f08a1e912d
232 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Linus Torvalds
|
91b6163be4 |
sysctl changes for v6.10-rc1
Summary
* Removed sentinel elements from ctl_table structs in kernel/*
Removing sentinels in ctl_table arrays reduces the build time size and
runtime memory consumed by ~64 bytes per array. Removals for net/, io_uring/,
mm/, ipc/ and security/ are set to go into mainline through their respective
subsystems making the next release the most likely place where the final
series that removes the check for proc_name == NULL will land. This PR adds
to removals already in arch/, drivers/ and fs/.
* Adjusted ctl_table definitions and references to allow constification
Adjustments:
- Removing unused ctl_table function arguments
- Moving non-const elements from ctl_table to ctl_table_header
- Making ctl_table pointers const in ctl_table_root structure
Making the static ctl_table structs const will increase safety by keeping the
pointers to proc_handler functions in .rodata. Though no ctl_tables where
made const in this PR, the ground work for making that possible has started
with these changes sent by Thomas Weißschuh.
Testing
* These changes went into linux-next after v6.9-rc4; giving it a good month of
testing.
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Merge tag 'sysctl-6.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl
Pull sysctl updates from Joel Granados:
- Remove sentinel elements from ctl_table structs in kernel/*
Removing sentinels in ctl_table arrays reduces the build time size
and runtime memory consumed by ~64 bytes per array. Removals for
net/, io_uring/, mm/, ipc/ and security/ are set to go into mainline
through their respective subsystems making the next release the most
likely place where the final series that removes the check for
proc_name == NULL will land.
This adds to removals already in arch/, drivers/ and fs/.
- Adjust ctl_table definitions and references to allow constification
- Remove unused ctl_table function arguments
- Move non-const elements from ctl_table to ctl_table_header
- Make ctl_table pointers const in ctl_table_root structure
Making the static ctl_table structs const will increase safety by
keeping the pointers to proc_handler functions in .rodata. Though no
ctl_tables where made const in this PR, the ground work for making
that possible has started with these changes sent by Thomas
Weißschuh.
* tag 'sysctl-6.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl:
sysctl: drop now unnecessary out-of-bounds check
sysctl: move sysctl type to ctl_table_header
sysctl: drop sysctl_is_perm_empty_ctl_table
sysctl: treewide: constify argument ctl_table_root::permissions(table)
sysctl: treewide: drop unused argument ctl_table_root::set_ownership(table)
bpf: Remove the now superfluous sentinel elements from ctl_table array
delayacct: Remove the now superfluous sentinel elements from ctl_table array
kprobes: Remove the now superfluous sentinel elements from ctl_table array
printk: Remove the now superfluous sentinel elements from ctl_table array
scheduler: Remove the now superfluous sentinel elements from ctl_table array
seccomp: Remove the now superfluous sentinel elements from ctl_table array
timekeeping: Remove the now superfluous sentinel elements from ctl_table array
ftrace: Remove the now superfluous sentinel elements from ctl_table array
umh: Remove the now superfluous sentinel elements from ctl_table array
kernel misc: Remove the now superfluous sentinel elements from ctl_table array
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Joel Granados
|
11a921909f |
kernel misc: Remove the now superfluous sentinel elements from ctl_table array
This commit comes at the tail end of a greater effort to remove the empty elements at the end of the ctl_table arrays (sentinels) which will reduce the overall build time size of the kernel and run time memory bloat by ~64 bytes per sentinel (further information Link : https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/) Remove the sentinel from ctl_table arrays. Reduce by one the values used to compare the size of the adjusted arrays. Signed-off-by: Joel Granados <j.granados@samsung.com> |
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Bitao Hu
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e9a9292e23 |
watchdog/softlockup: Report the most frequent interrupts
When the watchdog determines that the current soft lockup is due to an interrupt storm based on CPU utilization, reporting the most frequent interrupts could be good enough for further troubleshooting. Below is an example of interrupt storm. The call tree does not provide useful information, but analyzing which interrupt caused the soft lockup by comparing the counts of interrupts during the lockup period allows to identify the culprit. [ 638.870231] watchdog: BUG: soft lockup - CPU#9 stuck for 26s! [swapper/9:0] [ 638.870825] CPU#9 Utilization every 4s during lockup: [ 638.871194] #1: 0% system, 0% softirq, 100% hardirq, 0% idle [ 638.871652] #2: 0% system, 0% softirq, 100% hardirq, 0% idle [ 638.872107] #3: 0% system, 0% softirq, 100% hardirq, 0% idle [ 638.872563] #4: 0% system, 0% softirq, 100% hardirq, 0% idle [ 638.873018] #5: 0% system, 0% softirq, 100% hardirq, 0% idle [ 638.873494] CPU#9 Detect HardIRQ Time exceeds 50%. Most frequent HardIRQs: [ 638.873994] #1: 330945 irq#7 [ 638.874236] #2: 31 irq#82 [ 638.874493] #3: 10 irq#10 [ 638.874744] #4: 2 irq#89 [ 638.874992] #5: 1 irq#102 ... [ 638.875313] Call trace: [ 638.875315] __do_softirq+0xa8/0x364 Signed-off-by: Bitao Hu <yaoma@linux.alibaba.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Liu Song <liusong@linux.alibaba.com> Reviewed-by: Douglas Anderson <dianders@chromium.org> Link: https://lore.kernel.org/r/20240411074134.30922-6-yaoma@linux.alibaba.com |
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Bitao Hu
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d7037381d0 |
watchdog/softlockup: Low-overhead detection of interrupt storm
The following softlockup is caused by interrupt storm, but it cannot be
identified from the call tree. Because the call tree is just a snapshot
and doesn't fully capture the behavior of the CPU during the soft lockup.
watchdog: BUG: soft lockup - CPU#28 stuck for 23s! [fio:83921]
...
Call trace:
__do_softirq+0xa0/0x37c
__irq_exit_rcu+0x108/0x140
irq_exit+0x14/0x20
__handle_domain_irq+0x84/0xe0
gic_handle_irq+0x80/0x108
el0_irq_naked+0x50/0x58
Therefore, it is necessary to report CPU utilization during the
softlockup_threshold period (report once every sample_period, for a total
of 5 reportings), like this:
watchdog: BUG: soft lockup - CPU#28 stuck for 23s! [fio:83921]
CPU#28 Utilization every 4s during lockup:
#1: 0% system, 0% softirq, 100% hardirq, 0% idle
#2: 0% system, 0% softirq, 100% hardirq, 0% idle
#3: 0% system, 0% softirq, 100% hardirq, 0% idle
#4: 0% system, 0% softirq, 100% hardirq, 0% idle
#5: 0% system, 0% softirq, 100% hardirq, 0% idle
...
This is helpful in determining whether an interrupt storm has occurred or
in identifying the cause of the softlockup. The criteria for determination
are as follows:
a. If the hardirq utilization is high, then interrupt storm should be
considered and the root cause cannot be determined from the call tree.
b. If the softirq utilization is high, then the call might not necessarily
point at the root cause.
c. If the system utilization is high, then analyzing the root
cause from the call tree is possible in most cases.
The mechanism requires a considerable amount of global storage space
when configured for the maximum number of CPUs. Therefore, adding a
SOFTLOCKUP_DETECTOR_INTR_STORM Kconfig knob that defaults to "yes"
if the max number of CPUs is <= 128.
