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Author SHA1 Message Date
Paul E. McKenney 1c77e862b8 srcu: Document srcu_flip() memory-barrier D relation to SRCU-fast 
The smp_mb() memory barrier at the end of srcu_flip() has a comment,
but that comment does not make it clear that this memory barrier is an
optimization, as opposed to being needed for correctness.  This commit
therefore adds this information and points out that it is omitted
for SRCU-fast, where a much heavier weight synchronize_srcu() would
be required.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: <bpf@vger.kernel.org>
 2025-09-15 05:16:28 -07:00
Rafael J. Wysocki bd03c7020d Merge back earlier material related to system sleep for 6.18 2025-09-15 12:03:26 +02:00
Christian Loehle 1ebe8f7e78 PM: EM: Fix late boot with holes in CPU topology 
Commit e3f1164fc9 ("PM: EM: Support late CPUs booting and capacity
adjustment") added a mechanism to handle CPUs that come up late by
retrying when any of the `cpufreq_cpu_get()` call fails.

However, if there are holes in the CPU topology (offline CPUs, e.g.
nosmt), the first missing CPU causes the loop to break, preventing
subsequent online CPUs from being updated.

Instead of aborting on the first missing CPU policy, loop through all
and retry if any were missing.

Fixes: e3f1164fc9 ("PM: EM: Support late CPUs booting and capacity adjustment")
Suggested-by: Kenneth Crudup <kenneth.crudup@gmail.com>
Reported-by: Kenneth Crudup <kenneth.crudup@gmail.com>
Link: https://lore.kernel.org/linux-pm/40212796-734c-4140-8a85-854f72b8144d@panix.com/
Cc: 6.9+ <stable@vger.kernel.org> # 6.9+
Signed-off-by: Christian Loehle <christian.loehle@arm.com>
Link: https://patch.msgid.link/20250831214357.2020076-1-christian.loehle@arm.com
[ rjw: Drop the new pr_debug() message which is not very useful ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
 2025-09-15 12:02:24 +02:00
Aaron Lu 0d4eaf8caf sched/fair: Do not balance task to a throttled cfs_rq 
When doing load balance and the target cfs_rq is in throttled hierarchy,
whether to allow balancing there is a question.

The good side to allow balancing is: if the target CPU is idle or less
loaded and the being balanced task is holding some kernel resources,
then it seems a good idea to balance the task there and let the task get
the CPU earlier and release kernel resources sooner. The bad part is, if
the task is not holding any kernel resources, then the balance seems not
that useful.

While theoretically it's debatable, a performance test[0] which involves
200 cgroups and each cgroup runs hackbench(20 sender, 20 receiver) in
pipe mode showed a performance degradation on AMD Genoa when allowing
load balance to throttled cfs_rq. Analysis[1] showed hackbench doesn't
like task migration across LLC boundary. For this reason, add a check in
can_migrate_task() to forbid balancing to a cfs_rq that is in throttled
hierarchy. This reduced task migration a lot and performance restored.

[0]: https://lore.kernel.org/lkml/20250822110701.GB289@bytedance/
[1]: https://lore.kernel.org/lkml/20250903101102.GB42@bytedance/

Signed-off-by: Aaron Lu <ziqianlu@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>
 2025-09-15 09:38:38 +02:00
Aaron Lu 253b3f5872 sched/fair: Do not special case tasks in throttled hierarchy 
With the introduction of task based throttle model, task in a throttled
hierarchy is allowed to continue to run till it gets throttled on its
ret2user path.

For this reason, remove those throttled_hierarchy() checks in the
following functions so that those tasks can get their turn as normal
tasks: dequeue_entities(), check_preempt_wakeup_fair() and
yield_to_task_fair().

The benefit of doing it this way is: if those tasks gets the chance to
run earlier and if they hold any kernel resources, they can release
those resources earlier. The downside is, if they don't hold any kernel
resouces, all they can do is to throttle themselves on their way back to
user space so the favor to let them run seems not that useful and for
check_preempt_wakeup_fair(), that favor may be bad for curr.

K Prateek Nayak pointed out prio_changed_fair() can send a throttled
task to check_preempt_wakeup_fair(), further tests showed the affinity
change path from move_queued_task() can also send a throttled task to
check_preempt_wakeup_fair(), that's why the check of task_is_throttled()
in that function.

Signed-off-by: Aaron Lu <ziqianlu@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
 2025-09-15 09:38:37 +02:00
Aaron Lu fcd394866e sched/fair: update_cfs_group() for throttled cfs_rqs 
With task based throttle model, tasks in a throttled hierarchy are
allowed to continue to run if they are running in kernel mode. For this
reason, PELT clock is not stopped for these cfs_rqs in throttled
hierarchy when they still have tasks running or queued.

Since PELT clock is not stopped, whether to allow update_cfs_group()
doing its job for cfs_rqs which are in throttled hierarchy but still
have tasks running/queued is a question.

The good side is, continue to run update_cfs_group() can get these
cfs_rq entities with an up2date weight and that up2date weight can be
useful to derive an accurate load for the CPU as well as ensure fairness
if multiple tasks of different cgroups are running on the same CPU.
OTOH, as Benjamin Segall pointed: when unthrottle comes around the most
likely correct distribution is the distribution we had at the time of
throttle.

In reality, either way may not matter that much if tasks in throttled
hierarchy don't run in kernel mode for too long. But in case that
happens, let these cfs_rq entities have an up2date weight seems a good
thing to do.

Signed-off-by: Aaron Lu <ziqianlu@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
 2025-09-15 09:38:37 +02:00
Aaron Lu fe8d238e64 sched/fair: Propagate load for throttled cfs_rq 
Before task based throttle model, propagating load will stop at a
throttled cfs_rq and that propagate will happen on unthrottle time by
update_load_avg().

Now that there is no update_load_avg() on unthrottle for throttled
cfs_rq and all load tracking is done by task related operations, let the
propagate happen immediately.

While at it, add a comment to explain why cfs_rqs that are not affected
by throttle have to be added to leaf cfs_rq list in
propagate_entity_cfs_rq() per my understanding of commit 0258bdfaff
("sched/fair: Fix unfairness caused by missing load decay").

Signed-off-by: Aaron Lu <ziqianlu@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Chengming Zhou <chengming.zhou@linux.dev>
 2025-09-15 09:38:37 +02:00
Zhen Ni 9b5096761c rv: Fix missing mutex unlock in rv_register_monitor() 
If create_monitor_dir() fails, the function returns directly without
releasing rv_interface_lock. This leaves the mutex locked and causes
subsequent monitor registration attempts to deadlock.

Fix it by making the error path jump to out_unlock, ensuring that the
mutex is always released before returning.

Fixes: 24cbfe18d5 ("rv: Merge struct rv_monitor_def into struct rv_monitor")
Signed-off-by: Zhen Ni <zhen.ni@easystack.cn>
Reviewed-by: Gabriele Monaco <gmonaco@redhat.com>
Reviewed-by: Nam Cao <namcao@linutronix.de>
Link: https://lore.kernel.org/r/20250903065112.1878330-1-zhen.ni@easystack.cn
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
 2025-09-15 08:36:35 +02:00
Nam Cao de090d1cca rv: Fix wrong type cast in enabled_monitors_next() 
Argument 'p' of enabled_monitors_next() is not a pointer to struct
rv_monitor, it is actually a pointer to the list_head inside struct
rv_monitor. Therefore it is wrong to cast 'p' to struct rv_monitor *.

