.0”. The fallback
> to “1.0” is deprecated and will be removed at some point
> in the future, you should always document the desired
> source format in debian/source/format. See section
> SOURCE PACKAGE FORMATS for an extensive description of
> the various source package formats.
Thus it would be more foolproof to explicitly use 1.0 (as we always
did) than to rely on dpkg-source's defaults.
* In a similar vein, debian/rules is not made executable by mkdebian,
and dpkg-source warns about that but still silently fixes the file.
Let's be explicit once again.
Signed-off-by: Arseny Maslennikov <ar@cs.msu.ru>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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The of_find_device_by_node() takes a reference to the underlying device
structure, we should release that reference.
The implementation of this semantic code search is:
In a function, for a local variable returned by calling
of_find_device_by_node(),
a, if it is released by a function such as
put_device()/of_dev_put()/platform_device_put() after the last use,
it is considered that there is no reference leak;
b, if it is passed back to the caller via
dev_get_drvdata()/platform_get_drvdata()/get_device(), etc., the
reference will be released in other functions, and the current function
also considers that there is no reference leak;
c, for the rest of the situation, the current function should release the
reference by calling put_device, this code search will report the
corresponding error message.
By using this semantic code search, we have found some object reference leaks,
such as:
commit 11907e9d3533 ("ASoC: fsl-asoc-card: fix object reference leaks in
fsl_asoc_card_probe")
commit a12085d13997 ("mtd: rawnand: atmel: fix possible object reference leak")
commit 11493f26856a ("mtd: rawnand: jz4780: fix possible object reference leak")
There are still dozens of reference leaks in the current kernel code.
Further, for the case of b, the object returned to other functions may also
have a reference leak, we will continue to develop other cocci scripts to
further check the reference leak.
Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
Reviewed-by: Julia Lawall <Julia.Lawall@lip6.fr>
Reviewed-by: Markus Elfring <Markus.Elfring@web.de>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux
Pull pidfd system call from Christian Brauner:
"This introduces the ability to use file descriptors from /proc/<pid>/
as stable handles on struct pid. Even if a pid is recycled the handle
will not change. For a start these fds can be used to send signals to
the processes they refer to.
With the ability to use /proc/<pid> fds as stable handles on struct
pid we can fix a long-standing issue where after a process has exited
its pid can be reused by another process. If a caller sends a signal
to a reused pid it will end up signaling the wrong process.
With this patchset we enable a variety of use cases. One obvious
example is that we can now safely delegate an important part of
process management - sending signals - to processes other than the
parent of a given process by sending file descriptors around via scm
rights and not fearing that the given process will have been recycled
in the meantime. It also allows for easy testing whether a given
process is still alive or not by sending signal 0 to a pidfd which is
quite handy.
There has been some interest in this feature e.g. from systems
management (systemd, glibc) and container managers. I have requested
and gotten comments from glibc to make sure that this syscall is
suitable for their needs as well. In the future I expect it to take on
most other pid-based signal syscalls. But such features are left for
the future once they are needed.
This has been sitting in linux-next for quite a while and has not
caused any issues. It comes with selftests which verify basic
functionality and also test that a recycled pid cannot be signaled via
a pidfd.
Jon has written about a prior version of this patchset. It should
cover the basic functionality since not a lot has changed since then:
https://lwn.net/Articles/773459/
The commit message for the syscall itself is extensively documenting
the syscall, including it's functionality and extensibility"
* tag 'pidfd-v5.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
selftests: add tests for pidfd_send_signal()
signal: add pidfd_send_signal() syscall
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git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm
Pull device-dax updates from Dan Williams:
"New device-dax infrastructure to allow persistent memory and other
"reserved" / performance differentiated memories, to be assigned to
the core-mm as "System RAM".
Some users want to use persistent memory as additional volatile
memory. They are willing to cope with potential performance
differences, for example between DRAM and 3D Xpoint, and want to use
typical Linux memory management apis rather than a userspace memory
allocator layered over an mmap() of a dax file. The administration
model is to decide how much Persistent Memory (pmem) to use as System
RAM, create a device-dax-mode namespace of that size, and then assign
it to the core-mm. The rationale for device-dax is that it is a
generic memory-mapping driver that can be layered over any "special
purpose" memory, not just pmem. On subsequent boots udev rules can be
used to restore the memory assignment.
One implication of using pmem as RAM is that mlock() no longer keeps
data off persistent media. For this reason it is recommended to enable
NVDIMM Security (previously merged for 5.0) to encrypt pmem contents
at rest. We considered making this recommendation an actively enforced
requirement, but in the end decided to leave it as a distribution /
administrator policy to allow for emulation and test environments that
lack security capable NVDIMMs.
Summary:
- Replace the /sys/class/dax device model with /sys/bus/dax, and
include a compat driver so distributions can opt-in to the new ABI.
- Allow for an alternative driver for the device-dax address-range
- Introduce the 'kmem' driver to hotplug / assign a device-dax
address-range to the core-mm.
