Patch series "Align atomic storage", v7.
This series adds the __aligned attribute to atomic_t and atomic64_t
definitions in include/linux and include/asm-generic (respectively) to get
natural alignment of both types on csky, m68k, microblaze, nios2, openrisc
and sh.
This series also adds Kconfig options to enable a new run-time warning to
help reveal misaligned atomic accesses on platforms which don't trap that.
The performance impact is expected to vary across platforms and workloads.
The measurements I made on m68k show that some workloads run faster and
others slower.
This patch (of 4):
Align bpf_res_spin_lock to avoid a BUILD_BUG_ON() when the alignment
changes, as it will do on m68k when, in a subsequent patch, the minimum
alignment of the atomic_t member of struct rqspinlock gets increased from
2 to 4. Drop the BUILD_BUG_ON() as it becomes redundant.
Link: https://lkml.kernel.org/r/cover.1768281748.git.fthain@linux-m68k.org
Link: https://lkml.kernel.org/r/8a83876b07d1feacc024521e44059ae89abbb1ea.1768281748.git.fthain@linux-m68k.org
Signed-off-by: Finn Thain <fthain@linux-m68k.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Daniel Borkman <daniel@iogearbox.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: Gary Guo <gary@garyguo.net>
Cc: Guo Ren <guoren@kernel.org>
Cc: Hao Luo <haoluo@google.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Sasha Levin (Microsoft) <sashal@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stanislav Fomichev <sdf@fomichev.me>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Cc: Yonghong Song <yonghong.song@linux.dev>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This patch is a preparation step for HPCC, for the OOM killer
improvements. I suspect that this patch is useful on its own, because it
really makes no sense to sum up accounting statistics of use_mm within
kernel threads which are only temporarily using those mm.
When we hit acct_account_cputime within a irq handler over a kthread that
happens to use a userspace mm, we end up summing up the mm's RSS into the
tsk acct_rss_mem1, which eventually decays.
I don't see a good rationale behind tracking the mm's rss in that way when
a kthread use a userspace mm temporarily through use_mm.
It causes issues with init_mm and efi_mm which only partially initialize
their mm_struct when introducing the new hierarchical percpu counters to
replace RSS counters, which requires a pointer dereference when reading
the approximate counter sum. The current percpu counters simply load a
zeroed atomic counter, which happen to work.
Skip all kernel threads in acct_account_cputime(), not just those that
happen to have a NULL mm.
This is a preparation step before introducing the hierarchical percpu
counters.
Link: https://lkml.kernel.org/r/20251224173810.648699-2-mathieu.desnoyers@efficios.com
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Aboorva Devarajan <aboorvad@linux.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Christan König <christian.koenig@amd.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Liam R . Howlett" <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Martin Liu <liumartin@google.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: SeongJae Park <sj@kernel.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
kexec_handover_internal.h is included twice in kexec_handover.c. Remove
the redundant first inclusion to eliminate the duplication.
Link: https://lkml.kernel.org/r/20251216114400.2677311-1-longwei27@huawei.com
Signed-off-by: Long Wei <longwei27@huawei.com>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Alexander Graf <graf@amazon.com>
Cc: hewenliang <hewenliang4@huawei.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Pratyush Yadav <pratyush@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The comment for get_task_mm() in kernel/fork.c incorrectly references the
deprecated function `use_mm()`, which has been renamed to
`kthread_use_mm()` in kernel/kthread.c.
This patch updates the documentation to reflect the current function
names, ensuring accuracy when developers refer to the kernel thread memory
context API.
No functional changes were introduced.
Link: https://lkml.kernel.org/r/KUZPR04MB8965F954108B4DD7E8FFDB2B8F84A@KUZPR04MB8965.apcprd04.prod.outlook.com
Signed-off-by: mingzhu.wang <mingzhu.wang@transsion.com>
Cc: Ben Segall <bsegall@google.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiazi Li <jqqlijiazi@gmail.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Kees Cook <kees@kernel.org>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.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>
The `struct kho_vmalloc` defines the in-memory layout for preserving
vmalloc regions across kexec. This layout is a contract between kernels
and part of the KHO ABI.
To reflect this relationship, the related structs and helper macros are
relocated to the ABI header, `include/linux/kho/abi/kexec_handover.h`.
This move places the structure's definition under the protection of the
KHO_FDT_COMPATIBLE version string.
The structure and its components are now also documented within the ABI
header to describe the contract and prevent ABI breaks.
[rppt@kernel.org: update comment, per Pratyush]
Link: https://lkml.kernel.org/r/aW_Mqp6HcqLwQImS@kernel.org
Link: https://lkml.kernel.org/r/20260105165839.285270-6-rppt@kernel.org
Signed-off-by: Jason Miu <jasonmiu@google.com>
Co-developed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pratyush Yadav <pratyush@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Introduce the `include/linux/kho/abi/kexec_handover.h` header file, which
defines the stable ABI for the KHO mechanism. This header specifies how
preserved data is passed between kernels using an FDT.
The ABI contract includes the FDT structure, node properties, and the
"kho-v1" compatible string. By centralizing these definitions, this
header serves as the foundational agreement for inter-kernel communication
of preserved states, ensuring forward compatibility and preventing
misinterpretation of data across kexec transitions.
