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All 'u8' flags are true booleans, so make it entirely clear that these can
only contain true or false.
This is especially true for hrtimer::state, which has a historical leftover
of using the state with bitwise operations. That was used in the early
hrtimer implementation with several bits, but then converted to a boolean
state. But that conversion missed to replace the bit OR and bit check
operations all over the place, which creates suboptimal code. As of today
'state' is a misnomer because it's only purpose is to reflect whether the
timer is enqueued into the RB-tree or not. Rename it to 'is_queued' and
make all operations on it boolean.
This reduces text size from 8926 to 8732 bytes.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163430.542427240@kernel.org
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Use bool for the various flags as that creates better code in the hot path.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163430.475262618@kernel.org
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No point in accessing the timer twice.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163430.409352042@kernel.org
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As this code has some major surgery ahead, clean up coding style and bring
comments up to date.
No functional change intended.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163430.342740952@kernel.org
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Simplify and tidy up the code where possible.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163430.275551488@kernel.org
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hrtimer_start() when invoked with an already armed timer traces like:
<comm>-.. [032] d.h2. 5.002263: hrtimer_cancel: hrtimer= ....
<comm>-.. [032] d.h1. 5.002263: hrtimer_start: hrtimer= ....
Which is incorrect as the timer doesn't get canceled. Just the expiry time
changes. The internal dequeue operation which is required for that is not
really interesting for trace analysis. But it makes it tedious to keep real
cancellations and the above case apart.
Remove the cancel tracing in hrtimer_start() and add a 'was_armed'
indicator to the hrtimer start tracepoint, which clearly indicates what the
state of the hrtimer is when hrtimer_start() is invoked:
<comm>-.. [032] d.h1. 6.200103: hrtimer_start: hrtimer= .... was_armed=0
<comm>-.. [032] d.h1. 6.200558: hrtimer_start: hrtimer= .... was_armed=1
Fixes: c6a2a1770245 ("hrtimer: Add tracepoint for hrtimers")
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163430.208491877@kernel.org
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The debug object coverage in hrtimer_start_range_ns() happens too late to
do anything useful. Implement the init assert assertion part and invoke
that early in hrtimer_start_range_ns().
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163430.143098153@kernel.org
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Some clockevent devices are coupled to the system clocksource by
implementing a less than or equal comparator which compares the programmed
absolute expiry time against the underlying time counter.
The timekeeping core provides a function to convert and absolute
CLOCK_MONOTONIC based expiry time to a absolute clock cycles time which can
be directly fed into the comparator. That spares two time reads in the next
event progamming path, one to convert the absolute nanoseconds time to a
delta value and the other to convert the delta value back to a absolute
time value suitable for the comparator.
Provide a new clocksource callback which takes the absolute cycle value and
wire it up in clockevents_program_event(). Similar to clocksources allow
architectures to inline the rearm operation.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163430.010425428@kernel.org
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Some architectures have clockevent devices which are coupled to the system
clocksource by implementing a less than or equal comparator which compares
the programmed absolute expiry time against the underlying time
counter. Well known examples are TSC/TSC deadline timer and the S390 TOD
clocksource/comparator.
While the concept is nice it has some downsides:
1) The clockevents core code is strictly based on relative expiry times
as that's the most common case for clockevent device hardware. That
requires to convert the absolute expiry time provided by the caller
(hrtimers, NOHZ code) to a relative expiry time by reading and
substracting the current time.
The clockevent::set_next_event() callback must then read the counter
again to convert the relative expiry back into a absolute one.
2) The conversion factors from nanoseconds to counter clock cycles are
set up when the clockevent is registered. When NTP applies corrections
then the clockevent conversion factors can deviate from the
clocksource conversion substantially which either results in timers
firing late or in the worst case early. The early expiry then needs to
do a reprogam with a short delta.
In most cases this is papered over by the fact that the read in the
set_next_event() callback happens after the read which is used to
calculate the delta. So the tendency is that timers expire mostly
late.
All of this can be avoided by providing support for these devices in the
core code:
1) The timekeeping core keeps track of the last update to the clocksource
by storing the base nanoseconds and the corresponding clocksource
counter value. That's used to keep the conversion math for reading the
time within 64-bit in the common case.
This information can be used to avoid both reads of the underlying
clocksource in the clockevents reprogramming path:
delta = expiry - base_ns;
cycles = base_cycles + ((delta * clockevent::mult) >> clockevent::shift);
The resulting cycles value can be directly used to program the
comparator.
2) As #1 does not longer provide the "compensation" through the second
read the deviation of the clocksource and clockevent conversions
caused by NTP become more prominent.
