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[ Upstream commit 2658a1720a1944fbaeda937000ad2b3c3dfaf1bb ]
Fix an inconsistency between func_states_equal() and
collect_linked_regs():
- regsafe() uses check_ids() to verify that cached and current states
have identical register id mapping.
- func_states_equal() calls regsafe() only for registers computed as
live by compute_live_registers().
- clean_live_states() is supposed to remove dead registers from cached
states, but it can skip states belonging to an iterator-based loop.
- collect_linked_regs() collects all registers sharing the same id,
ignoring the marks computed by compute_live_registers().
Linked registers are stored in the state's jump history.
- backtrack_insn() marks all linked registers for an instruction
as precise whenever one of the linked registers is precise.
The above might lead to a scenario:
- There is an instruction I with register rY known to be dead at I.
- Instruction I is reached via two paths: first A, then B.
- On path A:
- There is an id link between registers rX and rY.
- Checkpoint C is created at I.
- Linked register set {rX, rY} is saved to the jump history.
- rX is marked as precise at I, causing both rX and rY
to be marked precise at C.
- On path B:
- There is no id link between registers rX and rY,
otherwise register states are sub-states of those in C.
- Because rY is dead at I, check_ids() returns true.
- Current state is considered equal to checkpoint C,
propagate_precision() propagates spurious precision
mark for register rY along the path B.
- Depending on a program, this might hit verifier_bug()
in the backtrack_insn(), e.g. if rY ∈ [r1..r5]
and backtrack_insn() spots a function call.
The reproducer program is in the next patch.
This was hit by sched_ext scx_lavd scheduler code.
Changes in tests:
- verifier_scalar_ids.c selftests need modification to preserve
some registers as live for __msg() checks.
- exceptions_assert.c adjusted to match changes in the verifier log,
R0 is dead after conditional instruction and thus does not get
range.
- precise.c adjusted to match changes in the verifier log, register r9
is dead after comparison and it's range is not important for test.
Reported-by: Emil Tsalapatis <emil@etsalapatis.com>
Fixes: 0fb3cf6110a5 ("bpf: use register liveness information for func_states_equal")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260306-linked-regs-and-propagate-precision-v1-1-18e859be570d@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 457965c13f0837a289c9164b842d0860133f6274 ]
If trigger_data_alloc() fails and returns NULL, event_hist_trigger_parse()
jumps to the out_free error path. While kfree() safely handles a NULL
pointer, trigger_data_free() does not. This causes a NULL pointer
dereference in trigger_data_free() when evaluating
data->cmd_ops->set_filter.
Fix the problem by adding a NULL pointer check to trigger_data_free().
The problem was found by an experimental code review agent based on
gemini-3.1-pro while reviewing backports into v6.18.y.
Cc: Miaoqian Lin <linmq006@gmail.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://patch.msgid.link/20260305193339.2810953-1-linux@roeck-us.net
Fixes: 0550069cc25f ("tracing: Properly process error handling in event_hist_trigger_parse()")
Assisted-by: Gemini:gemini-3.1-pro
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit e48a869957a70cc39b4090cd27c36a86f8db9b92 ]
The timekeeping_validate_timex() function validates the timex status
of an auxiliary system clock even when the status is not to be changed,
which causes unexpected errors for applications that make read-only
clock_adjtime() calls, or set some other timex fields, but without
clearing the status field.
Do the AUX-specific status validation only when the modes field contains
ADJ_STATUS, i.e. the application is actually trying to change the
status. This makes the AUX-specific clock_adjtime() behavior consistent
with CLOCK_REALTIME.
Fixes: 4eca49d0b621 ("timekeeping: Prepare do_adtimex() for auxiliary clocks")
Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260225085231.276751-1-mlichvar@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit d658686a1331db3bb108ca079d76deb3208ed949 ]
Running stress-ng --schedpolicy 0 on an RT kernel on a big machine
might lead to the following WARNINGs (edited).
sched: DL de-boosted task PID 22725: REPLENISH flag missing
WARNING: CPU: 93 PID: 0 at kernel/sched/deadline.c:239 dequeue_task_dl+0x15c/0x1f8
... (running_bw underflow)
Call trace:
dequeue_task_dl+0x15c/0x1f8 (P)
dequeue_task+0x80/0x168
deactivate_task+0x24/0x50
push_dl_task+0x264/0x2e0
dl_task_timer+0x1b0/0x228
__hrtimer_run_queues+0x188/0x378
hrtimer_interrupt+0xfc/0x260
...
The problem is that when a SCHED_DEADLINE task (lock holder) is
changed to a lower priority class via sched_setscheduler(), it may
fail to properly inherit the parameters of potential DEADLINE donors
if it didn't already inherit them in the past (shorter deadline than
donor's at that time). This might lead to bandwidth accounting
corruption, as enqueue_task_dl() won't recognize the lock holder as
boosted.
The scenario occurs when:
1. A DEADLINE task (donor) blocks on a PI mutex held by another
DEADLINE task (holder), but the holder doesn't inherit parameters
(e.g., it already has a shorter deadline)
2. sched_setscheduler() changes the holder from DEADLINE to a lower
class while still holding the mutex
3. The holder should now inherit DEADLINE parameters from the donor
and be enqueued with ENQUEUE_REPLENISH, but this doesn't happen
Fix the issue by introducing __setscheduler_dl_pi(), which detects when
a DEADLINE (proper or boosted) task gets setscheduled to a lower
priority class. In case, the function makes the task inherit DEADLINE
parameters of the donoer (pi_se) and sets ENQUEUE_REPLENISH flag to
ensure proper bandwidth accounting during the next enqueue operation.
