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Linux kernel
============
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In order to build the documentation, use ``make htmldocs`` or
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There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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Pull tracing warning fix from Steven Rostedt:
"Make the GCC 9 warning for sub struct memset go away.
GCC 9 now warns about calling memset() on partial structures when it
goes across multiple fields. This adds a helper for the place in
tracing that does this type of clearing of a structure"
* tag 'trace-v5.2-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing: Silence GCC 9 array bounds warning
Pull KVM fixes from Paolo Bonzini:
"The usual smattering of fixes and tunings that came in too late for
the merge window, but should not wait four months before they appear
in a release.
I also travelled a bit more than usual in the first part of May, which
didn't help with picking up patches and reports promptly"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (33 commits)
KVM: x86: fix return value for reserved EFER
tools/kvm_stat: fix fields filter for child events
KVM: selftests: Wrap vcpu_nested_state_get/set functions with x86 guard
kvm: selftests: aarch64: compile with warnings on
kvm: selftests: aarch64: fix default vm mode
kvm: selftests: aarch64: dirty_log_test: fix unaligned memslot size
KVM: s390: fix memory slot handling for KVM_SET_USER_MEMORY_REGION
KVM: x86/pmu: do not mask the value that is written to fixed PMUs
KVM: x86/pmu: mask the result of rdpmc according to the width of the counters
x86/kvm/pmu: Set AMD's virt PMU version to 1
KVM: x86: do not spam dmesg with VMCS/VMCB dumps
kvm: Check irqchip mode before assign irqfd
kvm: svm/avic: fix off-by-one in checking host APIC ID
KVM: selftests: do not blindly clobber registers in guest asm
KVM: selftests: Remove duplicated TEST_ASSERT in hyperv_cpuid.c
KVM: LAPIC: Expose per-vCPU timer_advance_ns to userspace
KVM: LAPIC: Fix lapic_timer_advance_ns parameter overflow
kvm: vmx: Fix -Wmissing-prototypes warnings
KVM: nVMX: Fix using __this_cpu_read() in preemptible context
kvm: fix compilation on s390
...
Starting with GCC 9, -Warray-bounds detects cases when memset is called
starting on a member of a struct but the size to be cleared ends up
writing over further members.
Such a call happens in the trace code to clear, at once, all members
after and including `seq` on struct trace_iterator:
In function 'memset',
inlined from 'ftrace_dump' at kernel/trace/trace.c:8914:3:
./include/linux/string.h:344:9: warning: '__builtin_memset' offset
[8505, 8560] from the object at 'iter' is out of the bounds of
referenced subobject 'seq' with type 'struct trace_seq' at offset
4368 [-Warray-bounds]
344 | return __builtin_memset(p, c, size);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
In order to avoid GCC complaining about it, we compute the address
ourselves by adding the offsetof distance instead of referring
directly to the member.
Since there are two places doing this clear (trace.c and trace_kdb.c),
take the chance to move the workaround into a single place in
the internal header.
Link: http://lkml.kernel.org/r/20190523124535.GA12931@gmail.com
Signed-off-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
[ Removed unnecessary parenthesis around "iter" ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Pull /dev/random fix from Ted Ts'o:
"Fix a soft lockup regression when reading from /dev/random in early
boot"
* tag 'random_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random:
random: fix soft lockup when trying to read from an uninitialized blocking pool
Commit 11988499e62b ("KVM: x86: Skip EFER vs. guest CPUID checks for
host-initiated writes", 2019-04-02) introduced a "return false" in a
function returning int, and anyway set_efer has a "nonzero on error"
conventon so it should be returning 1.
Reported-by: Pavel Machek <pavel@denx.de>
Fixes: 11988499e62b ("KVM: x86: Skip EFER vs. guest CPUID checks for host-initiated writes")
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Remove duplicate header which is included twice.
Link: http://lkml.kernel.org/r/1553725186-41442-1-git-send-email-jagdsh.linux@gmail.com
Reviewed-by: Mukesh Ojha <mojha@codeaurora.org>
Signed-off-by: Jagadeesh Pagadala <jagdsh.linux@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Pull ext4 fixes from Ted Ts'o:
"Bug fixes (including a regression fix) for ext4"
* tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
ext4: fix dcache lookup of !casefolded directories
ext4: do not delete unlinked inode from orphan list on failed truncate
ext4: wait for outstanding dio during truncate in nojournal mode
ext4: don't perform block validity checks on the journal inode
Fixes: eb9d1bf079bb: "random: only read from /dev/random after its pool has received 128 bits"
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
The fields filter would not work with child fields, as the respective
parents would not be included. No parents displayed == no childs displayed.
To reproduce, run on s390 (would work on other platforms, too, but would
require a different filter name):
- Run 'kvm_stat -d'
- Press 'f'
- Enter 'instruct'
Notice that events like instruction_diag_44 or instruction_diag_500 are not
displayed - the output remains empty.
