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Pull scheduler fixes from Ingo Molnar:
- Fix __sched_setscheduler() class change race causing
lost reschedules, exposed by recent RCU changes (K Prateek Nayak)
- Fix s64 multiplication overflow in place_entity()'s vlag
scaling code that can corrupt an entity's placement (Hui Su)
* tag 'sched-urgent-2026-10-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/fair: Avoid overflow in place_entity()
sched/core: Call wakeup_preempt() for queued tasks during class change
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Pull perf events fixes from Ingo Molnar:
- Fix x86 Intel uncore driver bug on Diamond Rapids CPUs
that erroneously always-cleared the invert bit (Guixiong Wei)
- Fix accounting bug in the perf mlock 'gift' code causing
unrelated RLIMIT_MEMLOCK functionality to fail (Lorenzo Stoakes)
- Fix perf_pmu_migrate_context() bug leaving events behind during
CPU hot-unplug (Haris Okanovic)
- Update cgroup time when rotating multiplexed events, to fix
time_running & scaled counts accounting bug (Antoine Huret)
* tag 'perf-urgent-2026-10-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf: Update cgroup time when rotating multiplexed events
perf: Fix perf_pmu_migrate_context() leaving events behind
perf: Track the perf mlock gift separately
perf/x86/intel/uncore: Fix DMR CXL CM invert filter
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Pull locking fixes from Ingo Molnar:
- Fix FUT_OFF_MMSHARED futex hashing bug that can cause
missed wakeups or spurious wakeups on futex-waiting
tasks (Jann Horn)
- Fix lockdep context tracking bug in the deferred hrtimer
rearming entry code, which causes a lockdep chain leak
that will eventually turn lockdep off (Mikhail Gavrilov)
* tag 'locking-urgent-2026-10-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
entry: Account the deferred hrtimer rearm as hardirq context for lockdep
futex: Fix mm reuse handling for FUT_OFF_MMSHARED
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Pull printk fixes from Petr Mladek:
- Switch NBCON consoles to the emergency mode in emergency_restart() to
see messages even in this shutdown code path
- Postpone the start of printk kthreads after smp_init(). It prevents
boot stalls on some HW
- Typo fix in a previous hot-fix patch
* tag 'printk-for-7.3-hotfix' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux:
printk: Postpone kthread startup
printk: fix kernel-doc name for nbcon_write_context_is_braille
nbcon/reboot: Switch NBCON consoles into the emergency mode in emergency_restart()
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Pull tracing fixes from Steven Rostedt:
- Fix NULL dereference when copying histogram field variable
If event_hist_trigger_parse() creates an action that uses one of
pseudo fields for its keys, the hist_data field element will have a
NULL for its field member. When looking to match that key, the lookup
uses key_field->field->name which will dereference a NULL pointer.
Instead use the helper function that handles such cases:
expr_field_str().
- Take the trace_types_lock when dropping the buffer_meta reference
The tracing_buffer_meta_open() error return drops the trace_array
reference with __trace_array_put() instead of trace_array_put() where
the former doesn't take the lock and the latter does.
- Fix NULL pointer dereference when reading per_cpu/cpuN/buffer_meta
These files are created for every possible CPU. But it only contains
data for CPUs that have come online. If one is read for a CPU that
hasn't come online yet, it triggers a NULL pointer dereference.
Have reading of CPUs that have not come on line yet return -ENODEV.
- Fix an out-of-bounds shift in the log2 histogram modifier
Histograms can take a log2 modifier to have the buckets defined by
log2 increments. If a shift is greater than ULONG_MAX or above 2^63,
the key falls into a lower order bucket.
Use order_base_2() instead of "ilog2(n - 1) + 1" to have all
overflowed keys go into the top bucket.
- Fix the persistent ring buffer rb_meta_subbuf_idx() accounting
The algorithm for finding the index of a sub-buffer in a persistent
ring buffer buffer did not take into account the meta data at the
beginning of the buffer causing the wrong index to be returned.
As rb_subbufs_from_meta() does the proper accounting to find the
first sub-buffer, use that function instead of repeating the logic
(incorrectly) and make the calculations based off of that.
- Fix the symbol name checks for the remote buffer code
The remote ring buffer has a build time check to make sure its not
using any code that will not be in the hypervisor. For various
architectures, there has been false positive reports from this
checker.
Fix them.
- Fix false warning in ring_buffer_map_get_reader()
There is a WARN_ON() after rb_get_reader_page() if no reader is
returned. But there are legitimate cases where this can happen.
Remove the WARN_ON() and also a check that covers one of the
legitimate cases that tries to exit out early. There's no need for
the check if it just simply allows the return of NULL from
rb_get_reader_page().
- Fix the ignored return value from resize_buffer_duplicate_size()
Some clean up of the code in tracing_snapshot_write() removed
checking the return value of resize_buffer_duplicate_size() and if
that failed it would not be detected.
- Fix the histogram timestamps for buffered events
The histogram timestamps are taken from the events that are recorded.
It currently reads ring_buffer_event_time_stamp() but if the event is
buffered it does not read it properly. Use tracing_event_time_stamp()
which handles both buffered and normal events.
- Do not initialize tracefs if tracing is disabled at boot
If tracing fails to allocate or some other error is detected,
tracing_disabled is set. Do not initialize tracefs in this case as it
may expect data to be initialized but is not.
- Free eventfs inode after an RCU grace period
Currently eventfs_inodes are freed after a SRCU grace period as the
iterations in the code use SRCU. There are locations that the inode
may still be accessed from the VFS that uses RCU which does not have
the same synchronization as SRCU. Add an RCU wait before free eventfs
inodes.
- Do not fail persistent and remote buffers under memory pressure
As persistent and remote buffers have their own pre-allocated memory,
there's no reason to check how much memory is available before
created them. By checking the memory pressure, these buffers may fail
to be created even though their memory is already present.
- Account for subbuffer size when checking how much memory is available
Before allocating a ring buffer, the size is checked against the
current memory pressure of the system. But it assumes every
sub-buffer is of page size. This is no longer the case. Use the
actual sub-buffer size when calculating how much memory will be used.
- Reject non-stack fields for synthetic stacktrace fields
Stack traces are special fields and the checks currently do not do
enough to make sure that the fields being processed as stack traces
are indeed stack traces. Update the logic to properly detect what is
or is not a stack trace.
- Fix a crash in print_graph_function_event()
When a tracer does not define static or default flags the
tr->current_trace_flags is set to NULL. If the ring buffer is not
cleared when switching tracers, the previous tracers events could be
read. The function_graph entries will dereference the
tr->current_trace_flags and cause a crash.
Set the tr->current_trace_flags to a empty set of flags to prevent it
from being NULL.
- Separate tracing filter predicate count from allocation
The amount allocated for the predicate program is the number of
predicates defined plus two for adding "true" and "false" at the end.
The nr_preds is incremented by two to accommodate the booleans but is
then used as the limit check for number of predicates. This is
incorrect as it is now two higher than what is expected.
Use a separate variable for the size of the predicate array.
- Fix the filter operator stack check
The operator stack increments the pointer and then writes the content
onto the stack. The check for overflow compared the current pointer
to see if it was greater than the stack size before doing so. This is
an off by 2 error as the write will be at the size - 1 and the
compare is done before the increment. Adjust the check accordingly.
* tag 'trace-v7.3-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
tracing: Check operator stack capacity before pushing
tracing: Keep the predicate limit separate from program capacity
tracing: Fix crash in print_graph_function_event()
tracing/histograms: Reject non-stacktrace fields for synthetic stacktrace fields
ring-buffer: Use subbuf_order in available memory estimation
ring-buffer: Skip si_mem_available() for persistent and remote buffers
eventfs: Free the eventfs_inode after an rcu grace period too
tracing: Do not initialize tracefs work if tracing is disabled
tracing: Fix hist trigger timestamps for buffered events
tracing: Fix ignored return value of resize_buffer_duplicate_size()
ring-buffer: Fix false warning in ring_buffer_map_get_reader()
tracing: Fix simple_ring_buffer undef check on sparc64
tracing: Fix simple_ring_buffer undef check on parisc
tracing: Fix empty symbol names in simple_ring_buffer undef check
ring-buffer: Fix the sub-buffer array base in rb_meta_subbuf_idx()
tracing: Fix the shift out of bounds in the log2 histogram modifier
ring-buffer: Do not show buffer_meta for CPUs without a buffer
tracing: Take trace_types_lock when dropping the buffer_meta reference
tracing: Fix NULL dereference when copying keys for a field variable
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Pull probes fix from Masami Hiramatsu:
- error out if BTF is required but unavailable
Fix to return an error instead of NULL if BTF is not available when
user specify '$args*' meta fetch argument for probe events.