Fixes: 2279f540ea7d ("sched/deadline: Fix priority inheritance with multiple scheduling classes")
Reported-by: Bruno Goncalves <bgoncalv@redhat.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260302-upstream-fix-deadline-piboost-b4-v3-1-6ba32184a9e0@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 6932256d3a3764f3a5e06e2cb8603be45b6a9fef ]
Commit 2dc164a48e6fd ("sysctl: Create converter functions with two new
macros") incorrectly returns error to user space when jiffies sysctl
converter is used. The old overflow check got replaced with an
unconditional one:
+ if (USER_HZ < HZ)
+ return -EINVAL;
which will always be true on configurations with "USER_HZ < HZ".
Remove the check; it is no longer needed as clock_t_to_jiffies() returns
ULONG_MAX for the overflow case and proc_int_u2k_conv_uop() checks for
"> INT_MAX" after conversion
Fixes: 2dc164a48e6fd ("sysctl: Create converter functions with two new macros")
Reported-by: Colm Harrington <colm.harrington@oracle.com>
Signed-off-by: Gerd Rausch <gerd.rausch@oracle.com>
Signed-off-by: Joel Granados <joel.granados@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 56145d237385ca0e7ca9ff7b226aaf2eb8ef368b ]
The root cause of this bug is that when 'bpf_link_put' reduces the
refcount of 'shim_link->link.link' to zero, the resource is considered
released but may still be referenced via 'tr->progs_hlist' in
'cgroup_shim_find'. The actual cleanup of 'tr->progs_hlist' in
'bpf_shim_tramp_link_release' is deferred. During this window, another
process can cause a use-after-free via 'bpf_trampoline_link_cgroup_shim'.
Based on Martin KaFai Lau's suggestions, I have created a simple patch.
To fix this:
Add an atomic non-zero check in 'bpf_trampoline_link_cgroup_shim'.
Only increment the refcount if it is not already zero.
Testing:
I verified the fix by adding a delay in
'bpf_shim_tramp_link_release' to make the bug easier to trigger:
static void bpf_shim_tramp_link_release(struct bpf_link *link)
{
/* ... */
if (!shim_link->trampoline)
return;
+ msleep(100);
WARN_ON_ONCE(bpf_trampoline_unlink_prog(&shim_link->link,
shim_link->trampoline, NULL));
bpf_trampoline_put(shim_link->trampoline);
}
Before the patch, running a PoC easily reproduced the crash(almost 100%)
with a call trace similar to KaiyanM's report.
After the patch, the bug no longer occurs even after millions of
iterations.
Fixes: 69fd337a975c ("bpf: per-cgroup lsm flavor")
Reported-by: Kaiyan Mei <M202472210@hust.edu.cn>
Closes: https://lore.kernel.org/bpf/3c4ebb0b.46ff8.19abab8abe2.Coremail.kaiyanm@hust.edu.cn/
Signed-off-by: Lang Xu <xulang@uniontech.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://patch.msgid.link/279EEE1BA1DDB49D+20260303095217.34436-1-xulang@uniontech.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit da46b5dfef48658d03347cda21532bcdbb521e67 ]
tracing_record_cmdline() internally uses __this_cpu_read() and
__this_cpu_write() on the per-CPU variable trace_cmdline_save, and
trace_save_cmdline() explicitly asserts preemption is disabled via
lockdep_assert_preemption_disabled(). These operations are only safe
when preemption is off, as they were designed to be called from the
scheduler context (probe_wakeup_sched_switch() / probe_wakeup()).
__blk_add_trace() was calling tracing_record_cmdline(current) early in
the blk_tracer path, before ring buffer reservation, from process
context where preemption is fully enabled. This triggers the following
using blktests/blktrace/002:
blktrace/002 (blktrace ftrace corruption with sysfs trace) [failed]
runtime 0.367s ... 0.437s
something found in dmesg:
[ 81.211018] run blktests blktrace/002 at 2026-02-25 22:24:33
[ 81.239580] null_blk: disk nullb1 created
[ 81.357294] BUG: using __this_cpu_read() in preemptible [00000000] code: dd/2516
[ 81.362842] caller is tracing_record_cmdline+0x10/0x40
[ 81.362872] CPU: 16 UID: 0 PID: 2516 Comm: dd Tainted: G N 7.0.0-rc1lblk+ #84 PREEMPT(full)
[ 81.362877] Tainted: [N]=TEST
[ 81.362878] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014
[ 81.362881] Call Trace:
[ 81.362884] <TASK>
[ 81.362886] dump_stack_lvl+0x8d/0xb0
...