- Arrange for the device-dax target-node to be onlined so that the
newly added memory range can be uniquely referenced by numa apis"
NOTE! I'm not entirely happy with the whole "PMEM as RAM" model because
we currently have special - and very annoying rules in the kernel about
accessing PMEM only with the "MC safe" accessors, because machine checks
inside the regular repeat string copy functions can be fatal in some
(not described) circumstances.
And apparently the PMEM modules can cause that a lot more than regular
RAM. The argument is that this happens because PMEM doesn't necessarily
get scrubbed at boot like RAM does, but that is planned to be added for
the user space tooling.
Quoting Dan from another email:
"The exposure can be reduced in the volatile-RAM case by scanning for
and clearing errors before it is onlined as RAM. The userspace tooling
for that can be in place before v5.1-final. There's also runtime
notifications of errors via acpi_nfit_uc_error_notify() from
background scrubbers on the DIMM devices. With that mechanism the
kernel could proactively clear newly discovered poison in the volatile
case, but that would be additional development more suitable for v5.2.
I understand the concern, and the need to highlight this issue by
tapping the brakes on feature development, but I don't see PMEM as RAM
making the situation worse when the exposure is also there via DAX in
the PMEM case. Volatile-RAM is arguably a safer use case since it's
possible to repair pages where the persistent case needs active
application coordination"
* tag 'devdax-for-5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
device-dax: "Hotplug" persistent memory for use like normal RAM
mm/resource: Let walk_system_ram_range() search child resources
mm/memory-hotplug: Allow memory resources to be children
mm/resource: Move HMM pr_debug() deeper into resource code
mm/resource: Return real error codes from walk failures
device-dax: Add a 'modalias' attribute to DAX 'bus' devices
device-dax: Add a 'target_node' attribute
device-dax: Auto-bind device after successful new_id
acpi/nfit, device-dax: Identify differentiated memory with a unique numa-node
device-dax: Add /sys/class/dax backwards compatibility
device-dax: Add support for a dax override driver
device-dax: Move resource pinning+mapping into the common driver
device-dax: Introduce bus + driver model
device-dax: Start defining a dax bus model
device-dax: Remove multi-resource infrastructure
device-dax: Kill dax_region base
device-dax: Kill dax_region ida
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Pull more SCSI updates from James Bottomley:
"This is the final round of mostly small fixes and performance
improvements to our initial submit.
The main regression fix is the ia64 simscsi build failure which was
missed in the serial number elimination conversion"
* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (24 commits)
scsi: ia64: simscsi: use request tag instead of serial_number
scsi: aacraid: Fix performance issue on logical drives
scsi: lpfc: Fix error codes in lpfc_sli4_pci_mem_setup()
scsi: libiscsi: Hold back_lock when calling iscsi_complete_task
scsi: hisi_sas: Change SERDES_CFG init value to increase reliability of HiLink
scsi: hisi_sas: Send HARD RESET to clear the previous affiliation of STP target port
scsi: hisi_sas: Set PHY linkrate when disconnected
scsi: hisi_sas: print PHY RX errors count for later revision of v3 hw
scsi: hisi_sas: Fix a timeout race of driver internal and SMP IO
scsi: hisi_sas: Change return variable type in phy_up_v3_hw()
scsi: qla2xxx: check for kstrtol() failure
scsi: lpfc: fix 32-bit format string warning
scsi: lpfc: fix unused variable warning
scsi: target: tcmu: Switch to bitmap_zalloc()
scsi: libiscsi: fall back to sendmsg for slab pages
scsi: qla2xxx: avoid printf format warning
scsi: lpfc: resolve static checker warning in lpfc_sli4_hba_unset
scsi: lpfc: Correct __lpfc_sli_issue_iocb_s4 lockdep check
scsi: ufs: hisi: fix ufs_hba_variant_ops passing
scsi: qla2xxx: Fix panic in qla_dfs_tgt_counters_show
...
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Pull more block layer changes from Jens Axboe:
"This is a collection of both stragglers, and fixes that came in after
I finalized the initial pull. This contains:
- An MD pull request from Song, with a few minor fixes
- Set of NVMe patches via Christoph
- Pull request from Konrad, with a few fixes for xen/blkback
- pblk fix IO calculation fix (Javier)
- Segment calculation fix for pass-through (Ming)
- Fallthrough annotation for blkcg (Mathieu)"
* tag 'for-5.1/block-post-20190315' of git://git.kernel.dk/linux-block: (25 commits)
blkcg: annotate implicit fall through
nvme-tcp: support C2HData with SUCCESS flag
nvmet: ignore EOPNOTSUPP for discard
nvme: add proper write zeroes setup for the multipath device
nvme: add proper discard setup for the multipath device
nvme: remove nvme_ns_config_oncs
nvme: disable Write Zeroes for qemu controllers
nvmet-fc: bring Disconnect into compliance with FC-NVME spec
nvmet-fc: fix issues with targetport assoc_list list walking
nvme-fc: reject reconnect if io queue count is reduced to zero
nvme-fc: fix numa_node when dev is null
nvme-fc: use nr_phys_segments to determine existence of sgl
nvme-loop: init nvmet_ctrl fatal_err_work when allocate
nvme: update comment to make the code easier to read
nvme: put ns_head ref if namespace fails allocation
nvme-trace: fix cdw10 buffer overrun
nvme: don't warn on block content change effects
nvme: add get-feature to admin cmds tracer
md: Fix failed allocation of md_register_thread
It's wrong to add len to sector_nr in raid10 reshape twice
...