This wrong type cast has been there since the beginning. But it still
worked because the list_head was the first field in struct rv_monitor_def.
This is no longer true since commit 24cbfe18d5 ("rv: Merge struct
rv_monitor_def into struct rv_monitor") moved the list_head, and this wrong
type cast became a functional problem.

Properly use container_of() instead.

Fixes: 24cbfe18d5 ("rv: Merge struct rv_monitor_def into struct rv_monitor")
Signed-off-by: Nam Cao <namcao@linutronix.de>
Reviewed-by: Gabriele Monaco <gmonaco@redhat.com>
Link: https://lore.kernel.org/r/20250806120911.989365-1-namcao@linutronix.de
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
 2025-09-15 08:36:35 +02:00
Palmer Dabbelt 03ee64b5e5 rv: Support systems with time64-only syscalls 
Some systems (like 32-bit RISC-V) only have the 64-bit time_t versions
of syscalls.  So handle the 32-bit time_t version of those being
undefined.

Fixes: f74f8bb246 ("rv: Add rtapp_sleep monitor")
Closes: https://lore.kernel.org/oe-kbuild-all/202508160204.SsFyNfo6-lkp@intel.com
Signed-off-by: Palmer Dabbelt <palmer@dabbelt.com>
Acked-by: Nam Cao <namcao@linutronix.de>
Link: https://lore.kernel.org/r/20250804194518.97620-2-palmer@dabbelt.com
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
 2025-09-15 08:36:27 +02:00
Greg Kroah-Hartman c319c4ec06 Merge 6.17-rc6 into driver-core-next 
We need the driver core fixes in here to build on top of.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 2025-09-15 08:26:05 +02:00
Linus Torvalds 8378c89172 Merge tag 'timers-urgent-2025-09-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 
Pull timer fix from Ingo Molnar:
 "Fix a lost-timeout CPU hotplug bug in the hrtimer code, which can
  trigger with certain hardware configs and regular HZ"

* tag 'timers-urgent-2025-09-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  hrtimers: Unconditionally update target CPU base after offline timer migration
 2025-09-14 08:38:05 -07:00
Ricardo B. Marliere 3b5eba544a perf: make pmu_bus const 
Now that the driver core can properly handle constant struct bus_type,
move the pmu_bus variable to be a constant structure as well,
placing it into read-only memory which can not be modified at runtime.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: "Ricardo B. Marliere" <ricardo@marliere.net>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20240204-bus_cleanup-events-v1-1-c779d1639c3a@marliere.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 2025-09-14 16:01:37 +02:00
Evangelos Petrongonas d6d5116391 kexec: introduce is_kho_boot() 
Patch series "efi: Fix EFI boot with kexec handover (KHO)", v3.

This patch series fixes a kernel panic that occurs when booting with both
EFI and KHO (Kexec HandOver) enabled.

The issue arises because EFI's `reserve_regions()` clears all memory
regions with `memblock_remove(0, PHYS_ADDR_MAX)` before rebuilding them
from EFI data.  This destroys KHO scratch regions that were set up early
during device tree scanning, causing a panic as the kernel has no valid
memory regions for early allocations.

The first patch introduces `is_kho_boot()` to allow early boot components
to reliably detect if the kernel was booted via KHO-enabled kexec.  The
existing `kho_is_enabled()` only checks the command line and doesn't
verify if an actual KHO FDT was passed.

The second patch modifies EFI's `reserve_regions()` to selectively remove
only non-KHO memory regions when KHO is active, preserving the critical
scratch regions while still allowing EFI to rebuild its memory map.


This patch (of 3):

During early initialisation, after a kexec, other components, like EFI
need to know if a KHO enabled kexec is performed.  The `kho_is_enabled`
function is not enough as in the early stages, it only reflects whether
the cmdline has KHO enabled, not if an actual KHO FDT exists.

Extend the KHO API with `is_kho_boot()` to provide a way for components to
check if a KHO enabled kexec is performed.

Link: https://lkml.kernel.org/r/cover.1755721529.git.epetron@amazon.de
Link: https://lkml.kernel.org/r/7dc6674a76bf6e68cca0222ccff32427699cc02e.1755721529.git.epetron@amazon.de
Signed-off-by: Evangelos Petrongonas <epetron@amazon.de>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Changyuan Lyu <changyuanl@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 17:32:56 -07:00
Coiby Xu 913e65a2fe crash: add KUnit tests for crash_exclude_mem_range 
crash_exclude_mem_range seems to be a simple function but there have been
multiple attempts to fix it,
 - commit a2e9a95d21 ("kexec: Improve & fix crash_exclude_mem_range()
   to handle overlapping ranges")
 - commit 6dff315972 ("crash_core: fix and simplify the logic of
   crash_exclude_mem_range()")

So add a set of unit tests to verify the correctness of current
implementation.  Shall we change the function in the future, the unit
tests can also help prevent any regression.  For example, we may make the
function smarter by allocating extra crash_mem range on demand thus there
is no need for the caller to foresee any memory range split or address
-ENOMEM failure.

The testing strategy is to verify the correctness of base case. The
base case is there is one to-be-excluded range A and one existing range
B. Then we can exhaust all possibilities of the position of A regarding
B. For example, here are two combinations,
    Case: A is completely inside B (causes split)
      Original:       [----B----]
      Exclude:          {--A--}
      Result:         [B1] .. [B2]

    Case: A overlaps B's left part
      Original:       [----B----]
      Exclude:  {---A---}
      Result:           [..B..]

In theory we can prove the correctness by induction,
   - Base case: crash_exclude_mem_range is correct in the case where n=1
     (n is the number of existing ranges).
   - Inductive step: If crash_exclude_mem_range is correct for n=k
     existing ranges, then the it's also correct for n=k+1 ranges.

But for the sake of simplicity, simply use unit tests to cover the base
case together with two regression tests.

Note most of the exclude_single_range_test() code is generated by Google
Gemini with some small tweaks.  The function specification, function body
and the exhausting test strategy are presented as prompts.

[akpm@linux-foundation.org: export crash_exclude_mem_range() to modules, for kernel/crash_core_test.c]
Link: https://lkml.kernel.org/r/20250904093855.1180154-2-coxu@redhat.com
Signed-off-by: Coiby Xu <coxu@redhat.com>
Assisted-by: Google Gemini
Cc: Baoquan He <bhe@redhat.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Dave Young <dyoung@redhat.com>
Cc: fuqiang wang <fuqiang.wang@easystack.cn>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 17:32:55 -07:00
Sergey Senozhatsky 37aa782df9 panic: remove redundant panic-cpu backtrace 
Backtraces from all CPUs are printed during panic() when
SYS_INFO_ALL_CPU_BT is set.  It shows the backtrace for the panic-CPU even
when it has already been explicitly printed before.