(See '/mnt/sda/blktests/results/nodev/blktrace/002.dmesg' for the entire message)
[ 81.211018] run blktests blktrace/002 at 2026-02-25 22:24:33
[ 81.239580] null_blk: disk nullb1 created
[ 81.357294] BUG: using __this_cpu_read() in preemptible [00000000] code: dd/2516
[ 81.362842] caller is tracing_record_cmdline+0x10/0x40
[ 81.362872] CPU: 16 UID: 0 PID: 2516 Comm: dd Tainted: G N 7.0.0-rc1lblk+ #84 PREEMPT(full)
[ 81.362877] Tainted: [N]=TEST
[ 81.362878] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014
[ 81.362881] Call Trace:
[ 81.362884] <TASK>
[ 81.362886] dump_stack_lvl+0x8d/0xb0
[ 81.362895] check_preemption_disabled+0xce/0xe0
[ 81.362902] tracing_record_cmdline+0x10/0x40
[ 81.362923] __blk_add_trace+0x307/0x5d0
[ 81.362934] ? lock_acquire+0xe0/0x300
[ 81.362940] ? iov_iter_extract_pages+0x101/0xa30
[ 81.362959] blk_add_trace_bio+0x106/0x1e0
[ 81.362968] submit_bio_noacct_nocheck+0x24b/0x3a0
[ 81.362979] ? lockdep_init_map_type+0x58/0x260
[ 81.362988] submit_bio_wait+0x56/0x90
[ 81.363009] __blkdev_direct_IO_simple+0x16c/0x250
[ 81.363026] ? __pfx_submit_bio_wait_endio+0x10/0x10
[ 81.363038] ? rcu_read_lock_any_held+0x73/0xa0
[ 81.363051] blkdev_read_iter+0xc1/0x140
[ 81.363059] vfs_read+0x20b/0x330
[ 81.363083] ksys_read+0x67/0xe0
[ 81.363090] do_syscall_64+0xbf/0xf00
[ 81.363102] entry_SYSCALL_64_after_hwframe+0x76/0x7e
[ 81.363106] RIP: 0033:0x7f281906029d
[ 81.363111] Code: 31 c0 e9 c6 fe ff ff 50 48 8d 3d 66 63 0a 00 e8 59 ff 01 00 66 0f 1f 84 00 00 00 00 00 80 3d 41 33 0e 00 00 74 17 31 c0 0f 05 <48> 3d 00 f0 ff ff 77 5b c3 66 2e 0f 1f 84 00 00 00 00 00 48 83 ec
[ 81.363113] RSP: 002b:00007ffca127dd48 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[ 81.363120] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f281906029d
[ 81.363122] RDX: 0000000000001000 RSI: 0000559f8bfae000 RDI: 0000000000000000
[ 81.363123] RBP: 0000000000001000 R08: 0000002863a10a81 R09: 00007f281915f000
[ 81.363124] R10: 00007f2818f77b60 R11: 0000000000000246 R12: 0000559f8bfae000
[ 81.363126] R13: 0000000000000000 R14: 0000000000000000 R15: 000000000000000a
[ 81.363142] </TASK>
The same BUG fires from blk_add_trace_plug(), blk_add_trace_unplug(),
and blk_add_trace_rq() paths as well.
The purpose of tracing_record_cmdline() is to cache the task->comm for
a given PID so that the trace can later resolve it. It is only
meaningful when a trace event is actually being recorded. Ring buffer
reservation via ring_buffer_lock_reserve() disables preemption, and
preemption remains disabled until the event is committed :-
__blk_add_trace()
__trace_buffer_lock_reserve()
__trace_buffer_lock_reserve()
ring_buffer_lock_reserve()
preempt_disable_notrace(); <---
With this fix blktests for blktrace pass:
blktests (master) # ./check blktrace
blktrace/001 (blktrace zone management command tracing) [passed]
runtime 3.650s ... 3.647s
blktrace/002 (blktrace ftrace corruption with sysfs trace) [passed]
runtime 0.411s ... 0.384s
Fixes: 7ffbd48d5cab ("tracing: Cache comms only after an event occurred")
Reported-by: Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit a7b4bc094fbaa7dc7b7b91ae33549bbd7eefaac1 ]
In the error path of load_module(), under the free_module label, the
code calls lockdep_free_key_range() to release lock classes associated
with the MOD_DATA, MOD_RODATA and MOD_RO_AFTER_INIT module regions, and
subsequently invokes module_deallocate().
Since commit ac3b43283923 ("module: replace module_layout with
module_memory"), the module_deallocate() function calls free_mod_mem(),
which releases the lock classes as well and considers all module
regions.
Attempting to free these classes twice is unnecessary. Remove the
redundant code in load_module().
Fixes: ac3b43283923 ("module: replace module_layout with module_memory")
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
Reviewed-by: Daniel Gomez <da.gomez@samsung.com>
Reviewed-by: Aaron Tomlin <atomlin@atomlin.com>
Acked-by: Song Liu <song@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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commit e39bb9e02b68942f8e9359d2a3efe7d37ae6be0e upstream.
When a process forks, the child process copies the parent's VMAs but the
user_mapped reference count is not incremented. As a result, when both the
parent and child processes exit, tracing_buffers_mmap_close() is called
twice. On the second call, user_mapped is already 0, causing the function to
return -ENODEV and triggering a WARN_ON.
Normally, this isn't an issue as the memory is mapped with VM_DONTCOPY set.
But this is only a hint, and the application can call
madvise(MADVISE_DOFORK) which resets the VM_DONTCOPY flag. When the
application does that, it can trigger this issue on fork.
Fix it by incrementing the user_mapped reference count without re-mapping
the pages in the VMA's open callback.