Since the ABI definitions are now centralized in the header files, the
YAML files that previously described the FDT interfaces are redundant.
These redundant files have therefore been removed.
Link: https://lkml.kernel.org/r/20260105165839.285270-5-rppt@kernel.org
Signed-off-by: Jason Miu <jasonmiu@google.com>
Co-developed-by: Mike Rapoport (Microsoft) <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: Jonathan Corbet <corbet@lwn.net>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Currently index.rst in KHO documentation looks empty and sad as it only
contains links to "Kexec Handover Concepts" and "KHO FDT" chapters.
Inline contents of these chapters into index.rst to provide a single
coherent chapter describing KHO.
While on it, drop parts of the KHO FDT description that will be superseded
by addition of KHO ABI documentation.
[rppt@kernel.org: fix Documentation/core-api/kho/index.rst]
Link: https://lkml.kernel.org/r/aV4bnHlBXGpT_FMc@kernel.org
Link: https://lkml.kernel.org/r/20260105165839.285270-4-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: Jason Miu <jasonmiu@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Pratyush Yadav <pratyush@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Decouple memfd preservation support from the core Live Update Orchestrator
configuration.
Previously, enabling CONFIG_LIVEUPDATE forced a dependency on CONFIG_SHMEM
and unconditionally compiled memfd_luo.o. However, Live Update may be
used for purposes that do not require memfd-backed memory preservation.
Introduce CONFIG_LIVEUPDATE_MEMFD to gate memfd_luo.o. This moves the
SHMEM and MEMFD_CREATE dependencies to the specific feature that needs
them, allowing the base LIVEUPDATE option to be selected independently of
shared memory support.
Link: https://lkml.kernel.org/r/20251230161402.1542099-1-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The current comment "Clear TID on mm_release()?" ends with a question
mark, implying uncertainty about whether the TID is actually cleared in
mm_release().
However, the code flow is deterministic. When a task exits, mm_release()
explicitly checks 'tsk->clear_child_tid' and clears.
Since this behavior is unambiguous, remove the confusing question mark and
rephrase the comment to clearly state that TID is cleared in mm_release().
Link: https://lkml.kernel.org/r/20251125000407.24470-1-s9430939@naver.com
Signed-off-by: Minu Jin <s9430939@naver.com>
Cc: Ben Segall <bsegall@google.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mel Gorman <mgorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
kallsyms_lookup_buildid() copies the symbol name into the given buffer so
that it can be safely read anytime later. But it just copies pointers to
mod->name and mod->build_id which might get reused after the related
struct module gets removed.
The lifetime of struct module is synchronized using RCU. Take the rcu
read lock for the entire __sprint_symbol().
Link: https://lkml.kernel.org/r/20251128135920.217303-8-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Aaron Tomlin <atomlin@atomlin.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkman <daniel@iogearbox.net>
Cc: Daniel Gomez <da.gomez@samsung.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Luis Chamberalin <mcgrof@kernel.org>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Petr Pavlu <petr.pavlu@suse.com>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
__sprint_symbol() might access an invalid pointer when
kallsyms_lookup_buildid() returns a symbol found by
ftrace_mod_address_lookup().
The ftrace lookup function must set both @modname and @modbuildid the same
way as module_address_lookup().
Link: https://lkml.kernel.org/r/20251128135920.217303-7-pmladek@suse.com
Fixes: 9294523e37 ("module: add printk formats to add module build ID to stacktraces")
Signed-off-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Aaron Tomlin <atomlin@atomlin.com>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkman <daniel@iogearbox.net>
Cc: Daniel Gomez <da.gomez@samsung.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Luis Chamberalin <mcgrof@kernel.org>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Petr Pavlu <petr.pavlu@suse.com>
Cc: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
bpf_address_lookup() has been used only in kallsyms_lookup_buildid(). It
was supposed to set @modname and @modbuildid when the symbol was in a
module.
But it always just cleared @modname because BPF symbols were never in a
module. And it did not clear @modbuildid because the pointer was not
passed.
The wrapper is no longer needed. Both @modname and @modbuildid are now
always initialized to NULL in kallsyms_lookup_buildid().
Remove the wrapper and rename __bpf_address_lookup() to
bpf_address_lookup() because this variant is used everywhere.
[akpm@linux-foundation.org: fix loongarch]
Link: https://lkml.kernel.org/r/20251128135920.217303-6-pmladek@suse.com
Fixes: 9294523e37 ("module: add printk formats to add module build ID to stacktraces")
Signed-off-by: Petr Mladek <pmladek@suse.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Cc: Aaron Tomlin <atomlin@atomlin.com>
Cc: Daniel Borkman <daniel@iogearbox.net>
Cc: Daniel Gomez <da.gomez@samsung.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Luis Chamberalin <mcgrof@kernel.org>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Petr Pavlu <petr.pavlu@suse.com>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Put the code for appending the optional "buildid" into a helper function,
It makes __sprint_symbol() better readable.
Also print a warning when the "modname" is set and the "buildid" isn't.
It might catch a situation when some lookup function in
kallsyms_lookup_buildid() does not handle the "buildid".
Use pr_*_once() to avoid an infinite recursion when the function is called
from printk(). The recursion is rather theoretical but better be on the
safe side.
