The sequence
static DEFINE_WW_CLASS(test_ww_class);
struct ww_acquire_ctx ww_ctx;
struct ww_mutex ww_lock_a;
struct ww_mutex ww_lock_b;
struct ww_mutex ww_lock_c;
struct mutex lock_c;
ww_acquire_init(&ww_ctx, &test_ww_class);
ww_mutex_init(&ww_lock_a, &test_ww_class);
ww_mutex_init(&ww_lock_b, &test_ww_class);
ww_mutex_init(&ww_lock_c, &test_ww_class);
mutex_init(&lock_c);
ww_mutex_lock(&ww_lock_a, &ww_ctx);
mutex_lock(&lock_c);
ww_mutex_lock(&ww_lock_b, &ww_ctx);
ww_mutex_lock(&ww_lock_c, &ww_ctx);
mutex_unlock(&lock_c); (*)
ww_mutex_unlock(&ww_lock_c);
ww_mutex_unlock(&ww_lock_b);
ww_mutex_unlock(&ww_lock_a);
ww_acquire_fini(&ww_ctx); (**)
will trigger the following error in __lock_release() when calling
mutex_release() at **:
DEBUG_LOCKS_WARN_ON(depth <= 0)
The problem is that the hlock merging happening at * updates the
references for test_ww_class incorrectly to 3 whereas it should've
updated it to 4 (representing all the instances for ww_ctx and
ww_lock_[abc]).
Fix this by updating the references during merging correctly taking into
account that we can have non-zero references (both for the hlock that we
merge into another hlock or for the hlock we are merging into).
Signed-off-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Link: https://lkml.kernel.org/r/20190524201509.9199-2-imre.deak@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The sequence
static DEFINE_WW_CLASS(test_ww_class);
struct ww_acquire_ctx ww_ctx;
struct ww_mutex ww_lock_a;
struct ww_mutex ww_lock_b;
struct mutex lock_c;
struct mutex lock_d;
ww_acquire_init(&ww_ctx, &test_ww_class);
ww_mutex_init(&ww_lock_a, &test_ww_class);
ww_mutex_init(&ww_lock_b, &test_ww_class);
mutex_init(&lock_c);
ww_mutex_lock(&ww_lock_a, &ww_ctx);
mutex_lock(&lock_c);
ww_mutex_lock(&ww_lock_b, &ww_ctx);
mutex_unlock(&lock_c); (*)
ww_mutex_unlock(&ww_lock_b);
ww_mutex_unlock(&ww_lock_a);
ww_acquire_fini(&ww_ctx);
triggers the following WARN in __lock_release() when doing the unlock at *:
DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1);
The problem is that the WARN check doesn't take into account the merging
of ww_lock_a and ww_lock_b which results in decreasing curr->lockdep_depth
by 2 not only 1.
Note that the following sequence doesn't trigger the WARN, since there
won't be any hlock merging.
ww_acquire_init(&ww_ctx, &test_ww_class);
ww_mutex_init(&ww_lock_a, &test_ww_class);
ww_mutex_init(&ww_lock_b, &test_ww_class);
mutex_init(&lock_c);
mutex_init(&lock_d);
ww_mutex_lock(&ww_lock_a, &ww_ctx);
mutex_lock(&lock_c);
mutex_lock(&lock_d);
ww_mutex_lock(&ww_lock_b, &ww_ctx);
mutex_unlock(&lock_d);
ww_mutex_unlock(&ww_lock_b);
ww_mutex_unlock(&ww_lock_a);
mutex_unlock(&lock_c);
ww_acquire_fini(&ww_ctx);
In general both of the above two sequences are valid and shouldn't
trigger any lockdep warning.
Fix this by taking the decrement due to the hlock merging into account
during lock release and hlock class re-setting. Merging can't happen
during lock downgrading since there won't be a new possibility to merge
hlocks in that case, so add a WARN if merging still happens then.
Signed-off-by: Imre Deak <imre.deak@intel.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: Will Deacon <will.deacon@arm.com>
Cc: ville.syrjala@linux.intel.com
Link: https://lkml.kernel.org/r/20190524201509.9199-1-imre.deak@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In mark_lock_irq(), the following checks are performed:
----------------------------------
| -> | unsafe | read unsafe |
|----------------------------------|
| safe | F B | F* B* |
|----------------------------------|
| read safe | F? B* | - |
----------------------------------
Where:
F: check_usage_forwards
B: check_usage_backwards
*: check enabled by STRICT_READ_CHECKS
?: check enabled by the !dir condition
From checking point of view, the special F? case does not make sense,
whereas it perhaps is made for peroformance concern. As later patch will
address this issue, remove this exception, which makes the checks
consistent later.