This can be cured by letting the timekeeping core compute and store
the reverse conversion factors when the clocksource cycles to
nanoseconds factors are modified by NTP:
CS::MULT (1 << NS_TO_CYC_SHIFT)
--------------- = ----------------------
(1 << CS:SHIFT) NS_TO_CYC_MULT
Ergo: NS_TO_CYC_MULT = (1 << (CS::SHIFT + NS_TO_CYC_SHIFT)) / CS::MULT
The NS_TO_CYC_SHIFT value is calculated when the clocksource is
installed so that it aims for a one hour maximum sleep time.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163429.944763521@kernel.org
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On some architectures clocksource::read() boils down to a single
instruction, so the indirect function call is just a massive overhead
especially with speculative execution mitigations in effect.
Allow architectures to enable conditional inlining of that read to avoid
that by:
- providing a static branch to switch to the inlined variant
- disabling the branch before clocksource changes
- enabling the branch after a clocksource change, when the clocksource
indicates in a feature flag that it is the one which provides the
inlined variant
This is intentionally not a static call as that would only remove the
indirect call, but not the rest of the overhead.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163429.675151545@kernel.org
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The only real usecase for this is the hrtimer based broadcast device.
No point in using two different feature flags for this.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163429.609049777@kernel.org
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The sequence of cancel and start is inefficient. It has to do the timer
lock/unlock twice and in the worst case has to reprogram the underlying
clock event device twice.
The reason why it is done this way is the usage of hrtimer_forward_now(),
which requires the timer to be inactive.
But that can be completely avoided as the forward can be done on a variable
and does not need any of the overrun accounting provided by
hrtimer_forward_now().
Implement a trivial forwarding mechanism and replace the cancel/reprogram
sequence with hrtimer_start(..., new_expiry).
For the non high resolution case the timer is not actually armed, but used
for storage so that code checking for expiry times can unconditially look
it up in the timer. So it is safe for that case to set the new expiry time
directly.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163429.542178086@kernel.org
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The hrtick timer is frequently rearmed before expiry and most of the time
the new expiry is past the armed one. As this happens on every context
switch it becomes expensive with scheduling heavy work loads especially in
virtual machines as the "hardware" reprogamming implies a VM exit.
hrtimer now provide a lazy rearm mode flag which skips the reprogamming if:
1) The timer was the first expiring timer before the rearm
2) The new expiry time is farther out than the armed time
This avoids a massive amount of reprogramming operations of the hrtick
timer for the price of eventually taking the alredy armed interrupt for
nothing.
Mark the hrtick timer accordingly.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163429.475409346@kernel.org
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The hrtick timer is frequently rearmed before expiry and most of the time
the new expiry is past the armed one. As this happens on every context
switch it becomes expensive with scheduling heavy work loads especially in
virtual machines as the "hardware" reprogamming implies a VM exit.
Add a lazy rearm mode flag which skips the reprogamming if:
1) The timer was the first expiring timer before the rearm
2) The new expiry time is farther out than the armed time
This avoids a massive amount of reprogramming operations of the hrtick
timer for the price of eventually taking the alredy armed interrupt for
nothing.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163429.408524456@kernel.org
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Tiny adjustments to the hrtick expiry time below 5 microseconds are just
causing extra work for no real value. Filter them out when restarting the
hrtick.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163429.340593047@kernel.org
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schedule() provides several mechanisms to update the hrtick timer:
1) When the next task is picked
2) When the balance callbacks are invoked before rq::lock is released
Each of them can result in a first expiring timer and cause a reprogram of
the clock event device.
Solve this by deferring the rearm to the end of schedule() right before
releasing rq::lock by setting a flag on entry which tells hrtick_start() to
cache the runtime constraint in rq::hrtick_delay without touching the timer
itself.
Right before releasing rq::lock evaluate the flags and either rearm or
cancel the hrtick timer.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163429.273068659@kernel.org
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Use the static branch based variant and thereby avoid following three
pointers.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163429.203610956@kernel.org
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The scheduler evaluates this via hrtimer_is_hres_active() every time it has
to update HRTICK. This needs to follow three pointers, which is expensive.
Provide a static branch based mechanism to avoid that.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163429.136503358@kernel.org
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Much like hrtimer_reprogram(), skip programming if the cpu_base is running
the hrtimer interrupt.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Reviewed-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260224163429.069535561@kernel.org
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The clock of the hrtick and deadline timers is known to be CLOCK_MONOTONIC.
No point in looking it up via hrtimer_cb_get_time().
Just use ktime_get() directly.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163429.001511662@kernel.org
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Since the tick causes hard preemption, the hrtick should too.
Letting the hrtick do lazy preemption completely defeats the purpose, since
it will then still be delayed until a old tick and be dependent on
CONFIG_HZ.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163428.933894105@kernel.org
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hrtick_update() was needed when the slice depended on nr_running, all that
code is gone. All that remains is starting the hrtick when nr_running
becomes more than 1.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163428.866374835@kernel.org
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The nominal duration for an EEVDF task to run is until its deadline. At
which point the deadline is moved ahead and a new task selection is done.