Link: https://lkml.kernel.org/r/20251128135920.217303-5-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Aaron Tomlin <atomlin@atomlin.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkman <daniel@iogearbox.net>
Cc: Daniel Gomez <da.gomez@samsung.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Luis Chamberalin <mcgrof@kernel.org>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Petr Pavlu <petr.pavlu@suse.com>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Add a helper function for reading the optional "build_id" member of struct
module. It is going to be used also in ftrace_mod_address_lookup().
Use "#ifdef" instead of "#if IS_ENABLED()" to match the declaration of the
optional field in struct module.
Link: https://lkml.kernel.org/r/20251128135920.217303-4-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Daniel Gomez <da.gomez@samsung.com>
Reviewed-by: Petr Pavlu <petr.pavlu@suse.com>
Cc: Aaron Tomlin <atomlin@atomlin.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkman <daniel@iogearbox.net>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Luis Chamberalin <mcgrof@kernel.org>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The @modname and @modbuildid optional return parameters are set only when
the symbol is in a module.
Always initialize them so that they do not need to be cleared when the
module is not in a module. It simplifies the logic and makes the code
even slightly more safe.
Note that bpf_address_lookup() function will get updated in a separate
patch.
Link: https://lkml.kernel.org/r/20251128135920.217303-3-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Aaron Tomlin <atomlin@atomlin.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkman <daniel@iogearbox.net>
Cc: Daniel Gomez <da.gomez@samsung.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Luis Chamberalin <mcgrof@kernel.org>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Petr Pavlu <petr.pavlu@suse.com>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "kallsyms: Prevent invalid access when showing module
buildid", v3.
We have seen nested crashes in __sprint_symbol(), see below. They seem to
be caused by an invalid pointer to "buildid". This patchset cleans up
kallsyms code related to module buildid and fixes this invalid access when
printing backtraces.
I made an audit of __sprint_symbol() and found several situations
when the buildid might be wrong:
+ bpf_address_lookup() does not set @modbuildid
+ ftrace_mod_address_lookup() does not set @modbuildid
+ __sprint_symbol() does not take rcu_read_lock and
the related struct module might get removed before
mod->build_id is printed.
This patchset solves these problems:
+ 1st, 2nd patches are preparatory
+ 3rd, 4th, 6th patches fix the above problems
+ 5th patch cleans up a suspicious initialization code.
This is the backtrace, we have seen. But it is not really important.
The problems fixed by the patchset are obvious:
crash64> bt [62/2029]
PID: 136151 TASK: ffff9f6c981d4000 CPU: 367 COMMAND: "btrfs"
#0 [ffffbdb687635c28] machine_kexec at ffffffffb4c845b3
#1 [ffffbdb687635c80] __crash_kexec at ffffffffb4d86a6a
#2 [ffffbdb687635d08] hex_string at ffffffffb51b3b61
#3 [ffffbdb687635d40] crash_kexec at ffffffffb4d87964
#4 [ffffbdb687635d50] oops_end at ffffffffb4c41fc8
#5 [ffffbdb687635d70] do_trap at ffffffffb4c3e49a
#6 [ffffbdb687635db8] do_error_trap at ffffffffb4c3e6a4
#7 [ffffbdb687635df8] exc_stack_segment at ffffffffb5666b33
#8 [ffffbdb687635e20] asm_exc_stack_segment at ffffffffb5800cf9
...
This patch (of 7)
The function kallsyms_lookup_buildid() initializes the given @namebuf by
clearing the first and the last byte. It is not clear why.
The 1st byte makes sense because some callers ignore the return code and
expect that the buffer contains a valid string, for example:
- function_stat_show()
- kallsyms_lookup()
- kallsyms_lookup_buildid()
The initialization of the last byte does not make much sense because it
can later be overwritten. Fortunately, it seems that all called functions
behave correctly:
- kallsyms_expand_symbol() explicitly adds the trailing '\0'
at the end of the function.
- All *__address_lookup() functions either use the safe strscpy()
or they do not touch the buffer at all.
Document the reason for clearing the first byte. And remove the useless
initialization of the last byte.
Link: https://lkml.kernel.org/r/20251128135920.217303-2-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Aaron Tomlin <atomlin@atomlin.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkman <daniel@iogearbox.net>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Luis Chamberalin <mcgrof@kernel.org>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Petr Pavlu <petr.pavlu@suse.com>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Daniel Gomez <da.gomez@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The softlockup_panic sysctl is currently a binary option: panic
immediately or never panic on soft lockups.
Panicking on any soft lockup, regardless of duration, can be overly
aggressive for brief stalls that may be caused by legitimate operations.
Conversely, never panicking may allow severe system hangs to persist
undetected.
Extend softlockup_panic to accept an integer threshold, allowing the
kernel to panic only when the normalized lockup duration exceeds N
watchdog threshold periods. This provides finer-grained control to
distinguish between transient delays and persistent system failures.
The accepted values are:
- 0: Don't panic (unchanged)
- 1: Panic when duration >= 1 * threshold (20s default, original behavior)
- N > 1: Panic when duration >= N * threshold (e.g., 2 = 40s, 3 = 60s.)
The original behavior is preserved for values 0 and 1, maintaining full
backward compatibility while allowing systems to tolerate brief lockups
while still catching severe, persistent hangs.