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Pull NFS client bugfixes from Trond Myklebust:
"Highlights include:
Bugfixes:
- Fix an Oops in SUNRPC back channel tracepoints
- Fix a SUNRPC client regression when handling oversized replies
- Fix the minimal size for SUNRPC reply buffer allocation
- rpc_decode_header() must always return a non-zero value on error
- Fix a typo in pnfs_update_layout()
Cleanup:
- Remove redundant check for the reply length in call_decode()"
* tag 'nfs-for-5.1-2' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
SUNRPC: Remove redundant check for the reply length in call_decode()
SUNRPC: Handle the SYSTEM_ERR rpc error
SUNRPC: rpc_decode_header() must always return a non-zero value on error
SUNRPC: Use the ENOTCONN error on socket disconnect
SUNRPC: Fix the minimal size for reply buffer allocation
SUNRPC: Fix a client regression when handling oversized replies
pNFS: Fix a typo in pnfs_update_layout
fix null pointer deref in tracepoints in back channel
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git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc fixes from Michael Ellerman:
"One fix to prevent runtime allocation of 16GB pages when running in a
VM (as opposed to bare metal), because it doesn't work.
A small fix to our recently added KCOV support to exempt some more
code from being instrumented.
Plus a few minor build fixes, a small dead code removal and a
defconfig update.
Thanks to: Alexey Kardashevskiy, Aneesh Kumar K.V, Christophe Leroy,
Jason Yan, Joel Stanley, Mahesh Salgaonkar, Mathieu Malaterre"
* tag 'powerpc-5.1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
powerpc/64s: Include <asm/nmi.h> header file to fix a warning
powerpc/powernv: Fix compile without CONFIG_TRACEPOINTS
powerpc/mm: Disable kcov for SLB routines
powerpc: remove dead code in head_fsl_booke.S
powerpc/configs: Sync skiroot defconfig
powerpc/hugetlb: Don't do runtime allocation of 16G pages in LPAR configuration
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git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs mount infrastructure fix from Al Viro:
"Fixup for sysfs braino.
Capabilities checks for sysfs mount do include those on netns, but
only if CONFIG_NET_NS is enabled. Sorry, should've caught that
earlier..."
* 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
fix sysfs_init_fs_context() in !CONFIG_NET_NS case
|
|
Permission checks on current's netns should be done only when
netns are enabled.
Reported-by: Dominik Brodowski <linux@dominikbrodowski.net>
Fixes: 23bf1b6be9c2
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
|
|
Pull more smb3 updates from Steve French:
"Various tracing and debugging improvements, crediting fixes, some
cleanup, and important fallocate fix (fixes three xfstests) and lock
fix.
Summary:
- Various additional dynamic tracing tracepoints
- Debugging improvements (including ability to query the server via
SMB3 fsctl from userspace tools which can help with stats and
debugging)
- One minor performance improvement (root directory inode caching)
- Crediting (SMB3 flow control) fixes
- Some cleanup (docs and to mknod)
- Important fixes: one to smb3 implementation of fallocate zero range
(which fixes three xfstests) and a POSIX lock fix"
* tag '5.1-rc-smb3' of git://git.samba.org/sfrench/cifs-2.6: (22 commits)
CIFS: fix POSIX lock leak and invalid ptr deref
SMB3: Allow SMB3 FSCTL queries to be sent to server from tools
cifs: fix incorrect handling of smb2_set_sparse() return in smb3_simple_falloc
smb2: fix typo in definition of a few error flags
CIFS: make mknod() an smb_version_op
cifs: minor documentation updates
cifs: remove unused value pointed out by Coverity
SMB3: passthru query info doesn't check for SMB3 FSCTL passthru
smb3: add dynamic tracepoints for simple fallocate and zero range
cifs: fix smb3_zero_range so it can expand the file-size when required
cifs: add SMB2_ioctl_init/free helpers to be used with compounding
smb3: Add dynamic trace points for various compounded smb3 ops
cifs: cache FILE_ALL_INFO for the shared root handle
smb3: display volume serial number for shares in /proc/fs/cifs/DebugData
cifs: simplify how we handle credits in compound_send_recv()
smb3: add dynamic tracepoint for timeout waiting for credits
smb3: display security information in /proc/fs/cifs/DebugData more accurately
cifs: add a timeout argument to wait_for_free_credits
cifs: prevent starvation in wait_for_free_credits for multi-credit requests
cifs: wait_for_free_credits() make it possible to wait for >=1 credits
...