Try and predict the time 'lost' to higher scheduling classes. Since this is
an estimate, the timer can be both early or late. In case it is early
task_tick_fair() will take the !need_resched() path and restarts the timer.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://patch.msgid.link/20260224163428.798198874@kernel.org
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git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull misc fixes from Andrew Morton:
"12 hotfixes. 7 are cc:stable. 8 are for MM.
All are singletons - please see the changelogs for details"
* tag 'mm-hotfixes-stable-2026-02-26-14-14' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
MAINTAINERS: update Yosry Ahmed's email address
mailmap: add entry for Daniele Alessandrelli
mm: fix NULL NODE_DATA dereference for memoryless nodes on boot
mm/tracing: rss_stat: ensure curr is false from kthread context
mm/kfence: fix KASAN hardware tag faults during late enablement
mm/damon/core: disallow non-power of two min_region_sz
Squashfs: check metadata block offset is within range
MAINTAINERS, mailmap: update e-mail address for Vlastimil Babka
liveupdate: luo_file: remember retrieve() status
mm: thp: deny THP for files on anonymous inodes
mm: change vma_alloc_folio_noprof() macro to inline function
mm/kfence: disable KFENCE upon KASAN HW tags enablement
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git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux
Pull dma-mapping fixes from Marek Szyprowski:
"Two DMA-mapping fixes for the recently merged API rework (Jiri Pirko
and Stian Halseth)"
* tag 'dma-mapping-7.0-2026-02-26' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux:
sparc: Fix page alignment in dma mapping
dma-mapping: avoid random addr value print out on error path
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SCX_EFLAG_INITIALIZED is the sole member of enum scx_exit_flags with no
explicit value, so the compiler assigns it 0. This makes the bitwise OR
in scx_ops_init() a no-op:
sch->exit_info->flags |= SCX_EFLAG_INITIALIZED; /* |= 0 */
As a result, BPF schedulers cannot distinguish whether ops.init()
completed successfully by inspecting exit_info->flags.
Assign the value 1LLU << 0 so the flag is actually set.
Fixes: f3aec2adce8d ("sched_ext: Add SCX_EFLAG_INITIALIZED to indicate successful ops.init()")
Signed-off-by: David Carlier <devnexen@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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get_upper_ifindexes() iterates over all upper devices and writes their
indices into an array without checking bounds.
Also the callers assume that the max number of upper devices is
MAX_NEST_DEV and allocate excluded_devices[1+MAX_NEST_DEV] on the stack,
but that assumption is not correct and the number of upper devices could
be larger than MAX_NEST_DEV (e.g., many macvlans), causing a
stack-out-of-bounds write.
Add a max parameter to get_upper_ifindexes() to avoid the issue.
When there are too many upper devices, return -EOVERFLOW and abort the
redirect.
To reproduce, create more than MAX_NEST_DEV(8) macvlans on a device with
an XDP program attached using BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS.
Then send a packet to the device to trigger the XDP redirect path.
Reported-by: syzbot+10cc7f13760b31bd2e61@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/698c4ce3.050a0220.340abe.000b.GAE@google.com/T/
Fixes: aeea1b86f936 ("bpf, devmap: Exclude XDP broadcast to master device")
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Kohei Enju <kohei@enjuk.jp>
Link: https://lore.kernel.org/r/20260225053506.4738-1-kohei@enjuk.jp
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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We don't check if cookies are available on the kprobe_multi link
before accessing them in show_fdinfo callback, we should.
Cc: stable@vger.kernel.org
Fixes: da7e9c0a7fbc ("bpf: Add show_fdinfo for kprobe_multi")
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20260225111249.186230-1-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull kmalloc_obj fixes from Kees Cook:
- Fix pointer-to-array allocation types for ubd and kcsan
- Force size overflow helpers to __always_inline
- Bump __builtin_counted_by_ref to Clang 22.1 from 22.0 (Nathan Chancellor)
* tag 'kmalloc_obj-v7.0-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
kcsan: test: Adjust "expect" allocation type for kmalloc_obj
overflow: Make sure size helpers are always inlined
init/Kconfig: Adjust fixed clang version for __builtin_counted_by_ref
ubd: Use pointer-to-pointers for io_thread_req arrays
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The call to kmalloc_obj(observed.lines) returns "char (*)[3][512]",
a pointer to the whole 2D array. But "expect" wants to be "char (*)[512]",
the decayed pointer type, as if it were observed.lines itself (though
without the "3" bounds). This produces the following build error:
../kernel/kcsan/kcsan_test.c: In function '__report_matches':
../kernel/kcsan/kcsan_test.c:171:16: error: assignment to 'char (*)[512]' from incompatible pointer type 'char (*)[3][512]'
[-Wincompatible-pointer-types]
171 | expect = kmalloc_obj(observed.lines);
| ^
Instead of changing the "expect" type to "char (*)[3][512]" and
requiring a dereference at each use (e.g. "(expect*)[0]"), just
explicitly cast the return to the desired type.