[lirongqing@baidu.com: v2]
Link: https://lkml.kernel.org/r/20251218074300.4080-1-lirongqing@baidu.com
Link: https://lkml.kernel.org/r/20251216074521.2796-1-lirongqing@baidu.com
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Song Liu <song@kernel.org>
Cc: Stanislav Fomichev <sdf@fomichev.me>
Cc: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
kimage_crash_copy_vmcoreinfo() currently assumes vmcoreinfo fits in a
single page. This breaks if VMCOREINFO_BYTES exceeds PAGE_SIZE.
Allocate the required order of control pages and vmap all pages needed to
safely copy vmcoreinfo into the crash kernel image.
Link: https://lkml.kernel.org/r/20251216132801.807260-3-pnina.feder@mobileye.com
Signed-off-by: Pnina Feder <pnina.feder@mobileye.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "vmcoreinfo: support VMCOREINFO_BYTES larger than PAGE_SIZE".
VMCOREINFO_BYTES is defined as a configurable size, but multiple
code paths implicitly assume it always fits into a single page.
This series removes that assumption by allocating and mapping
vmcoreinfo based on its actual size.
Patch 1 updates vmcoreinfo allocation to use get_order(VMCOREINFO_BYTES).
Patch 2 updates crash kernel handling to correctly allocate and map
multiple pages when copying vmcoreinfo.
This makes vmcoreinfo size consistent across the kernel and avoids
future breakage if VMCOREINFO_BYTES grows.
(No functional change when VMCOREINFO_BYTES == PAGE_SIZE.)
This patch (of 2):
VMCOREINFO_BYTES defines the size of vmcoreinfo data, but the current
implementation assumes a single page allocation.
Allocate vmcoreinfo_data using get_order(VMCOREINFO_BYTES) so that
vmcoreinfo can safely grow beyond PAGE_SIZE.
This avoids hidden assumptions and keeps vmcoreinfo size consistent across
the kernel.
Link: https://lkml.kernel.org/r/20251216132801.807260-1-pnina.feder@mobileye.com
Link: https://lkml.kernel.org/r/20251216132801.807260-2-pnina.feder@mobileye.com
Signed-off-by: Pnina Feder <pnina.feder@mobileye.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
We were wasting a byte due to an off-by-one bug. s[c]nprintf() doesn't
write more than $2 bytes including the null byte, so trying to pass
'size-1' there is wasting one byte.
This is essentially the same as the previous commit, in a different
file.
Link: https://lkml.kernel.org/r/b4a945a4d40b7104364244f616eb9fb9f1fa691f.1765449750.git.alx@kernel.org
Signed-off-by: Alejandro Colomar <alx@kernel.org>
Cc: Marco Elver <elver@google.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Christopher Bazley <chris.bazley.wg14@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Marco Elver <elver@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Maciej W. Rozycki <macro@orcam.me.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Remove <linux/hex.h> from <linux/kernel.h> and update all users/callers of
hex.h interfaces to directly #include <linux/hex.h> as part of the process
of putting kernel.h on a diet.
Removing hex.h from kernel.h means that 36K C source files don't have to
pay the price of parsing hex.h for the roughly 120 C source files that
need it.
This change has been build-tested with allmodconfig on most ARCHes. Also,
all users/callers of <linux/hex.h> in the entire source tree have been
updated if needed (if not already #included).
Link: https://lkml.kernel.org/r/20251215005206.2362276-1-rdunlap@infradead.org
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Yury Norov (NVIDIA) <yury.norov@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
'struct configfs_item_operations' and 'configfs_group_operations' are not
modified in this driver.
Constifying these structures moves some data to a read-only section, so
increases overall security, especially when the structure holds some
function pointers.
On a x86_64, with allmodconfig, as an example:
Before:
======
text data bss dec hex filename
16339 11001 384 27724 6c4c kernel/crash_dump_dm_crypt.o
After:
=====
text data bss dec hex filename
16499 10841 384 27724 6c4c kernel/crash_dump_dm_crypt.o
Link: https://lkml.kernel.org/r/d046ee5666d2f6b1a48ca1a222dfbd2f7c44462f.1765735035.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Coiby Xu <coxu@redhat.com>
Tested-by: Coiby Xu <coxu@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
- A 4 patch series from David Hildenbrand which fixes a few things
realted to hugetlb PMD sharing
- The remainder are singletons, please see their changelogs for details.