With STRICT_READ_CHECKS = 1 which is default, there is no functional
change.
Signed-off-by: Yuyang Du <duyuyang@gmail.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: bvanassche@acm.org
Cc: frederic@kernel.org
Cc: ming.lei@redhat.com
Cc: will.deacon@arm.com
Link: https://lkml.kernel.org/r/20190506081939.74287-24-duyuyang@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
As Peter has put it all sound and complete for the cause, I simply quote:
"It (check_redundant) was added for cross-release (which has since been
reverted) which would generate a lot of redundant links (IIRC) but
having it makes the reports more convoluted -- basically, if we had an
A-B-C relation, then A-C will not be added to the graph because it is
already covered. This then means any report will include B, even though
a shorter cycle might have been possible."
This would increase the number of direct dependencies. For a simple workload
(make clean; reboot; make vmlinux -j8), the data looks like this:
CONFIG_LOCKDEP_SMALL: direct dependencies: 6926
!CONFIG_LOCKDEP_SMALL: direct dependencies: 9052 (+30.7%)
Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Yuyang Du <duyuyang@gmail.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: bvanassche@acm.org
Cc: frederic@kernel.org
Cc: ming.lei@redhat.com
Cc: will.deacon@arm.com
Link: https://lkml.kernel.org/r/20190506081939.74287-21-duyuyang@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
held_lock->class_idx is used to point to the class of the held lock. The
index is shifted by 1 to make index 0 mean no class, which results in class
index shifting back and forth but is not worth doing so.
The reason is: (1) there will be no "no-class" held_lock to begin with, and
(2) index 0 seems to be used for error checking, but if something wrong
indeed happened, the index can't be counted on to distinguish it as that
something won't set the class_idx to 0 on purpose to tell us it is wrong.
Therefore, change the index to start from 0. This saves a lot of
back-and-forth shifts and a class slot back to lock_classes.
Since index 0 is now used for lock class, we change the initial chain key to
-1 to avoid key collision, which is due to the fact that __jhash_mix(0, 0, 0) = 0.
Actually, the initial chain key can be any arbitrary value other than 0.
In addition, a bitmap is maintained to keep track of the used lock classes,
and we check the validity of the held lock against that bitmap.
Signed-off-by: Yuyang Du <duyuyang@gmail.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: bvanassche@acm.org
Cc: frederic@kernel.org
Cc: ming.lei@redhat.com
Cc: will.deacon@arm.com
Link: https://lkml.kernel.org/r/20190506081939.74287-10-duyuyang@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull x86 fixes from Ingo Molnar:
"Two fixes: a quirk for KVM guests running on certain AMD CPUs, and a
KASAN related build fix"
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/CPU/AMD: Don't force the CPB cap when running under a hypervisor
x86/boot: Provide KASAN compatible aliases for string routines
Pull perf fixes from Ingo Molnar:
"On the kernel side there's a bunch of ring-buffer ordering fixes for a
reproducible bug, plus a PEBS constraints regression fix.
Plus tooling fixes"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
tools headers UAPI: Sync kvm.h headers with the kernel sources
perf record: Fix s390 missing module symbol and warning for non-root users
perf machine: Read also the end of the kernel
perf test vmlinux-kallsyms: Ignore aliases to _etext when searching on kallsyms
perf session: Add missing swap ops for namespace events
perf namespace: Protect reading thread's namespace
tools headers UAPI: Sync drm/drm.h with the kernel
tools headers UAPI: Sync drm/i915_drm.h with the kernel
tools headers UAPI: Sync linux/fs.h with the kernel
tools headers UAPI: Sync linux/sched.h with the kernel
tools arch x86: Sync asm/cpufeatures.h with the with the kernel
tools include UAPI: Update copy of files related to new fspick, fsmount, fsconfig, fsopen, move_mount and open_tree syscalls
perf arm64: Fix mksyscalltbl when system kernel headers are ahead of the kernel
perf data: Fix 'strncat may truncate' build failure with recent gcc
perf/ring-buffer: Use regular variables for nesting
perf/ring-buffer: Always use {READ,WRITE}_ONCE() for rb->user_page data
perf/ring_buffer: Add ordering to rb->nest increment
perf/ring_buffer: Fix exposing a temporarily decreased data_head
perf/x86/intel/ds: Fix EVENT vs. UEVENT PEBS constraints
Pull EFI fixes from Ingo Molnar:
"Two EFI fixes: a quirk for weird systabs, plus add more robust error
handling in the old 1:1 mapping code"
* 'efi-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
efi: Allow the number of EFI configuration tables entries to be zero
efi/x86/Add missing error handling to old_memmap 1:1 mapping code
Pull SPDX fixes from Greg KH:
"Here are just two small patches, that fix up some found SPDX
identifier issues.