Do not change the legacy code which prints the backtrace in various
contexts, for example, as part of Oops report, right after panic message. 
It will always be visible in the crash dump.

Instead, remember when the backtrace was printed, and skip it when dumping
the optional backtraces on all CPUs.

[akpm@linux-foundation.org: make panic_this_cpu_backtrace_printed static]
  Closes: https://lore.kernel.org/oe-kbuild-all/202509050048.FMpVvh1u-lkp@intel.com/
[pmladek@suse.com: Handle situations when the backtrace was not printed for the panic CPU]
Link: https://lkml.kernel.org/r/20250903100418.410026-1-pmladek@suse.com
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Link: https://lore.kernel.org/r/20250731030314.3818040-1-senozhatsky@chromium.org
Signed-off-by: Petr Mladek <pmladek@suse.com>
Tested-by: Feng Tang <feng.tang@linux.alibaba.com>
Reviewed-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 17:32:54 -07:00
Jinchao Wang 652ab7c8fa panic: use angle-bracket include for panic.h 
Replace quoted includes of panic.h with `#include <linux/panic.h>` for
consistency across the kernel.

Link: https://lkml.kernel.org/r/20250829051312.33773-1-wangjinchao600@gmail.com
Signed-off-by: Jinchao Wang <wangjinchao600@gmail.com>
Reviewed-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Qianqiang Liu <qianqiang.liu@163.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 17:32:54 -07:00
Jinchao Wang 3d5f4f15b7 watchdog: skip checks when panic is in progress 
This issue was found when an EFI pstore was configured for kdump logging
with the NMI hard lockup detector enabled.  The efi-pstore write operation
was slow, and with a large number of logs, the pstore dump callback within
kmsg_dump() took a long time.

This delay triggered the NMI watchdog, leading to a nested panic.  The
call flow demonstrates how the secondary panic caused an
emergency_restart() to be triggered before the initial pstore operation
could finish, leading to a failure to dump the logs:

  real panic() {
	kmsg_dump() {
		...
		pstore_dump() {
			start_dump();
			... // long time operation triggers NMI watchdog
			nmi panic() {
				...
				emergency_restart(); // pstore unfinished
			}
			...
			finish_dump(); // never reached
		}
	}
  }

Both watchdog_buddy_check_hardlockup() and watchdog_overflow_callback()
may trigger during a panic.  This can lead to recursive panic handling.

Add panic_in_progress() checks so watchdog activity is skipped once a
panic has begun.

This prevents recursive panic and keeps the panic path more reliable.

Link: https://lkml.kernel.org/r/20250825022947.1596226-10-wangjinchao600@gmail.com
Signed-off-by: Jinchao Wang <wangjinchao600@gmail.com>
Reviewed-by: Yury Norov (NVIDIA) <yury.norov@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Dave Young <dyoung@redhat.com>
Cc: Doug Anderson <dianders@chromium.org>
Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Kees Cook <kees@kernel.org>
Cc: Li Huafei <lihuafei1@huawei.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Luo Gengkun <luogengkun@huaweicloud.com>
Cc: Max Kellermann <max.kellermann@ionos.com>
Cc: Nam Cao <namcao@linutronix.de>
Cc: oushixiong <oushixiong@kylinos.cn>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Qianqiang Liu <qianqiang.liu@163.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Sohil Mehta <sohil.mehta@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Zimemrmann <tzimmermann@suse.de>
Cc: Thorsten Blum <thorsten.blum@linux.dev>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Yicong Yang <yangyicong@hisilicon.com>
Cc: Yunhui Cui <cuiyunhui@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 17:32:53 -07:00
Jinchao Wang d4a36db563 panic/printk: replace other_cpu_in_panic() with panic_on_other_cpu() 
The helper other_cpu_in_panic() duplicated logic already provided by
panic_on_other_cpu().

Remove other_cpu_in_panic() and update all users to call
panic_on_other_cpu() instead.

This removes redundant code and makes panic handling consistent.

Link: https://lkml.kernel.org/r/20250825022947.1596226-9-wangjinchao600@gmail.com
Signed-off-by: Jinchao Wang <wangjinchao600@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Dave Young <dyoung@redhat.com>
Cc: Doug Anderson <dianders@chromium.org>
Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Kees Cook <kees@kernel.org>
Cc: Li Huafei <lihuafei1@huawei.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Luo Gengkun <luogengkun@huaweicloud.com>
Cc: Max Kellermann <max.kellermann@ionos.com>
Cc: Nam Cao <namcao@linutronix.de>
Cc: oushixiong <oushixiong@kylinos.cn>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Qianqiang Liu <qianqiang.liu@163.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Sohil Mehta <sohil.mehta@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Zimemrmann <tzimmermann@suse.de>
Cc: Thorsten Blum <thorsten.blum@linux.dev>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Yicong Yang <yangyicong@hisilicon.com>
Cc: Yunhui Cui <cuiyunhui@bytedance.com>
Cc: Yury Norov (NVIDIA) <yury.norov@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 17:32:52 -07:00
Jinchao Wang c6be36e299 panic/printk: replace this_cpu_in_panic() with panic_on_this_cpu() 
The helper this_cpu_in_panic() duplicated logic already provided by
panic_on_this_cpu().

Remove this_cpu_in_panic() and switch all users to panic_on_this_cpu().

This simplifies the code and avoids having two helpers for the same check.

Link: https://lkml.kernel.org/r/20250825022947.1596226-8-wangjinchao600@gmail.com
Signed-off-by: Jinchao Wang <wangjinchao600@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Dave Young <dyoung@redhat.com>
Cc: Doug Anderson <dianders@chromium.org>
Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Kees Cook <kees@kernel.org>
Cc: Li Huafei <lihuafei1@huawei.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Luo Gengkun <luogengkun@huaweicloud.com>
Cc: Max Kellermann <max.kellermann@ionos.com>
Cc: Nam Cao <namcao@linutronix.de>
Cc: oushixiong <oushixiong@kylinos.cn>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Qianqiang Liu <qianqiang.liu@163.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Sohil Mehta <sohil.mehta@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Zimemrmann <tzimmermann@suse.de>
Cc: Thorsten Blum <thorsten.blum@linux.dev>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Yicong Yang <yangyicong@hisilicon.com>
Cc: Yunhui Cui <cuiyunhui@bytedance.com>
Cc: Yury Norov (NVIDIA) <yury.norov@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 17:32:52 -07:00
Jinchao Wang 2325e8eadf printk/nbcon: use panic_on_this_cpu() helper 
nbcon_context_try_acquire() compared panic_cpu directly with
smp_processor_id().  This open-coded check is now provided by
panic_on_this_cpu().

Switch to panic_on_this_cpu() to simplify the code and improve readability.