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Merge tag 'mm-hotfixes-stable-2026-01-20-13-09' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull misc fixes from Andrew Morton:
- A patch series from David Hildenbrand which fixes a few things
related to hugetlb PMD sharing
- The remainder are singletons, please see their changelogs for details
* tag 'mm-hotfixes-stable-2026-01-20-13-09' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
mm: restore per-memcg proactive reclaim with !CONFIG_NUMA
mm/kfence: fix potential deadlock in reboot notifier
Docs/mm/allocation-profiling: describe sysctrl limitations in debug mode
mm: do not copy page tables unnecessarily for VM_UFFD_WP
mm/hugetlb: fix excessive IPI broadcasts when unsharing PMD tables using mmu_gather
mm/rmap: fix two comments related to huge_pmd_unshare()
mm/hugetlb: fix two comments related to huge_pmd_unshare()
mm/hugetlb: fix hugetlb_pmd_shared()
mm: remove unnecessary and incorrect mmap lock assert
x86/kfence: avoid writing L1TF-vulnerable PTEs
mm/vma: do not leak memory when .mmap_prepare swaps the file
migrate: correct lock ordering for hugetlb file folios
panic: only warn about deprecated panic_print on write access
fs/writeback: skip AS_NO_DATA_INTEGRITY mappings in wait_sb_inodes()
mm: take into account mm_cid size for mm_struct static definitions
mm: rename cpu_bitmap field to flexible_array
mm: add missing static initializer for init_mm::mm_cid.lock
- minor fixes for the corner cases of the SWIOTLB pool management (Robin Murphy)
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Merge tag 'dma-mapping-6.19-2026-01-20' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux
Pull dma-mapping fixes from Marek Szyprowski:
- minor fixes for the corner cases of the SWIOTLB pool management
(Robin Murphy)
* tag 'dma-mapping-6.19-2026-01-20' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux:
dma/pool: Avoid allocating redundant pools
mm_zone: Generalise has_managed_dma()
dma/pool: Improve pool lookup
The panic_print_deprecated() warning is being triggered on both read and
write operations to the panic_print parameter.
This causes spurious warnings when users run 'sysctl -a' to list all
sysctl values, since that command reads /proc/sys/kernel/panic_print and
triggers the deprecation notice.
Modify the handlers to only emit the deprecation warning when the
parameter is actually being set:
- sysctl_panic_print_handler(): check 'write' flag before warning.
- panic_print_get(): remove the deprecation call entirely.
This way, users are only warned when they actively try to use the
deprecated parameter, not when passively querying system state.
Link: https://lkml.kernel.org/r/20260106163321.83586-1-gal@nvidia.com
Fixes: ee13240cd7 ("panic: add note that panic_print sysctl interface is deprecated")
Fixes: 2683df6539 ("panic: add note that 'panic_print' parameter is deprecated")
Signed-off-by: Gal Pressman <gal@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Reviewed-by: Nimrod Oren <noren@nvidia.com>
Cc: Feng Tang <feng.tang@linux.alibaba.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
- Add Chen Ridong as cpuset reviewer.
- Add SPDX license identifiers to cgroup files that were missing them.
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Merge tag 'cgroup-for-6.19-rc5-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fixes from Tejun Heo:
- Add Chen Ridong as cpuset reviewer
- Add SPDX license identifiers to cgroup files that were missing them
* tag 'cgroup-for-6.19-rc5-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
kernel: cgroup: Add LGPL-2.1 SPDX license ID to legacy_freezer.c
kernel: cgroup: Add SPDX-License-Identifier lines
MAINTAINERS: Add Chen Ridong as cpuset reviewer
may result in incorrect skipping of hrtimer IPIs.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'timers-urgent-2026-01-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer fix from Ingo Molnar:
"Fix the update_needs_ipi() check in the hrtimer code that may result
in incorrect skipping of hrtimer IPIs"
* tag 'timers-urgent-2026-01-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
hrtimer: Fix softirq base check in update_needs_ipi()
discovered and fixed recently:
- Fix a race condition in the DL server
- Fix a DL server bug which can result in incorrectly going
idle when there's work available
- Fix DL server bug which triggers a WARN() due to broken
get_prio_dl() logic and subsequent misbehavior
- Fix double update_rq_clock() calls
- Fix setscheduler() assumption about static priorities
- Make sure balancing callbacks are always called
- Plus a handful of preparatory commits for the fixes.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-urgent-2026-01-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Ingo Molnar:
"Misc deadline scheduler fixes, mainly for a new category of bugs that
were discovered and fixed recently:
- Fix a race condition in the DL server
- Fix a DL server bug which can result in incorrectly going idle when
there's work available
- Fix DL server bug which triggers a WARN() due to broken
get_prio_dl() logic and subsequent misbehavior
- Fix double update_rq_clock() calls
- Fix setscheduler() assumption about static priorities
- Make sure balancing callbacks are always called
- Plus a handful of preparatory commits for the fixes"
* tag 'sched-urgent-2026-01-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/deadline: Use ENQUEUE_MOVE to allow priority change
sched: Deadline has dynamic priority
sched: Audit MOVE vs balance_callbacks
sched: Fold rq-pin swizzle into __balance_callbacks()
sched/deadline: Avoid double update_rq_clock()
sched/deadline: Ensure get_prio_dl() is up-to-date
sched/deadline: Fix server stopping with runnable tasks
sched: Provide idle_rq() helper
sched/deadline: Fix potential race in dl_add_task_root_domain()
sched/deadline: Remove unnecessary comment in dl_add_task_root_domain()
- Fix a memory leak in em_create_pd() error path (Malaya Kumar Rout)
- Fix stale description of the cost field in struct em_perf_state to
reflect the current code (Yaxiong Tian)
- Fix and revamp the energy model YNL specification added recently
along with the energy model netlink interface (Changwoo Min)
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Merge tag 'pm-6.19-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management fixes from Rafael Wysocki:
"These fix an error path memory leak in the energy model management
code, fix a kerneldoc comment in it, and fix and revamp the energy
model YNL specification added recently along with the new energy model
management netlink interface (that received feedback after being
added):
- Fix a memory leak in em_create_pd() error path (Malaya Kumar Rout)
- Fix stale description of the cost field in struct em_perf_state to
reflect the current code (Yaxiong Tian)
- Fix and revamp the energy model YNL specification added recently
along with the energy model netlink interface (Changwoo Min)"
* tag 'pm-6.19-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
PM: EM: Add dump to get-perf-domains in the EM YNL spec
PM: EM: Change cpus' type from string to u64 array in the EM YNL spec
PM: EM: Rename em.yaml to dev-energymodel.yaml
PM: EM: Fix yamllint warnings in the EM YNL spec
PM: EM: Fix memory leak in em_create_pd() error path
PM: EM: Fix incorrect description of the cost field in struct em_perf_state
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Merge tag 'printk-for-6.19-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux
Pull printk fix from Petr Mladek:
- Prevent softlockup by restoring IRQs in atomic flush after each
record
* tag 'printk-for-6.19-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux:
printk/nbcon: Restore IRQ in atomic flush after each emitted record
Merge fixes related to the energy model management for 6.19-rc6:
- Fix a memory leak in em_create_pd() error path (Malaya Kumar Rout)
- Fix stale description of the cost field in struct em_perf_state to
reflect the current code (Yaxiong Tian)
- Fix and revamp the energy model YNL specification added recently
along with the energy model netlink interface (Changwoo Min)
* pm-em:
PM: EM: Add dump to get-perf-domains in the EM YNL spec
PM: EM: Change cpus' type from string to u64 array in the EM YNL spec
PM: EM: Rename em.yaml to dev-energymodel.yaml
PM: EM: Fix yamllint warnings in the EM YNL spec
PM: EM: Fix memory leak in em_create_pd() error path
PM: EM: Fix incorrect description of the cost field in struct em_perf_state
Add an appropriate SPDX-License-Identifier line to the file,
and remove the GNU boilerplate text.
Signed-off-by: Tim Bird <tim.bird@sony.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Add GPL-2.0 SPDX license id lines to a few old
files, replacing the reference to the COPYING file.
The COPYING file at the time of creation of these files
(2007 and 2005) was GPL-v2.0, with an additional clause
indicating that only v2 applied.
Signed-off-by: Tim Bird <tim.bird@sony.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Add a GPL-2.0 license identifier line for this file.
kmod.c was originally introduced in the kernel in February
of 1998 by Linus Torvalds - who was familiar with kernel
licensing at the time this was introduced.
Signed-off-by: Tim Bird <tim.bird@sony.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- Fix allocation accounting on boot up
The ftrace records for each function that ftrace can attach to is
done in a group of pages. At boot up, the number of pages are
calculated and allocated. After that, the pages are filled with data.
It may allocate more than needed due to some functions not being
recorded (because they are unused weak functions), this too is
recorded.
After the data is filled in, a check is made to make sure the right
number of pages were allocated. But this was off due to the
assumption that the same number of entries fit per every page.
Because the size of an entry does not evenly divide into PAGE_SIZE,
there is a rounding error when a large number of pages is allocated
to hold the events. This causes the check to fail and triggers a
warning.
Fix the accounting by finding out how many pages are actually
allocated from the functions that allocate them and use that to see
if all the pages allocated were used and the ones not used are
properly freed.
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Merge tag 'ftrace-v6.19-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull ftrace fix from Steven Rostedt:
- Fix allocation accounting on boot up
The ftrace records for each function that ftrace can attach to is
done in a group of pages. At boot up, the number of pages are
calculated and allocated. After that, the pages are filled with data.
It may allocate more than needed due to some functions not being
recorded (because they are unused weak functions), this too is
recorded.
After the data is filled in, a check is made to make sure the right
number of pages were allocated. But this was off due to the
assumption that the same number of entries fit per every page.
Because the size of an entry does not evenly divide into PAGE_SIZE,
there is a rounding error when a large number of pages is allocated
to hold the events. This causes the check to fail and triggers a
warning.
Fix the accounting by finding out how many pages are actually
allocated from the functions that allocate them and use that to see
if all the pages allocated were used and the ones not used are
properly freed.
* tag 'ftrace-v6.19-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
ftrace: Do not over-allocate ftrace memory
Pierre reported hitting balance callback warnings for deadline tasks
after commit 6455ad5346 ("sched: Move sched_class::prio_changed()
into the change pattern").
It turns out that DEQUEUE_SAVE+ENQUEUE_RESTORE does not preserve DL
priority and subsequently trips a balance pass -- where one was not
expected.
From discussion with Juri and Luca, the purpose of this clause was to
deal with tasks new to DL and all those sites will have MOVE set (as
well as CLASS, but MOVE is move conservative at this point).
Per the previous patches MOVE is audited to always run the balance
callbacks, so switch enqueue_dl_entity() to use MOVE for this case.
Fixes: 6455ad5346 ("sched: Move sched_class::prio_changed() into the change pattern")
Reported-by: Pierre Gondois <pierre.gondois@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Pierre Gondois <pierre.gondois@arm.com>
Tested-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://patch.msgid.link/20260114130528.GB831285@noisy.programming.kicks-ass.net
While FIFO/RR have static priority, DEADLINE is a dynamic priority
scheme. Notably it has static priority -1. Do not assume the priority
doesn't change for deadline tasks just because the static priority
doesn't change.