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git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml
Pull UML updates from Richard Weinberger:
"Bugfix for the UML block device driver"
* 'for-linus-5.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml:
um: Fix for a possible OOPS in ubd initialization
um: Remove duplicated include from vector_user.c
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|
Pull KVM updates from Paolo Bonzini:
"ARM:
- some cleanups
- direct physical timer assignment
- cache sanitization for 32-bit guests
s390:
- interrupt cleanup
- introduction of the Guest Information Block
- preparation for processor subfunctions in cpu models
PPC:
- bug fixes and improvements, especially related to machine checks
and protection keys
x86:
- many, many cleanups, including removing a bunch of MMU code for
unnecessary optimizations
- AVIC fixes
Generic:
- memcg accounting"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (147 commits)
kvm: vmx: fix formatting of a comment
KVM: doc: Document the life cycle of a VM and its resources
MAINTAINERS: Add KVM selftests to existing KVM entry
Revert "KVM/MMU: Flush tlb directly in the kvm_zap_gfn_range()"
KVM: PPC: Book3S: Add count cache flush parameters to kvmppc_get_cpu_char()
KVM: PPC: Fix compilation when KVM is not enabled
KVM: Minor cleanups for kvm_main.c
KVM: s390: add debug logging for cpu model subfunctions
KVM: s390: implement subfunction processor calls
arm64: KVM: Fix architecturally invalid reset value for FPEXC32_EL2
KVM: arm/arm64: Remove unused timer variable
KVM: PPC: Book3S: Improve KVM reference counting
KVM: PPC: Book3S HV: Fix build failure without IOMMU support
Revert "KVM: Eliminate extra function calls in kvm_get_dirty_log_protect()"
x86: kvmguest: use TSC clocksource if invariant TSC is exposed
KVM: Never start grow vCPU halt_poll_ns from value below halt_poll_ns_grow_start
KVM: Expose the initial start value in grow_halt_poll_ns() as a module parameter
KVM: grow_halt_poll_ns() should never shrink vCPU halt_poll_ns
KVM: x86/mmu: Consolidate kvm_mmu_zap_all() and kvm_mmu_zap_mmio_sptes()
KVM: x86/mmu: WARN if zapping a MMIO spte results in zapping children
...
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git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fixes and cleanups from Steven Rostedt:
"This contains a series of last minute clean ups, small fixes and error
checks"
* tag 'trace-v5.1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing/probe: Verify alloc_trace_*probe() result
tracing/probe: Check event/group naming rule at parsing
tracing/probe: Check the size of argument name and body
tracing/probe: Check event name length correctly
tracing/probe: Check maxactive error cases
tracing: kdb: Fix ftdump to not sleep
trace/probes: Remove kernel doc style from non kernel doc comment
tracing/probes: Make reserved_field_names static
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git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu
Pull IOMMU fix from Joerg Roedel:
"Fix a NULL-pointer dereference issue in the ACPI device matching code
of the AMD IOMMU driver"
* tag 'iommu-fix-v5.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu:
iommu/amd: Fix NULL dereference bug in match_hid_uid
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Pull ARM updates from Russell King:
- An improvement from Ard Biesheuvel, who noted that the identity map
setup was taking a long time due to flush_cache_louis().
- Update a comment about dma_ops from Wolfram Sang.
- Remove use of "-p" with ld, where this flag has been a no-op since
2004.
- Remove the printing of the virtual memory layout, which is no longer
useful since we hide pointers.
- Correct SCU help text.
- Remove legacy TWD registration method.
- Add pgprot_device() implementation for mapping PCI sysfs resource
files.
- Initialise PFN limits earlier for kmemleak.
- Fix argument count to match macro definition (affects clang builds)
- Use unified assembler language almost everywhere for clang, and other
clang improvements (from Stefan Agner, Nathan Chancellor).
- Support security extension for noMMU and other noMMU cleanups (from
Vladimir Murzin).
- Remove unnecessary SMP bringup code (which was incorrectly copy'n'
pasted from the ARM platform implementations) and remove it from the
arch code to discourge further copys of it appearing.
- Add Cortex A9 erratum preventing kexec working on some SoCs.
- AMBA bus identification updates from Mike Leach.
- More use of raw spinlocks to avoid -RT kernel issues (from Yang Shi
and Sebastian Andrzej Siewior).
- MCPM hyp/svc mode mismatch fixes from Marek Szyprowski.
* tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm: (32 commits)
ARM: 8849/1: NOMMU: Fix encodings for PMSAv8's PRBAR4/PRLAR4
ARM: 8848/1: virt: Align GIC version check with arm64 counterpart
ARM: 8847/1: pm: fix HYP/SVC mode mismatch when MCPM is used
ARM: 8845/1: use unified assembler in c files
ARM: 8844/1: use unified assembler in assembly files
ARM: 8843/1: use unified assembler in headers
ARM: 8841/1: use unified assembler in macros
ARM: 8840/1: use a raw_spinlock_t in unwind
ARM: 8839/1: kprobe: make patch_lock a raw_spinlock_t
ARM: 8837/1: coresight: etmv4: Update ID register table to add UCI support
ARM: 8836/1: drivers: amba: Update component matching to use the CoreSight UCI values.
ARM: 8838/1: drivers: amba: Updates to component identification for driver matching.
ARM: 8833/1: Ensure that NEON code always compiles with Clang
ARM: avoid Cortex-A9 livelock on tight dmb loops
ARM: smp: remove arch-provided "pen_release"
ARM: actions: remove boot_lock and pen_release
ARM: oxnas: remove CPU hotplug implementation
ARM: qcom: remove unnecessary boot_lock
ARM: 8832/1: NOMMU: Limit visibility for CONFIG_FLASH_{MEM_BASE,SIZE}
ARM: 8831/1: NOMMU: pmsa-v8: remove unneeded semicolon
...
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Pull NTB updates from Jon Mason:
- fixes for switchtec debugability and mapping table entries
- NTB transport improvements
- a reworking of the peer_db_addr for better abstraction
* tag 'ntb-5.1' of git://github.com/jonmason/ntb:
NTB: add new parameter to peer_db_addr() db_bit and db_data
NTB: ntb_transport: Ensure the destination buffer is mapped for TX DMA
NTB: ntb_transport: Free MWs in ntb_transport_link_cleanup()
ntb_hw_switchtec: Added support of >=4G memory windows
ntb_hw_switchtec: NT req id mapping table register entry number should be 512
ntb_hw_switchtec: debug print 64bit aligned crosslink BAR Numbers
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Pull fbdev updates from Bartlomiej Zolnierkiewicz:
"Just a couple of small fixes and cleanups:
- fix memory access if logo is bigger than the screen (Manfred
Schlaegl)
- silence fbcon logo on 'quiet' boots (Prarit Bhargava)
- use kvmalloc() for scrollback buffer in fbcon (Konstantin Khorenko)
- misc fixes (Colin Ian King, YueHaibing, Matteo Croce, Mathieu
Malaterre, Anders Roxell, Arnd Bergmann)
- misc cleanups (Rob Herring, Lubomir Rintel, Greg Kroah-Hartman,
Jani Nikula, Michal Vokáč)"
* tag 'fbdev-v5.1' of git://github.com/bzolnier/linux:
fbdev: mbx: fix a misspelled variable name
fbdev: omap2: fix warnings in dss core
video: fbdev: Fix potential NULL pointer dereference
fbcon: Silence fbcon logo on 'quiet' boots
printk: Export console_printk
ARM: dts: imx28-cfa10036: Fix the reset gpio signal polarity
video: ssd1307fb: Do not hard code active-low reset sequence
dt-bindings: display: ssd1307fb: Remove reset-active-low from examples
fbdev: fbmem: fix memory access if logo is bigger than the screen
video/fbdev: refactor video= cmdline parsing
fbdev: mbx: fix up debugfs file creation
fbdev: omap2: no need to check return value of debugfs_create functions
video: fbdev: geode: remove ifdef OLPC noise
video: offb: annotate implicit fall throughs
omapfb: fix typo
fbdev: Use of_node_name_eq for node name comparisons
fbcon: use kvmalloc() for scrollback buffer
fbdev: chipsfb: remove set but not used variable 'size'
fbdev/via: fix spelling mistake "Expandsion" -> "Expansion"
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git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux
Pull i2c fixes from Wolfram Sang:
"A set of driver bugfixes and an improvement for a core helper"
* 'i2c/for-current-fixed' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
i2c: i2c-designware-platdrv: Always use a dynamic adapter number
i2c: i2c-designware-platdrv: Cleanup setting of the adapter number
i2c: add extra check to safe DMA buffer helper
i2c: i2c-stm32f7: Fix SDADEL minimum formula
i2c: rcar: explain the lockless design
i2c: rcar: fix concurrency issue related to ICDMAER
i2c: sis630: correct format strings
i2c: mediatek: modify threshold passed to i2c_get_dma_safe_msg_buf()
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git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound
Pull sound fixes from Takashi Iwai:
"Some cleaning after the first batch; mostly about HD-audio quirks but
also some NULL dereference fixes in corner cases and a random build
error fix, too"
* tag 'sound-fix-5.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound:
ALSA: hda/realtek - Add support headset mode for New DELL WYSE NB
ALSA: hda/realtek - Add support headset mode for DELL WYSE AIO
ALSA: hda/realtek: merge alc_fixup_headset_jack to alc295_fixup_chromebook
ALSA: pcm: Fix function name in kernel-doc comment
ALSA: hda: hdmi - add Icelake support
ALSA: hda - add more quirks for HP Z2 G4 and HP Z240
ALSA: hda/realtek - Fixed Headset Mic JD not stable
ALSA: hda/realtek: Enable headset MIC of Acer TravelMate X514-51T with ALC255
ALSA: hda/tegra: avoid build error without CONFIG_PM
ALSA: usx2y: Fix potential NULL pointer dereference
ALSA: hda: Avoid NULL pointer dereference at snd_hdac_stream_start()
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Pull drm fixes and updates from Dave Airlie:
"A few various fixes pulls and one late etnaviv pull but it was nearly
all fixes anyways.