Signed-off-by: Bitao Hu <yaoma@linux.alibaba.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Liu Song <liusong@linux.alibaba.com>
Link: https://lore.kernel.org/r/20240411074134.30922-5-yaoma@linux.alibaba.com
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Thomas Weißschuh
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75060b6ead |
watchdog/core: remove sysctl handlers from public header
The functions are only used in the file where they are defined. Remove them from the header and make them static. Also guard proc_soft_watchdog with a #define-guard as it is not used otherwise. Link: https://lkml.kernel.org/r/20240306-const-sysctl-prep-watchdog-v1-1-bd45da3a41cf@weissschuh.net Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Douglas Anderson
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55efe4abf9 |
watchdog: if panicking and we dumped everything, don't re-enable dumping
If, as part of handling a hardlockup or softlockup, we've already dumped all CPUs and we're just about to panic, don't reenable dumping and give some other CPU a chance to hop in there and add some confusing logs right as the panic is happening. Link: https://lkml.kernel.org/r/20231220131534.4.Id3a9c7ec2d7d83e4080da6f8662ba2226b40543f@changeid Signed-off-by: Douglas Anderson <dianders@chromium.org> Cc: John Ogness <john.ogness@linutronix.de> Cc: Lecopzer Chen <lecopzer.chen@mediatek.com> Cc: Li Zhe <lizhe.67@bytedance.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Pingfan Liu <kernelfans@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Douglas Anderson
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ee6bdb3f4b |
watchdog/hardlockup: use printk_cpu_sync_get_irqsave() to serialize reporting
If two CPUs end up reporting a hardlockup at the same time then their logs could get interleaved which is hard to read. The interleaving problem was especially bad with the "perf" hardlockup detector where the locked up CPU is always the same as the running CPU and we end up in show_regs(). show_regs() has no inherent serialization so we could mix together two crawls if two hardlockups happened at the same time (and if we didn't have `sysctl_hardlockup_all_cpu_backtrace` set). With this change we'll fully serialize hardlockups when using the "perf" hardlockup detector. The interleaving problem was less bad with the "buddy" hardlockup detector. With "buddy" we always end up calling `trigger_single_cpu_backtrace(cpu)` on some CPU other than the running one. trigger_single_cpu_backtrace() always at least serializes the individual stack crawls because it eventually uses printk_cpu_sync_get_irqsave(). Unfortunately the fact that trigger_single_cpu_backtrace() eventually calls printk_cpu_sync_get_irqsave() (on a different CPU) means that we have to drop the "lock" before calling it and we can't fully serialize all printouts associated with a given hardlockup. However, we still do get the advantage of serializing the output of print_modules() and print_irqtrace_events(). Aside from serializing hardlockups from each other, this change also has the advantage of serializing hardlockups and softlockups from each other if they happen to happen at the same time since they are both using the same "lock". Even though nobody is expected to hang while holding the lock associated with printk_cpu_sync_get_irqsave(), out of an abundance of caution, we don't call printk_cpu_sync_get_irqsave() until after we print out about the hardlockup. This makes extra sure that, even if printk_cpu_sync_get_irqsave() somehow never runs we at least print that we saw the hardlockup. This is different than the choice made for softlockup because hardlockup is really our last resort. Link: https://lkml.kernel.org/r/20231220131534.3.I6ff691b3b40f0379bc860f80c6e729a0485b5247@changeid Signed-off-by: Douglas Anderson <dianders@chromium.org> Reviewed-by: John Ogness <john.ogness@linutronix.de> Cc: Lecopzer Chen <lecopzer.chen@mediatek.com> Cc: Li Zhe <lizhe.67@bytedance.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Pingfan Liu <kernelfans@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Douglas Anderson
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896260a6d6 |
watchdog/softlockup: use printk_cpu_sync_get_irqsave() to serialize reporting
Instead of introducing a spinlock, use printk_cpu_sync_get_irqsave() and printk_cpu_sync_put_irqrestore() to serialize softlockup reporting. Alone this doesn't have any real advantage over the spinlock, but this will allow us to use the same function in a future change to also serialize hardlockup crawls. NOTE: for the most part this serialization is important because we often end up in the show_regs() path and that has no built-in serialization if there are multiple callers at once. However, even in the case where we end up in the dump_stack() path this still has some advantages because the stack will be guaranteed to be together in the logs with the lockup message with no interleaving. NOTE: the fact that printk_cpu_sync_get_irqsave() is allowed to be called multiple times on the same CPU is important here. Specifically we hold the "lock" while calling dump_stack() which also gets the same "lock". This is explicitly documented to be OK and means we don't need to introduce a variant of dump_stack() that doesn't grab the lock. Link: https://lkml.kernel.org/r/20231220131534.2.Ia5906525d440d8e8383cde31b7c61c2aadc8f907@changeid Signed-off-by: Douglas Anderson <dianders@chromium.org> Reviewed-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Li Zhe <lizhe.67@bytedance.com> Cc: Lecopzer Chen <lecopzer.chen@mediatek.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Pingfan Liu <kernelfans@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Douglas Anderson
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6dcde5d5f2 |
watchdog/hardlockup: adopt softlockup logic avoiding double-dumps
Patch series "watchdog: Better handling of concurrent lockups".
When we get multiple lockups at roughly the same time, the output in the
kernel logs can be very confusing since the reports about the lockups end
up interleaved in the logs. There is some code in the kernel to try to
handle this but it wasn't that complete.
Li Zhe recently made this a bit better for softlockups (specifically for
the case where `kernel.softlockup_all_cpu_backtrace` is not set) in commit
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Li Zhe
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9d02330abd |
softlockup: serialized softlockup's log
If multiple CPUs trigger softlockup at the same time with 'softlockup_all_cpu_backtrace=0', the softlockup's logs will appear staggeredly in dmesg, which will affect the viewing of the logs for developer. Since the code path for outputting softlockup logs is not a kernel hotspot and the performance requirements for the code are not strict, locks are used to serialize the softlockup log output to improve the readability of the logs. Link: https://lkml.kernel.org/r/20231123084022.10302-1-lizhe.67@bytedance.com Signed-off-by: Li Zhe <lizhe.67@bytedance.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Douglas Anderson <dianders@chromium.org> Cc: Lecopzer Chen <lecopzer.chen@mediatek.com> Cc: Pingfan Liu <kernelfans@gmail.com> Cc: Zefan Li <lizefan.x@bytedance.com> Cc: John Ogness <john.ogness@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Krister Johansen
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8b793bcda6 |
watchdog: move softlockup_panic back to early_param
Setting softlockup_panic from do_sysctl_args() causes it to take effect later in boot. The lockup detector is enabled before SMP is brought online, but do_sysctl_args runs afterwards. If a user wants to set softlockup_panic on boot and have it trigger should a softlockup occur during onlining of the non-boot processors, they could do this prior to commit |
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Douglas Anderson
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1f38c86bb2 |
watchdog/hardlockup: avoid large stack frames in watchdog_hardlockup_check()
After commit |