With this patch, we will filter by matching events and their parents.
However, consider the following example where we filter by
instruction_diag_44:
kvm statistics - summary
regex filter: instruction_diag_44
Event Total %Total CurAvg/s
exit_instruction 276 100.0 12
instruction_diag_44 256 92.8 11
Total 276 12
Note that the parent ('exit_instruction') displays the total events, but
the childs listed do not match its total (256 instead of 276). This is
intended (since we're filtering all but one child), but might be confusing
on first sight.
Signed-off-by: Stefan Raspl <raspl@linux.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Without this check a snapshot is taken whenever a bucket's max is hit,
rather than only when the global max is hit, as it should be.
Before:
In this example, we do a first run of the workload (cyclictest),
examine the output, note the max ('triggering value') (347), then do
a second run and note the max again.
In this case, the max in the second run (39) is below the max in the
first run, but since we haven't cleared the histogram, the first max
is still in the histogram and is higher than any other max, so it
should still be the max for the snapshot. It isn't however - the
value should still be 347 after the second run.
# echo 'hist:keys=pid:ts0=common_timestamp.usecs if comm=="cyclictest"' >> /sys/kernel/debug/tracing/events/sched/sched_waking/trigger
# echo 'hist:keys=next_pid:wakeup_lat=common_timestamp.usecs-$ts0:onmax($wakeup_lat).save(next_prio,next_comm,prev_pid,prev_prio,prev_comm):onmax($wakeup_lat).snapshot() if next_comm=="cyclictest"' >> /sys/kernel/debug/tracing/events/sched/sched_switch/trigger
# cyclictest -p 80 -n -s -t 2 -D 2
# cat /sys/kernel/debug/tracing/events/sched/sched_switch/hist
{ next_pid: 2143 } hitcount: 199
max: 44 next_prio: 120 next_comm: cyclictest
prev_pid: 0 prev_prio: 120 prev_comm: swapper/4
{ next_pid: 2145 } hitcount: 1325
max: 38 next_prio: 19 next_comm: cyclictest
prev_pid: 0 prev_prio: 120 prev_comm: swapper/2
{ next_pid: 2144 } hitcount: 1982
max: 347 next_prio: 19 next_comm: cyclictest
prev_pid: 0 prev_prio: 120 prev_comm: swapper/6
Snapshot taken (see tracing/snapshot). Details:
triggering value { onmax($wakeup_lat) }: 347
triggered by event with key: { next_pid: 2144 }
# cyclictest -p 80 -n -s -t 2 -D 2
# cat /sys/kernel/debug/tracing/events/sched/sched_switch/hist
{ next_pid: 2143 } hitcount: 199
max: 44 next_prio: 120 next_comm: cyclictest
prev_pid: 0 prev_prio: 120 prev_comm: swapper/4
{ next_pid: 2148 } hitcount: 199
max: 16 next_prio: 120 next_comm: cyclictest
prev_pid: 0 prev_prio: 120 prev_comm: swapper/1
{ next_pid: 2145 } hitcount: 1325
max: 38 next_prio: 19 next_comm: cyclictest
prev_pid: 0 prev_prio: 120 prev_comm: swapper/2
{ next_pid: 2150 } hitcount: 1326
max: 39 next_prio: 19 next_comm: cyclictest
prev_pid: 0 prev_prio: 120 prev_comm: swapper/4
{ next_pid: 2144 } hitcount: 1982
max: 347 next_prio: 19 next_comm: cyclictest
prev_pid: 0 prev_prio: 120 prev_comm: swapper/6
{ next_pid: 2149 } hitcount: 1983
max: 130 next_prio: 19 next_comm: cyclictest
prev_pid: 0 prev_prio: 120 prev_comm: swapper/0
Snapshot taken (see tracing/snapshot). Details:
triggering value { onmax($wakeup_lat) }: 39
triggered by event with key: { next_pid: 2150 }
After:
In this example, we do a first run of the workload (cyclictest),
examine the output, note the max ('triggering value') (375), then do
a second run and note the max again.
In this case, the max in the second run is still 375, the highest in
any bucket, as it should be.