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Vincent Donnefort <vdonnefort@google.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Link: https://patch.msgid.link/20260227025842.1085206-1-wangqing7171@gmail.com
Fixes: cf9f0f7c4c5bb ("tracing: Allow user-space mapping of the ring-buffer")
Reported-by: syzbot+3b5dd2030fe08afdf65d@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=3b5dd2030fe08afdf65d
Tested-by: syzbot+3b5dd2030fe08afdf65d@syzkaller.appspotmail.com
Signed-off-by: Qing Wang <wangqing7171@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit efc11a667878a1d655ff034a93a539debbfedb12 ]
We're hitting an invariant violation in Cilium that sometimes leads to
BPF programs being rejected and Cilium failing to start [1]. The
following extract from verifier logs shows what's happening:
from 201 to 236: R1=0 R6=ctx() R7=1 R9=scalar(smin=umin=smin32=umin32=3584,smax=umax=smax32=umax32=3840,var_off=(0xe00; 0x100)) R10=fp0
236: R1=0 R6=ctx() R7=1 R9=scalar(smin=umin=smin32=umin32=3584,smax=umax=smax32=umax32=3840,var_off=(0xe00; 0x100)) R10=fp0
; if (magic == MARK_MAGIC_HOST || magic == MARK_MAGIC_OVERLAY || magic == MARK_MAGIC_ENCRYPT) @ bpf_host.c:1337
236: (16) if w9 == 0xe00 goto pc+45 ; R9=scalar(smin=umin=smin32=umin32=3585,smax=umax=smax32=umax32=3840,var_off=(0xe00; 0x100))
237: (16) if w9 == 0xf00 goto pc+1
verifier bug: REG INVARIANTS VIOLATION (false_reg1): range bounds violation u64=[0xe01, 0xe00] s64=[0xe01, 0xe00] u32=[0xe01, 0xe00] s32=[0xe01, 0xe00] var_off=(0xe00, 0x0)
We reach instruction 236 with two possible values for R9, 0xe00 and
0xf00. This is perfectly reflected in the tnum, but of course the ranges
are less accurate and cover [0xe00; 0xf00]. Taking the fallthrough path
at instruction 236 allows the verifier to reduce the range to
[0xe01; 0xf00]. The tnum is however not updated.
With these ranges, at instruction 237, the verifier is not able to
deduce that R9 is always equal to 0xf00. Hence the fallthrough pass is
explored first, the verifier refines the bounds using the assumption
that R9 != 0xf00, and ends up with an invariant violation.
This pattern of impossible branch + bounds refinement is common to all
invariant violations seen so far. The long-term solution is likely to
rely on the refinement + invariant violation check to detect dead
branches, as started by Eduard. To fix the current issue, we need
something with less refactoring that we can backport.
This patch uses the tnum_step helper introduced in the previous patch to
detect the above situation. In particular, three cases are now detected
in the bounds refinement:
1. The u64 range and the tnum only overlap in umin.
u64: ---[xxxxxx]-----
tnum: --xx----------x-
2. The u64 range and the tnum only overlap in the maximum value
represented by the tnum, called tmax.
u64: ---[xxxxxx]-----
tnum: xx-----x--------
3. The u64 range and the tnum only overlap in between umin (excluded)
and umax.
u64: ---[xxxxxx]-----
tnum: xx----x-------x-
To detect these three cases, we call tnum_step(tnum, umin), which
returns the smallest member of the tnum greater than umin, called
tnum_next here. We're in case (1) if umin is part of the tnum and
tnum_next is greater than umax. We're in case (2) if umin is not part of
the tnum and tnum_next is equal to tmax. Finally, we're in case (3) if
umin is not part of the tnum, tnum_next is inferior or equal to umax,
and calling tnum_step a second time gives us a value past umax.
This change implements these three cases. With it, the above bytecode
looks as follows:
0: (85) call bpf_get_prandom_u32#7 ; R0=scalar()
1: (47) r0 |= 3584 ; R0=scalar(smin=0x8000000000000e00,umin=umin32=3584,smin32=0x80000e00,var_off=(0xe00; 0xfffffffffffff1ff))
2: (57) r0 &= 3840 ; R0=scalar(smin=umin=smin32=umin32=3584,smax=umax=smax32=umax32=3840,var_off=(0xe00; 0x100))
3: (15) if r0 == 0xe00 goto pc+2 ; R0=3840
4: (15) if r0 == 0xf00 goto pc+1
4: R0=3840
6: (95) exit
In addition to the new selftests, this change was also verified with
Agni [3]. For the record, the raw SMT is available at [4]. The property
it verifies is that: If a concrete value x is contained in all input
abstract values, after __update_reg_bounds, it will continue to be
contained in all output abstract values.
Link: https://github.com/cilium/cilium/issues/44216 [1]
Link: https://pchaigno.github.io/test-verifier-complexity.html [2]
Link: https://github.com/bpfverif/agni [3]
Link: https://pastebin.com/raw/naCfaqNx [4]
Fixes: 0df1a55afa83 ("bpf: Warn on internal verifier errors")
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Tested-by: Marco Schirrmeister <mschirrmeister@gmail.com>
Co-developed-by: Harishankar Vishwanathan <harishankar.vishwanathan@gmail.com>
Signed-off-by: Harishankar Vishwanathan <harishankar.vishwanathan@gmail.com>
Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>
Link: https://lore.kernel.org/r/ef254c4f68be19bd393d450188946821c588565d.1772225741.git.paul.chaignon@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 76e954155b45294c502e3d3a9e15757c858ca55e ]
This commit introduces tnum_step(), a function that, when given t, and a
number z returns the smallest member of t larger than z. The number z
must be greater or equal to the smallest member of t and less than the
largest member of t.