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Douglas Anderson
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8d539b84f1 |
nmi_backtrace: allow excluding an arbitrary CPU
The APIs that allow backtracing across CPUs have always had a way to exclude the current CPU. This convenience means callers didn't need to find a place to allocate a CPU mask just to handle the common case. Let's extend the API to take a CPU ID to exclude instead of just a boolean. This isn't any more complex for the API to handle and allows the hardlockup detector to exclude a different CPU (the one it already did a trace for) without needing to find space for a CPU mask. Arguably, this new API also encourages safer behavior. Specifically if the caller wants to avoid tracing the current CPU (maybe because they already traced the current CPU) this makes it more obvious to the caller that they need to make sure that the current CPU ID can't change. [akpm@linux-foundation.org: fix trigger_allbutcpu_cpu_backtrace() stub] Link: https://lkml.kernel.org/r/20230804065935.v4.1.Ia35521b91fc781368945161d7b28538f9996c182@changeid Signed-off-by: Douglas Anderson <dianders@chromium.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: kernel test robot <lkp@intel.com> Cc: Lecopzer Chen <lecopzer.chen@mediatek.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Pingfan Liu <kernelfans@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Petr Mladek
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47f4cb4339 |
watchdog/sparc64: define HARDLOCKUP_DETECTOR_SPARC64
The HAVE_ prefix means that the code could be enabled. Add another variable for HAVE_HARDLOCKUP_DETECTOR_SPARC64 without this prefix. It will be set when it should be built. It will make it compatible with the other hardlockup detectors. Before, it is far from obvious that the SPARC64 variant is actually used: $> make ARCH=sparc64 defconfig $> grep HARDLOCKUP_DETECTOR .config CONFIG_HAVE_HARDLOCKUP_DETECTOR_BUDDY=y CONFIG_HAVE_HARDLOCKUP_DETECTOR_SPARC64=y After, it is more clear: $> make ARCH=sparc64 defconfig $> grep HARDLOCKUP_DETECTOR .config CONFIG_HAVE_HARDLOCKUP_DETECTOR_BUDDY=y CONFIG_HAVE_HARDLOCKUP_DETECTOR_SPARC64=y CONFIG_HARDLOCKUP_DETECTOR_SPARC64=y Link: https://lkml.kernel.org/r/20230616150618.6073-6-pmladek@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Douglas Anderson <dianders@chromium.org> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: "David S. Miller" <davem@davemloft.net> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Petr Mladek
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a5fcc2367e |
watchdog/hardlockup: make HAVE_NMI_WATCHDOG sparc64-specific
There are several hardlockup detector implementations and several Kconfig values which allow selection and build of the preferred one. CONFIG_HARDLOCKUP_DETECTOR was introduced by the commit |
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Douglas Anderson
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28168eca32 |
watchdog/hardlockup: move SMP barriers from common code to buddy code
It's been suggested that since the SMP barriers are only potentially useful for the buddy hardlockup detector, not the perf hardlockup detector, that the barriers belong in the buddy code. Let's move them and add clearer comments about why they're needed. Link: https://lkml.kernel.org/r/20230526184139.9.I5ab0a0eeb0bd52fb23f901d298c72fa5c396e22b@changeid Signed-off-by: Douglas Anderson <dianders@chromium.org> Suggested-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: "David S. Miller" <davem@davemloft.net> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Douglas Anderson
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d3b62ace0f |
watchdog/buddy: cleanup how watchdog_buddy_check_hardlockup() is called
In the patch ("watchdog/hardlockup: detect hard lockups using secondary
(buddy) CPUs"), we added a call from the common watchdog.c file into the
buddy. That call could be done more cleanly. Specifically:
1. If we move the call into watchdog_hardlockup_kick() then it keeps
watchdog_timer_fn() simpler.
2. We don't need to pass an "unsigned long" to the buddy for the timer
count. In the patch ("watchdog/hardlockup: add a "cpu" param to
watchdog_hardlockup_check()") the count was changed to "atomic_t"
which is backed by an int, so we should match types.
Link: https://lkml.kernel.org/r/20230526184139.6.I006c7d958a1ea5c4e1e4dc44a25596d9bb5fd3ba@changeid
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Suggested-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Douglas Anderson
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7a71d8e650 |
watchdog/hardlockup: in watchdog_hardlockup_check() use cpumask_copy()
In the patch ("watchdog/hardlockup: add a "cpu" param to
watchdog_hardlockup_check()") we started using a cpumask to keep track of
which CPUs to backtrace. When setting up this cpumask, it's better to use
cpumask_copy() than to just copy the structure directly. Fix this.
Link: https://lkml.kernel.org/r/20230526184139.4.Iccee2d1ea19114dafb6553a854ea4d8ab2a3f25b@changeid
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Suggested-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Douglas Anderson
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2711e4adef |
watchdog/hardlockup: don't use raw_cpu_ptr() in watchdog_hardlockup_kick()
In the patch ("watchdog/hardlockup: add a "cpu" param to
watchdog_hardlockup_check()") there was no reason to use raw_cpu_ptr().
Using this_cpu_ptr() works fine.
Link: https://lkml.kernel.org/r/20230526184139.3.I660e103077dcc23bb29aaf2be09cb234e0495b2d@changeid
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Suggested-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Douglas Anderson
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6426e8d1f2 |
watchdog/hardlockup: HAVE_NMI_WATCHDOG must implement watchdog_hardlockup_probe()
Right now there is one arch (sparc64) that selects HAVE_NMI_WATCHDOG without selecting HAVE_HARDLOCKUP_DETECTOR_ARCH. Because of that one architecture, we have some special case code in the watchdog core to handle the fact that watchdog_hardlockup_probe() isn't implemented. Let's implement watchdog_hardlockup_probe() for sparc64 and get rid of the special case. As a side effect of doing this, code inspection tells us that we could fix a minor bug where the system won't properly realize that NMI watchdogs are disabled. Specifically, on powerpc if CONFIG_PPC_WATCHDOG is turned off the arch might still select CONFIG_HAVE_HARDLOCKUP_DETECTOR_ARCH which selects CONFIG_HAVE_NMI_WATCHDOG. Since CONFIG_PPC_WATCHDOG was off then nothing will override the "weak" watchdog_hardlockup_probe() and we'll fallback to looking at CONFIG_HAVE_NMI_WATCHDOG. Link: https://lkml.kernel.org/r/20230526184139.2.Ic6ebbf307ca0efe91f08ce2c1eb4a037ba6b0700@changeid Signed-off-by: Douglas Anderson <dianders@chromium.org> Suggested-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: "David S. Miller" <davem@davemloft.net> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Douglas Anderson
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9ec272c586 |
watchdog/hardlockup: keep kernel.nmi_watchdog sysctl as 0444 if probe fails
Patch series "watchdog: Cleanup / fixes after buddy series v5 reviews".
This patch series attempts to finish resolving the feedback received
from Petr Mladek on the v5 series I posted.
Probably the only thing that wasn't fully as clean as Petr requested was
the Kconfig stuff. I couldn't find a better way to express it without a
more major overhaul. In the very least, I renamed "NON_ARCH" to
"PERF_OR_BUDDY" in the hopes that will make it marginally better.
Nothing in this series is terribly critical and even the bugfixes are
small. However, it does cleanup a few things that were pointed out in
review.
This patch (of 10):
The permissions for the kernel.nmi_watchdog sysctl have always been set at
compile time despite the fact that a watchdog can fail to probe. Let's
fix this and set the permissions based on whether the hardlockup detector
actually probed.