Link: https://lkml.kernel.org/r/20250825022947.1596226-7-wangjinchao600@gmail.com
Signed-off-by: Jinchao Wang <wangjinchao600@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Dave Young <dyoung@redhat.com>
Cc: Doug Anderson <dianders@chromium.org>
Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Kees Cook <kees@kernel.org>
Cc: Li Huafei <lihuafei1@huawei.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Luo Gengkun <luogengkun@huaweicloud.com>
Cc: Max Kellermann <max.kellermann@ionos.com>
Cc: Nam Cao <namcao@linutronix.de>
Cc: oushixiong <oushixiong@kylinos.cn>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Qianqiang Liu <qianqiang.liu@163.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Sohil Mehta <sohil.mehta@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Zimemrmann <tzimmermann@suse.de>
Cc: Thorsten Blum <thorsten.blum@linux.dev>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Yicong Yang <yangyicong@hisilicon.com>
Cc: Yunhui Cui <cuiyunhui@bytedance.com>
Cc: Yury Norov (NVIDIA) <yury.norov@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 17:32:52 -07:00
Jinchao Wang 6f313b5585 panic: use panic_try_start() in vpanic() 
vpanic() had open-coded logic to claim panic_cpu with atomic_try_cmpxchg. 
This is already handled by panic_try_start().

Switch to panic_try_start() and use panic_on_other_cpu() for the fallback
path.

This removes duplicate code and makes panic handling consistent across
functions.

Link: https://lkml.kernel.org/r/20250825022947.1596226-6-wangjinchao600@gmail.com
Signed-off-by: Jinchao Wang <wangjinchao600@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Dave Young <dyoung@redhat.com>
Cc: Doug Anderson <dianders@chromium.org>
Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Kees Cook <kees@kernel.org>
Cc: Li Huafei <lihuafei1@huawei.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Luo Gengkun <luogengkun@huaweicloud.com>
Cc: Max Kellermann <max.kellermann@ionos.com>
Cc: Nam Cao <namcao@linutronix.de>
Cc: oushixiong <oushixiong@kylinos.cn>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Qianqiang Liu <qianqiang.liu@163.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Sohil Mehta <sohil.mehta@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Zimemrmann <tzimmermann@suse.de>
Cc: Thorsten Blum <thorsten.blum@linux.dev>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Yicong Yang <yangyicong@hisilicon.com>
Cc: Yunhui Cui <cuiyunhui@bytedance.com>
Cc: Yury Norov (NVIDIA) <yury.norov@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 17:32:52 -07:00
Jinchao Wang 6b69c7ef96 panic: use panic_try_start() in nmi_panic() 
nmi_panic() duplicated the logic to claim panic_cpu with
atomic_try_cmpxchg.  This is already wrapped in panic_try_start().

Replace the open-coded logic with panic_try_start(), and use
panic_on_other_cpu() for the fallback path.

This removes duplication and keeps panic handling code consistent.

Link: https://lkml.kernel.org/r/20250825022947.1596226-5-wangjinchao600@gmail.com
Signed-off-by: Jinchao Wang <wangjinchao600@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Dave Young <dyoung@redhat.com>
Cc: Doug Anderson <dianders@chromium.org>
Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Kees Cook <kees@kernel.org>
Cc: Li Huafei <lihuafei1@huawei.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Luo Gengkun <luogengkun@huaweicloud.com>
Cc: Max Kellermann <max.kellermann@ionos.com>
Cc: Nam Cao <namcao@linutronix.de>
Cc: oushixiong <oushixiong@kylinos.cn>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Qianqiang Liu <qianqiang.liu@163.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Sohil Mehta <sohil.mehta@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Zimemrmann <tzimmermann@suse.de>
Cc: Thorsten Blum <thorsten.blum@linux.dev>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Yicong Yang <yangyicong@hisilicon.com>
Cc: Yunhui Cui <cuiyunhui@bytedance.com>
Cc: Yury Norov (NVIDIA) <yury.norov@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 17:32:51 -07:00
Jinchao Wang 33effbcaf1 crash_core: use panic_try_start() in crash_kexec() 
crash_kexec() had its own code to exclude parallel execution by setting
panic_cpu.  This is already handled by panic_try_start().  Switch to
panic_try_start() to remove the duplication and keep the logic consistent.

Link: https://lkml.kernel.org/r/20250825022947.1596226-4-wangjinchao600@gmail.com
Signed-off-by: Jinchao Wang <wangjinchao600@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Dave Young <dyoung@redhat.com>
Cc: Doug Anderson <dianders@chromium.org>
Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Kees Cook <kees@kernel.org>
Cc: Li Huafei <lihuafei1@huawei.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Luo Gengkun <luogengkun@huaweicloud.com>
Cc: Max Kellermann <max.kellermann@ionos.com>
Cc: Nam Cao <namcao@linutronix.de>
Cc: oushixiong <oushixiong@kylinos.cn>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Qianqiang Liu <qianqiang.liu@163.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Sohil Mehta <sohil.mehta@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Zimemrmann <tzimmermann@suse.de>
Cc: Thorsten Blum <thorsten.blum@linux.dev>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Yicong Yang <yangyicong@hisilicon.com>
Cc: Yunhui Cui <cuiyunhui@bytedance.com>
Cc: Yury Norov (NVIDIA) <yury.norov@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 17:32:51 -07:00
Jinchao Wang d0d9c72355 panic: introduce helper functions for panic state 
Patch series "panic: introduce panic status function family", v2.

This series introduces a family of helper functions to manage panic state
and updates existing code to use them.

Before this series, panic state helpers were scattered and inconsistent. 
For example, panic_in_progress() was defined in printk/printk.c, not in
panic.c or panic.h.  As a result, developers had to look in unexpected
places to understand or re-use panic state logic.  Other checks were open-
coded, duplicating logic across panic, crash, and watchdog paths.

The new helpers centralize the functionality in panic.c/panic.h:
  - panic_try_start()
  - panic_reset()
  - panic_in_progress()
  - panic_on_this_cpu()
  - panic_on_other_cpu()

Patches 1–8 add the helpers and convert panic/crash and printk/nbcon
code to use them.

Patch 9 fixes a bug in the watchdog subsystem by skipping checks when a
panic is in progress, avoiding interference with the panic CPU.

Together, this makes panic state handling simpler, more discoverable, and
more robust.


This patch (of 9):

This patch introduces four new helper functions to abstract the management
of the panic_cpu variable.  These functions will be used in subsequent
patches to refactor existing code.

The direct use of panic_cpu can be error-prone and ambiguous, as it
requires manual checks to determine which CPU is handling the panic.  The
new helpers clarify intent:

panic_try_start():
Atomically sets the current CPU as the panicking CPU.

panic_reset():
Reset panic_cpu to PANIC_CPU_INVALID.

panic_in_progress():
Checks if a panic has been triggered.

panic_on_this_cpu():
Returns true if the current CPU is the panic originator.

panic_on_other_cpu():
Returns true if a panic is on another CPU.

This change lays the groundwork for improved code readability
and robustness in the panic handling subsystem.