* tag 'probes-fixes-v7.3-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
tracing: probes: error if BTF is required but unavailable
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There have been various bug reports related to SMP systems hanging
on boot. The reports vary but seem to have some overlap with regard
to missed IPI's during SMP setup. The reports also show that
reverting NBCON console usage allows the bugs to disappear.
The NBCON kthreads for console printing are started very early
during boot using early_initcall(). Since these kthreads are
asynchronously enabling/disabling interrupts during early boot, they
may be interfering with early SMP setup on some hardware platforms.
Starting the console printing kthreads later has shown to avoid the
hanging on systems that could previously reproduce the issue.
Postpone kthread starting until after all arch initcalls have
completed.
Reported-by: Derek Barbosa <debarbos@redhat.com>
Closes: https://lore.kernel.org/linux-rt-users/arPmYPbFLf2EldIl@debarbos-thinkpadt14gen5.rmtusma.csb
Fixes: 76f258bf3f2a ("printk: nbcon: Introduce printer kthreads")
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Tested-by: Derek Barbosa <debarbos@redhat.com>
Link: https://patch.msgid.link/20261016085441.857695-1-john.ogness@linutronix.de
Signed-off-by: Petr Mladek <pmladek@suse.com>
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Pull vfs fixes from Christian Brauner:
- Fix a range of use-after-frees during rcu pathwalk caused by non-rcu
frees.
Whatever ->permission(), ->d_revalidate(), ->get_link(), ->d_hash()
and ->d_compare() read in rcu mode has to be freed after a grace
period. umount(2) hides most of it because namespace_unlock() waits
for one, but a chdir() out of a lazily unmounted directory or the
close() of the last file on it drops the last reference without.
* ext4_get_link() reads the sbi and the extent status counters for a
symlink stored in a data block. Both are freed after a grace
period now.
* The unicode map of casefolded ext4, f2fs and tmpfs was freed under
generic_ci_d_hash() and generic_ci_d_compare().
* ntfs3 with nocase freed its sbi and mount options under its dentry
hash and compare. A remount freed the old options right away too.
* eventfs freed an eventfs_inode after an SRCU grace period only
while tracefs_d_revalidate() reads it under rcu_read_lock().
* afs and 9p are only saved by the grace period their private bdi
gets in bdi_unregister(). They stop depending on it.
* create_ipc_ns() leaked the mqueue mount and its superblock on a
late failure. A long-term mount needs kern_unmount().
- Don't let idle threads pin the initramfs.
The idle threads of the secondary cpus are forked from PID 1 with a
private copy of its fs_struct, aren't on the task list so
pivot_root() never moves them and never exit. So the initramfs stayed
pinned forever on every machine with more than one cpu, 70 to 150 MB
in the reports. They share init_fs now like init_task does.
- A mount that copy_tree() leaves out can't take over a lock.
copy_tree() drops mounts of mount namespace files from the copies it
makes for unshare(CLONE_NEWNS) and propagation without looking at
MNT_LOCKED. So root in a user namespace could bind a child's
/proc/<pid>/ns/mnt beneath a locked cover, let it take the lock over,
unshare(CLONE_NEWNS) and read the file. copy_tree() refuses with
EPERM now and the move beneath a locked mount is refused up front.
- Revert "namei: don't reveal overmounted entries in refwalk" from the
rc7 fixes. The bug class is bigger than that patch.
- namei: lookup_fast_for_open() checked ->d_inode while
traverse_mounts() checks the type in d_flags, which is set second, so
a refwalk racing the instantiation could fail an O_CREAT open with
ENOENT. Use d_is_negative() in both places.
- Drop the smp_mb()s in mntput_no_expire_slowpath() and do_umount()
that mnt_get_count()'s own barrier made redundant.
- fsnotify: a mark added while fsnotify_destroy_marks() walks the
connector could be missed and the connector detached, so an fdinfo
read called igrab(NULL). New marks are refused during teardown.
- pipe: a failed second fasync enable on an O_RDWR FIFO removed the
existing reader entry and cleared FASYNC while the writer entry
stayed, a use-after-free in send_sigio() later.
- watch_queue: post_one_notification() could see nr_notes before the
note pool behind it and dereference a NULL array. An unprivileged
user can trigger that with a key watch. Publish nr_notes last.
- pid_namespace: zap_pid_ns_processes() waits without bound for a
tracer outside the namespace to reap its zombies and neither wait was
freezable, so every suspend attempt failed.
- exit: is_child_subreaper and has_child_subreaper shared a word with
other bitfields written without a common lock, so racing prctl()s
lost a bit. They are separate bools now.
- autofs: a notification write that failed on a pipe the daemon had
already replaced put the superblock into catatonic mode again and
closed the replacement. Only do that for the current pipe.
- ovl: reject a lowerdir ending with an unescaped backslash with EINVAL
instead of a confusing ENOENT later.
- ocfs2/dlm: take dlm_reco_state_lock when the debugfs state file walks
the recovery participant list.
- samples/pidfd: fix the userprogs typo that kept pidfd-metadata from
being built.
* tag 'vfs-7.3-rc8.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (24 commits)
Revert "namei: don't reveal overmounted entries in refwalk"
selftests/filesystems: test that a mntns file can't take over a lock
fs: let idle threads share init_fs
namespace: a mount that copy_tree() leaves out can't take over a lock
namei: test for a negative dentry the way traverse_mounts() does
fs: pass flags to copy_fs()
ovl: reject lowerdir ending with unescaped backslash
fsnotify: prevent mark additions during connector teardown
pid_namespace: make zap_pid_ns_processes() freezable
fs: drop the smp_mb()s that mnt_get_count() made redundant
autofs: ignore notification errors from a replaced pipe
ntfs3: free replaced mount options after a grace period
ntfs3: free the sbi after a grace period
unicode: free the map after a grace period
ipc: drop the mqueue mount with kern_unmount() on setup failure
eventfs: free the eventfs_inode after an rcu grace period too
9p: free the session after a grace period
watch_queue: Fix note pool publication race in watch_queue_set_size()
afs: free the super info after a grace period
pipe: preserve existing fasync readers on writer setup failure
...
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Since commit bd2756811766 ("perf: Rewrite core context handling"),
perf_rotate_context() only updates the context time before scheduling
out the flexible events. It no longer updates the cgroup time, which
ctx_sched_out() used to do.
Cgroup events take their times from the per-cpu cgroup clock, so
between two cgroup switches the rotations see a frozen clock. The
events rotated out lose the running time they accumulated, and the next
update, usually a read, credits the whole interval to the events that
happen to be on the PMU at that moment.
As a result, the time_running of multiplexed cgroup events is wrong,
and so are their scaled counts, as long as no other cgroup runs on the
CPU, e.g. a busy job alone on its CPUs. Counting cycles over one second
of a busy loop in a cgroup gives from half to several times the max
frequency of the CPU.
Update the cgroup time before rotating the CPU context, as was done
before the rewrite.
Fixes: bd2756811766 ("perf: Rewrite core context handling")
Closes: https://lore.kernel.org/r/PR3PR07MB69223331EED5BEBE150375B7849C2@PR3PR07MB6922.eurprd07.prod.outlook.com/
Assisted-by: Claude:claude-opus-5-5
Signed-off-by: Antoine Huret <antoine.huret@bull.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20261015-perf-cgroup-rotation-time-v1-1-93e177dfee5d@bull.com
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__perf_pmu_remove() walks the group leaders of a CPU and PMU with
perf_event_groups_for_cpu_pmu(), removing each one as it goes.
perf_remove_from_context() takes the leader out of the groups rbtree,
after which rb_next() on that node returns NULL, prematurely ending the
walk. Other groups stay behind in the source context.