Link: https://lkml.kernel.org/r/20230527014153.2793931-1-dianders@chromium.org
Link: https://lkml.kernel.org/r/20230526184139.1.I0d75971cc52a7283f495aac0bd5c3041aadc734e@changeid
Fixes:
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Lecopzer Chen
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930d8f8dba |
watchdog/perf: adapt the watchdog_perf interface for async model
When lockup_detector_init()->watchdog_hardlockup_probe(), PMU may be not ready yet. E.g. on arm64, PMU is not ready until device_initcall(armv8_pmu_driver_init). And it is deeply integrated with the driver model and cpuhp. Hence it is hard to push this initialization before smp_init(). But it is easy to take an opposite approach and try to initialize the watchdog once again later. The delayed probe is called using workqueues. It need to allocate memory and must be proceed in a normal context. The delayed probe is able to use if watchdog_hardlockup_probe() returns non-zero which means the return code returned when PMU is not ready yet. Provide an API - lockup_detector_retry_init() for anyone who needs to delayed init lockup detector if they had ever failed at lockup_detector_init(). The original assumption is: nobody should use delayed probe after lockup_detector_check() which has __init attribute. That is, anyone uses this API must call between lockup_detector_init() and lockup_detector_check(), and the caller must have __init attribute Link: https://lkml.kernel.org/r/20230519101840.v5.16.If4ad5dd5d09fb1309cebf8bcead4b6a5a7758ca7@changeid Reviewed-by: Petr Mladek <pmladek@suse.com> Co-developed-by: Pingfan Liu <kernelfans@gmail.com> Signed-off-by: Pingfan Liu <kernelfans@gmail.com> Signed-off-by: Lecopzer Chen <lecopzer.chen@mediatek.com> Signed-off-by: Douglas Anderson <dianders@chromium.org> Suggested-by: Petr Mladek <pmladek@suse.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chen-Yu Tsai <wens@csie.org> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Colin Cross <ccross@android.com> Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Guenter Roeck <groeck@chromium.org> Cc: Ian Rogers <irogers@google.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masayoshi Mizuma <msys.mizuma@gmail.com> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com> Cc: Ricardo Neri <ricardo.neri@intel.com> Cc: Stephane Eranian <eranian@google.com> Cc: Stephen Boyd <swboyd@chromium.org> Cc: Sumit Garg <sumit.garg@linaro.org> Cc: Tzung-Bi Shih <tzungbi@chromium.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Douglas Anderson
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1f423c905a |
watchdog/hardlockup: detect hard lockups using secondary (buddy) CPUs
Implement a hardlockup detector that doesn't doesn't need any extra arch-specific support code to detect lockups. Instead of using something arch-specific we will use the buddy system, where each CPU watches out for another one. Specifically, each CPU will use its softlockup hrtimer to check that the next CPU is processing hrtimer interrupts by verifying that a counter is increasing. NOTE: unlike the other hard lockup detectors, the buddy one can't easily show what's happening on the CPU that locked up just by doing a simple backtrace. It relies on some other mechanism in the system to get information about the locked up CPUs. This could be support for NMI backtraces like [1], it could be a mechanism for printing the PC of locked CPUs at panic time like [2] / [3], or it could be something else. Even though that means we still rely on arch-specific code, this arch-specific code seems to often be implemented even on architectures that don't have a hardlockup detector. This style of hardlockup detector originated in some downstream Android trees and has been rebased on / carried in ChromeOS trees for quite a long time for use on arm and arm64 boards. Historically on these boards we've leveraged mechanism [2] / [3] to get information about hung CPUs, but we could move to [1]. Although the original motivation for the buddy system was for use on systems without an arch-specific hardlockup detector, it can still be useful to use even on systems that _do_ have an arch-specific hardlockup detector. On x86, for instance, there is a 24-part patch series [4] in progress switching the arch-specific hard lockup detector from a scarce perf counter to a less-scarce hardware resource. Potentially the buddy system could be a simpler alternative to free up the perf counter but still get hard lockup detection. Overall, pros (+) and cons (-) of the buddy system compared to an arch-specific hardlockup detector (which might be implemented using perf): + The buddy system is usable on systems that don't have an arch-specific hardlockup detector, like arm32 and arm64 (though it's being worked on for arm64 [5]). + The buddy system may free up scarce hardware resources. + If a CPU totally goes out to lunch (can't process NMIs) the buddy system could still detect the problem (though it would be unlikely to be able to get a stack trace). + The buddy system uses the same timer function to pet the hardlockup detector on the running CPU as it uses to detect hardlockups on other CPUs. Compared to other hardlockup detectors, this means it generates fewer interrupts and thus is likely better able to let CPUs stay idle longer. - If all CPUs are hard locked up at the same time the buddy system can't detect it. - If we don't have SMP we can't use the buddy system. - The buddy system needs an arch-specific mechanism (possibly NMI backtrace) to get info about the locked up CPU. [1] https://lore.kernel.org/r/20230419225604.21204-1-dianders@chromium.org [2] https://issuetracker.google.com/172213129 [3] https://docs.kernel.org/trace/coresight/coresight-cpu-debug.html [4] https://lore.kernel.org/lkml/20230301234753.28582-1-ricardo.neri-calderon@linux.intel.com/ [5] https://lore.kernel.org/linux-arm-kernel/20220903093415.15850-1-lecopzer.chen@mediatek.com/ Link: https://lkml.kernel.org/r/20230519101840.v5.14.I6bf789d21d0c3d75d382e7e51a804a7a51315f2c@changeid Signed-off-by: Colin Cross <ccross@android.com> Signed-off-by: Matthias Kaehlcke <mka@chromium.org> Signed-off-by: Guenter Roeck <groeck@chromium.org> Signed-off-by: Tzung-Bi Shih <tzungbi@chromium.org> Signed-off-by: Douglas Anderson <dianders@chromium.org> Cc: Andi Kleen <ak@linux.intel.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chen-Yu Tsai <wens@csie.org> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Ian Rogers <irogers@google.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masayoshi Mizuma <msys.mizuma@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Pingfan Liu <kernelfans@gmail.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com> Cc: Ricardo Neri <ricardo.neri@intel.com> Cc: Stephane Eranian <eranian@google.com> Cc: Stephen Boyd <swboyd@chromium.org> Cc: Sumit Garg <sumit.garg@linaro.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Douglas Anderson
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d9b3629ade |
watchdog/hardlockup: have the perf hardlockup use __weak functions more cleanly
The fact that there watchdog_hardlockup_enable(), watchdog_hardlockup_disable(), and watchdog_hardlockup_probe() are declared __weak means that the configured hardlockup detector can define non-weak versions of those functions if it needs to. Instead of doing this, the perf hardlockup detector hooked itself into the default __weak implementation, which was a bit awkward. Clean this up. From comments, it looks as if the original design was done because the __weak function were expected to implemented by the architecture and not by the configured hardlockup detector. This got awkward when we tried to add the buddy lockup detector which was not arch-specific but wanted to hook into those same functions. This is not expected to have any functional impact. Link: https://lkml.kernel.org/r/20230519101840.v5.13.I847d9ec852449350997ba00401d2462a9cb4302b@changeid Signed-off-by: Douglas Anderson <dianders@chromium.org> Reviewed-by: Petr Mladek <pmladek@suse.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chen-Yu Tsai <wens@csie.org> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Colin Cross <ccross@android.com> Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Guenter Roeck <groeck@chromium.org> Cc: Ian Rogers <irogers@google.com> Cc: Lecopzer Chen <lecopzer.chen@mediatek.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masayoshi Mizuma <msys.mizuma@gmail.com> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Pingfan Liu <kernelfans@gmail.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com> Cc: Ricardo Neri <ricardo.neri@intel.com> Cc: Stephane Eranian <eranian@google.com> Cc: Stephen Boyd <swboyd@chromium.org> Cc: Sumit Garg <sumit.garg@linaro.org> Cc: Tzung-Bi Shih <tzungbi@chromium.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Douglas Anderson