Link: https://lkml.kernel.org/r/20250825022947.1596226-1-wangjinchao600@gmail.com
Link: https://lkml.kernel.org/r/20250825022947.1596226-2-wangjinchao600@gmail.com
Signed-off-by: Jinchao Wang <wangjinchao600@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Dave Young <dyoung@redhat.com>
Cc: Doug Anderson <dianders@chromium.org>
Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Kees Cook <kees@kernel.org>
Cc: Li Huafei <lihuafei1@huawei.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Luo Gengkun <luogengkun@huaweicloud.com>
Cc: Max Kellermann <max.kellermann@ionos.com>
Cc: Nam Cao <namcao@linutronix.de>
Cc: oushixiong <oushixiong@kylinos.cn>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Qianqiang Liu <qianqiang.liu@163.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Sohil Mehta <sohil.mehta@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Zimemrmann <tzimmermann@suse.de>
Cc: Thorsten Blum <thorsten.blum@linux.dev>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Yicong Yang <yangyicong@hisilicon.com>
Cc: Yunhui Cui <cuiyunhui@bytedance.com>
Cc: Yury Norov (NVIDIA) <yury.norov@gmail.com>b
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 17:32:51 -07:00
Petr Mladek e40d2014b2 panic: clean up message about deprecated 'panic_print' parameter 
Remove duplication of the message about deprecated 'panic_print'
parameter.

Also make the wording more direct.  Make it clear that the new parameters
already exist and should be used instead.

Link: https://lkml.kernel.org/r/20250825025701.81921-5-feng.tang@linux.alibaba.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Tested-by: Lance Yang <lance.yang@linux.dev>
Reviewed-by: Feng Tang <feng.tang@linux.alibaba.com>
Cc: Askar Safin <safinaskar@zohomail.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 17:32:50 -07:00
Feng Tang 2683df6539 panic: add note that 'panic_print' parameter is deprecated 
Just like for 'panic_print's systcl interface, add similar note for setup
of kernel cmdline parameter and parameter under /sys/module/kernel/.

Also add __core_param_cb() macro, which enables to add special get/set
operation for a kernel parameter.

Link: https://lkml.kernel.org/r/20250825025701.81921-4-feng.tang@linux.alibaba.com
Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
Suggested-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Askar Safin <safinaskar@zohomail.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 17:32:50 -07:00
Liao Yuanhong 13818f7b8c kexec_core: remove redundant 0 value initialization 
The kimage struct is already zeroed by kzalloc(). It's redundant to
initialize image->head to 0.

Link: https://lkml.kernel.org/r/20250825123307.306634-1-liaoyuanhong@vivo.com
Signed-off-by: Liao Yuanhong <liaoyuanhong@vivo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 17:32:49 -07:00
Oleg Nesterov f7071db2fe fork: kill the pointless lower_32_bits() in create_io_thread(), kernel_thread(), and user_mode_thread() 
Unlike sys_clone(), these helpers have only in kernel users which should
pass the correct "flags" argument.  lower_32_bits(flags) just adds the
unnecessary confusion and doesn't allow to use the CLONE_ flags which
don't fit into 32 bits.

create_io_thread() looks especially confusing because:

	- "flags" is a compile-time constant, so lower_32_bits() simply
	  has no effect

	- .exit_signal = (lower_32_bits(flags) & CSIGNAL) is harmless but
	  doesn't look right, copy_process(CLONE_THREAD) will ignore this
	  argument anyway.

None of these helpers actually need CLONE_UNTRACED or "& ~CSIGNAL", but
their presence does not add any confusion and improves code clarity.

Link: https://lkml.kernel.org/r/20250820163946.GA18549@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Kees Cook <kees@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 17:32:49 -07:00
Tio Zhang b32730e68d fork: remove #ifdef CONFIG_LOCKDEP in copy_process() 
lockdep_init_task() is defined as an empty when CONFIG_LOCKDEP is not set.
So the #ifdef here is redundant, remove it.

Link: https://lkml.kernel.org/r/20250820101826.GA2484@didi-ThinkCentre-M930t-N000
Signed-off-by: Tio Zhang <tiozhang@didiglobal.com>
Cc: Kees Cook <kees@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 17:32:48 -07:00
ZhenguoYao 95f091274f watchdog/softlockup: fix incorrect CPU utilization output during softlockup 
Since we use 16-bit precision, the raw data will undergo integer division,
which may sometimes result in data loss.  This can lead to slightly
inaccurate CPU utilization calculations.  Under normal circumstances, this
isn't an issue.  However, when CPU utilization reaches 100%, the
calculated result might exceed 100%.  For example, with raw data like the
following:

sample_period 400000134 new_stat 83648414036 old_stat 83247417494

sample_period=400000134/2^24=23
new_stat=83648414036/2^24=4985
old_stat=83247417494/2^24=4961
util=105%

Below log will output：

CPU#3 Utilization every 0s during lockup:
    #1:   0% system,          0% softirq,   105% hardirq,     0% idle
    #2:   0% system,          0% softirq,   105% hardirq,     0% idle
    #3:   0% system,          0% softirq,   100% hardirq,     0% idle
    #4:   0% system,          0% softirq,   105% hardirq,     0% idle
    #5:   0% system,          0% softirq,   105% hardirq,     0% idle

To avoid confusion, we enforce a 100% display cap when calculations exceed
this threshold.

We also round to the nearest multiple of 16.8 milliseconds to improve the
accuracy.

[yaozhenguo1@gmail.com: make get_16bit_precision() more accurate, fix comment layout]
  Link: https://lkml.kernel.org/r/20250818081438.40540-1-yaozhenguo@jd.com
Link: https://lkml.kernel.org/r/20250812082510.32291-1-yaozhenguo@jd.com
Signed-off-by: ZhenguoYao <yaozhenguo1@gmail.com>
Cc: Bitao Hu <yaoma@linux.alibaba.com>
Cc: Li Huafei <lihuafei1@huawei.com>
Cc: Max Kellermann <max.kellermann@ionos.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 17:32:47 -07:00
ZhenguoYao 41f88ddfd4 watchdog/softlockup: fix wrong output when watchdog_thresh < 3 
When watchdog_thresh is below 3, sample_period will be less than 1 second.
So the following output will print when softlockup:

CPU#3 Utilization every 0s during lockup

Fix this by changing time unit from seconds to milliseconds.

Link: https://lkml.kernel.org/r/20250812074132.27810-1-yaozhenguo@jd.com
Signed-off-by: ZhenguoYao <yaozhenguo1@gmail.com>
Cc: Bitao Hu <yaoma@linux.alibaba.com>
Cc: Li Huafei <lihuafei1@huawei.com>
Cc: Max Kellermann <max.kellermann@ionos.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 17:32:47 -07:00
Soham Bagchi c2fe368b6e kcov: use write memory barrier after memcpy() in kcov_move_area() 
KCOV Remote uses two separate memory buffers, one private to the kernel
space (kcov_remote_areas) and the second one shared between user and
kernel space (kcov->area).  After every pair of kcov_remote_start() and
kcov_remote_stop(), the coverage data collected in the kcov_remote_areas
is copied to kcov->area so the user can read the collected coverage data. 
This memcpy() is located in kcov_move_area().

The load/store pattern on the kernel-side [1] is:

```
/* dst_area === kcov->area, dst_area[0] is where the count is stored */
dst_len = READ_ONCE(*(unsigned long *)dst_area);
...
memcpy(dst_entries, src_entries, ...);
...
WRITE_ONCE(*(unsigned long *)dst_area, dst_len + entries_moved);
```

And for the user [2]:

```
/* cover is equivalent to kcov->area */
n = __atomic_load_n(&cover[0], __ATOMIC_RELAXED);
```

Without a write-memory barrier, the atomic load for the user can
potentially read fresh values of the count stored at cover[0], but
continue to read stale coverage data from the buffer itself.  Hence, we
recommend adding a write-memory barrier between the memcpy() and the
WRITE_ONCE() in kcov_move_area().