Note that I'm intentionally not switching back to byte-based "kmalloc"
here because I cannot find a way for the Coccinelle script (which will
be used going forward to catch future conversions) to exclude this case.
Tested with:
$ ./tools/testing/kunit/kunit.py run \
--kconfig_add CONFIG_DEBUG_KERNEL=y \
--kconfig_add CONFIG_KCSAN=y \
--kconfig_add CONFIG_KCSAN_KUNIT_TEST=y \
--arch=x86_64 --qemu_args '-smp 2' kcsan
Reported-by: Nathan Chancellor <nathan@kernel.org>
Fixes: 69050f8d6d07 ("treewide: Replace kmalloc with kmalloc_obj for non-scalar types")
Signed-off-by: Kees Cook <kees@kernel.org>
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Guillaume reported crashes via corrupted RCU callback function pointers
during KUnit testing. The crash was traced back to the pidfs rhashtable
conversion which replaced the 24-byte rb_node with an 8-byte rhash_head
in struct pid, shrinking it from 160 to 144 bytes.
struct kthread (without CONFIG_BLK_CGROUP) is also 144 bytes. With
CONFIG_SLAB_MERGE_DEFAULT and SLAB_HWCACHE_ALIGN both round up to
192 bytes and share the same slab cache. struct pid.rcu.func and
struct kthread.affinity_node both sit at offset 0x78.
When a kthread exits via make_task_dead() it bypasses kthread_exit() and
misses the affinity_node cleanup. free_kthread_struct() frees the memory
while the node is still linked into the global kthread_affinity_list. A
subsequent list_del() by another kthread writes through dangling list
pointers into the freed and reused memory, corrupting the pid's
rcu.func pointer.
Instead of patching free_kthread_struct() to handle the missed cleanup,
consolidate all kthread exit paths. Turn kthread_exit() into a macro
that calls do_exit() and add kthread_do_exit() which is called from
do_exit() for any task with PF_KTHREAD set. This guarantees that
kthread-specific cleanup always happens regardless of the exit path -
make_task_dead(), direct do_exit(), or kthread_exit().
Replace __to_kthread() with a new tsk_is_kthread() accessor in the
public header. Export do_exit() since module code using the
kthread_exit() macro now needs it directly.
Reported-by: Guillaume Tucker <gtucker@gtucker.io>
Tested-by: Guillaume Tucker <gtucker@gtucker.io>
Tested-by: Mark Brown <broonie@kernel.org>
Tested-by: David Gow <davidgow@google.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/all/20260224-mittlerweile-besessen-2738831ae7f6@brauner
Co-developed-by: Linus Torvalds <torvalds@linux-foundation.org>
Fixes: 4d13f4304fa4 ("kthread: Implement preferred affinity")
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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scx_idle_node_masks is allocated with num_possible_nodes() elements but
indexed by NUMA node IDs via for_each_node(). On systems with
non-contiguous NUMA node numbering (e.g. nodes 0 and 4), node IDs can
exceed the array size, causing out-of-bounds memory corruption.
Use nr_node_ids instead, which represents the maximum node ID range and
is the correct size for arrays indexed by node ID.
Fixes: 7c60329e3521 ("sched_ext: Add NUMA-awareness to the default idle selection policy")
Signed-off-by: David Carlier <devnexen@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs fixes from Christian Brauner:
- Fix an uninitialized variable in file_getattr().
The flags_valid field wasn't initialized before calling
vfs_fileattr_get(), triggering KMSAN uninit-value reports in fuse
- Fix writeback wakeup and logging timeouts when DETECT_HUNG_TASK is
not enabled.
sysctl_hung_task_timeout_secs is 0 in that case causing spurious
"waiting for writeback completion for more than 1 seconds" warnings
- Fix a null-ptr-deref in do_statmount() when the mount is internal
- Add missing kernel-doc description for the @private parameter in
iomap_readahead()
- Fix mount namespace creation to hold namespace_sem across the mount
copy in create_new_namespace().