# cyclictest -p 80 -n -s -t 2 -D 2
# cat /sys/kernel/debug/tracing/events/sched/sched_switch/hist
{ next_pid: 2072 } hitcount: 200
max: 28 next_prio: 120 next_comm: cyclictest
prev_pid: 0 prev_prio: 120 prev_comm: swapper/5
{ next_pid: 2074 } hitcount: 1323
max: 375 next_prio: 19 next_comm: cyclictest
prev_pid: 0 prev_prio: 120 prev_comm: swapper/2
{ next_pid: 2073 } hitcount: 1980
max: 153 next_prio: 19 next_comm: cyclictest
prev_pid: 0 prev_prio: 120 prev_comm: swapper/6
Snapshot taken (see tracing/snapshot). Details:
triggering value { onmax($wakeup_lat) }: 375
triggered by event with key: { next_pid: 2074 }
# cyclictest -p 80 -n -s -t 2 -D 2
# cat /sys/kernel/debug/tracing/events/sched/sched_switch/hist
{ next_pid: 2101 } hitcount: 199
max: 49 next_prio: 120 next_comm: cyclictest
prev_pid: 0 prev_prio: 120 prev_comm: swapper/6
{ next_pid: 2072 } hitcount: 200
max: 28 next_prio: 120 next_comm: cyclictest
prev_pid: 0 prev_prio: 120 prev_comm: swapper/5
{ next_pid: 2074 } hitcount: 1323
max: 375 next_prio: 19 next_comm: cyclictest
prev_pid: 0 prev_prio: 120 prev_comm: swapper/2
{ next_pid: 2103 } hitcount: 1325
max: 74 next_prio: 19 next_comm: cyclictest
prev_pid: 0 prev_prio: 120 prev_comm: swapper/4
{ next_pid: 2073 } hitcount: 1980
max: 153 next_prio: 19 next_comm: cyclictest
prev_pid: 0 prev_prio: 120 prev_comm: swapper/6
{ next_pid: 2102 } hitcount: 1981
max: 84 next_prio: 19 next_comm: cyclictest
prev_pid: 12 prev_prio: 120 prev_comm: kworker/0:1
Snapshot taken (see tracing/snapshot). Details:
triggering value { onmax($wakeup_lat) }: 375
triggered by event with key: { next_pid: 2074 }
Link: http://lkml.kernel.org/r/95958351329f129c07504b4d1769c47a97b70d65.1555597045.git.tom.zanussi@linux.intel.com
Cc: stable@vger.kernel.org
Fixes: a3785b7eca8fd ("tracing: Add hist trigger snapshot() action")
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Pull libnvdimm fixes from Dan Williams:
- Fix a regression that disabled device-mapper dax support
- Remove unnecessary hardened-user-copy overhead (>30%) for dax
read(2)/write(2).
- Fix some compilation warnings.
* tag 'libnvdimm-fixes-5.2-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
libnvdimm/pmem: Bypass CONFIG_HARDENED_USERCOPY overhead
dax: Arrange for dax_supported check to span multiple devices
libnvdimm: Fix compilation warnings with W=1
Found by visual inspection, this wasn't caught by my xfstest, since it's
effect is ignoring positive dentries in the cache the fallback just goes
to the disk. it was introduced in the last iteration of the
case-insensitive patch.
d_compare should return 0 when the entries match, so make sure we are
correctly comparing the entire string if the encoding feature is set and
we are on a case-INsensitive directory.
Fixes: b886ee3e778e ("ext4: Support case-insensitive file name lookups")
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
The per-CPU variable batched_entropy_uXX is protected by get_cpu_var().
This is just a preempt_disable() which ensures that the variable is only
from the local CPU. It does not protect against users on the same CPU
from another context. It is possible that a preemptible context reads
slot 0 and then an interrupt occurs and the same value is read again.
The above scenario is confirmed by lockdep if we add a spinlock:
| ================================
| WARNING: inconsistent lock state
| 5.1.0-rc3+ #42 Not tainted
| --------------------------------
| inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
| ksoftirqd/9/56 [HC0[0]:SC1[1]:HE0:SE0] takes:
| (____ptrval____) (batched_entropy_u32.lock){+.?.}, at: get_random_u32+0x3e/0xe0
| {SOFTIRQ-ON-W} state was registered at:
| _raw_spin_lock+0x2a/0x40
| get_random_u32+0x3e/0xe0
| new_slab+0x15c/0x7b0
| ___slab_alloc+0x492/0x620
| __slab_alloc.isra.73+0x53/0xa0
| kmem_cache_alloc_node+0xaf/0x2a0
| copy_process.part.41+0x1e1/0x2370
| _do_fork+0xdb/0x6d0
| kernel_thread+0x20/0x30
| kthreadd+0x1ba/0x220
| ret_from_fork+0x3a/0x50
…
| other info that might help us debug this:
| Possible unsafe locking scenario:
|
| CPU0
| ----
| lock(batched_entropy_u32.lock);
| <Interrupt>
| lock(batched_entropy_u32.lock);
|
| *** DEADLOCK ***
|
| stack backtrace:
| Call Trace:
…
| kmem_cache_alloc_trace+0x20e/0x270
| ipmi_alloc_recv_msg+0x16/0x40
…
| __do_softirq+0xec/0x48d
| run_ksoftirqd+0x37/0x60
| smpboot_thread_fn+0x191/0x290
| kthread+0xfe/0x130
| ret_from_fork+0x3a/0x50
Add a spinlock_t to the batched_entropy data structure and acquire the
lock while accessing it. Acquire the lock with disabled interrupts
because this function may be used from interrupt context.
Remove the batched_entropy_reset_lock lock. Now that we have a lock for
the data scructure, we can access it from a remote CPU.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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