On CPU hotplug, they are then torn down with the dying CPU. They keep
running until teardown, while the PMU's interrupt and migrated events
are on a new CPU, which drivers rely on never happening.
Walk ctx->event_list instead and pick out the PMU's events by their
pmu_ctx.
Fixes: bd2756811766 ("perf: Rewrite core context handling")
Signed-off-by: Haris Okanovic <harisokn@amazon.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20261013185603.1347265-2-harisokn@amazon.com
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The locked_vm field in struct user_struct was originally introduced by
commit 789f90fcf6b0 ("perf_counter: per user mlock gift") to provide an
mlock-like budget for perf measured against mm->pinned_vm (since 2011).
perf grants each user a 'gift' of perf_event_mlock_kb * online CPUs of
buffer pages which is charged to user->locked_vm without any RLIMIT_MEMLOCK
check.
Only pages beyond the gift are checked against RLIMIT_MEMLOCK, per-mm, via
mm->pinned_vm, which makes it different from the standard mlock() check,
which is per-mm and made against RLIMIT_MEMLOCK.
However, since this was introduced, a number of other components have
utilised this field where a shared resource needed to be limited against
RLIMIT_MEMLOCK.
The other users are currently MSG_ZEROCOPY, io_uring, AF_XDP, iommufd,
s390 KVM zPCI and most recently, secretmem in commit 97d34aa65c29
("mm/secretmem: properly account locked pages").
This field is shared between all of these, but because the gift is not
checked against RLIMIT_MEMLOCK, user->locked_vm alone can exceed it - 16
CPUs * 516 KiB is already more than the default 8 MiB - after which every
other user of the field fails unconditionally.
This was reported by a user who saw secretmem failing while running a
simultaneous perf record.
Resolve the issue by simply giving perf its own field separate from the
rest.
BPF used user->locked_vm up until commit 80ee81e0403c ("bpf: Eliminate
rlimit-based memory accounting infra for bpf maps") which landed in 5.11.
Thus also eliminate the now-defunct ifdef for CONFIG_BPF_SYSCALL for
user->locked_vm.
This issue exists between all of the components which use user->locked_vm
and perf, however secretmem is the first user who has caused a report over
many years and has been backported, so target the fix at that.
Fixes: 97d34aa65c29 ("mm/secretmem: properly account locked pages")
Closes: https://lore.kernel.org/20261002175651.811343-1-ameer.hamza@truenas.com
Reported-by: Ameer Hamza <ameer.hamza@truenas.com>
Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20261003-perf-locked-vm-fix-v1-1-d214dcaf0d76@kernel.org
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place_entity() inflates an entity's virtual lag with
lag * (load + weight) / load
Commit 4823725d9d1d ("sched/fair: Increase weight bits for avg_vruntime")
replaced the scaled-down weights used in this calculation with
avg_vruntime_weight(), removing the arithmetic headroom provided by
scale_load_down().
The multiplication can overflow s64 before the division even when the
final quotient is representable. A task's hierarchical effective weight
can be as small as 2 after avg_vruntime_weight() scaling under group
scheduling, while entity_lag() bounds |vlag| by
calc_delta_fair(cfs_rq_max_slice(cfs_rq) + TICK_NSEC, se)
For example, with HZ=1000, NICE_0_LOAD=1048576, and the minimum scaled
hierarchical weight scale_load(2)=2048, this bound is 891289600. With 114
maximum-weight entities, the runqueue load is 10361604096. The
intermediate product is:
891289600 * (10361604096 + 2)
= 9235189971864780800
> S64_MAX
The signed overflow corrupts the entity's placement.
Rewrite
lag * (load + weight) / load
as
lag + lag * weight / load
The two expressions are equivalent, but the latter avoids multiplying the
virtual lag by the total runqueue weight. entity_lag() bounds vlag against
the entity's effective weight, so the remaining lag * weight product stays
bounded. rescale_entity() preserves this scale across h_load changes and
already relies on the same product when rescaling vlag.
Keep the original zero-load warning semantics by multiplying lag by weight
after replacing the divisor with one.
Fixes: 4823725d9d1d ("sched/fair: Increase weight bits for avg_vruntime")
Signed-off-by: Hui Su <sh_def@163.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260928124754.1692077-1-sh_def@163.com
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predicate_parse() uses the first operator stack entry before processing
any opening parentheses. A push then increments top before writing.
The existing check still permits that write when top already points to
the last allocated entry, which can access beyond the operator stack.
Reject the push when top reaches the last allocated entry.
Cc: stable@vger.kernel.org
Fixes: 39f7c41c908b ("tracing/filters: Enable filtering a cpumask field by another cpumask")
Link: https://patch.msgid.link/atELO9L0I9kg5CpC@Taeyangs-MacBook-Pro.local
Signed-off-by: Taeyang Lee <0wn@theori.io>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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predicate_parse() adds two to nr_preds to reserve the terminal TRUE
and FALSE entries. It also uses that increased value as the limit for
parsed predicates. If the initial count is smaller than the number
actually parsed, the program can fill the allocation and subsequent
accesses can go past its end.
Keep nr_preds as the predicate limit and use a separate value for the
allocation size. This leaves space for both terminal entries and a
zeroed entry when parsing stops at the limit.
Cc: stable@vger.kernel.org
Fixes: 39f7c41c908b ("tracing/filters: Enable filtering a cpumask field by another cpumask")
Link: https://patch.msgid.link/atELCd1XjKVhrkFL@Taeyangs-MacBook-Pro.local
Signed-off-by: Taeyang Lee <0wn@theori.io>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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tracing_set_tracer() assigns the flags of the newly selected tracer
with:
tr->current_trace_flags = t->flags ? : t->tracer->flags;
If the new tracer defines neither static flags nor default flags, like
hwlat, irqsoff or wakeup, add_tracer() has no per instance flags copy
for it, and both operands are NULL, so tr->current_trace_flags ends up
being NULL as well.
The ring buffer is not cleared when switching tracers: it is reset
inside tracer_init(), after current_trace_flags was already assigned.
If the buffer still holds function_graph entries of the previous
tracer, printing one of them dereferences the NULL pointer. This was
hit by cat trace during an ftrace stress test:
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor read access in kernel mode
RIP: 0010:print_graph_function_event+0xe/0x20
Call Trace:
s_show+0x4d/0x110
seq_read_iter+0x2d4/0x490
seq_read+0x130/0x170
vfs_read+0xb5/0x370
ksys_read+0x6d/0xe0
do_syscall_64+0xbc/0x450
The snapshot buffer is not reset at all, so this can be reproduced
without a race:
echo function_graph > /sys/kernel/tracing/current_tracer
echo 1 > /sys/kernel/tracing/snapshot
echo hwlat > /sys/kernel/tracing/current_tracer
cat /sys/kernel/tracing/snapshot
Rather than teaching every user of tr->current_trace_flags about this
corner case, make sure it is never NULL: when the newly selected
tracer has no flags at all, tracing_set_tracer() falls back to a
static empty no_tracer_flags. run_tracer_selftest() can hit the same
case, so the same fallback is added there too. The existing users
already handle opts == NULL, so these tracers keep behaving as before.
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20261015130658.221198-1-hao.ge@linux.dev
Fixes: e29aa918a928 ("tracing: Have function graph tracer define options per instance")
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Hao Ge <hao.ge@linux.dev>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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In check_synth_field(), when a synthetic event field is a stacktrace
(field->is_stack) and the histogram field is not a "long[" stacktrace
array, validation falls through to the generic size and signedness
comparison.
Because parse_synth_field() sets a stacktrace field's type to
"__data_loc unsigned long[]", its size is sizeof(u64) and
synth_field_signed() marks it as signed. Consequently, any 8-byte
signed scalar histogram field passes the fallback check, and its scalar
value is subsequently dereferenced as a kernel stacktrace pointer in
get_field_size() and trace_stack().
Furthermore, checking strstr(hist_field->type, "long[") is insufficient
because tracepoint fields defined with __bitmask() or __rel_bitmask()
also have type "__data_loc unsigned long[]" or "__rel_loc unsigned
long[]", whilst create_hist_field() treats them as 4-byte scalar values
without HIST_FIELD_FL_STACKTRACE.