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df95d3085c |
watchdog/hardlockup: rename some "NMI watchdog" constants/function
Do a search and replace of: - NMI_WATCHDOG_ENABLED => WATCHDOG_HARDLOCKUP_ENABLED - SOFT_WATCHDOG_ENABLED => WATCHDOG_SOFTOCKUP_ENABLED - watchdog_nmi_ => watchdog_hardlockup_ - nmi_watchdog_available => watchdog_hardlockup_available - nmi_watchdog_user_enabled => watchdog_hardlockup_user_enabled - soft_watchdog_user_enabled => watchdog_softlockup_user_enabled - NMI_WATCHDOG_DEFAULT => WATCHDOG_HARDLOCKUP_DEFAULT Then update a few comments near where names were changed. This is specifically to make it less confusing when we want to introduce the buddy hardlockup detector, which isn't using NMIs. As part of this, we sanitized a few names for consistency. [trix@redhat.com: make variables static] Link: https://lkml.kernel.org/r/20230525162822.1.I0fb41d138d158c9230573eaa37dc56afa2fb14ee@changeid Link: https://lkml.kernel.org/r/20230519101840.v5.12.I91f7277bab4bf8c0cb238732ed92e7ce7bbd71a6@changeid Signed-off-by: Douglas Anderson <dianders@chromium.org> Signed-off-by: Tom Rix <trix@redhat.com> Reviewed-by: Tom Rix <trix@redhat.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chen-Yu Tsai <wens@csie.org> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Colin Cross <ccross@android.com> Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Guenter Roeck <groeck@chromium.org> Cc: Ian Rogers <irogers@google.com> Cc: Lecopzer Chen <lecopzer.chen@mediatek.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masayoshi Mizuma <msys.mizuma@gmail.com> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Pingfan Liu <kernelfans@gmail.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com> Cc: Ricardo Neri <ricardo.neri@intel.com> Cc: Stephane Eranian <eranian@google.com> Cc: Stephen Boyd <swboyd@chromium.org> Cc: Sumit Garg <sumit.garg@linaro.org> Cc: Tzung-Bi Shih <tzungbi@chromium.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Douglas Anderson
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ed92e1ef52 |
watchdog/hardlockup: move perf hardlockup watchdog petting to watchdog.c
In preparation for the buddy hardlockup detector, which wants the same petting logic as the current perf hardlockup detector, move the code to watchdog.c. While doing this, rename the global variable to match others nearby. As part of this change we have to change the code to account for the fact that the CPU we're running on might be different than the one we're checking. Currently the code in watchdog.c is guarded by CONFIG_HARDLOCKUP_DETECTOR_PERF, which makes this change seem silly. However, a future patch will change this. Link: https://lkml.kernel.org/r/20230519101840.v5.11.I00dfd6386ee00da25bf26d140559a41339b53e57@changeid Signed-off-by: Douglas Anderson <dianders@chromium.org> Cc: Andi Kleen <ak@linux.intel.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chen-Yu Tsai <wens@csie.org> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Colin Cross <ccross@android.com> Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Guenter Roeck <groeck@chromium.org> Cc: Ian Rogers <irogers@google.com> Cc: Lecopzer Chen <lecopzer.chen@mediatek.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masayoshi Mizuma <msys.mizuma@gmail.com> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Pingfan Liu <kernelfans@gmail.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com> Cc: Ricardo Neri <ricardo.neri@intel.com> Cc: Stephane Eranian <eranian@google.com> Cc: Stephen Boyd <swboyd@chromium.org> Cc: Sumit Garg <sumit.garg@linaro.org> Cc: Tzung-Bi Shih <tzungbi@chromium.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Douglas Anderson
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77c12fc959 |
watchdog/hardlockup: add a "cpu" param to watchdog_hardlockup_check()
In preparation for the buddy hardlockup detector where the CPU checking for lockup might not be the currently running CPU, add a "cpu" parameter to watchdog_hardlockup_check(). As part of this change, make hrtimer_interrupts an atomic_t since now the CPU incrementing the value and the CPU reading the value might be different. Technially this could also be done with just READ_ONCE and WRITE_ONCE, but atomic_t feels a little cleaner in this case. While hrtimer_interrupts is made atomic_t, we change hrtimer_interrupts_saved from "unsigned long" to "int". The "int" is needed to match the data type backing atomic_t for hrtimer_interrupts. Even if this changes us from 64-bits to 32-bits (which I don't think is true for most compilers), it doesn't really matter. All we ever do is increment it every few seconds and compare it to an old value so 32-bits is fine (even 16-bits would be). The "signed" vs "unsigned" also doesn't matter for simple equality comparisons. hrtimer_interrupts_saved is _not_ switched to atomic_t nor even accessed with READ_ONCE / WRITE_ONCE. The hrtimer_interrupts_saved is always consistently accessed with the same CPU. NOTE: with the upcoming "buddy" detector there is one special case. When a CPU goes offline/online then we can change which CPU is the one to consistently access a given instance of hrtimer_interrupts_saved. We still can't end up with a partially updated hrtimer_interrupts_saved, however, because we end up petting all affected CPUs to make sure the new and old CPU can't end up somehow read/write hrtimer_interrupts_saved at the same time. Link: https://lkml.kernel.org/r/20230519101840.v5.10.I3a7d4dd8c23ac30ee0b607d77feb6646b64825c0@changeid Signed-off-by: Douglas Anderson <dianders@chromium.org> Cc: Andi Kleen <ak@linux.intel.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chen-Yu Tsai <wens@csie.org> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Colin Cross <ccross@android.com> Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Guenter Roeck <groeck@chromium.org> Cc: Ian Rogers <irogers@google.com> Cc: Lecopzer Chen <lecopzer.chen@mediatek.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masayoshi Mizuma <msys.mizuma@gmail.com> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Pingfan Liu <kernelfans@gmail.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com> Cc: Ricardo Neri <ricardo.neri@intel.com> Cc: Stephane Eranian <eranian@google.com> Cc: Stephen Boyd <swboyd@chromium.org> Cc: Sumit Garg <sumit.garg@linaro.org> Cc: Tzung-Bi Shih <tzungbi@chromium.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Douglas Anderson
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1610611aad |
watchdog/hardlockup: style changes to watchdog_hardlockup_check() / is_hardlockup()
These are tiny style changes: - Add a blank line before a "return". - Renames two globals to use the "watchdog_hardlockup" prefix. - Store processor id in "unsigned int" rather than "int". - Minor comment rewording. - Use "else" rather than extra returns since it seemed more symmetric. Link: https://lkml.kernel.org/r/20230519101840.v5.9.I818492c326b632560b09f20d2608455ecf9d3650@changeid Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Douglas Anderson <dianders@chromium.org> Cc: Andi Kleen <ak@linux.intel.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chen-Yu Tsai <wens@csie.org> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Colin Cross <ccross@android.com> Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Guenter Roeck <groeck@chromium.org> Cc: Ian Rogers <irogers@google.com> Cc: Lecopzer Chen <lecopzer.chen@mediatek.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masayoshi Mizuma <msys.mizuma@gmail.com> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Pingfan Liu <kernelfans@gmail.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com> Cc: Ricardo Neri <ricardo.neri@intel.com> Cc: Stephane Eranian <eranian@google.com> Cc: Stephen Boyd <swboyd@chromium.org> Cc: Sumit Garg <sumit.garg@linaro.org> Cc: Tzung-Bi Shih <tzungbi@chromium.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Douglas Anderson
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81972551df |
watchdog/hardlockup: move perf hardlockup checking/panic to common watchdog.c