The previous drop-and-reacquire pattern was fragile and failed to
clean up mount propagation links if the real rootfs was a shared or
dependent mount
- Fix /proc mount iteration where m->index wasn't updated when
m->show() overflows, causing a restart to repeatedly show the same
mount entry in a rapidly expanding mount table
- Return EFSCORRUPTED instead of ENOSPC in minix_new_inode() when the
inode number is out of range
- Fix unshare(2) when CLONE_NEWNS is set and current->fs isn't shared.
copy_mnt_ns() received the live fs_struct so if a subsequent
namespace creation failed the rollback would leave pwd and root
pointing to detached mounts. Always allocate a new fs_struct when
CLONE_NEWNS is requested
- fserror bug fixes:
- Remove the unused fsnotify_sb_error() helper now that all callers
have been converted to fserror_report_metadata
- Fix a lockdep splat in fserror_report() where igrab() takes
inode::i_lock which can be held in IRQ context.
Replace igrab() with a direct i_count bump since filesystems
should not report inodes that are about to be freed or not yet
exposed
- Handle error pointer in procfs for try_lookup_noperm()
- Fix an integer overflow in ep_loop_check_proc() where recursive calls
returning INT_MAX would overflow when +1 is added, breaking the
recursion depth check
- Fix a misleading break in pidfs
* tag 'vfs-7.0-rc2.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
pidfs: avoid misleading break
eventpoll: Fix integer overflow in ep_loop_check_proc()
proc: Fix pointer error dereference
fserror: fix lockdep complaint when igrabbing inode
fsnotify: drop unused helper
unshare: fix unshare_fs() handling
minix: Correct errno in minix_new_inode
namespace: fix proc mount iteration
mount: hold namespace_sem across copy in create_new_namespace()
iomap: Describe @private in iomap_readahead()
statmount: Fix the null-ptr-deref in do_statmount()
writeback: Fix wakeup and logging timeouts for !DETECT_HUNG_TASK
fs: init flags_valid before calling vfs_fileattr_get
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A null-pointer-dereference bug was reported by syzbot:
Oops: general protection fault, probably for address 0xdffffc0000000000:
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
RIP: 0010:bitmap_subset include/linux/bitmap.h:433 [inline]
RIP: 0010:cpumask_subset include/linux/cpumask.h:836 [inline]
RIP: 0010:rebuild_sched_domains_locked kernel/cgroup/cpuset.c:967
RSP: 0018:ffffc90003ecfbc0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000020
RDX: ffff888028de0000 RSI: ffffffff8200f003 RDI: ffffffff8df14f28
RBP: 0000000000000000 R08: 0000000000000cc0 R09: 00000000ffffffff
R10: ffffffff8e7d95b3 R11: 0000000000000001 R12: 0000000000000000
R13: 00000000000f4240 R14: dffffc0000000000 R15: 0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2f463fff CR3: 000000003704c000 CR4: 00000000003526f0
Call Trace:
<TASK>
rebuild_sched_domains_cpuslocked kernel/cgroup/cpuset.c:983 [inline]
rebuild_sched_domains+0x21/0x40 kernel/cgroup/cpuset.c:990
sched_rt_handler+0xb5/0xe0 kernel/sched/rt.c:2911
proc_sys_call_handler+0x47f/0x5a0 fs/proc/proc_sysctl.c:600
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x6ac/0x1070 fs/read_write.c:688
ksys_write+0x12a/0x250 fs/read_write.c:740
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
The issue occurs when generate_sched_domains() returns ndoms = 1 and
doms = NULL due to a kmalloc failure. This leads to a null-pointer
dereference when accessing doms in rebuild_sched_domains_locked().
Fix this by adding a NULL check for doms before accessing it.
Fixes: 6ee43047e8ad ("cpuset: Remove unnecessary checks in rebuild_sched_domains_locked")
Reported-by: syzbot+460792609a79c085f79f@syzkaller.appspotmail.com
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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sched_getattr() for DEADLINE tasks
The SCHED_DEADLINE scheduler allows reading the statically configured
run-time, deadline, and period parameters through the sched_getattr()
system call. However, there is no immediate way to access, from user space,
the current parameters used within the scheduler: the instantaneous runtime
left in the current cycle, as well as the current absolute deadline.
The `flags' sched_getattr() parameter, so far mandated to contain zero,
now supports the SCHED_GETATTR_FLAG_DL_DYNAMIC=1 flag, to request
retrieval of the leftover runtime and absolute deadline, converted to a
CLOCK_MONOTONIC reference, instead of the statically configured parameters.
This feature is useful for adaptive SCHED_DEADLINE tasks that need to
modify their behavior depending on whether or not there is enough runtime
left in the current period, and/or what is the current absolute deadline.
Notes:
- before returning the instantaneous parameters, the runtime is updated;
- the abs deadline is returned shifted from rq_clock() to ktime_get_ns(),
in CLOCK_MONOTONIC reference; this causes multiple invocations from the
same period to return values that may differ for a few ns (showing some
small drift), albeit the deadline doesn't move, in rq_clock() reference;
- the abs deadline value returned to user-space, as unsigned 64-bit value,
can represent nearly 585 years since boot time;
- setting flags=0 provides the old behavior (retrieve static parameters).