This ensures DL always sees {DE,EN}QUEUE_MOVE where appropriate.
Fixes: ff77e46853 ("sched/rt: Fix PI handling vs. sched_setscheduler()")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Pierre Gondois <pierre.gondois@arm.com>
Tested-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://patch.msgid.link/20260114130528.GB831285@noisy.programming.kicks-ass.net
The {DE,EN}QUEUE_MOVE flag indicates a task is allowed to change
priority, which means there could be balance callbacks queued.
Therefore audit all MOVE users and make sure they do run balance
callbacks before dropping rq-lock.
Fixes: 6455ad5346 ("sched: Move sched_class::prio_changed() into the change pattern")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Pierre Gondois <pierre.gondois@arm.com>
Tested-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://patch.msgid.link/20260114130528.GB831285@noisy.programming.kicks-ass.net
When setup_new_dl_entity() is called from enqueue_task_dl() ->
enqueue_dl_entity(), the rq-clock should already be updated, and
calling update_rq_clock() again is not right.
Move the update_rq_clock() to the one other caller of
setup_new_dl_entity(): sched_init_dl_server().
Fixes: 9f239df555 ("sched/deadline: Initialize dl_servers after SMP")
Reported-by: Pierre Gondois <pierre.gondois@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Pierre Gondois <pierre.gondois@arm.com>
Link: https://patch.msgid.link/20260113115622.GA831285@noisy.programming.kicks-ass.net
Pratheek tripped a WARN and noted the following issue:
> Inspecting the set of events that led to the warning being triggered
> showed the following:
>
> systemd-1 [008] dN.31 ...: do_set_cpus_allowed: set_cpus_allowed begin!
>
> systemd-1 [008] dN.31 ...: sched_change_begin: Begin!
> systemd-1 [008] dN.31 ...: sched_change_begin: Before dequeue_task()!
> systemd-1 [008] dN.31 ...: update_curr_dl_se: update_curr_dl_se: ENQUEUE_REPLENISH
> systemd-1 [008] dN.31 ...: enqueue_dl_entity: enqueue_dl_entity: ENQUEUE_REPLENISH
> systemd-1 [008] dN.31 ...: replenish_dl_entity: Replenish before: 14815760217
> systemd-1 [008] dN.31 ...: replenish_dl_entity: Replenish after: 14816960047
> systemd-1 [008] dN.31 ...: sched_change_begin: Before put_prev_task()!
>
> systemd-1 [008] dN.31 ...: sched_change_end: Before enqueue_task()!
> systemd-1 [008] dN.31 ...: sched_change_end: Before put_prev_task()!
> systemd-1 [008] dN.31 ...: prio_changed_dl: Queuing pull task on prio change: 14815760217 -> 14816960047
> systemd-1 [008] dN.31 ...: prio_changed_dl: Queuing balance callback!
> systemd-1 [008] dN.31 ...: sched_change_end: End!
>
> systemd-1 [008] dN.31 ...: do_set_cpus_allowed: set_cpus_allowed end!
> systemd-1 [008] dN.21 ...: __schedule: Woops! Balance callback found!
>
> 1. sched_change_begin() from guard(sched_change) in
> do_set_cpus_allowed() stashes the priority, which for the deadline
> task, is "p->dl.deadline".
> 2. The dequeue of the deadline task replenishes the deadline.
> 3. The task is enqueued back after guard's scope ends and since there is
> no *_CLASS flags set, sched_change_end() calls
> dl_sched_class->prio_changed() which compares the deadline.
> 4. Since deadline was moved on dequeue, prio_changed_dl() sees the value
> differ from the stashed value and queues a balance pull callback.
> 5. do_set_cpus_allowed() finishes and drops the rq_lock without doing a
> do_balance_callbacks().
> 6. Grabbing the rq_lock() at subsequent __schedule() triggers the
> warning since the balance pull callback was never executed before
> dropping the lock.
Meaning get_prio_dl() ought to update current and return an up-to-date
value.
Fixes: 6455ad5346 ("sched: Move sched_class::prio_changed() into the change pattern")
Reported-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://patch.msgid.link/20260106104113.GX3707891@noisy.programming.kicks-ass.net
- four kerneldoc fixes from Bagas Sanjaya
- four DAMON fixes from SeongJae
- four mremap VMA-related fixes from Lorenzo
- various singletons - please see the changelogs for details
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Merge tag 'mm-hotfixes-stable-2026-01-15-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull misc fixes from Andrew Morton:
- kerneldoc fixes from Bagas Sanjaya
- DAMON fixes from SeongJae
- mremap VMA-related fixes from Lorenzo
- various singletons - please see the changelogs for details
* tag 'mm-hotfixes-stable-2026-01-15-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (30 commits)
drivers/dax: add some missing kerneldoc comment fields for struct dev_dax
mm: numa,memblock: include <asm/numa.h> for 'numa_nodes_parsed'
mailmap: add entry for Daniel Thompson
tools/testing/selftests: fix gup_longterm for unknown fs
mm/page_alloc: prevent pcp corruption with SMP=n
iommu/sva: include mmu_notifier.h header
mm: kmsan: fix poisoning of high-order non-compound pages
tools/testing/selftests: add forked (un)/faulted VMA merge tests
mm/vma: enforce VMA fork limit on unfaulted,faulted mremap merge too
tools/testing/selftests: add tests for !tgt, src mremap() merges
mm/vma: fix anon_vma UAF on mremap() faulted, unfaulted merge
mm/zswap: fix error pointer free in zswap_cpu_comp_prepare()
mm/damon/sysfs-scheme: cleanup access_pattern subdirs on scheme dir setup failure
mm/damon/sysfs-scheme: cleanup quotas subdirs on scheme dir setup failure
mm/damon/sysfs: cleanup attrs subdirs on context dir setup failure
mm/damon/sysfs: cleanup intervals subdirs on attrs dir setup failure
mm/damon/core: remove call_control in inactive contexts
powerpc/watchdog: add support for hardlockup_sys_info sysctl
mips: fix HIGHMEM initialization
mm/hugetlb: ignore hugepage kernel args if hugepages are unsupported
...