The perf hardlockup detector works by looking at interrupt counts and seeing if they change from run to run. The interrupt counts are managed by the common watchdog code via its watchdog_timer_fn(). Currently the API between the perf detector and the common code is a function: is_hardlockup(). When the hard lockup detector sees that function return true then it handles printing out debug info and inducing a panic if necessary. Let's change the API a little bit in preparation for the buddy hardlockup detector. The buddy hardlockup detector wants to print nearly the same debug info and have nearly the same panic behavior. That means we want to move all that code to the common file. For now, the code in the common file will only be there if the perf hardlockup detector is enabled, but eventually it will be selected by a common config. Right now, this _just_ moves the code from the perf detector file to the common file and changes the names. It doesn't make the changes that the buddy hardlockup detector will need and doesn't do any style cleanups. A future patch will do cleanup to make it more obvious what changed. With the above, we no longer have any callers of is_hardlockup() outside of the "watchdog.c" file, so we can remove it from the header, make it static, and move it to the same "#ifdef" block as our new watchdog_hardlockup_check(). While doing this, it can be noted that even if no hardlockup detectors were configured the existing code used to still have the code for counting/checking "hrtimer_interrupts" even if the perf hardlockup detector wasn't configured. We didn't need to do that, so move all the "hrtimer_interrupts" counting to only be there if the perf hardlockup detector is configured as well. This change is expected to be a no-op. Link: https://lkml.kernel.org/r/20230519101840.v5.8.Id4133d3183e798122dc3b6205e7852601f289071@changeid Signed-off-by: Douglas Anderson <dianders@chromium.org> Reviewed-by: Petr Mladek <pmladek@suse.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chen-Yu Tsai <wens@csie.org> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Colin Cross <ccross@android.com> Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Guenter Roeck <groeck@chromium.org> Cc: Ian Rogers <irogers@google.com> Cc: Lecopzer Chen <lecopzer.chen@mediatek.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masayoshi Mizuma <msys.mizuma@gmail.com> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Pingfan Liu <kernelfans@gmail.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com> Cc: Ricardo Neri <ricardo.neri@intel.com> Cc: Stephane Eranian <eranian@google.com> Cc: Stephen Boyd <swboyd@chromium.org> Cc: Sumit Garg <sumit.garg@linaro.org> Cc: Tzung-Bi Shih <tzungbi@chromium.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Lecopzer Chen
|
730211182e |
watchdog/hardlockup: change watchdog_nmi_enable() to void
Nobody cares about the return value of watchdog_nmi_enable(), changing its prototype to void. Link: https://lkml.kernel.org/r/20230519101840.v5.4.Ic3a19b592eb1ac4c6f6eade44ffd943e8637b6e5@changeid Signed-off-by: Pingfan Liu <kernelfans@gmail.com> Signed-off-by: Lecopzer Chen <lecopzer.chen@mediatek.com> Signed-off-by: Douglas Anderson <dianders@chromium.org> Reviewed-by: Petr Mladek <pmladek@suse.com> Acked-by: Nicholas Piggin <npiggin@gmail.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chen-Yu Tsai <wens@csie.org> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Colin Cross <ccross@android.com> Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Guenter Roeck <groeck@chromium.org> Cc: Ian Rogers <irogers@google.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masayoshi Mizuma <msys.mizuma@gmail.com> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com> Cc: Ricardo Neri <ricardo.neri@intel.com> Cc: Stephane Eranian <eranian@google.com> Cc: Stephen Boyd <swboyd@chromium.org> Cc: Sumit Garg <sumit.garg@linaro.org> Cc: Tzung-Bi Shih <tzungbi@chromium.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Lecopzer Chen
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810b560e89 |
watchdog: remove WATCHDOG_DEFAULT
No reference to WATCHDOG_DEFAULT, remove it. Link: https://lkml.kernel.org/r/20230519101840.v5.3.I6a729209a1320e0ad212176e250ff945b8f91b2a@changeid Signed-off-by: Pingfan Liu <kernelfans@gmail.com> Signed-off-by: Lecopzer Chen <lecopzer.chen@mediatek.com> Signed-off-by: Douglas Anderson <dianders@chromium.org> Reviewed-by: Petr Mladek <pmladek@suse.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chen-Yu Tsai <wens@csie.org> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Colin Cross <ccross@android.com> Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Guenter Roeck <groeck@chromium.org> Cc: Ian Rogers <irogers@google.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masayoshi Mizuma <msys.mizuma@gmail.com> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com> Cc: Ricardo Neri <ricardo.neri@intel.com> Cc: Stephane Eranian <eranian@google.com> Cc: Stephen Boyd <swboyd@chromium.org> Cc: Sumit Garg <sumit.garg@linaro.org> Cc: Tzung-Bi Shih <tzungbi@chromium.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Linus Torvalds
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cae4199f93 |
powerpc updates for 6.0
- Add support for syscall stack randomization.
- Add support for atomic operations to the 32 & 64-bit BPF JIT.
- Full support for KASAN on 64-bit Book3E.
- Add a watchdog driver for the new PowerVM hypervisor watchdog.
- Add a number of new selftests for the Power10 PMU support.
- Add a driver for the PowerVM Platform KeyStore.
- Increase the NMI watchdog timeout during live partition migration, to avoid timeouts
due to increased memory access latency.
- Add support for using the 'linux,pci-domain' device tree property for PCI domain
assignment.
- Many other small features and fixes.
Thanks to: Alexey Kardashevskiy, Andy Shevchenko, Arnd Bergmann, Athira Rajeev, Bagas
Sanjaya, Christophe Leroy, Erhard Furtner, Fabiano Rosas, Greg Kroah-Hartman, Greg Kurz,
Haowen Bai, Hari Bathini, Jason A. Donenfeld, Jason Wang, Jiang Jian, Joel Stanley, Juerg
Haefliger, Kajol Jain, Kees Cook, Laurent Dufour, Madhavan Srinivasan, Masahiro Yamada,
Maxime Bizon, Miaoqian Lin, Murilo Opsfelder Araújo, Nathan Lynch, Naveen N. Rao, Nayna
Jain, Nicholas Piggin, Ning Qiang, Pali Rohár, Petr Mladek, Rashmica Gupta, Sachin Sant,
Scott Cheloha, Segher Boessenkool, Stephen Rothwell, Uwe Kleine-König, Wolfram Sang, Xiu
Jianfeng, Zhouyi Zhou.
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Merge tag 'powerpc-6.0-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc updates from Michael Ellerman:
- Add support for syscall stack randomization
- Add support for atomic operations to the 32 & 64-bit BPF JIT
- Full support for KASAN on 64-bit Book3E
- Add a watchdog driver for the new PowerVM hypervisor watchdog
- Add a number of new selftests for the Power10 PMU support
- Add a driver for the PowerVM Platform KeyStore
- Increase the NMI watchdog timeout during live partition migration, to
avoid timeouts due to increased memory access latency
- Add support for using the 'linux,pci-domain' device tree property for
PCI domain assignment
- Many other small features and fixes
Thanks to Alexey Kardashevskiy, Andy Shevchenko, Arnd Bergmann, Athira
Rajeev, Bagas Sanjaya, Christophe Leroy, Erhard Furtner, Fabiano Rosas,
Greg Kroah-Hartman, Greg Kurz, Haowen Bai, Hari Bathini, Jason A.
Donenfeld, Jason Wang, Jiang Jian, Joel Stanley, Juerg Haefliger, Kajol
Jain, Kees Cook, Laurent Dufour, Madhavan Srinivasan, Masahiro Yamada,
Maxime Bizon, Miaoqian Lin, Murilo Opsfelder Araújo, Nathan Lynch,
Naveen N. Rao, Nayna Jain, Nicholas Piggin, Ning Qiang, Pali Rohár,
Petr Mladek, Rashmica Gupta, Sachin Sant, Scott Cheloha, Segher
Boessenkool, Stephen Rothwell, Uwe Kleine-König, Wolfram Sang, Xiu
Jianfeng, and Zhouyi Zhou.
* tag 'powerpc-6.0-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (191 commits)
powerpc/64e: Fix kexec build error
EDAC/ppc_4xx: Include required of_irq header directly
powerpc/pci: Fix PHB numbering when using opal-phbid
powerpc/64: Init jump labels before parse_early_param()
selftests/powerpc: Avoid GCC 12 uninitialised variable warning
powerpc/cell/axon_msi: Fix refcount leak in setup_msi_msg_address
powerpc/xive: Fix refcount leak in xive_get_max_prio
powerpc/spufs: Fix refcount leak in spufs_init_isolated_loader
powerpc/perf: Include caps feature for power10 DD1 version
powerpc: add support for syscall stack randomization
powerpc: Move system_call_exception() to syscall.c
powerpc/powernv: rename remaining rng powernv_ functions to pnv_
powerpc/powernv/kvm: Use darn for H_RANDOM on Power9
powerpc/powernv: Avoid crashing if rng is NULL
selftests/powerpc: Fix matrix multiply assist test
powerpc/signal: Update comment for clarity
powerpc: make facility_unavailable_exception 64s
powerpc/platforms/83xx/suspend: Remove write-only global variable
powerpc/platforms/83xx/suspend: Prevent unloading the driver
powerpc/platforms/83xx/suspend: Reorder to get rid of a forward declaration
...