Propagate HIST_FIELD_FL_STACKTRACE to variable references and field
variables (whilst excluding variable aliases from per-element
stacktrace capture), and reject any mismatch between
HIST_FIELD_FL_STACKTRACE and field->is_stack in check_synth_field().
Cc: stable@vger.kernel.org
Fixes: 00cf3d672a9d ("tracing: Allow synthetic events to pass around stacktraces")
Link: https://patch.msgid.link/20261013112449.1006088-1-lee@kernel.org
Signed-off-by: Lee Jones <lee@kernel.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
|
|
To avoid failing in the middle of an allocation of a ring-buffer,
__rb_allocate_pages() looks at the available memory estimation with
si_mem_available(). Use the subbuffer order with this estimation to fail
early if necessary for ring-buffers with an order > 0.
Link: https://patch.msgid.link/20261013102047.1488347-3-vdonnefort@google.com
Fixes: f9b94daa542a ("ring-buffer: Set new size of the ring buffer sub page")
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
|
|
traceprobe_expand_meta_args expands probe arguments based on BTF info.
Return an error if we have arguments that need expanding but BTF is not
supported.
The params variable is now unused, it can be removed.
Link: https://lore.kernel.org/all/20261014083838.31020-1-martin@kaiser.cx/
Fixes: d157d7694460 ("tracing/probes: Support BTF field access from $retval")
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
|
|
Pull workqueue fix from Tejun Heo:
- Fix a NULL dereference in the check for whether the current task is
running a memory reclaim work item when called from a kworker outside
work item execution
* tag 'wq-for-7.3-rc7-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: Fix NULL current_pwq deref in mem-reclaim helper
|
|
Persistent and remote buffer memory is pre-allocated by the time
__rb_allocate_pages() is called. Skip si_mem_available() to avoid
wrongly failing the allocation under memory pressure.
For the same reason, unset user_thread.
Link: https://patch.msgid.link/20261013102047.1488347-2-vdonnefort@google.com
Fixes: be68d63a139b ("ring-buffer: Add ring_buffer_alloc_range()")
Fixes: 2e67fabd8b77 ("ring-buffer: Introduce ring-buffer remotes")
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
|
|
If trace buffer allocation fails during early boot (e.g. in
early_trace_init() -> allocate_trace_buffers()), tracing_disabled is
left set to 1 and the global trace array events list remains
uninitialized.
Later during boot, tracer_init_tracefs() (invoked via fs_initcall)
queues tracerfs_init_work asynchronously without checking if tracing was
disabled. When tracer_init_tracefs_work_func() runs, it calls
event_trace_init() and init_tracer_tracefs(&global_trace, NULL)
unconditionally. This leads to __find_event_file() dereferencing an
uninitialized tr->events list, causing an early boot NULL pointer
dereference Oops:
BUG: Kernel NULL pointer dereference on read at 0x00000010
Faulting instruction address: 0xc000000000485be0
Oops: Kernel access of bad area, sig: 7 [#1]
...
NIP [c000000000485be0] __find_event_file+0x70/0x3c0
LR [c000000000448874] init_tracer_tracefs+0x274/0xc80
Call Trace:
init_tracer_tracefs+0x274/0xc80
tracer_init_tracefs_work_func+0x50/0x320
process_one_work+0x1e8/0x5c0
worker_thread+0x1dc/0x3d0
kthread+0x194/0x1b0
start_kernel_thread+0x14/0x18
Check tracing_disabled at the beginning of tracer_init_tracefs_work_func()
and return immediately if tracing is disabled or failed to initialize,
preventing the crash.
Cc: stable@vger.kernel.org
Fixes: 6621a7004684 ("tracing: make tracer_init_tracefs initcall asynchronous")
Link: https://patch.msgid.link/20261009163557.88467-2-amachhiw@linux.ibm.com
Reported-by: Michal Suchánek <msuchanek@suse.de>
Closes: https://lore.kernel.org/all/arYskzbiaNzBR9MD@kunlun.suse.cz/
Signed-off-by: Amit Machhiwal <amachhiw@linux.ibm.com>
Tested-by: Michal Suchánek <msuchanek@suse.de>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
|
|
Syzkaller triggered a WARN_ON_ONCE(!nest) warning:
WARNING: kernel/trace/ring_buffer.c:821 at ring_buffer_event_time_stamp
Call trace:
ring_buffer_event_time_stamp
hist_field_timestamp
hist_fn_call
event_hist_trigger
event_triggers_call
__event_trigger_test_discard
trace_event_buffer_commit
do_trace_event_raw_event_sched_switch
trace_event_raw_event_sched_switch
The warning is probabilistically reproducible and is related to syzkaller
executing the following commands:
echo 'prev_pid == 999999' > events/sched/sched_switch/filter
echo 'hist:keys=common_timestamp' > events/sched/sched_switch/trigger
The specific triggering process is as follows:
CPU 0 CPU 1
(context switching) (echo 'hist:keys=common_timestamp' > \
events/sched/sched_switch/trigger)
do_trace_event_raw_event_##call
trace_event_buffer_lock_reserve
if (!tr->no_filter_buffering_ref &&
trace_file->flags & EVENT_FILE_FL_FILTERED)
return entry; // return directly
event_hist_trigger_parse
hist_register_trigger
tracing_set_filter_buffering(file->tr, true);
tr->no_filter_buffering_ref++;
__trace_buffer_lock_reserve
rb_start_commit
local_inc(&cpu_buffer->committing); // skipped and not executed
trace_event_buffer_commit
__event_trigger_test_discard
event_triggers_call
event_hist_trigger
hist_fn_call
hist_field_timestamp
ring_buffer_event_time_stamp
nest = local_read(&cpu_buffer->committing);
WARN_ON_ONCE(!nest) // trigger warning
The root cause is that when an event file has a filter attached and the
hist trigger has not yet been attached, trace_event_buffer_lock_reserve()
writes the event into the per-CPU trace_buffered_event temp buffer instead
of reserving it in the ring buffer, so cpu_buffer->committing is not
incremented. When the event is later processed at commit time by a hist
trigger, hist_field_timestamp() -> ring_buffer_event_time_stamp() sees a
zero committing count, triggering WARN_ON_ONCE(!nest).
tracing_event_time_stamp() was added by commit d8279bfc5e959 ("tracing:
Add tracing_event_time_stamp() API") for exactly this case: if the event
is the per-CPU trace_buffered_event, it returns the current ring buffer
timestamp. But it never gained a caller. Use it in hist_field_timestamp(),
so that a hist trigger that races onto a buffered event records the
current time, which is only marginally later than when the event was
recorded, instead of warning and recording a bogus timestamp.
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260929104015.1689921-1-wutengda@huaweicloud.com
Fixes: b94bc80df648 ("tracing: Use a no_filter_buffering_ref to stop using the filter buffer")
Signed-off-by: Tengda Wu <wutengda@huaweicloud.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
|
|
When tr->allocated_snapshot is true, resize_buffer_duplicate_size() is
called to update the snapshot buffer size. However, its return value was
not checked. In case of a failed resize this could lead next snapshot
being incomplete.
Add resize_buffer_duplicate_size() result check and return error if
resize fails.
Compile tested only.
Found by Linux Verification Center (linuxtesting.org) with SVACE.
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260928152634.4354-1-d.kandybka@gmail.com
Fixes: 180e4e390978 ("tracing: Add snapshot refcount")
Signed-off-by: Dmitry Kandybka <d.kandybka@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
|
|
The mmap reader can warn when it catches up with a writer that is still
committing events. rb_get_reader_page() returns NULL in this case, but
ring_buffer_map_get_reader() treats that result as an error.
The initial rb_per_cpu_empty() check filters out an empty buffer, but it
does not guarantee that the next reader page has committed data. Writers
do not take reader_lock and can advance commit_page before publishing the
committed length on the new page. rb_get_reader_page() can swap to that
page, catch up with the writer and return NULL.
Handle NULL through the existing no-data exit without warning. Remove the
caller's reader_page == commit_page check as well, since the reader-page
helper already handles that case. The existing metadata update and return
path remain in place.