The first step is to compute j, a number that keeps all of t's known
bits, and matches all unknown bits to z's bits. Since j is a member of
the t, it is already a candidate for result. However, we want our result
to be (minimally) greater than z.
There are only two possible cases:
(1) Case j <= z. In this case, we want to increase the value of j and
make it > z.
(2) Case j > z. In this case, we want to decrease the value of j while
keeping it > z.
(Case 1) j <= z
t = xx11x0x0
z = 10111101 (189)
j = 10111000 (184)
^
k
(Case 1.1) Let's first consider the case where j < z. We will address j
== z later.
Since z > j, there had to be a bit position that was 1 in z and a 0 in
j, beyond which all positions of higher significance are equal in j and
z. Further, this position could not have been unknown in a, because the
unknown positions of a match z. This position had to be a 1 in z and
known 0 in t.
Let k be position of the most significant 1-to-0 flip. In our example, k
= 3 (starting the count at 1 at the least significant bit). Setting (to
1) the unknown bits of t in positions of significance smaller than
k will not produce a result > z. Hence, we must set/unset the unknown
bits at positions of significance higher than k. Specifically, we look
for the next larger combination of 1s and 0s to place in those
positions, relative to the combination that exists in z. We can achieve
this by concatenating bits at unknown positions of t into an integer,
adding 1, and writing the bits of that result back into the
corresponding bit positions previously extracted from z.
>From our example, considering only positions of significance greater
than k:
t = xx..x
z = 10..1
+ 1
-----
11..0
This is the exact combination 1s and 0s we need at the unknown bits of t
in positions of significance greater than k. Further, our result must
only increase the value minimally above z. Hence, unknown bits in
positions of significance smaller than k should remain 0. We finally
have,
result = 11110000 (240)
(Case 1.2) Now consider the case when j = z, for example
t = 1x1x0xxx
z = 10110100 (180)
j = 10110100 (180)
Matching the unknown bits of the t to the bits of z yielded exactly z.
To produce a number greater than z, we must set/unset the unknown bits
in t, and *all* the unknown bits of t candidates for being set/unset. We
can do this similar to Case 1.1, by adding 1 to the bits extracted from
the masked bit positions of z. Essentially, this case is equivalent to
Case 1.1, with k = 0.
t = 1x1x0xxx
z = .0.1.100
+ 1
---------
.0.1.101
This is the exact combination of bits needed in the unknown positions of
t. After recalling the known positions of t, we get
result = 10110101 (181)
(Case 2) j > z
t = x00010x1
z = 10000010 (130)
j = 10001011 (139)
^
k
Since j > z, there had to be a bit position which was 0 in z, and a 1 in
j, beyond which all positions of higher significance are equal in j and
z. This position had to be a 0 in z and known 1 in t. Let k be the
position of the most significant 0-to-1 flip. In our example, k = 4.
Because of the 0-to-1 flip at position k, a member of t can become
greater than z if the bits in positions greater than k are themselves >=
to z. To make that member *minimally* greater than z, the bits in
positions greater than k must be exactly = z. Hence, we simply match all
of t's unknown bits in positions more significant than k to z's bits. In
positions less significant than k, we set all t's unknown bits to 0
to retain minimality.
In our example, in positions of greater significance than k (=4),
t=x000. These positions are matched with z (1000) to produce 1000. In
positions of lower significance than k, t=10x1. All unknown bits are set
to 0 to produce 1001. The final result is:
result = 10001001 (137)
This concludes the computation for a result > z that is a member of t.
The procedure for tnum_step() in this commit implements the idea
described above. As a proof of correctness, we verified the algorithm
against a logical specification of tnum_step. The specification asserts
the following about the inputs t, z and output res that:
1. res is a member of t, and
2. res is strictly greater than z, and
3. there does not exist another value res2 such that
3a. res2 is also a member of t, and
3b. res2 is greater than z
3c. res2 is smaller than res
We checked the implementation against this logical specification using
an SMT solver. The verification formula in SMTLIB format is available
at [1]. The verification returned an "unsat": indicating that no input
assignment exists for which the implementation and the specification
produce different outputs.
In addition, we also automatically generated the logical encoding of the
C implementation using Agni [2] and verified it against the same
specification. This verification also returned an "unsat", confirming
that the implementation is equivalent to the specification. The formula
for this check is also available at [3].
Link: https://pastebin.com/raw/2eRWbiit [1]
Link: https://github.com/bpfverif/agni [2]
Link: https://pastebin.com/raw/EztVbBJ2 [3]
Co-developed-by: Srinivas Narayana <srinivas.narayana@rutgers.edu>
Signed-off-by: Srinivas Narayana <srinivas.narayana@rutgers.edu>
Co-developed-by: Santosh Nagarakatte <santosh.nagarakatte@rutgers.edu>
Signed-off-by: Santosh Nagarakatte <santosh.nagarakatte@rutgers.edu>
Signed-off-by: Harishankar Vishwanathan <harishankar.vishwanathan@gmail.com>
Link: https://lore.kernel.org/r/93fdf71910411c0f19e282ba6d03b4c65f9c5d73.1772225741.git.paul.chaignon@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Stable-dep-of: efc11a667878 ("bpf: Improve bounds when tnum has a single possible value")
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 9d21199842247ab05c675fb9b6c6ca393a5c0024 ]
This patch implements bitwise tracking (tnum analysis) for BPF_END
(byte swap) operation.