See also the notes from discussion held at OSPM 2025 on the topic
"Making user space aware of current deadline-scheduler parameters".
Signed-off-by: Tommaso Cucinotta <tommaso.cucinotta@santannapisa.it>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Matteo Martelli <matteo.martelli@codethink.co.uk>
Link: https://patch.msgid.link/20250912053937.31636-2-tommaso.cucinotta@santannapisa.it
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Make sure that __perf_event_overflow() runs with IRQs disabled for all
possible callchains. Specifically the software events can end up running
it with only preemption disabled.
This opens up a race vs perf_event_exit_event() and friends that will go
and free various things the overflow path expects to be present, like
the BPF program.
Fixes: 592903cdcbf6 ("perf_counter: add an event_list")
Reported-by: Simond Hu <cmdhh1767@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Simond Hu <cmdhh1767@gmail.com>
Link: https://patch.msgid.link/20260224122909.GV1395416@noisy.programming.kicks-ass.net
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scx_claim_exit() atomically sets exit_kind, which prevents scx_error() from
triggering further error handling. After claiming exit, the caller must kick
the helper kthread work which initiates bypass mode and teardown.
If the calling task gets preempted between claiming exit and kicking the
helper work, and the BPF scheduler fails to schedule it back (since error
handling is now disabled), the helper work is never queued, bypass mode
never activates, tasks stop being dispatched, and the system wedges.
Disable preemption across scx_claim_exit() and the subsequent work kicking
in all callers - scx_disable() and scx_vexit(). Add
lockdep_assert_preemption_disabled() to scx_claim_exit() to enforce the
requirement.
Fixes: f0e1a0643a59 ("sched_ext: Implement BPF extensible scheduler class")
Cc: stable@vger.kernel.org # v6.12+
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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LUO keeps track of successful retrieve attempts on a LUO file. It does so
to avoid multiple retrievals of the same file. Multiple retrievals cause
problems because once the file is retrieved, the serialized data
structures are likely freed and the file is likely in a very different
state from what the code expects.
The retrieve boolean in struct luo_file keeps track of this, and is passed
to the finish callback so it knows what work was already done and what it
has left to do.
All this works well when retrieve succeeds. When it fails,
luo_retrieve_file() returns the error immediately, without ever storing
anywhere that a retrieve was attempted or what its error code was. This
results in an errored LIVEUPDATE_SESSION_RETRIEVE_FD ioctl to userspace,
but nothing prevents it from trying this again.
The retry is problematic for much of the same reasons listed above. The
file is likely in a very different state than what the retrieve logic
normally expects, and it might even have freed some serialization data
structures. Attempting to access them or free them again is going to
break things.
For example, if memfd managed to restore 8 of its 10 folios, but fails on
the 9th, a subsequent retrieve attempt will try to call
kho_restore_folio() on the first folio again, and that will fail with a
warning since it is an invalid operation.
Apart from the retry, finish() also breaks. Since on failure the
retrieved bool in luo_file is never touched, the finish() call on session
close will tell the file handler that retrieve was never attempted, and it
will try to access or free the data structures that might not exist, much
in the same way as the retry attempt.
There is no sane way of attempting the retrieve again. Remember the error
retrieve returned and directly return it on a retry. Also pass this
status code to finish() so it can make the right decision on the work it
needs to do.
This is done by changing the bool to an integer. A value of 0 means
retrieve was never attempted, a positive value means it succeeded, and a
negative value means it failed and the error code is the value.
Link: https://lkml.kernel.org/r/20260216132221.987987-1-pratyush@kernel.org
Fixes: 7c722a7f44e0 ("liveupdate: luo_file: implement file systems callbacks")
Signed-off-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Currently, tailcall count is incremented in the interpreter even when
tailcall fails due to non-existent prog. Fix this by holding off on
the tailcall count increment until after NULL check on the prog.
Suggested-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Link: https://lore.kernel.org/r/20260220062959.195101-1-hbathini@linux.ibm.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Add .kunitconfig file to the time directory to enable easy execution of
KUnit tests.
With the .kunitconfig, developers can run the tests:
$ ./tools/testing/kunit/kunit.py run --kunitconfig kernel/time
Also, add the new .kunitconfig file to the TIMEKEEPING section in the
MAINTAINERS file.
Signed-off-by: Ryota Sakamoto <sakamo.ryota@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260223-add-time-kunitconfig-v1-1-1801eeb33ece@gmail.com
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For the following scenario:
struct tree_node {
struct bpf_refcount ref;
struct bpf_rb_node node;
struct node_data __kptr * node_data;
u64 key;
};
This means node_data would have the type PTR_TO_BTF_ID | MEM_ALLOC |
NON_OWN_REF | MEM_RCU.