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Laurent Dufour
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7c56a8733d |
watchdog: export lockup_detector_reconfigure
In some circumstances it may be interesting to reconfigure the watchdog from inside the kernel. On PowerPC, this may helpful before and after a LPAR migration (LPM) is initiated, because it implies some latencies, watchdog, and especially NMI watchdog is expected to be triggered during this operation. Reconfiguring the watchdog with a factor, would prevent it to happen too frequently during LPM. Rename lockup_detector_reconfigure() as __lockup_detector_reconfigure() and create a new function lockup_detector_reconfigure() calling __lockup_detector_reconfigure() under the protection of watchdog_mutex. Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com> [mpe: Squash in build fix from Laurent, reported by Sachin] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20220713154729.80789-3-ldufour@linux.ibm.com |
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Petr Mladek
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51889d225c | Merge branch 'rework/kthreads' into for-linus | ||
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Petr Mladek
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07a22b6194 |
Revert "printk: add functions to prefer direct printing"
This reverts commit
|
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Linus Torvalds
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6f664045c8 |
Not a lot of material this cycle. Many singleton patches against various
subsystems. Most notably some maintenance work in ocfs2 and initramfs. -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQTTMBEPP41GrTpTJgfdBJ7gKXxAjgUCYo/6xQAKCRDdBJ7gKXxA jkD9AQCPczLBbRWpe1edL+5VHvel9ePoHQmvbHQnufdTh9rB5QEAu0Uilxz4q9cx xSZypNhj2n9f8FCYca/ZrZneBsTnAA8= =AJEO -----END PGP SIGNATURE----- Merge tag 'mm-nonmm-stable-2022-05-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Pull misc updates from Andrew Morton: "The non-MM patch queue for this merge window. Not a lot of material this cycle. Many singleton patches against various subsystems. Most notably some maintenance work in ocfs2 and initramfs" * tag 'mm-nonmm-stable-2022-05-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (65 commits) kcov: update pos before writing pc in trace function ocfs2: dlmfs: fix error handling of user_dlm_destroy_lock ocfs2: dlmfs: don't clear USER_LOCK_ATTACHED when destroying lock fs/ntfs: remove redundant variable idx fat: remove time truncations in vfat_create/vfat_mkdir fat: report creation time in statx fat: ignore ctime updates, and keep ctime identical to mtime in memory fat: split fat_truncate_time() into separate functions MAINTAINERS: add Muchun as a memcg reviewer proc/sysctl: make protected_* world readable ia64: mca: drop redundant spinlock initialization tty: fix deadlock caused by calling printk() under tty_port->lock relay: remove redundant assignment to pointer buf fs/ntfs3: validate BOOT sectors_per_clusters lib/string_helpers: fix not adding strarray to device's resource list kernel/crash_core.c: remove redundant check of ck_cmdline ELF, uapi: fixup ELF_ST_TYPE definition ipc/mqueue: use get_tree_nodev() in mqueue_get_tree() ipc: update semtimedop() to use hrtimer ipc/sem: remove redundant assignments ... |
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Rasmus Villemoes
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67fca000e1 |
lib/Kconfig.debug: remove more CONFIG_..._VALUE indirections
As in "kernel/panic.c: remove CONFIG_PANIC_ON_OOPS_VALUE indirection", use the IS_ENABLED() helper rather than having a hidden config option. Link: https://lkml.kernel.org/r/20220321121301.1389693-1-linux@rasmusvillemoes.dk Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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John Ogness
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2bb2b7b57f |
printk: add functions to prefer direct printing
Once kthread printing is available, console printing will no longer occur in the context of the printk caller. However, there are some special contexts where it is desirable for the printk caller to directly print out kernel messages. Using pr_flush() to wait for threaded printers is only possible if the caller is in a sleepable context and the kthreads are active. That is not always the case. Introduce printk_prefer_direct_enter() and printk_prefer_direct_exit() functions to explicitly (and globally) activate/deactivate preferred direct console printing. The term "direct console printing" refers to printing to all enabled consoles from the context of the printk caller. The term "prefer" is used because this type of printing is only best effort. If the console is currently locked or other printers are already actively printing, the printk caller will need to rely on the other contexts to handle the printing. This preferred direct printing is how all printing has been handled until now (unless it was explicitly deferred). When kthread printing is introduced, there may be some unanticipated problems due to kthreads being unable to flush important messages. In order to minimize such risks, preferred direct printing is activated for the primary important messages when the system experiences general types of major errors. These are: - emergency reboot/shutdown - cpu and rcu stalls - hard and soft lockups - hung tasks - warn - sysrq Note that since kthread printing does not yet exist, no behavior changes result from this commit. This is only implementing the counter and marking the various places where preferred direct printing is active. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Acked-by: Paul E. McKenney <paulmck@kernel.org> # for RCU Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20220421212250.565456-13-john.ogness@linutronix.de |
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Frederic Weisbecker
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04d4e665a6 |
sched/isolation: Use single feature type while referring to housekeeping cpumask
Refer to housekeeping APIs using single feature types instead of flags. This prevents from passing multiple isolation features at once to housekeeping interfaces, which soon won't be possible anymore as each isolation features will have their own cpumask. Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Juri Lelli <juri.lelli@redhat.com> Reviewed-by: Phil Auld <pauld@redhat.com> Link: https://lore.kernel.org/r/20220207155910.527133-5-frederic@kernel.org |
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Xiaoming Ni
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dd0693fdf0 |
watchdog: move watchdog sysctl interface to watchdog.c
The kernel/sysctl.c is a kitchen sink where everyone leaves their dirty dishes, this makes it very difficult to maintain. To help with this maintenance let's start by moving sysctls to places where they actually belong. The proc sysctl maintainers do not want to know what sysctl knobs you wish to add for your own piece of code, we just care about the core logic of proc sysctl. So, move the watchdog syscl interface to watchdog.c. Use register_sysctl() to register the sysctl interface to avoid merge conflicts when different features modify sysctl.c at the same time. [mcgrof@kernel.org: justify the move on the commit log] Link: https://lkml.kernel.org/r/20211123202347.818157-5-mcgrof@kernel.org Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Petr Mladek <pmladek@suse.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Amir Goldstein <amir73il@gmail.com> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Benjamin LaHaise <bcrl@kvack.org> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Iurii Zaikin <yzaikin@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Qing Wang <wangqing@vivo.com> Cc: Sebastian Reichel <sre@kernel.org> Cc: Sergey Senozhatsky <senozhatsky@chromium.org> Cc: Stephen Kitt <steve@sk2.org> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Antti Palosaari <crope@iki.fi> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Clemens Ladisch <clemens@ladisch.de> Cc: David Airlie <airlied@linux.ie> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Joseph Qi <joseph.qi@linux.alibaba.com> Cc: Julia Lawall <julia.lawall@inria.fr> Cc: Lukas Middendorf <kernel@tuxforce.de> Cc: Mark Fasheh <mark@fasheh.com> Cc: Phillip Potter <phil@philpotter.co.uk> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Douglas Gilbert <dgilbert@interlog.com> Cc: James E.J. Bottomley <jejb@linux.ibm.com> Cc: Jani Nikula <jani.nikula@intel.com> Cc: John Ogness <john.ogness@linutronix.de> Cc: Martin K. Petersen <martin.petersen@oracle.com> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Wang Qing