Currently, the BPF verifier does not track value for BPF_END operation,
treating the result as completely unknown. This limits the verifier's
ability to prove safety of programs that perform endianness conversions,
which are common in networking code.
For example, the following code pattern for port number validation:
int test(struct pt_regs *ctx) {
__u64 x = bpf_get_prandom_u32();
x &= 0x3f00; // Range: [0, 0x3f00], var_off: (0x0; 0x3f00)
x = bswap16(x); // Should swap to range [0, 0x3f], var_off: (0x0; 0x3f)
if (x > 0x3f) goto trap;
return 0;
trap:
return *(u64 *)NULL; // Should be unreachable
}
Currently generates verifier output:
1: (54) w0 &= 16128 ; R0=scalar(smin=smin32=0,smax=umax=smax32=umax32=16128,var_off=(0x0; 0x3f00))
2: (d7) r0 = bswap16 r0 ; R0=scalar()
3: (25) if r0 > 0x3f goto pc+2 ; R0=scalar(smin=smin32=0,smax=umax=smax32=umax32=63,var_off=(0x0; 0x3f))
Without this patch, even though the verifier knows `x` has certain bits
set, after bswap16, it loses all tracking information and treats port
as having a completely unknown value [0, 65535].
According to the BPF instruction set[1], there are 3 kinds of BPF_END:
1. `bswap(16|32|64)`: opcode=0xd7 (BPF_END | BPF_ALU64 | BPF_TO_LE)
- do unconditional swap
2. `le(16|32|64)`: opcode=0xd4 (BPF_END | BPF_ALU | BPF_TO_LE)
- on big-endian: do swap
- on little-endian: truncation (16/32-bit) or no-op (64-bit)
3. `be(16|32|64)`: opcode=0xdc (BPF_END | BPF_ALU | BPF_TO_BE)
- on little-endian: do swap
- on big-endian: truncation (16/32-bit) or no-op (64-bit)
Since BPF_END operations are inherently bit-wise permutations, tnum
(bitwise tracking) offers the most efficient and precise mechanism
for value analysis. By implementing `tnum_bswap16`, `tnum_bswap32`,
and `tnum_bswap64`, we can derive exact `var_off` values concisely,
directly reflecting the bit-level changes.
Here is the overview of changes:
1. In `tnum_bswap(16|32|64)` (kernel/bpf/tnum.c):
Call `swab(16|32|64)` function on the value and mask of `var_off`, and
do truncation for 16/32-bit cases.
2. In `adjust_scalar_min_max_vals` (kernel/bpf/verifier.c):
Call helper function `scalar_byte_swap`.
- Only do byte swap when
* alu64 (unconditional swap) OR
* switching between big-endian and little-endian machines.
- If need do byte swap:
* Firstly call `tnum_bswap(16|32|64)` to update `var_off`.
* Then reset the bound since byte swap scrambles the range.
- For 16/32-bit cases, truncate dst register to match the swapped size.
This enables better verification of networking code that frequently uses
byte swaps for protocol processing, reducing false positive rejections.
[1] https://www.kernel.org/doc/Documentation/bpf/standardization/instruction-set.rst
Co-developed-by: Shenghao Yuan <shenghaoyuan0928@163.com>
Signed-off-by: Shenghao Yuan <shenghaoyuan0928@163.com>
Co-developed-by: Yazhou Tang <tangyazhou518@outlook.com>
Signed-off-by: Yazhou Tang <tangyazhou518@outlook.com>
Signed-off-by: Tianci Cao <ziye@zju.edu.cn>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260204111503.77871-2-ziye@zju.edu.cn
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Stable-dep-of: efc11a667878 ("bpf: Improve bounds when tnum has a single possible value")
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 1872e75375c40add4a35990de3be77b5741c252c ]
On PREEMPT_RT kernels, the per-CPU xdp_dev_bulk_queue (bq) can be
accessed concurrently by multiple preemptible tasks on the same CPU.
The original code assumes bq_enqueue() and __dev_flush() run atomically
with respect to each other on the same CPU, relying on
local_bh_disable() to prevent preemption. However, on PREEMPT_RT,
local_bh_disable() only calls migrate_disable() (when
PREEMPT_RT_NEEDS_BH_LOCK is not set) and does not disable
preemption, which allows CFS scheduling to preempt a task during
bq_xmit_all(), enabling another task on the same CPU to enter
bq_enqueue() and operate on the same per-CPU bq concurrently.
This leads to several races:
1. Double-free / use-after-free on bq->q[]: bq_xmit_all() snapshots
cnt = bq->count, then iterates bq->q[0..cnt-1] to transmit frames.
If preempted after the snapshot, a second task can call bq_enqueue()
-> bq_xmit_all() on the same bq, transmitting (and freeing) the
same frames. When the first task resumes, it operates on stale
pointers in bq->q[], causing use-after-free.
2. bq->count and bq->q[] corruption: concurrent bq_enqueue() modifying
bq->count and bq->q[] while bq_xmit_all() is reading them.