When traversing an rbtree using bpf_rbtree_left/right, if we need to
use bpf_kptr_xchg to read the __kptr pointer, we still need to follow
the remove-read-add sequence.
This patch allows us to use bpf_kptr_xchg to directly read the __kptr
pointer without any prior operations.
Signed-off-by: Kaitao Cheng <chengkaitao@kylinos.cn>
Signed-off-by: Feng Yang <yangfeng@kylinos.cn>
Link: https://lore.kernel.org/r/20260214124042.62229-5-pilgrimtao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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When traversing an rbtree using bpf_rbtree_left/right, if bpf_kptr_xchg
is used to access the __kptr pointer contained in a node, it currently
requires first removing the node with bpf_rbtree_remove and clearing the
NON_OWN_REF flag, then re-adding the node to the original rbtree with
bpf_rbtree_add after usage. This process significantly degrades rbtree
traversal performance. The patch enables accessing __kptr pointers with
the NON_OWN_REF flag set while holding the lock, eliminating the need
for this remove-read-add sequence.
Signed-off-by: Kaitao Cheng <chengkaitao@kylinos.cn>
Signed-off-by: Feng Yang <yangfeng@kylinos.cn>
Link: https://lore.kernel.org/r/20260214124042.62229-3-pilgrimtao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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For the following scenario:
struct tree_node {
struct bpf_rb_node node;
struct request __kptr *req;
u64 key;
};
struct bpf_rb_root tree_root __contains(tree_node, node);
struct bpf_spin_lock tree_lock;
If we need to traverse all nodes in the rbtree, retrieve the __kptr
pointer from each node, and read kernel data from the referenced
object, using bpf_kptr_xchg appears unavoidable.
This patch skips the BPF verifier checks for bpf_kptr_xchg when
called while holding a lock.
Signed-off-by: Kaitao Cheng <chengkaitao@kylinos.cn>
Link: https://lore.kernel.org/r/20260214124042.62229-2-pilgrimtao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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The current cpuset partition code is able to dynamically update
the sched domains of a running system and the corresponding
HK_TYPE_DOMAIN housekeeping cpumask to perform what is essentially the
"isolcpus=domain,..." boot command line feature at run time.
The housekeeping cpumask update requires flushing a number of different
workqueues which may not be safe with cpus_read_lock() held as the
workqueue flushing code may acquire cpus_read_lock() or acquiring locks
which have locking dependency with cpus_read_lock() down the chain. Below
is an example of such circular locking problem.
======================================================
WARNING: possible circular locking dependency detected
6.18.0-test+ #2 Tainted: G S
------------------------------------------------------
test_cpuset_prs/10971 is trying to acquire lock:
ffff888112ba4958 ((wq_completion)sync_wq){+.+.}-{0:0}, at: touch_wq_lockdep_map+0x7a/0x180
but task is already holding lock:
ffffffffae47f450 (cpuset_mutex){+.+.}-{4:4}, at: cpuset_partition_write+0x85/0x130
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #4 (cpuset_mutex){+.+.}-{4:4}:
-> #3 (cpu_hotplug_lock){++++}-{0:0}:
-> #2 (rtnl_mutex){+.+.}-{4:4}:
-> #1 ((work_completion)(&arg.work)){+.+.}-{0:0}:
-> #0 ((wq_completion)sync_wq){+.+.}-{0:0}:
Chain exists of:
(wq_completion)sync_wq --> cpu_hotplug_lock --> cpuset_mutex
5 locks held by test_cpuset_prs/10971:
#0: ffff88816810e440 (sb_writers#7){.+.+}-{0:0}, at: ksys_write+0xf9/0x1d0
#1: ffff8891ab620890 (&of->mutex#2){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x260/0x5f0
#2: ffff8890a78b83e8 (kn->active#187){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x2b6/0x5f0
#3: ffffffffadf32900 (cpu_hotplug_lock){++++}-{0:0}, at: cpuset_partition_write+0x77/0x130
#4: ffffffffae47f450 (cpuset_mutex){+.+.}-{4:4}, at: cpuset_partition_write+0x85/0x130
Call Trace:
<TASK>
:
touch_wq_lockdep_map+0x93/0x180
__flush_workqueue+0x111/0x10b0
housekeeping_update+0x12d/0x2d0
update_parent_effective_cpumask+0x595/0x2440
update_prstate+0x89d/0xce0
cpuset_partition_write+0xc5/0x130
cgroup_file_write+0x1a5/0x680
kernfs_fop_write_iter+0x3df/0x5f0
vfs_write+0x525/0xfd0
ksys_write+0xf9/0x1d0
do_syscall_64+0x95/0x520
entry_SYSCALL_64_after_hwframe+0x76/0x7e
To avoid such a circular locking dependency problem, we have to
call housekeeping_update() without holding the cpus_read_lock() and
cpuset_mutex. The current set of wq's flushed by housekeeping_update()
may not have work functions that call cpus_read_lock() directly,
but we are likely to extend the list of wq's that are flushed in the
future. Moreover, the current set of work functions may hold locks that
may have cpu_hotplug_lock down the dependency chain.