etnaviv:
- late next pull
- mmu mapping fix
- build non-ARM arches
- misc fixes
i915:
- HDCP state handling fix
- shrinker interaction fix
- atomic state leak fix
qxl:
- kick out framebuffers early fix
amdgpu:
- Powerplay fixes
- DC fixes
- BACO turned off for now on vega20
- Locking fix
- KFD MQD fix
- gfx9 golden register updates"
* tag 'drm-next-2019-03-15' of git://anongit.freedesktop.org/drm/drm: (43 commits)
drm/amdgpu: Update gc golden setting for vega family
drm/amd/powerplay: correct power reading on fiji
drm/amd/powerplay: set max fan target temperature as 105C
drm/i915: Relax mmap VMA check
drm/i915: Fix atomic state leak when resetting HDMI link
drm/i915: Acquire breadcrumb ref before cancelling
drm/i915/selftests: Always free spinner on __sseu_prepare error
drm/i915: Reacquire priolist cache after dropping the engine lock
drm/i915: Protect i915_active iterators from the shrinker
drm/i915: HDCP state handling in ddi_update_pipe
drm/qxl: remove conflicting framebuffers earlier
drm/fb-helper: call vga_remove_vgacon automatically.
drm: move i915_kick_out_vgacon to vgaarb
drm/amd/display: don't call dm_pp_ function from an fpu block
drm: add __user attribute to ptr_to_compat()
drm/amdgpu: clear PDs/PTs only after initializing them
drm/amd/display: Pass app_tf by value rather than by reference
Revert "drm/amdgpu: use BACO reset on vega20 if platform support"
drm/amd/powerplay: show the right override pcie parameters
drm/amd/powerplay: honor the OD settings
...
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Pull xfs cleanups from Darrick Wong:
"Here's a few more cleanups that trickled in for the merge window.
It's all fixes for static checker complaints and slowly unwinding
typedef usage. The four patches here have gone through a few days
worth of fstest runs with no new problems observed.
Summary:
- Fix some clang/smatch/sparse warnings about uninitialized
variables.
- Clean up some typedef usage"
* tag 'xfs-5.1-merge-5' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
xfs: clean up xfs_dir2_leaf_addname
xfs: zero initialize highstale and lowstale in xfs_dir2_leaf_addname
xfs: clean up xfs_dir2_leafn_add
xfs: Zero initialize highstale and lowstale in xfs_dir2_leafn_add
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git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs
Pull f2fs updates from Jaegeuk Kim:
"We've continued mainly to fix bugs in this round, as f2fs has been
shipped in more devices. Especially, we've focused on stabilizing
checkpoint=disable feature, and provided some interfaces for QA.
Enhancements:
- expose FS_NOCOW_FL for pin_file
- run discard jobs at unmount time with timeout
- tune discarding thread to avoid idling which consumes power
- some checking codes to address vulnerabilities
- give random value to i_generation
- shutdown with more flags for QA
Bug fixes:
- clean up stale objects when mount is failed along with
checkpoint=disable
- fix system being stuck due to wrong count by atomic writes
- handle some corrupted disk cases
- fix a deadlock in f2fs_read_inline_dir
We've also added some minor build error fixes and clean-up patches"
* tag 'f2fs-for-5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs: (53 commits)
f2fs: set pin_file under CAP_SYS_ADMIN
f2fs: fix to avoid deadlock in f2fs_read_inline_dir()
f2fs: fix to adapt small inline xattr space in __find_inline_xattr()
f2fs: fix to do sanity check with inode.i_inline_xattr_size
f2fs: give some messages for inline_xattr_size
f2fs: don't trigger read IO for beyond EOF page
f2fs: fix to add refcount once page is tagged PG_private
f2fs: remove wrong comment in f2fs_invalidate_page()
f2fs: fix to use kvfree instead of kzfree
f2fs: print more parameters in trace_f2fs_map_blocks
f2fs: trace f2fs_ioc_shutdown
f2fs: fix to avoid deadlock of atomic file operations
f2fs: fix to dirty inode for i_mode recovery
f2fs: give random value to i_generation
f2fs: no need to take page lock in readdir
f2fs: fix to update iostat correctly in IPU path
f2fs: fix encrypted page memory leak
f2fs: make fault injection covering __submit_flush_wait()
f2fs: fix to retry fill_super only if recovery failed
f2fs: silence VM_WARN_ON_ONCE in mempool_alloc
...