3. dev_rx/xdp_prog teardown race: __dev_flush() clears bq->dev_rx and
bq->xdp_prog after bq_xmit_all(). If preempted between
bq_xmit_all() return and bq->dev_rx = NULL, a preempting
bq_enqueue() sees dev_rx still set (non-NULL), skips adding bq to
the flush_list, and enqueues a frame. When __dev_flush() resumes,
it clears dev_rx and removes bq from the flush_list, orphaning the
newly enqueued frame.
4. __list_del_clearprev() on flush_node: similar to the cpumap race,
both tasks can call __list_del_clearprev() on the same flush_node,
the second dereferences the prev pointer already set to NULL.
The race between task A (__dev_flush -> bq_xmit_all) and task B
(bq_enqueue -> bq_xmit_all) on the same CPU:
Task A (xdp_do_flush) Task B (ndo_xdp_xmit redirect)
---------------------- --------------------------------
__dev_flush(flush_list)
bq_xmit_all(bq)
cnt = bq->count /* e.g. 16 */
/* start iterating bq->q[] */
<-- CFS preempts Task A -->
bq_enqueue(dev, xdpf)
bq->count == DEV_MAP_BULK_SIZE
bq_xmit_all(bq, 0)
cnt = bq->count /* same 16! */
ndo_xdp_xmit(bq->q[])
/* frames freed by driver */
bq->count = 0
<-- Task A resumes -->
ndo_xdp_xmit(bq->q[])
/* use-after-free: frames already freed! */
Fix this by adding a local_lock_t to xdp_dev_bulk_queue and acquiring
it in bq_enqueue() and __dev_flush(). These paths already run under
local_bh_disable(), so use local_lock_nested_bh() which on non-RT is
a pure annotation with no overhead, and on PREEMPT_RT provides a
per-CPU sleeping lock that serializes access to the bq.
Fixes: 3253cb49cbad ("softirq: Allow to drop the softirq-BKL lock on PREEMPT_RT")
Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Jiayuan Chen <jiayuan.chen@shopee.com>
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Link: https://lore.kernel.org/r/20260225121459.183121-3-jiayuan.chen@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 869c63d5975d55e97f6b168e885452b3da20ea47 ]
On PREEMPT_RT kernels, the per-CPU xdp_bulk_queue (bq) can be accessed
concurrently by multiple preemptible tasks on the same CPU.
The original code assumes bq_enqueue() and __cpu_map_flush() run
atomically with respect to each other on the same CPU, relying on
local_bh_disable() to prevent preemption. However, on PREEMPT_RT,
local_bh_disable() only calls migrate_disable() (when
PREEMPT_RT_NEEDS_BH_LOCK is not set) and does not disable
preemption, which allows CFS scheduling to preempt a task during
bq_flush_to_queue(), enabling another task on the same CPU to enter
bq_enqueue() and operate on the same per-CPU bq concurrently.
This leads to several races:
1. Double __list_del_clearprev(): after bq->count is reset in
bq_flush_to_queue(), a preempting task can call bq_enqueue() ->
bq_flush_to_queue() on the same bq when bq->count reaches
CPU_MAP_BULK_SIZE. Both tasks then call __list_del_clearprev()
on the same bq->flush_node, the second call dereferences the
prev pointer that was already set to NULL by the first.
2. bq->count and bq->q[] races: concurrent bq_enqueue() can corrupt
the packet queue while bq_flush_to_queue() is processing it.
The race between task A (__cpu_map_flush -> bq_flush_to_queue) and
task B (bq_enqueue -> bq_flush_to_queue) on the same CPU:
Task A (xdp_do_flush) Task B (cpu_map_enqueue)
---------------------- ------------------------
bq_flush_to_queue(bq)
spin_lock(&q->producer_lock)
/* flush bq->q[] to ptr_ring */
bq->count = 0
spin_unlock(&q->producer_lock)
bq_enqueue(rcpu, xdpf)
<-- CFS preempts Task A --> bq->q[bq->count++] = xdpf
/* ... more enqueues until full ... */
bq_flush_to_queue(bq)
spin_lock(&q->producer_lock)
/* flush to ptr_ring */
spin_unlock(&q->producer_lock)
__list_del_clearprev(flush_node)
/* sets flush_node.prev = NULL */
<-- Task A resumes -->
__list_del_clearprev(flush_node)
flush_node.prev->next = ...
/* prev is NULL -> kernel oops */
Fix this by adding a local_lock_t to xdp_bulk_queue and acquiring it
in bq_enqueue() and __cpu_map_flush(). These paths already run under
local_bh_disable(), so use local_lock_nested_bh() which on non-RT is
a pure annotation with no overhead, and on PREEMPT_RT provides a
per-CPU sleeping lock that serializes access to the bq.
To reproduce, insert an mdelay(100) between bq->count = 0 and
__list_del_clearprev() in bq_flush_to_queue(), then run reproducer
provided by syzkaller.
Fixes: 3253cb49cbad ("softirq: Allow to drop the softirq-BKL lock on PREEMPT_RT")
Reported-by: syzbot+2b3391f44313b3983e91@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/69369331.a70a0220.38f243.009d.GAE@google.com/T/
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Jiayuan Chen <jiayuan.chen@shopee.com>
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Link: https://lore.kernel.org/r/20260225121459.183121-2-jiayuan.chen@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 749989b2d90ddc7dd253ad3b11a77cf882721acf ]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit b7bf516c3ecd9a2aae2dc2635178ab87b734fef1 ]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit c9bc1753b3cc41d0e01fbca7f035258b5f4db0ae ]
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
Signed-off-by: Sasha Levin <sashal@kernel.org>
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update_cpumasks_hier()
[ Upstream commit 68230aac8b9aad243626fbaf3ca170012c17fec5 ]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit f9a1767ce3a34bc33c3d33473f65dc13a380e379 ]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 486ff5ad49bc50315bcaf6d45f04a33ef0a45ced ]
Lockdep found a bug in the event scheduling when a pinned event was
failed and wakes up the threads in the ring buffer like below.