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b124ac45bd |
kernel: watchdog: modify the explanation related to watchdog thread
The watchdog thread has been replaced by cpu_stop_work, modify the explanation related. Link: https://lkml.kernel.org/r/1619687073-24686-2-git-send-email-wangqing@vivo.com Signed-off-by: Wang Qing <wangqing@vivo.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Cc: Joe Perches <joe@perches.com> Cc: Stephen Kitt <steve@sk2.org> Cc: Kees Cook <keescook@chromium.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: "Guilherme G. Piccoli" <gpiccoli@canonical.com> Cc: Qais Yousef <qais.yousef@arm.com> Cc: Santosh Sivaraj <santosh@fossix.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Petr Mladek
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0f90b88dbc |
watchdog: reliable handling of timestamps
Commit |
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Petr Mladek
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9bf3bc949f |
watchdog: cleanup handling of false positives
Commit |
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Petr Mladek
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9f113bf760 |
watchdog: fix barriers when printing backtraces from all CPUs
Any parallel softlockup reports are skipped when one CPU is already printing backtraces from all CPUs. The exclusive rights are synchronized using one bit in soft_lockup_nmi_warn. There is also one memory barrier that does not make much sense. Use two barriers on the right location to prevent mixing two reports. [pmladek@suse.com: use bit lock operations to prevent multiple soft-lockup reports] Link: https://lkml.kernel.org/r/YFSVsLGVWMXTvlbk@alley Link: https://lkml.kernel.org/r/20210311122130.6788-6-pmladek@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Laurence Oberman <loberman@redhat.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vincent Whitchurch <vincent.whitchurch@axis.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Petr Mladek
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1bc503cb4a |
watchdog/softlockup: remove logic that tried to prevent repeated reports
The softlockup detector does some gymnastic with the variable soft_watchdog_warn. It was added by the commit |
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Petr Mladek
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fef06efc2e |
watchdog/softlockup: report the overall time of softlockups
The softlockup detector currently shows the time spent since the last report. As a result it is not clear whether a CPU is infinitely hogged by a single task or if it is a repeated event. The situation can be simulated with a simply busy loop: while (true) cpu_relax(); The softlockup detector produces: [ 168.277520] watchdog: BUG: soft lockup - CPU#1 stuck for 22s! [cat:4865] [ 196.277604] watchdog: BUG: soft lockup - CPU#1 stuck for 22s! [cat:4865] [ 236.277522] watchdog: BUG: soft lockup - CPU#1 stuck for 23s! [cat:4865] But it should be, something like: [ 480.372418] watchdog: BUG: soft lockup - CPU#2 stuck for 26s! [cat:4943] [ 508.372359] watchdog: BUG: soft lockup - CPU#2 stuck for 52s! [cat:4943] [ 548.372359] watchdog: BUG: soft lockup - CPU#2 stuck for 89s! [cat:4943] [ 576.372351] watchdog: BUG: soft lockup - CPU#2 stuck for 115s! [cat:4943] For the better output, add an additional timestamp of the last report. Only this timestamp is reset when the watchdog is intentionally touched from slow code paths or when printing the report. Link: https://lkml.kernel.org/r/20210311122130.6788-4-pmladek@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Laurence Oberman <loberman@redhat.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vincent Whitchurch <vincent.whitchurch@axis.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Petr Mladek
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c9ad17c991 |
watchdog: explicitly update timestamp when reporting softlockup
The softlockup situation might stay for a long time or even forever. When it happens, the softlockup debug messages are printed in regular intervals defined by get_softlockup_thresh(). There is a mystery. The repeated message is printed after the full interval that is defined by get_softlockup_thresh(). But the timer callback is called more often as defined by sample_period. The code looks like the soflockup should get reported in every sample_period when it was once behind the thresh. It works only by chance. The watchdog is touched when printing the stall report, for example, in printk_stack_address(). Make the behavior clear and predictable by explicitly updating the timestamp in watchdog_timer_fn() when the report gets printed. Link: https://lkml.kernel.org/r/20210311122130.6788-3-pmladek@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Laurence Oberman <loberman@redhat.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vincent Whitchurch <vincent.whitchurch@axis.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Petr Mladek
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7c0012f522 |
watchdog: rename __touch_watchdog() to a better descriptive name
Patch series "watchdog/softlockup: Report overall time and some cleanup", v2. I dug deep into the softlockup watchdog history when time permitted this year. And reworked the patchset that fixed timestamps and cleaned up the code[2]. I split it into very small steps and did even more code clean up. The result looks quite strightforward and I am pretty confident with the changes. [1] v2: https://lore.kernel.org/r/20201210160038.31441-1-pmladek@suse.com [2] v1: https://lore.kernel.org/r/20191024114928.15377-1-pmladek@suse.com This patch (of 6): There are many touch_*watchdog() functions. They are called in situations where the watchdog could report false positives or create unnecessary noise. For example, when CPU is entering idle mode, a virtual machine is stopped, or a lot of messages are printed in the atomic context. These functions set SOFTLOCKUP_RESET instead of a real timestamp. It allows to call them even in a context where jiffies might be outdated. For example, in an atomic context. The real timestamp is set by __touch_watchdog() that is called from the watchdog timer callback. Rename this callback to update_touch_ts(). It better describes the effect and clearly distinguish is from the other touch_*watchdog() functions. Another motivation is that two timestamps are going to be used. One will be used for the total softlockup time. The other will be used to measure time since the last report. The new function name will help to distinguish which timestamp is being updated. Link: https://lkml.kernel.org/r/20210311122130.6788-1-pmladek@suse.com Link: https://lkml.kernel.org/r/20210311122130.6788-2-pmladek@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Laurence Oberman <loberman@redhat.com> Cc: Vincent Whitchurch <vincent.whitchurch@axis.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Wang Qing
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89e28ce60c |
workqueue/watchdog: Make unbound workqueues aware of touch_softlockup_watchdog()
84;0;0c84;0;0c
There are two workqueue-specific watchdog timestamps:
+ @wq_watchdog_touched_cpu (per-CPU) updated by
touch_softlockup_watchdog()
+ @wq_watchdog_touched (global) updated by
touch_all_softlockup_watchdogs()
watchdog_timer_fn() checks only the global @wq_watchdog_touched for
unbound workqueues. As a result, unbound workqueues are not aware
of touch_softlockup_watchdog(). The watchdog might report a stall
even when the unbound workqueues are blocked by a known slow code.
Solution:
touch_softlockup_watchdog() must touch also the global @wq_watchdog_touched
timestamp.
The global timestamp can no longer be used for bound workqueues because
it is now updated from all CPUs. Instead, bound workqueues have to check
only @wq_watchdog_touched_cpu and these timestamps have to be updated for
all CPUs in touch_all_softlockup_watchdogs().
Beware:
The change might cause the opposite problem. An unbound workqueue
might get blocked on CPU A because of a real softlockup. The workqueue
watchdog would miss it when the timestamp got touched on CPU B.
It is acceptable because softlockups are detected by softlockup
watchdog. The workqueue watchdog is there to detect stalls where
a work never finishes, for example, because of dependencies of works
queued into the same workqueue.
V3:
- Modify the commit message clearly according to Petr's suggestion.
Signed-off-by: Wang Qing <wangqing@vivo.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Santosh Sivaraj
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e7e046155a |
kernel/watchdog: fix watchdog_allowed_mask not used warning
Define watchdog_allowed_mask only when SOFTLOCKUP_DETECTOR is enabled.
Fixes:
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