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Merge the left-over patches from Andrew Morton.
This merges the remaining two patches from Andrew's pile of "little bit
more MM". I mulled it over, and we emailed back and forth with Josef,
and he pointed out where I was wrong.
Rule #51 of kernel maintenance: when somebody makes it clear that they
know the code better than you did, stop arguing and just apply the damn
patch.
Add a third patch by me to add a comment for the case that I had thought
was buggy and Josef corrected me on.
* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
filemap: add a comment about FAULT_FLAG_RETRY_NOWAIT behavior
filemap: drop the mmap_sem for all blocking operations
filemap: kill page_cache_read usage in filemap_fault
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I thought Josef Bacik's patch to drop the mmap_sem was buggy, because
when looking at the error cases, there was one case where we returned
VM_FAULT_RETRY without actually dropping the mmap_sem.
Josef had to explain to me (using small words) that yes, that's actually
what we're supposed to do, and his patch was correct. Which not only
convinced me he knew what he was doing and I should stop arguing with
him, but also that I should add a comment to the case I was confused
about.
Patiently-pointed-out-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Eliminate a gratuitous conflict with 5.0.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
|
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The series to add memcg accounting to KVM allocations[1] states:
There are many KVM kernel memory allocations which are tied to the
life of the VM process and should be charged to the VM process's
cgroup.
While it is correct to account KVM kernel allocations to the cgroup of
the process that created the VM, it's technically incorrect to state
that the KVM kernel memory allocations are tied to the life of the VM
process. This is because the VM itself, i.e. struct kvm, is not tied to
the life of the process which created it, rather it is tied to the life
of its associated file descriptor. In other words, kvm_destroy_vm() is
not invoked until fput() decrements its associated file's refcount to
zero. A simple example is to fork() in Qemu and have the child sleep
indefinitely; kvm_destroy_vm() isn't called until Qemu closes its file
descriptor *and* the rogue child is killed.
The allocations are guaranteed to be *accounted* to the process which
created the VM, but only because KVM's per-{VM,vCPU} ioctls reject the
ioctl() with -EIO if kvm->mm != current->mm. I.e. the child can keep
the VM "alive" but can't do anything useful with its reference.
Note that because 'struct kvm' also holds a reference to the mm_struct
of its owner, the above behavior also applies to userspace allocations.
Given that mucking with a VM's file descriptor can lead to subtle and
undesirable behavior, e.g. memcg charges persisting after a VM is shut
down, explicitly document a VM's lifecycle and its impact on the VM's
resources.
Alternatively, KVM could aggressively free resources when the creating
process exits, e.g. via mmu_notifier->release(). However, mmu_notifier
isn't guaranteed to be available, and freeing resources when the creator
exits is likely to be error prone and fragile as KVM would need to
ensure that it only freed resources that are truly out of reach. In
practice, the existing behavior shouldn't be problematic as a properly
configured system will prevent a child process from being moved out of
the appropriate cgroup hierarchy, i.e. prevent hiding the process from
the OOM killer, and will prevent an unprivileged user from being able to
to hold a reference to struct kvm via another method, e.g. debugfs.
[1]https://patchwork.kernel.org/patch/10806707/
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
|
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Currently we only drop the mmap_sem if there is contention on the page
lock. The idea is that we issue readahead and then go to lock the page
while it is under IO and we want to not hold the mmap_sem during the IO.
The problem with this is the assumption that the readahead does anything.
In the case that the box is under extreme memory or IO pressure we may end
up not reading anything at all for readahead, which means we will end up
reading in the page under the mmap_sem.
Even if the readahead does something, it could get throttled because of io
pressure on the system and the process is in a lower priority cgroup.
Holding the mmap_sem while doing IO is problematic because it can cause
system-wide priority inversions. Consider some large company that does a
lot of web traffic. This large company has load balancing logic in it's
core web server, cause some engineer thought this was a brilliant plan.
This load balancing logic gets statistics from /proc about the system,
which trip over processes mmap_sem for various reasons. Now the web
server application is in a protected cgroup, but these other processes may
not be, and if they are being throttled while their mmap_sem is held we'll
stall, and cause this nice death spiral.
Instead rework filemap fault path to drop the mmap sem at any point that
we may do IO or block for an extended period of time. This includes while
issuing readahead, locking the page, or needing to call ->readpage because
readahead did not occur. Then once we have a fully uptodate page we can
return with VM_FAULT_RETRY and come back again to find our nicely in-cache
page that was gotten outside of the mmap_sem.
This patch also adds a new helper for locking the page with the mmap_sem
dropped. This doesn't make sense currently as generally speaking if the
page is already locked it'll have been read in (unless there was an error)
before it was unlocked. However a forthcoming patchset will change this
with the ability to abort read-ahead bio's if necessary, making it more
likely that we could contend for a page lock and still have a not uptodate
page. This allows us to deal with this case by grabbing the lock and
issuing the IO without the mmap_sem held, and then returning
VM_FAULT_RETRY to come back around.