Link: https://lkml.kernel.org/r/20250728184318.1839137-1-soham.bagchi@utah.edu
Link: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/kernel/kcov.c?h=master#n978 [1]
Link: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/Documentation/dev-tools/kcov.rst#n364 [2]
Signed-off-by: Soham Bagchi <soham.bagchi@utah.edu>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dmitriy Vyukov <dvyukov@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 17:32:44 -07:00
Brian Mak f367474b58 x86/kexec: carry forward the boot DTB on kexec 
Currently, the kexec_file_load syscall on x86 does not support passing a
device tree blob to the new kernel.  Some embedded x86 systems use device
trees.  On these systems, failing to pass a device tree to the new kernel
causes a boot failure.

To add support for this, we copy the behavior of ARM64 and PowerPC and
copy the current boot's device tree blob for use in the new kernel.  We do
this on x86 by passing the device tree blob as a setup_data entry in
accordance with the x86 boot protocol.

This behavior is gated behind the KEXEC_FILE_FORCE_DTB flag.

Link: https://lkml.kernel.org/r/20250805211527.122367-3-makb@juniper.net
Signed-off-by: Brian Mak <makb@juniper.net>
Cc: Alexander Graf <graf@amazon.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Dave Young <dyoung@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Saravana Kannan <saravanak@google.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 17:32:43 -07:00
Masami Hiramatsu (Google) 1440648c0f hung_task: dump blocker task if it is not hung 
Dump the lock blocker task if it is not hung because if the blocker task
is also hung, it should be dumped by the detector.  This will de-duplicate
the same stackdumps if the blocker task is also blocked by another task
(and hung).

Link: https://lkml.kernel.org/r/175391351423.688839.11917911323784986774.stgit@devnote2
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Suggested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Tested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Acked-by: Lance Yang <lance.yang@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 17:32:43 -07:00
Pratyush Yadav e76e09bdf9 kho: make sure kho_scratch argument is fully consumed 
When specifying fixed sized scratch areas, the parser only parses the
three scratch sizes and ignores the rest of the argument.  This means the
argument can have any bogus trailing characters.

For example, "kho_scratch=256M,512M,512Mfoobar" results in successful
parsing:

    [    0.000000] KHO: scratch areas: lowmem: 256MiB global: 512MiB pernode: 512MiB

It is generally a good idea to parse arguments as strictly as possible. 
In addition, if bogus trailing characters are allowed in the kho_scratch
argument, it is possible that some people might end up using them and
later extensions to the argument format will cause unexpected breakages.

Make sure the argument is fully consumed after all three scratch sizes are
parsed.  With this change, the bogus argument
"kho_scratch=256M,512M,512Mfoobar" results in:

    [    0.000000] Malformed early option 'kho_scratch'

Link: https://lkml.kernel.org/r/20250826123817.64681-1-pratyush@kernel.org
Signed-off-by: Pratyush Yadav <pratyush@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Changyuan Lyu <changyuanl@google.com>
Cc: Pratyush Yadav <pratyush@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 16:55:18 -07:00
David Hildenbrand 9dc21bbd62 prctl: extend PR_SET_THP_DISABLE to optionally exclude VM_HUGEPAGE 
Patch series "prctl: extend PR_SET_THP_DISABLE to only provide THPs when
advised", v5.

This will allow individual processes to opt-out of THP = "always" into THP
= "madvise", without affecting other workloads on the system.  This has
been extensively discussed on the mailing list and has been summarized
very well by David in the first patch which also includes the links to
alternatives, please refer to the first patch commit message for the
motivation for this series.

Patch 1 adds the PR_THP_DISABLE_EXCEPT_ADVISED flag to implement this,
along with the MMF changes.

Patch 2 is a cleanup patch for tva_flags that will allow the forced
collapse case to be transmitted to vma_thp_disabled (which is done in
patch 3).

Patch 4 adds documentation for PR_SET_THP_DISABLE/PR_GET_THP_DISABLE.

Patches 6-7 implement the selftests for PR_SET_THP_DISABLE for completely
disabling THPs (old behaviour) and only enabling it at advise
(PR_THP_DISABLE_EXCEPT_ADVISED).


This patch (of 7):

People want to make use of more THPs, for example, moving from the "never"
system policy to "madvise", or from "madvise" to "always".

While this is great news for every THP desperately waiting to get
allocated out there, apparently there are some workloads that require a
bit of care during that transition: individual processes may need to
opt-out from this behavior for various reasons, and this should be
permitted without needing to make all other workloads on the system
similarly opt-out.

The following scenarios are imaginable:

(1) Switch from "none" system policy to "madvise"/"always", but keep THPs
    disabled for selected workloads.

(2) Stay at "none" system policy, but enable THPs for selected
    workloads, making only these workloads use the "madvise" or "always"
    policy.

(3) Switch from "madvise" system policy to "always", but keep the
    "madvise" policy for selected workloads: allocate THPs only when
    advised.

(4) Stay at "madvise" system policy, but enable THPs even when not advised
    for selected workloads -- "always" policy.

Once can emulate (2) through (1), by setting the system policy to
"madvise"/"always" while disabling THPs for all processes that don't want
THPs.  It requires configuring all workloads, but that is a user-space
problem to sort out.

(4) can be emulated through (3) in a similar way.

Back when (1) was relevant in the past, as people started enabling THPs,
we added PR_SET_THP_DISABLE, so relevant workloads that were not ready yet
(i.e., used by Redis) were able to just disable THPs completely.  Redis
still implements the option to use this interface to disable THPs
completely.

With PR_SET_THP_DISABLE, we added a way to force-disable THPs for a
workload -- a process, including fork+exec'ed process hierarchy.  That
essentially made us support (1): simply disable THPs for all workloads
that are not ready for THPs yet, while still enabling THPs system-wide.

The quest for handling (3) and (4) started, but current approaches
(completely new prctl, options to set other policies per process,
alternatives to prctl -- mctrl, cgroup handling) don't look particularly
promising.  Likely, the future will use bpf or something similar to
implement better policies, in particular to also make better decisions
about THP sizes to use, but this will certainly take a while as that work
just started.

Long story short: a simple enable/disable is not really suitable for the
future, so we're not willing to add completely new toggles.

While we could emulate (3)+(4) through (1)+(2) by simply disabling THPs
completely for these processes, this is a step backwards, because these
processes can no longer allocate THPs in regions where THPs were
explicitly advised: regions flagged as VM_HUGEPAGE.  Apparently, that
imposes a problem for relevant workloads, because "not THPs" is certainly
worse than "THPs only when advised".

Could we simply relax PR_SET_THP_DISABLE, to "disable THPs unless not
explicitly advised by the app through MAD_HUGEPAGE"?  *maybe*, but this
would change the documented semantics quite a bit, and the versatility to
use it for debugging purposes, so I am not 100% sure that is what we want
-- although it would certainly be much easier.