So housekeeping_update() is now called after releasing cpus_read_lock
and cpuset_mutex at the end of a cpuset operation. These two locks are
then re-acquired later before calling rebuild_sched_domains_locked().
To enable mutual exclusion between the housekeeping_update() call and
other cpuset control file write actions, a new top level cpuset_top_mutex
is introduced. This new mutex will be acquired first to allow sharing
variables used by both code paths. However, cpuset update from CPU
hotplug can still happen in parallel with the housekeeping_update()
call, though that should be rare in production environment.
As cpus_read_lock() is now no longer held when
tmigr_isolated_exclude_cpumask() is called, it needs to acquire it
directly.
The lockdep_is_cpuset_held() is also updated to return true if either
cpuset_top_mutex or cpuset_mutex is held.
Fixes: 03ff73510169 ("cpuset: Update HK_TYPE_DOMAIN cpumask from cpuset")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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The cpuset_handle_hotplug() may need to invoke housekeeping_update(),
for instance, when an isolated partition is invalidated because its
last active CPU has been put offline.
As we are going to enable dynamic update to the nozh_full housekeeping
cpumask (HK_TYPE_KERNEL_NOISE) soon with the help of CPU hotplug,
allowing the CPU hotplug path to call into housekeeping_update() directly
from update_isolation_cpumasks() will likely cause deadlock. So we
have to defer any call to housekeeping_update() after the CPU hotplug
operation has finished. This is now done via the workqueue where
the update_hk_sched_domains() function will be invoked via the
hk_sd_workfn().
An concurrent cpuset control file write may have executed the required
update_hk_sched_domains() function before the work function is called. So
the work function call may become a no-op when it is invoked.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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With the latest changes in sched/isolation.c, rebuild_sched_domains*()
requires the HK_TYPE_DOMAIN housekeeping cpumask to be properly
updated first, if needed, before the sched domains can be
rebuilt. So the two naturally fit together. Do that by creating a new
update_hk_sched_domains() helper to house both actions.
The name of the isolated_cpus_updating flag to control the
call to housekeeping_update() is now outdated. So change it to
update_housekeeping to better reflect its purpose. Also move the call
to update_hk_sched_domains() to the end of cpuset and hotplug operations
before releasing the cpuset_mutex.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
|
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As cpuset is updating HK_TYPE_DOMAIN housekeeping mask when there is
a change in the set of isolated CPUs, making this change is now more
costly than before. Right now, the isolated_cpus_updating flag can be
set even if there is no real change in isolated_cpus. Put in additional
checks to make sure that isolated_cpus_updating is set only if there
is a real change in isolated_cpus.
Reviewed-by: Chen Ridong <chenridong@huaweicloud.com>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Clarify the locking rules associated with file level internal variables
inside the cpuset code. There is no functional change.
Reviewed-by: Chen Ridong <chenridong@huaweicloud.com>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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update_cpumasks_hier()
Commit e2ffe502ba45 ("cgroup/cpuset: Add cpuset.cpus.exclusive for v2")
incorrectly changed the 2nd parameter of cpuset_update_tasks_cpumask()
from tmp->new_cpus to cp->effective_cpus. This second parameter is just
a temporary cpumask for internal use. The cpuset_update_tasks_cpumask()
function was originally called update_tasks_cpumask() before commit
381b53c3b549 ("cgroup/cpuset: rename functions shared between v1
and v2").
This mistake can incorrectly change the effective_cpus of the
cpuset when it is the top_cpuset or in arm64 architecture where
task_cpu_possible_mask() may differ from cpu_possible_mask. So far
top_cpuset hasn't been passed to update_cpumasks_hier() yet, but arm64
arch can still be impacted. Fix it by reverting the incorrect change.
Fixes: e2ffe502ba45 ("cgroup/cpuset: Add cpuset.cpus.exclusive for v2")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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The effective_xcpus of a cpuset can contain offline CPUs. In
partition_xcpus_del(), the xcpus parameter is incorrectly used as
a temporary cpumask to mask out offline CPUs. As xcpus can be the
effective_xcpus of a cpuset, this can result in unexpected changes
in that cpumask. Fix this problem by not making any changes to the
xcpus parameter.
Fixes: 11e5f407b64a ("cgroup/cpuset: Keep track of CPUs in isolated partitions")
Reviewed-by: Chen Ridong <chenridong@huaweicloud.com>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
|