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260924084946.20104-1-krystianmkaniewski@gmail.com
Fixes: 117c39200d9d ("ring-buffer: Introducing ring-buffer mapping functions")
Assisted-by: Gemini:gemini-3.8-flash syzbot
Reported-by: syzbot+de3d7f9bcc9212f3fae1@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=de3d7f9bcc9212f3fae1
Link: https://syzkaller.appspot.com/ai_job?id=488adc18-a10e-42d2-a205-25327c38837f
Signed-off-by: Krystian Kaniewski <krystianmkaniewski@gmail.com>
Reviewed-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
|
|
simple_ring_buffer relies on headers that end up including
<asm/thread_info.h>. On sparc64, this emits the undefined symbol
current_thread_info_reg. Allow this symbol.
Link: https://patch.msgid.link/20260923074213.3077182-4-vdonnefort@google.com
Fixes: 1211907ac0b5 ("tracing: Generate undef symbols allowlist for simple_ring_buffer")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Closes: https://lore.kernel.org/all/5574c9e6-9ed2-4ee6-a2b2-fb6ee81e83a1@roeck-us.net/
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
|
|
simple_ring_buffer uses local_set() and cmpxchg() on unsigned long. Add
them to undefsyms_base.c to extend the allowlist for the parisc
architecture.
Link: https://patch.msgid.link/20260923074213.3077182-3-vdonnefort@google.com
Fixes: 1211907ac0b5 ("tracing: Generate undef symbols allowlist for simple_ring_buffer")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Closes: https://lore.kernel.org/all/5574c9e6-9ed2-4ee6-a2b2-fb6ee81e83a1@roeck-us.net/
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
|
|
Sparc64 emits empty symmbol names. Skips them when establishing the
allowlist and when extracing undefined symbols.
Link: https://patch.msgid.link/20260923074213.3077182-2-vdonnefort@google.com
Fixes: 1211907ac0b5 ("tracing: Generate undef symbols allowlist for simple_ring_buffer")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Closes: https://lore.kernel.org/all/5574c9e6-9ed2-4ee6-a2b2-fb6ee81e83a1@roeck-us.net/
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
|
|
Pull sched_ext fixes from Tejun Heo:
- A task that skipped the BPF scheduler on its way back to its CPU's
local queue could stall there until the watchdog fired, as the CPU
had already decided to go idle.
- Use-after-free of a destroyed user dispatch queue by a deferred
re-enqueue request.
- A task could be moved off a dispatch queue while the dispatching CPU
was still running ops.dequeue() on it.
- Bypass mode mishandled a sub-scheduler bypass overlapping an
ancestor's, as across a system suspend. Descendants could leave
bypass mid-teardown and tasks could be stranded on bypass queues.
- The idle CPU selection helper could return a CPU outside the allowed
CPUs of a pinned or migration-disabled task.
* tag 'sched_ext-for-7.3-rc7-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext:
sched_ext: Wait for SCX_OPSS_DISPATCHING before moving tasks off DSQs
sched_ext: Rename scx_reenq_wait_dispatching() to scx_wait_dispatching()
sched_ext: idle: Respect task affinity in restricted CPU selection
sched_ext: Fix the bypass dispatch claim for schedulers bypassed by an ancestor
sched_ext: Propagate every bypass depth change to the descendants
sched_ext: Fix use-after-free of a destroyed user DSQ by a deferred reenqueue
sched_ext: Fix stall when a task enqueued with SCX_ENQ_LAST lands back on its CPU's local DSQ
|
|
On a persistent ring buffer, rb_meta_subbuf_idx() can return an index one
sub-buffer too high. rb_setup_ids_meta_page() then fills subbuf_ids[]
shifted by one and leaves subbuf_ids[0] NULL, which __rb_map_vma()
dereferences when userspace maps trace_pipe_raw. rb_update_meta_reader()
writes two such indices into meta->buffers[], which rb_cpu_meta_valid()
would reject on the next boot, discarding the previous boot's trace.
A CPU's sub-buffer array starts after its meta header and the nr_subbufs
integers that follow, aligned up to a sub-buffer. rb_meta_subbuf_idx()
inverts that calculation but skips only the integers, not the header, so
its base is one sub-buffer low whenever the omitted header size crosses
the alignment boundary.
Invert the calculation with rb_subbufs_from_meta() rather than repeating
it. rb_range_buffer() maps an index back to an address through the same
helper, so the two directions can no longer disagree.
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260918071507.1019251-1-donggeunyoo.kernel@gmail.com
Fixes: b14d032973d4 ("ring-buffer: Add ring_buffer_meta data")
Signed-off-by: Donggeun Yoo <donggeunyoo.kernel@gmail.com>
Reviewed-by: Vincent Donnefort <vdonnefort@google.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
|
|
The .log2 key modifier files a value under its base-2 order:
# echo 'hist:keys=bytes_req.log2' > events/kmem/kmalloc/trigger
hist_field_log2() computes that as ilog2(roundup_pow_of_two(val)). The
out-of-line form of roundup_pow_of_two() is
return 1UL << fls_long(n - 1);
which shifts by 64 on a 64-bit kernel both when n is 0, where n - 1
wraps to ULONG_MAX, and when n is above 2^63. Both are ordinary keys,
because the field fetch hands every value over as a u64: a syscall
argument of 0 reaches the first, and one above 2^63 reaches the second.
Keying sys_enter_lseek on offset.log2 and passing 0, 1, 2, 3, 1000,
2^63+1 and U64_MAX gives
{ offset: ~ 2^1 } hitcount: 1
{ offset: ~ 2^10 } hitcount: 1
{ offset: ~ 2^2 } hitcount: 1
{ offset: ~ 2^0 } hitcount: 4
Keys above 2^63 land in the lowest bucket. With CONFIG_UBSAN_SHIFT=y
the shift is also reported:
UBSAN: shift-out-of-bounds in include/linux/log2.h:57:13
shift exponent 64 is too large for 64-bit type 'long unsigned int'
__ubsan_handle_shift_out_of_bounds.cold+0xdd/0x1cb
hist_fn_call.cold+0x8b/0xd9
event_hist_trigger+0x1cc/0x790
ftrace_syscall_enter+0x197/0x360
do_syscall_64+0x402/0x4b0
Use order_base_2(), which is ilog2(n - 1) + 1 for n > 1 and 0 below
that. It returns what the old expression returned on every input the
old one was defined for. Where it was not, 0 stays in bucket 0, which
is where x86_64 had been putting it, and the keys above 2^63 move into
bucket 64.
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260916002735.808520-1-donggeunyoo.kernel@gmail.com
Fixes: 4b94f5b7b4a5 ("tracing: Add hist trigger 'log2' modifier")
Signed-off-by: Donggeun Yoo <donggeunyoo.kernel@gmail.com>
Assisted-by: Claude:claude-fable-5
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
|
|
The per_cpu/cpuN/buffer_meta files are created for every possible CPU,
but buffer->buffers[cpu] is only allocated once that CPU comes online.
Reading the file of a CPU that never came online dereferences a NULL
cpu_buffer in rbm_start().
Fail the open with -ENODEV when the CPU has no buffer, as the other
per CPU ring buffer interfaces do.
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260914133506.4865-3-devnexen@gmail.com
Fixes: 950032ffcee7 ("ring-buffer: Add output of ring buffer meta page")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://lore.kernel.org/all/20260913134906.6E8A01F000FF@smtp.kernel.org/
Signed-off-by: David Carlier <devnexen@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
|
|
tracing_buffer_meta_open() drops the trace_array reference with
__trace_array_put() when ring_buffer_meta_seq_init() fails, without
holding trace_types_lock. Use trace_array_put() like every other open
error path.
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260914133506.4865-2-devnexen@gmail.com
Fixes: 950032ffcee7 ("ring-buffer: Add output of ring buffer meta page")
Signed-off-by: David Carlier <devnexen@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
|
|
In event_hist_trigger_parse() where it needs to create actions like
"onmatch", it calls:
event_hist_trigger_parse() {
create_actions() {
action_create() {
trace_action_create() {
trace_action_create_field_var() {
create_field_var_hist()
Where create_field_var_hist() does a loop on the hist_data
representing the keys. The issue is, if the keys uses one of the
pseudo field types (like common_cpu), the hist_data field element
will have NULL for its field member causing a NULL pointer
dereference when accessing the key_field->field->name.