So instead, as an easy way forward for (3) and (4), add an option to
make PR_SET_THP_DISABLE disable *less* THPs for a process.

In essence, this patch:

(A) Adds PR_THP_DISABLE_EXCEPT_ADVISED, to be used as a flag in arg3
    of prctl(PR_SET_THP_DISABLE) when disabling THPs (arg2 != 0).

    prctl(PR_SET_THP_DISABLE, 1, PR_THP_DISABLE_EXCEPT_ADVISED).

(B) Makes prctl(PR_GET_THP_DISABLE) return 3 if
    PR_THP_DISABLE_EXCEPT_ADVISED was set while disabling.

    Previously, it would return 1 if THPs were disabled completely. Now
    it returns the set flags as well: 3 if PR_THP_DISABLE_EXCEPT_ADVISED
    was set.

(C) Renames MMF_DISABLE_THP to MMF_DISABLE_THP_COMPLETELY, to express
    the semantics clearly.

    Fortunately, there are only two instances outside of prctl() code.

(D) Adds MMF_DISABLE_THP_EXCEPT_ADVISED to express "no THP except for VMAs
    with VM_HUGEPAGE" -- essentially "thp=madvise" behavior

    Fortunately, we only have to extend vma_thp_disabled().

(E) Indicates "THP_enabled: 0" in /proc/pid/status only if THPs are
    disabled completely

    Only indicating that THPs are disabled when they are really disabled
    completely, not only partially.

    For now, we don't add another interface to obtained whether THPs
    are disabled partially (PR_THP_DISABLE_EXCEPT_ADVISED was set). If
    ever required, we could add a new entry.

The documented semantics in the man page for PR_SET_THP_DISABLE "is
inherited by a child created via fork(2) and is preserved across
execve(2)" is maintained.  This behavior, for example, allows for
disabling THPs for a workload through the launching process (e.g., systemd
where we fork() a helper process to then exec()).

For now, MADV_COLLAPSE will *fail* in regions without VM_HUGEPAGE and
VM_NOHUGEPAGE.  As MADV_COLLAPSE is a clear advise that user space thinks
a THP is a good idea, we'll enable that separately next (requiring a bit
of cleanup first).

There is currently not way to prevent that a process will not issue
PR_SET_THP_DISABLE itself to re-enable THP.  There are not really known
users for re-enabling it, and it's against the purpose of the original
interface.  So if ever required, we could investigate just forbidding to
re-enable them, or make this somehow configurable.

Link: https://lkml.kernel.org/r/20250815135549.130506-1-usamaarif642@gmail.com
Link: https://lkml.kernel.org/r/20250815135549.130506-2-usamaarif642@gmail.com
Acked-by: Zi Yan <ziy@nvidia.com>
Acked-by: Usama Arif <usamaarif642@gmail.com>
Tested-by: Usama Arif <usamaarif642@gmail.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Usama Arif <usamaarif642@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mariano Pache <npache@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yafang <laoar.shao@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 16:55:05 -07:00
Lorenzo Stoakes d14d3f535e mm: convert remaining users to mm_flags_*() accessors 
As part of the effort to move to mm->flags becoming a bitmap field,
convert existing users to making use of the mm_flags_*() accessors which
will, when the conversion is complete, be the only means of accessing
mm_struct flags.

No functional change intended.

Link: https://lkml.kernel.org/r/cc67a56f9a8746a8ec7d9791853dc892c1c33e0b.1755012943.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Mariano Pache <npache@redhat.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Namhyung kim <namhyung@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 16:54:58 -07:00
Lorenzo Stoakes 19148a19da mm: update fork mm->flags initialisation to use bitmap 
We now need to account for flag initialisation on fork.  We retain the
existing logic as much as we can, but dub the existing flag mask legacy.

These flags are therefore required to fit in the first 32-bits of the
flags field.

However, further flag propagation upon fork can be implemented in
mm_init() on a per-flag basis.

We ensure we clear the entire bitmap prior to setting it, and use
__mm_flags_get_word() and __mm_flags_set_word() to manipulate these legacy
fields efficiently.

Link: https://lkml.kernel.org/r/9fb8954a7a0f0184f012a8e66f8565bcbab014ba.1755012943.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Mariano Pache <npache@redhat.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Namhyung kim <namhyung@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 16:54:57 -07:00
Lorenzo Stoakes c0951573e0 mm: convert uprobes to mm_flags_*() accessors 
As part of the effort to move to mm->flags becoming a bitmap field,
convert existing users to making use of the mm_flags_*() accessors which
will, when the conversion is complete, be the only means of accessing
mm_struct flags.

No functional change intended.

Link: https://lkml.kernel.org/r/1d4fe5963904cc0c707da1f53fbfe6471d3eff10.1755012943.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Mariano Pache <npache@redhat.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Namhyung kim <namhyung@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 16:54:57 -07:00
Lorenzo Stoakes 879d0d9954 mm: convert prctl to mm_flags_*() accessors 
As part of the effort to move to mm->flags becoming a bitmap field,
convert existing users to making use of the mm_flags_*() accessors which
will, when the conversion is complete, be the only means of accessing
mm_struct flags.

No functional change intended.

Link: https://lkml.kernel.org/r/b64f07b94822d02beb88d0d21a6a85f9ee45fc69.1755012943.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Mariano Pache <npache@redhat.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Namhyung kim <namhyung@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 16:54:56 -07:00
Mike Rapoport (Microsoft) be564840bb kho: allow scratch areas with zero size 
Patch series "kho: fixes and cleanups", v3.

These are small KHO and KHO test fixes and cleanups.


This patch (of 3):

Parsing of kho_scratch parameter treats zero size as an invalid value,
although it should be fine for user to request zero sized scratch area for
some types if scratch memory, when for example there is no need to create
scratch area in the low memory.

Treat zero as a valid value for a scratch area size but reject kho_scratch
parameter that defines no scratch memory at all.

Link: https://lkml.kernel.org/r/20250811082510.4154080-1-rppt@kernel.org
Link: https://lkml.kernel.org/r/20250811082510.4154080-2-rppt@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Changyuan Lyu <changyuanl@google.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 16:54:54 -07:00
Ye Liu 79e1c24285 mm: replace (20 - PAGE_SHIFT) with common macros for pages<->MB conversion 
Replace repeated (20 - PAGE_SHIFT) calculations with standard macros:
- MB_TO_PAGES(mb)    converts MB to page count
- PAGES_TO_MB(pages) converts pages to MB

No functional change.

[akpm@linux-foundation.org: remove arc's private PAGES_TO_MB, remove its unused PAGES_TO_KB]
[akpm@linux-foundation.org: don't include mm.h due to include file ordering mess]
Link: https://lkml.kernel.org/r/20250718024134.1304745-1-ye.liu@linux.dev
Signed-off-by: Ye Liu <liuye@kylinos.cn>
Acked-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Chris Li <chrisl@kernel.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lai jiangshan <jiangshanlai@gmail.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mariano Pache <npache@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mel Gorman <mgorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 16:54:42 -07:00
Ruan Shiyang 337135e612 mm: memory-tiering: fix PGPROMOTE_CANDIDATE counting 
Goto-san reported confusing pgpromote statistics where the
pgpromote_success count significantly exceeded pgpromote_candidate.