It seems it should not grab a wait-queue lock under perf-context lock.
Let's do it with irq_work.
[ 39.913691] =============================
[ 39.914157] [ BUG: Invalid wait context ]
[ 39.914623] 6.15.0-next-20250530-next-2025053 #1 Not tainted
[ 39.915271] -----------------------------
[ 39.915731] repro/837 is trying to lock:
[ 39.916191] ffff88801acfabd8 (&event->waitq){....}-{3:3}, at: __wake_up+0x26/0x60
[ 39.917182] other info that might help us debug this:
[ 39.917761] context-{5:5}
[ 39.918079] 4 locks held by repro/837:
[ 39.918530] #0: ffffffff8725cd00 (rcu_read_lock){....}-{1:3}, at: __perf_event_task_sched_in+0xd1/0xbc0
[ 39.919612] #1: ffff88806ca3c6f8 (&cpuctx_lock){....}-{2:2}, at: __perf_event_task_sched_in+0x1a7/0xbc0
[ 39.920748] #2: ffff88800d91fc18 (&ctx->lock){....}-{2:2}, at: __perf_event_task_sched_in+0x1f9/0xbc0
[ 39.921819] #3: ffffffff8725cd00 (rcu_read_lock){....}-{1:3}, at: perf_event_wakeup+0x6c/0x470
Fixes: f4b07fd62d4d ("perf/core: Use POLLHUP for a pinned event in error")
Closes: https://lore.kernel.org/lkml/aD2w50VDvGIH95Pf@ly-workstation
Reported-by: "Lai, Yi" <yi1.lai@linux.intel.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: "Lai, Yi" <yi1.lai@linux.intel.com>
Link: https://patch.msgid.link/20250603045105.1731451-1-namhyung@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 26d43a90be81fc90e26688a51d3ec83188602731 ]
The rseq registration validates that the rseq_size argument is greater
or equal to 32 (the original rseq size), but the comment associated with
this check does not clearly state this.
Clarify the comment to that effect.
Fixes: ee3e3ac05c26 ("rseq: Introduce extensible rseq ABI")
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260220200642.1317826-2-mathieu.desnoyers@efficios.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 6e3c0a4e1ad1e0455b7880fad02b3ee179f56c09 ]
Vincent reported that he was seeing undue lag clamping in a mixed
slice workload. Implement the max_slice tracking as per the todo
comment.
Fixes: 147f3efaa241 ("sched/fair: Implement an EEVDF-like scheduling policy")
Reported-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Vincent Guittot <vincent.guittot@linaro.org>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Tested-by: Shubhang Kaushik <shubhang@os.amperecomputing.com>
Link: https://patch.msgid.link/20250422101628.GA33555@noisy.programming.kicks-ass.net
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit ff38424030f98976150e42ca35f4b00e6ab8fa23 ]
In the EEVDF framework with Run-to-Parity protection, `se->vprot` is an
independent variable defining the virtual protection timestamp.
When `reweight_entity()` is called (e.g., via nice/renice), it performs
the following actions to preserve Lag consistency:
1. Scales `se->vlag` based on the new weight.
2. Calls `place_entity()`, which recalculates `se->vruntime` based on
the new weight and scaled lag.
However, the current implementation fails to update `se->vprot`, leading
to mismatches between the task's actual runtime and its expected duration.
Fixes: 63304558ba5d ("sched/eevdf: Curb wakeup-preemption")
Suggested-by: Zhang Qiao <zhangqiao22@huawei.com>
Signed-off-by: Wang Tao <wangtao554@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Tested-by: Shubhang Kaushik <shubhang@os.amperecomputing.com>
Link: https://patch.msgid.link/20260120123113.3518950-1-wangtao554@huawei.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit bcd74b2ffdd0a2233adbf26b65c62fc69a809c8e ]
We should not (re)set slice protection in the sched_change pattern
which calls put_prev_task() / set_next_task().
Fixes: 63304558ba5d ("sched/eevdf: Curb wakeup-preemption")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Tested-by: Shubhang Kaushik <shubhang@os.amperecomputing.com>
Link: https://patch.msgid.link/20260219080624.561421378%40infradead.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit b3d99f43c72b56cf7a104a364e7fb34b0702828b ]
It turns out that zero_vruntime tracking is broken when there is but a single
task running. Current update paths are through __{en,de}queue_entity(), and
when there is but a single task, pick_next_task() will always return that one
task, and put_prev_set_next_task() will end up in neither function.
This can cause entity_key() to grow indefinitely large and cause overflows,
leading to much pain and suffering.
Furtermore, doing update_zero_vruntime() from __{de,en}queue_entity(), which
are called from {set_next,put_prev}_entity() has problems because:
- set_next_entity() calls __dequeue_entity() before it does cfs_rq->curr = se.
This means the avg_vruntime() will see the removal but not current, missing
the entity for accounting.
- put_prev_e |