# echo 'hist:keys=common_cpu:ts0=common_timestamp.usecs' > \
events/sched/sched_waking/trigger
# echo 'my_synth u64 lat; int prio' > synthetic_events
# echo 'hist:keys=common_cpu:wakeup_lat=common_timestamp.usecs-$ts0:\
onmatch(sched.sched_waking).my_synth($wakeup_lat,prio)' > \
events/sched/sched_switch/trigger
KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
RIP: 0010:create_field_var_hist+0x771/0x1380
Call Trace:
trace_action_create_field_var+0x360/0x600
trace_action_create+0x393/0xe80
event_hist_trigger_parse+0x3e47/0x69e0
trigger_process_regex+0x1a6/0x250
event_trigger_write+0xce/0x160
Instead of accessing it directly, use the proper handler
expr_field_str() to get the name.
The three previous patches are prerequisites: without them a .buckets
key and a common_stacktrace key each render into a command that cannot
be parsed back.
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260914053443.981201-5-donggeunyoo.kernel@gmail.com
Fixes: 02205a6752f2 ("tracing: Add support for 'field variables'")
Signed-off-by: Donggeun Yoo <donggeunyoo.kernel@gmail.com>
Assisted-by: Claude:claude-fable-5
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
|
|
With nullfs as the real rootfs userspace can pivot_root() away from the
initramfs and unmount it:
chdir(rootfs);
pivot_root(".", ".");
umount2(".", MNT_DETACH);
That's what systemd does and the initramfs is supposed to go away at
that point together with all the memory it uses. But on every machine
with more than one possible cpu the initramfs superblock stays around
forever (cf. [1]). With ramfs as rootfs the unpacked initramfs shows up
as Unevictable in /proc/meminfo, with tmpfs as Shmem, and it is never
freed. In the reports that's between 70MB and 150MB.
The idle threads of the secondary cpus are created by fork_idle() from
smp_init(). That runs in kernel_init(), i.e., in PID 1, after
init_userspace_fs() moved PID 1 from nullfs into the initramfs.
fork_idle() doesn't pass CLONE_FS so each idle thread gets a private
copy of PID 1's fs_struct and with it a reference to the initramfs as
root and as pwd.
pivot_root() relies on chroot_fs_refs() to move everyone whose root or
pwd is the old root over to the new root. Idle threads aren't on the
task list though so chroot_fs_refs() never finds them. They never exit
either. So they keep the initramfs mount and with it the superblock
alive for good. I overlooked this when I added nullfs. Before that the
rootfs could never be unmounted anyway so it didn't matter what pinned
it.
Idle threads are kernel threads and init_task, the idle thread of the
boot cpu, already uses init_fs. So let the idle threads of the other
cpus share init_fs as well instead of copying PID 1's filesystem state.
Note that kernels before 7.3 need a different backport. There PID 1
still shares init_fs with all kthreads so passing CLONE_FS in
fork_idle() is enough. They also have a second pin: devtmpfsd unshares
a copy of the initial mount namespace, initramfs mount included. That
was fixed in commit 66d2faeccbff ("devtmpfs: create private mount
namespace").
Reproducer, as /init in an initramfs together with a 128MB ballast
file, booted with root=/dev/sda to get ramfs and with -smp 4:
// SPDX-License-Identifier: GPL-2.0
/* initramfs /init: switch root like systemd, check the old root */
#define _GNU_SOURCE
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mount.h>
#include <sys/reboot.h>
#include <sys/sendfile.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/sysmacros.h>
#include <unistd.h>
static void meminfo(void)
{
char line[256];
FILE *f = fopen("/proc/meminfo", "re");
while (f && fgets(line, sizeof(line), f))
if (!strncmp(line, "Unevictable:", 12) ||
!strncmp(line, "Shmem:", 6))
fputs(line, stdout);
if (f)
fclose(f);
}
int main(int argc, char *argv[])
{
struct stat st;
char dev[32], buf[32];
unsigned int maj, min;
int fd, in, out;
long r;
if (argc > 1) {
sleep(2);
meminfo();
/* ustat() only finds live superblocks */
r = syscall(SYS_ustat, (unsigned)atoi(argv[1]), buf);
printf("initramfs superblock %s\n", r ? "freed" : "pinned");
fflush(stdout);
sleep(1);
reboot(RB_POWER_OFF);
}
mount("proc", "/proc", "proc", 0, NULL);
mount("devtmpfs", "/dev", "devtmpfs", 0, NULL);
/* drop the fds console_on_rootfs() opened in the initramfs */
fd = open("/dev/console", O_RDWR);
dup2(fd, 0);
dup2(fd, 1);
dup2(fd, 2);
close(fd);
setvbuf(stdout, NULL, _IOLBF, 0);
meminfo();
stat("/", &st);
maj = major(st.st_dev);
min = minor(st.st_dev);
/* new_encode_dev(), what ustat() expects */
snprintf(dev, sizeof(dev), "%u",
(min & 0xff) | (maj << 8) | ((min & ~0xffu) << 12));
mkdir("/sysroot", 0755);
mount("tmpfs", "/sysroot", "tmpfs", 0, NULL);
mkdir("/sysroot/proc", 0755);
mkdir("/sysroot/dev", 0755);
in = open("/init", O_RDONLY);
out = open("/sysroot/init", O_WRONLY | O_CREAT, 0755);
fstat(in, &st);
sendfile(out, in, NULL, st.st_size);
close(in);
close(out);
mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, NULL);
mount("/proc", "/sysroot/proc", NULL, MS_BIND | MS_REC, NULL);
mount("/dev", "/sysroot/dev", NULL, MS_BIND | MS_REC, NULL);
chdir("/sysroot");
if (syscall(SYS_pivot_root, ".", ".") || umount2(".", MNT_DETACH))
perror("pivot_root");
execl("/init", "/init", dev, NULL);
return 1;
}
Before:
Unevictable: 131812 kB
Shmem: 0 kB
Unevictable: 131812 kB
Shmem: 792 kB
initramfs superblock pinned
After:
Unevictable: 131812 kB
Shmem: 0 kB
Unevictable: 0 kB
Shmem: 792 kB
initramfs superblock freed
With -smp 1 the superblock is freed without this patch as well.
[1]: https://github.com/systemd/systemd/issues/43911
Fixes: 576ee5dfd459 ("fs: add immutable rootfs")
Link: https://patch.msgid.link/20261013-work-fs-idle_fs-v1-2-2063d1bcb5aa@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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Turn the umh boolean into a flags argument. Idle threads need their own
case in copy_fs() as well and that's nicer than a second boolean.
No functional changes.
Link: https://patch.msgid.link/20261013-work-fs-idle_fs-v1-1-2063d1bcb5aa@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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When the init of a pid namespace exits, zap_pid_ns_processes() waits
until all other pids in the namespace are freed. A tracer outside the
namespace that does not reap its traced zombies keeps those pids
allocated, so this wait has no upper bound, and while it lasts every
suspend attempt fails:
Freezing user space processes failed after 20.006 seconds (2 tasks refusing to freeze, wq_busy=0):
Neither wait is freezable. The first loop sleeps in do_wait(), which
returns -ERESTARTSYS on the freezer's fake signal; the loop then clears
TIF_SIGPENDING and waits again without ever freezing. The final loop
sleeps in TASK_INTERRUPTIBLE, and since nothing clears TIF_SIGPENDING
there, schedule() returns immediately after the first freeze attempt
and the task spins until the wait ends.
Sleep in TASK_INTERRUPTIBLE | TASK_FREEZABLE in do_wait(), so that the
freezer can freeze tasks waiting there directly, and in TASK_IDLE |
TASK_FREEZABLE in the final loop, like coredump_task_exit() does.
This was hit with Chromium-based browsers: crashpad ptrace-attaches the
threads of a crashed renderer, which is a pid namespace init, and does
not reap those killed during the dump.