The first patch fixes an error in a previous SPDX fixup patch, that
causes build errors when doing 'make clean' on the tree (the fact that
almost no one noticed it reflects the fact that kernel developers
don't like doing that option very often...)
The second patch fixes up a number of places in the tree where people
mistyped the string "SPDX-License-Identifier". Given that people can
not even type their own name all the time without mistakes, this was
bound to happen, and odds are, we will have to add some type of check
for this to checkpatch.pl to catch this happening in the future.
Both of these have passed testing by 0-day"
* tag 'spdx-5.2-rc3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
treewide: fix typos of SPDX-License-Identifier
crypto: ux500 - fix license comment syntax error
Pull powerpc fixes from Michael Ellerman:
"A minor fix to our IMC PMU code to print a less confusing error
message when the driver can't initialise properly.
A fix for a bug where a user requesting an unsupported branch sampling
filter can corrupt PMU state, preventing the PMU from counting
properly.
And finally a fix for a bug in our support for kexec_file_load(),
which prevented loading a kernel and initramfs. Most versions of kexec
don't yet use kexec_file_load().
Thanks to: Anju T Sudhakar, Dave Young, Madhavan Srinivasan, Ravi
Bangoria, Thiago Jung Bauermann"
* tag 'powerpc-5.2-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
powerpc/kexec: Fix loading of kernel + initramfs with kexec_file_load()
powerpc/perf: Fix MMCRA corruption by bhrb_filter
powerpc/powernv: Return for invalid IMC domain
Pull KVM fixes from Paolo Bonzini:
"Fixes for PPC and s390"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: PPC: Book3S HV: Restore SPRG3 in kvmhv_p9_guest_entry()
KVM: PPC: Book3S HV: Fix lockdep warning when entering guest on POWER9
KVM: PPC: Book3S HV: XIVE: Fix page offset when clearing ESB pages
KVM: PPC: Book3S HV: XIVE: Take the srcu read lock when accessing memslots
KVM: PPC: Book3S HV: XIVE: Do not clear IRQ data of passthrough interrupts
KVM: PPC: Book3S HV: XIVE: Introduce a new mutex for the XIVE device
KVM: PPC: Book3S HV: XIVE: Fix the enforced limit on the vCPU identifier
KVM: PPC: Book3S HV: XIVE: Do not test the EQ flag validity when resetting
KVM: PPC: Book3S HV: XIVE: Clear file mapping when device is released
KVM: PPC: Book3S HV: Don't take kvm->lock around kvm_for_each_vcpu
KVM: PPC: Book3S: Use new mutex to synchronize access to rtas token list
KVM: PPC: Book3S HV: Use new mutex to synchronize MMU setup
KVM: PPC: Book3S HV: Avoid touching arch.mmu_ready in XIVE release functions
KVM: s390: Do not report unusabled IDs via KVM_CAP_MAX_VCPU_ID
kvm: fix compile on s390 part 2
Pull i2c fixes from Wolfram Sang:
"A memleak fix for the core, two driver bugfixes, as well as fixing
missing file patterns to MAINTAINERS"
* 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
MAINTAINERS: add I2C DT bindings to ARM platforms
MAINTAINERS: add DT bindings to i2c drivers
i2c: synquacer: fix synquacer_i2c_doxfer() return value
i2c: mlxcpld: Fix wrong initialization order in probe
i2c: dev: fix potential memory leak in i2cdev_ioctl_rdwr
Pull thermal SoC fix from Eduardo Valentin:
"A single revert, detected to cause issues on the tsens driver"
* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/evalenti/linux-soc-thermal:
Revert "drivers: thermal: tsens: Add new operation to check if a sensor is enabled"
Pull LED fix from Jacek Anaszewski:
"Fix for a recent change in LED core, that didn't take into account the
possibility of calling led_blink_setup() from atomic context"
* tag 'led-fixes-for-5.2-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/j.anaszewski/linux-leds:
leds: avoid flush_work in atomic context