On a system with three nodes (nodes 0-1: DRAM 4GB, node 2: NVDIMM 4GB):
 # Enable demotion only
 echo 1 > /sys/kernel/mm/numa/demotion_enabled
 numactl -m 0-1 memhog -r200 3500M >/dev/null &
 pid=$!
 sleep 2
 numactl memhog -r100 2500M >/dev/null &
 sleep 10
 kill -9 $pid # terminate the 1st memhog
 # Enable promotion
 echo 2 > /proc/sys/kernel/numa_balancing

After a few seconds, we observeed `pgpromote_candidate < pgpromote_success`
$ grep -e pgpromote /proc/vmstat
pgpromote_success 2579
pgpromote_candidate 0

In this scenario, after terminating the first memhog, the conditions for
pgdat_free_space_enough() are quickly met, and triggers promotion. 
However, these migrated pages are only counted for in PGPROMOTE_SUCCESS,
not in PGPROMOTE_CANDIDATE.

To solve these confusing statistics, introduce PGPROMOTE_CANDIDATE_NRL to
count the missed promotion pages.  And also, not counting these pages into
PGPROMOTE_CANDIDATE is to avoid changing the existing algorithm or
performance of the promotion rate limit.

Link: https://lkml.kernel.org/r/20250901090122.124262-1-ruansy.fnst@fujitsu.com
Link: https://lkml.kernel.org/r/20250729035101.1601407-1-ruansy.fnst@fujitsu.com
Fixes: c6833e1000 ("memory tiering: rate limit NUMA migration throughput")
Co-developed-by: Li Zhijian <lizhijian@fujitsu.com>
Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>
Signed-off-by: Ruan Shiyang <ruansy.fnst@fujitsu.com>
Reported-by: Yasunori Gotou (Fujitsu) <y-goto@fujitsu.com>
Suggested-by: Huang Ying <ying.huang@linux.alibaba.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Huang Ying <ying.huang@linux.alibaba.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 16:54:42 -07:00
Thomas Gleixner 6eb350a223 rseq: Protect event mask against membarrier IPI 
rseq_need_restart() reads and clears task::rseq_event_mask with preemption
disabled to guard against the scheduler.

But membarrier() uses an IPI and sets the PREEMPT bit in the event mask
from the IPI, which leaves that RMW operation unprotected.

Use guard(irq) if CONFIG_MEMBARRIER is enabled to fix that.

Fixes: 2a36ab717e ("rseq/membarrier: Add MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: stable@vger.kernel.org
 2025-09-13 19:51:59 +02:00
Marco Crivellari 4fcd322914 padata: WQ_PERCPU added to alloc_workqueue users 
Currently if a user enqueue a work item using schedule_delayed_work() the
used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to
schedule_work() that is using system_wq and queue_work(), that makes use
again of WORK_CPU_UNBOUND.
This lack of consistentcy cannot be addressed without refactoring the API.

alloc_workqueue() treats all queues as per-CPU by default, while unbound
workqueues must opt-in via WQ_UNBOUND.

This default is suboptimal: most workloads benefit from unbound queues,
allowing the scheduler to place worker threads where they’re needed and
reducing noise when CPUs are isolated.

This default is suboptimal: most workloads benefit from unbound queues,
allowing the scheduler to place worker threads where they’re needed and
reducing noise when CPUs are isolated.

This patch adds a new WQ_PERCPU flag to explicitly request the use of
the per-CPU behavior. Both flags coexist for one release cycle to allow
callers to transition their calls.

Once migration is complete, WQ_UNBOUND can be removed and unbound will
become the implicit default.

With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND),
any alloc_workqueue() caller that doesn’t explicitly specify WQ_UNBOUND
must now use WQ_PERCPU.

All existing users have been updated accordingly.

Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
 2025-09-13 12:11:06 +08:00
Marco Crivellari b6d02e0e41 padata: replace use of system_unbound_wq with system_dfl_wq 
Currently if a user enqueue a work item using schedule_delayed_work() the
used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to
schedule_work() that is using system_wq and queue_work(), that makes use
again of WORK_CPU_UNBOUND.

This lack of consistentcy cannot be addressed without refactoring the API.

system_unbound_wq should be the default workqueue so as not to enforce
locality constraints for random work whenever it's not required.

Adding system_dfl_wq to encourage its use when unbound work should be used.

queue_work() / queue_delayed_work() / mod_delayed_work() will now use the
new unbound wq: whether the user still use the old wq a warn will be
printed along with a wq redirect to the new one.

The old system_unbound_wq will be kept for a few release cycles.

Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
 2025-09-13 12:11:06 +08:00
Jakub Kicinski fc3a281041 Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 
Cross-merge networking fixes after downstream PR (net-6.17-rc6).

Conflicts:

net/netfilter/nft_set_pipapo.c
net/netfilter/nft_set_pipapo_avx2.c
  c4eaca2e10 ("netfilter: nft_set_pipapo: don't check genbit from packetpath lookups")
  84c1da7b38 ("netfilter: nft_set_pipapo: use avx2 algorithm for insertions too")

Only trivial adjacent changes (in a doc and a Makefile).

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
 2025-09-11 17:40:13 -07:00
Leon Romanovsky f7326196a7 dma-mapping: export new dma_*map_phys() interface 
Introduce new DMA mapping functions dma_map_phys() and dma_unmap_phys()
that operate directly on physical addresses instead of page+offset
parameters. This provides a more efficient interface for drivers that
already have physical addresses available.

The new functions are implemented as the primary mapping layer, with
the existing dma_map_page_attrs()/dma_map_resource() and
dma_unmap_page_attrs()/dma_unmap_resource() functions converted to simple
wrappers around the phys-based implementations.

In case dma_map_page_attrs(), the struct page is converted to physical
address with help of page_to_phys() function and dma_map_resource()
provides physical address as is together with addition of DMA_ATTR_MMIO
attribute.

The old page-based API is preserved in mapping.c to ensure that existing
code won't be affected by changing EXPORT_SYMBOL to EXPORT_SYMBOL_GPL
variant for dma_*map_phys().

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/54cc52af91777906bbe4a386113437ba0bcfba9c.1757423202.git.leonro@nvidia.com
 2025-09-12 00:18:21 +02:00
Leon Romanovsky 18c9cbb042 dma-mapping: implement DMA_ATTR_MMIO for dma_(un)map_page_attrs() 
Make dma_map_page_attrs() and dma_map_page_attrs() respect
DMA_ATTR_MMIO.

DMA_ATR_MMIO makes the functions behave the same as
dma_(un)map_resource():
 - No swiotlb is possible
 - Legacy dma_ops arches use ops->map_resource()
 - No kmsan
 - No arch_dma_map_phys_direct()

The prior patches have made the internal functions called here
support DMA_ATTR_MMIO.

This is also preparation for turning dma_map_resource() into an inline
calling dma_map_phys(DMA_ATTR_MMIO) to consolidate the flows.

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/3660e2c78ea409d6c483a215858fb3af52cd0ed3.1757423202.git.leonro@nvidia.com
 2025-09-12 00:18:20 +02:00