Fixes: 3eb07c8c8adb ("pid namespaces: destroy pid namespace on init's death")
Fixes: b9a985db9896 ("pid_ns: Sleep in TASK_INTERRUPTIBLE in zap_pid_ns_processes")
Cc: stable@vger.kernel.org # 6.1+
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Aviv Vaknin <vaknins33@gmail.com>
Link: https://patch.msgid.link/20261002202820.3433318-1-vaknins33@gmail.com
Acked-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Bradley Morgan <brads@mainlining.org>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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There is a race between watch_queue_set_size() and post_one_notification().
watch_queue_set_size() publishes wqueue->notes, notes_bitmap, nr_pages and
nr_notes with plain stores, and post_one_notification() reads them with
plain loads under a different lock, so nothing orders the four stores
against the poster's loads: depending on the build, notes can be stored
last (gcc 14 on x86-64 does this). Since keyctl_watch_key() lets a watch
attach to a queue before it is sized, post_one_notification() can already
be running on another CPU at that moment: it reads nr_notes > 0, passes
its bounds check, and then reads notes while it is still NULL,
dereferencing notes[0].
An unprivileged user triggers this reliably by watching one of its own
keys through a notification pipe and racing ioctl(IOC_WATCH_QUEUE_SET_SIZE)
on that pipe against keyctl(KEYCTL_SETPERM) on the key from another CPU,
triggering:
BUG: kernel NULL pointer dereference, address: 0000000000000000
RIP: 0010:post_one_notification.isra.0+0xa2/0x1e0
Call Trace:
__post_watch_notification+0x148/0x180
keyctl_setperm_key+0x119/0x130
do_syscall_64+0x108/0x4c0
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Kernel panic - not syncing: Fatal exception in interrupt
Fix this by publishing nr_notes last with smp_store_release(), and by
reading it once with smp_load_acquire() in post_one_notification() before
the bitmap and the page array are touched. A poster that observes a
non-zero nr_notes then also observes the pool behind it; one that observes
zero drops the notification as before.
Fixes: c73be61cede5 ("pipe: Add general notification queue support")
Reported-by: Dae R. Jeong <threeearcat@gmail.com>
Closes: https://lore.kernel.org/all/ZT-S8Q7tyutcvu_q@dragonet/
Reported-by: AutonomousCodeSecurity@microsoft.com
Suggested-by: Dae R. Jeong <threeearcat@gmail.com>
Signed-off-by: Cen Zhang (Microsoft) <cenzhang@linux.microsoft.com>
Link: https://patch.msgid.link/20261009224715.46121-1-cenzhang@linux.microsoft.com
Reviewed-by: Bradley Morgan <brads@mainlining.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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A FUT_OFF_MMSHARED futex is a shared futex that refers to an MM.
It is possible for a process to wait on a shared futex with a different MM
because a FUT_OFF_INODE waiter can be requeued onto a FUT_OFF_MMSHARED
futex by another process.
This can cause FUT_OFF_MMSHARED waiters on a freed MM to consume
wakeups intended for a newly allocated MM at the same address.
Fix it by keying FUT_OFF_MMSHARED using a unique 64-bit per-MM ID.
Leave private futexes as before to avoid influencing the performance of the
hotpath.
(Multi-threaded processes typically implicitly use FUT_OFF_MMSHARED by
setting clear_child_tid such that it points into anonymous memory, which
causes mm_release() in a multi-threaded mm to perform FUTEX_WAKE.)
Fixes: 222993395ed3 ("futex: Remove pointless mmgrap() + mmdrop()")
Closes: https://lore.kernel.org/r/CAG48ez0dLBpc3QtbAhMMVNHwHL94iHh2G+h-=BVFR4dDuzZr1g@mail.gmail.com/
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260929-futex-mmshared-fix-v1-1-262b1ffeb3d0@google.com
Cc: stable@vger.kernel.org
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Paul reported recent RCU changes exposed a lost resched where CPU idles
with a rcutorture thread waiting while being completely runnable.
Dumping the rq state at the time of idling with runnable tasks showed
the following:
rq->next_class = &fair_sched_class
rq->nr_running = 1
rq->cfs.h_nr_queued = 0
rq->rt.rt_nr_running = 1
Although the waiting task was an RT task, "rq->next_class" did not point
to rt_sched_class and was stuck at the lower priority fair_sched_class.
Inspecting sched_change_end() revealed the following race with
__sched_setscheduler() for queued, but non-running tasks:
CPU0 CPU1
==== ====
__schedule()
/*
* rq->donor is a fair task that blocks.
* rq->next_class = &fair_sched_class
*/
rq_lock(rq0)
pick_next_task()
/* nr_running = 0 */
pick_task_fair()
sched_balance_newidle()
raw_spin_rq_unlock(rq0)
rq_lock(rq0)
activate_task(rq0, p)
/* p is a fair task */
rq0->nr_running++;
rq0->cfs.h_nr_queued++;
wakeup_preempt(rq, p)
rq->next_class = &fair_sched_class
resched_curr()
rq_unlock(rq0)
__sched_setscheduler(p)
/* p is moved to SCHED_RR */
task_rq_lock(p)
sched_change_begin()
rq0->cfs.h_nr_queued--;
rq0->rt.rt_nr_running++;
sched_change_end()
/*
* p->on_rq = 1 (ctx->queued)
* but p is not rq->donor
* (!ctx->running) hence
* resched_curr() is and
* rq->next_class upgrade is
* skipped.
*/
task_rq_unlock()
raw_spin_rq_lock(rq0)
/*
* rq->nr_running = 1
* rq->cfs.h_nr_queued = 0
* rq->rt.rt_nr_running = 1
* rq->next_class = &fair_sched_class
*/
if (rq->cfs.h_nr_queued && ...)
/* Above is false */
if (rq_modified_above(this_rq, &fair_sched_class))
/* Also false since rq->next_class is still fair */
/*
* sched_balance_newidle() is considered to
* have failed to pull any fair tasks and no
* other wakeups were detected.
*/
return NULL; /* pick_task_fair() */
pick_task_idle()
return rq->idle;
next = rq->idle;
/* Preemption indicators are lost */
clear_tsk_need_resched(prev);
clear_preempt_need_resched();
rq->curr = rq->idle;
!!! rq->idle switches in with rq->running == 1 but !need_resched() !!!
In simple words, enqueue, followed by a class change of the newly queued
task goes unnoticed in rq->next_class indicator and
sched_balance_newidle() sees no fair task, nor any higher priority task
enqueued.
The above sequence will lead to CPU idling with a runnable task on the
CPU.
Call wakeup_preempt() for ctx->queued cases in sched_change_end() to
re-evaluate rq->next_class after class change (ENQUEUE_CLASS) and set
the NEED_RESCHED indicator accordingly.
Newidle balance will correctly see an enqueue of a higher priority
task if a queued task was upgraded when the rq_lock() was dropped and
will retry the pick.
Closes: https://lore.kernel.org/lkml/8fa7f795-518c-4507-b684-60b0c1cac2c5@paulmck-laptop/
Fixes: 704069649b5b ("sched/core: Rework sched_class::wakeup_preempt() and rq_modified_*()")
Reported-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Phil Auld <pauld@redhat.com>
Link: https://patch.msgid.link/20261013152455.9039-1-kprateek.nayak@amd.com
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|
Use the function name in the kerneldoc description.
Fixes: c83e3d291243 ("braille: nbcon: Allow to use a serial console with NBCON API as Braille console")
Signed-off-by: Muhammad Mahdi Amirpour <ampr.mhd@gmail.com>
Reviewed-by: John Ogness <john.ogness@linutronix.de>
Link: https://patch.msgid.link/20261013151300.75966-1-ampr.mhd@gmail.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
|
|
When the system is going down a normal way, the NBCON kthreads are
flushed and stopped properly via a syscore shutdown callback, see
printk_kthreads_shutdown().
One missing piece is emergency_restart() where the kthreads are not
stopped. It might be called from several non-panic code paths,
e.g. sysrq-o, kdb_reboot(), or some watchdogs.
Fix it by explicitly entering the emergency (atomic) mode and trying
to flush the consoles there.
Note that printk_trigger_flush() must be used instead of pr_flush()
because the later is not safe in an atomic context.
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/all/202608061008.48a1e76e-lkp@intel.com/
Suggested-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: John Ogness <john.ogness@linutronix.de>
Link: https://patch.msgid.link/20261013154141.94016-1-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
|
|
A task can be found on a non-local DSQ while the CPU which dispatched it
is still running ops.dequeue() and hasn't cleared SCX_OPSS_DISPATCHING.