[josef@toxicpanda.com: v6]
Link: http://lkml.kernel.org/r/20181212152757.10017-1-josef@toxicpanda.com
[kirill@shutemov.name: fix race in filemap_fault()]
Link: http://lkml.kernel.org/r/20181228235106.okk3oastsnpxusxs@kshutemo-mobl1
[akpm@linux-foundation.org: coding style fixes]
Link: http://lkml.kernel.org/r/20181211173801.29535-4-josef@toxicpanda.com
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Tested-by: syzbot+b437b5a429d680cf2217@syzkaller.appspotmail.com
Cc: Dave Chinner <david@fromorbit.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
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Patch series "drop the mmap_sem when doing IO in the fault path", v6.
Now that we have proper isolation in place with cgroups2 we have started
going through and fixing the various priority inversions. Most are all
gone now, but this one is sort of weird since it's not necessarily a
priority inversion that happens within the kernel, but rather because of
something userspace does.
We have giant applications that we want to protect, and parts of these
giant applications do things like watch the system state to determine how
healthy the box is for load balancing and such. This involves running
'ps' or other such utilities. These utilities will often walk
/proc/<pid>/whatever, and these files can sometimes need to
down_read(&task->mmap_sem). Not usually a big deal, but we noticed when
we are stress testing that sometimes our protected application has latency
spikes trying to get the mmap_sem for tasks that are in lower priority
cgroups.
This is because any down_write() on a semaphore essentially turns it into
a mutex, so even if we currently have it held for reading, any new readers
will not be allowed on to keep from starving the writer. This is fine,
except a lower priority task could be stuck doing IO because it has been
throttled to the point that its IO is taking much longer than normal. But
because a higher priority group depends on this completing it is now stuck
behind lower priority work.
In order to avoid this particular priority inversion we want to use the
existing retry mechanism to stop from holding the mmap_sem at all if we
are going to do IO. This already exists in the read case sort of, but
needed to be extended for more than just grabbing the page lock. With
io.latency we throttle at submit_bio() time, so the readahead stuff can
block and even page_cache_read can block, so all these paths need to have
the mmap_sem dropped.
The other big thing is ->page_mkwrite. btrfs is particularly shitty here
because we have to reserve space for the dirty page, which can be a very
expensive operation. We use the same retry method as the read path, and
simply cache the page and verify the page is still setup properly the next
pass through ->page_mkwrite().
I've tested these patches with xfstests and there are no regressions.
This patch (of 3):
If we do not have a page at filemap_fault time we'll do this weird forced
page_cache_read thing to populate the page, and then drop it again and
loop around and find it. This makes for 2 ways we can read a page in
filemap_fault, and it's not really needed. Instead add a FGP_FOR_MMAP
flag so that pagecache_get_page() will return a unlocked page that's in
pagecache. Then use the normal page locking and readpage logic already in
filemap_fault. This simplifies the no page in page cache case
significantly.
[akpm@linux-foundation.org: fix comment text]
[josef@toxicpanda.com: don't unlock null page in FGP_FOR_MMAP case]
Link: http://lkml.kernel.org/r/20190312201742.22935-1-josef@toxicpanda.com
Link: http://lkml.kernel.org/r/20181211173801.29535-2-josef@toxicpanda.com
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc into HEAD
Third PPC KVM update for 5.1
- Tell userspace about whether a particular hardware workaround for
one of the Spectre vulnerabilities is available, so that userspace
can inform the guest.
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It's safe to assume Paolo and Radim are maintaining the KVM selftests
given that the vast majority of commits have their SOBs. Play nice
with get_maintainers and make it official.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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This reverts commit 71883a62fcd6c70639fa12cda733378b4d997409.
The above commit contains an optimization to kvm_zap_gfn_range which
uses gfn-limited TLB flushes, if enabled. If using these limited flushes,
kvm_zap_gfn_range passes lock_flush_tlb=false to slot_handle_level_range
which creates a race when the function unlocks to call cond_resched.
See an example of this race below:
CPU 0 CPU 1 CPU 3
// zap_direct_gfn_range
mmu_lock()
// *ptep == pte_1
*ptep = 0
if (lock_flush_tlb)
flush_tlbs()
mmu_unlock()
// In invalidate range
// MMU notifier
mmu_lock()
if (pte != 0)
*ptep = 0
flush = true
if (flush)
flush_remote_tlbs()
mmu_unlock()
return
// Host MM reallocates
// page previously
// backing guest memory.
// Guest accesses
// invalid page
// through pte_1
// in its TLB!!
Tested: Ran all kvm-unit-tests on a Intel Haswell machine with and
without this patch. The patch introduced no new failures.
Signed-off-by: Ben Gardon <bgardon@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Use the request tag for logging instead of the scsi command serial
number.
Signed-off-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
[jejb: fix commit oneliner]
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
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