The DSQ consume and move paths don't wait for the dispatch to finish and
can operate on the task concurrently with the dispatcher.
Call scx_wait_dispatching() in scx_move_local_task_to_local_dsq(),
unlink_dsq_and_switch_rq_lock() and move_task_between_dsqs() before they
operate on the task. In scx_move_local_task_to_local_dsq(), wait before
scx_resolve_local_dsq() as it may update p->scx.flags.
Fixes: ebf1ccff79c4 ("sched_ext: Fix ops.dequeue() semantics")
Fixes: cb86607ada73 ("sched_ext: Don't run ops.dequeue() with a DSQ lock held")
Cc: stable@vger.kernel.org # v7.1+
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Assisted-by: Claude:claude-opus-5.5
Signed-off-by: Kuba Piecuch <jpiecuch@google.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
|
|
Waiting for SCX_OPSS_DISPATCHING to clear isn't specific to the reenqueue
paths. Any path which takes a task off a DSQ can find it while the
dispatch is still in flight, and the next patch calls the helper from the
DSQ consume and move paths. Rename it to scx_wait_dispatching() and
update its comment accordingly.
No functional change.
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Assisted-by: Claude:claude-opus-5.5
Signed-off-by: Kuba Piecuch <jpiecuch@google.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
|
|
The restricted select_cpu kfunc path handles single-CPU and
migration-disabled tasks without going through scx_select_cpu_dfl().
It currently uses prev_cpu as the candidate, even though prev_cpu is only a
hint and may no longer be usable after an affinity change. With a
caller-provided @allowed mask, this can also return an idle CPU outside
p->cpus_ptr.
Derive the candidate from task state instead: use the sole CPU in
p->cpus_ptr for single-CPU tasks and task_cpu(p) for migration-disabled
tasks. Validate it against p->cpus_ptr and @allowed before claiming its
idle state.
Since the derived candidate may be on a different NUMA node from
prev_cpu, also preserve SCX_PICK_IDLE_IN_NODE by rejecting cross-node
candidates.
Perform all checks before scx_idle_test_and_clear_cpu(), as a successful
call consumes the CPU's idle bit.
Fixes: 683d2d0faba1 ("sched_ext: idle: Introduce scx_bpf_select_cpu_and()")
Cc: stable@vger.kernel.org
Signed-off-by: Hui Su <sh_def@163.com>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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|
scx_bypass() claims bypass dispatch when the scheduler's depth goes from
zero to one and releases it when the depth returns to zero, but propagates
only the depth to the descendants, not the claim. A descendant that starts
bypassing with its ancestor never claims, and one whose own bypass ends
under the ancestor's keeps its claim, as its depth does not return to zero.
A sub-scheduler enable whose bypass ends under a PM suspend thus leaks its
claim: the parent keeps hosting bypass dispatch and the sub-scheduler's next
bypass trips the WARN_ON_ONCE() on the claim. A sub-scheduler disable that
starts under a PM suspend has no claim, so once the resume lifts the root's
bypass its tasks sit on the parent's bypass DSQs with nobody consuming them.
Claim for every descendant whose depth goes from zero to one in the
propagation and release every scheduler in the subtree whose depth returned
to zero once the tasks have moved out of the bypass DSQs. A parent that is
bypassing itself when a descendant claims consumes only its own bypass DSQs,
empty until it leaves bypass and becomes the host.
Fixes: aa2a0a19686c ("sched_ext: Separate bypass dispatch enabling from bypass depth tracking")
Cc: stable@vger.kernel.org # v7.1+
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
|
|
scx_bypass() propagates a depth change to the descendants only when the
scheduler's own depth crosses zero, so an own bypass that starts under an
ancestor's never reaches them. When the ancestor's bypass ends first, the
descendants leave bypass while the scheduler is still bypassing: a
sub-scheduler disabled under a PM suspend has its children re-queue their
tasks through their own BPF schedulers at resume, mid-teardown. If the own
bypass then ends, every descendant is decremented once more than incremented
and dec_bypass_depth() warns, though no current caller gets there.
Propagate on every call so that a descendant's depth is the sum of its own
bypasses and its ancestors'. The early return follows the walk, as a
descendant's depth is at least the scheduler's and nothing changes bypass
state unless the scheduler's own does.
Fixes: c7f0e467a27a ("sched_ext: Prepare bypass mode for hierarchical operation")
Cc: stable@vger.kernel.org # v7.1+
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
|
|
A deferred reenqueue can read a freed user DSQ. The request stays on its
CPU's deferred list until run_deferred() takes it, and the RCU callback that
frees the DSQ assumes that the grace period has flushed it, so exit_dsq()
checks the per-CPU node without the deferred list lock. A grace period waits
for readers in flight, not for a pending run_deferred(). A run_deferred()
which starts after the grace period began can detach the request right
before the callback looks and then read the freed DSQ's id.
Cancel the pending requests before the grace period instead. The irq work
that frees the DSQ unlinks every CPU's request under the per-CPU deferred
list lock, and schedule_dsq_reenq() ignores a new request under the same
lock once the id is invalid. Only a run_deferred() that started before the
grace period can hold a request, and it runs with IRQs disabled, so the
grace period waits for it and nothing touches the DSQ after the callback.
Fixes: 84b1a0ea0b7c ("sched_ext: Implement scx_bpf_dsq_reenq() for user DSQs")
Cc: stable@vger.kernel.org # v7.1+
Reported-and-tested-by: Hui Su <sh_def@163.com>
Link: https://lore.kernel.org/all/20261008024753.4096008-1-sh_def@163.com/
Signed-off-by: Tejun Heo <tj@kernel.org>
|
|
With SCX_OPS_ENQ_LAST, the last runnable task on a CPU is passed to
ops.enqueue() instead of being kept running. Exiting tasks without
SCX_OPS_ENQ_EXITING, migration disabled tasks without
SCX_OPS_ENQ_MIGRATION_DISABLED and tasks on an offline rq skip ops.enqueue()
and go straight to the local DSQ. This happens in put_prev_task_scx() after
the pick has settled on idle, so nothing reschedules the CPU, which idles
with the task queued until an unrelated wakeup lands on it or the watchdog
fires.
scx_mitosis, which sets SCX_OPS_ENQ_LAST without SCX_OPS_ENQ_EXITING, hit
this during mass cgroup teardown: exiting tasks stuck in exit_mmap() for
over 40 seconds.
A task put on the local DSQ runs, as anywhere else. If the SCX_ENQ_LAST
enqueue left the task on this CPU's local DSQ, set need_resched on the task
being switched in, as proxy_resched_idle() does. resched_curr() would flag
the task being put instead, and __schedule() clears that right after the
pick.
Fixes: f0e1a0643a59 ("sched_ext: Implement BPF extensible scheduler class")
Cc: stable@vger.kernel.org # v6.12+
Reported-by: Xiangyu Bu <xbu@meta.com>
Link: https://github.com/sched-ext/scx/pull/3870
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Dan Schatzberg <schatzberg.dan@gmail.com>
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Pull dma-mapping fixes from Marek Szyprowski:
"Two more fixes for the corner cases in the DMA-mapping SWIOTLB code
(Peng Fan and Marek Szyprowski)"
* tag 'dma-mapping-7.3-2026-10-09' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux:
swiotlb: fix default_swiotlb_limit() for non-growable default pool
iommu/dma: skip swiotlb bounce for DMA_ATTR_MMIO in iommu_dma_map_phys
|
Linus Torvalds
Petr Mladek
John Ogness
Antoine Huret
Haris Okanovic
Lorenzo Stoakes (ARM)
Hui Su
Taeyang Lee
Hao Ge
Lee Jones
Vincent Donnefort
Martin Kaiser
Amit Machhiwal
Tengda Wu
Dmitry Kandybka
Krystian Kaniewski
Donggeun Yoo
David Carlier
Christian Brauner
Aviv Vaknin
Cen Zhang (Microsoft)
Jann Horn
K Prateek Nayak
Muhammad Mahdi Amirpour
Kuba Piecuch
Tejun Heo