The pg_remaining calculation in ftrace_process_locs() assumes that
ENTRIES_PER_PAGE multiplied by 2^order equals the actual capacity of the
allocated page group. However, ENTRIES_PER_PAGE is PAGE_SIZE / ENTRY_SIZE
(integer division). When PAGE_SIZE is not a multiple of ENTRY_SIZE (e.g.
4096 / 24 = 170 with remainder 16), high-order allocations (like 256 pages)
have significantly more capacity than 256 * 170. This leads to pg_remaining
being underestimated, which in turn makes skip (derived from skipped -
pg_remaining) larger than expected, causing the WARN(skip != remaining)
to trigger.
Extra allocated pages for ftrace: 2 with 654 skipped
WARNING: CPU: 0 PID: 0 at kernel/trace/ftrace.c:7295 ftrace_process_locs+0x5bf/0x5e0
A similar problem in ftrace_allocate_records() can result in allocating
too many pages. This can trigger the second warning in
ftrace_process_locs().
Extra allocated pages for ftrace
WARNING: CPU: 0 PID: 0 at kernel/trace/ftrace.c:7276 ftrace_process_locs+0x548/0x580
Use the actual capacity of a page group to determine the number of pages
to allocate. Have ftrace_allocate_pages() return the number of allocated
pages to avoid having to calculate it. Use the actual page group capacity
when validating the number of unused pages due to skipped entries.
Drop the definition of ENTRIES_PER_PAGE since it is no longer used.
Cc: stable@vger.kernel.org
Fixes: 4a3efc6baf ("ftrace: Update the mcount_loc check of skipped entries")
Link: https://patch.msgid.link/20260113152243.3557219-1-linux@roeck-us.net
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Commit a9af76a787 ("watchdog: add sys_info sysctls to dump sys info on
system lockup") adds 'hardlock_sys_info' systcl knob for general kernel
watchdog to control what kinds of system debug info to be dumped on
hardlockup.
Add similar support in powerpc watchdog code to make the sysctl knob more
general, which also fixes a compiling warning in general watchdog code
reported by 0day bot.
Link: https://lkml.kernel.org/r/20251231080309.39642-1-feng.tang@linux.alibaba.com
Fixes: a9af76a787 ("watchdog: add sys_info sysctls to dump sys info on system lockup")
Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202512030920.NFKtekA7-lkp@intel.com/
Suggested-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
If the previous kernel enabled KHO but did not call kho_finalize() (e.g.,
CONFIG_LIVEUPDATE=n or userspace skipped the finalization step), the
'preserved-memory-map' property in the FDT remains empty/zero.
Previously, kho_populate() would succeed regardless of the memory map's
state, reserving the incoming scratch regions in memblock. However,
kho_memory_init() would later fail to deserialize the empty map. By that
time, the scratch regions were already registered, leading to partial
initialization and subsequent list corruption (freeing scratch area twice)
during kho_init().
Move the validation of the preserved memory map earlier into
kho_populate(). If the memory map is empty/NULL:
1. Abort kho_populate() immediately with -ENOENT.
2. Do not register or reserve the incoming scratch memory, allowing the new
kernel to reclaim those pages as standard free memory.
3. Leave the global 'kho_in' state uninitialized.
Consequently, kho_memory_init() sees no active KHO context
(kho_in.mem_chunks_phys is 0) and falls back to kho_reserve_scratch(),
allocating fresh scratch memory as if it were a standard cold boot.
Link: https://lkml.kernel.org/r/20251223140140.2090337-1-pasha.tatashin@soleen.com
Fixes: de51999e68 ("kho: allow memory preservation state updates after finalization")
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reported-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Closes: https://lore.kernel.org/all/20251218215613.GA17304@ranerica-svr.sc.intel.com
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Tested-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
On smaller systems, e.g. embedded arm64, it is common for all memory
to end up in ZONE_DMA32 or even ZONE_DMA. In such cases it is redundant
to allocate a nominal pool for an empty higher zone that just ends up
coming from a lower zone that should already have its own pool anyway.
We already have logic to skip allocating a ZONE_DMA pool when that is
empty, so generalise that to save memory in the case of other zones too.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Tested-by: Vladimir Kondratiev <vladimir.kondratiev@mobileye.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/8ab8d8a620dee0109f33f5cb63d6bfeed35aac37.1768230104.git.robin.murphy@arm.com
If CONFIG_ZONE_DMA32 is enabled, but we have not allocated the
corresponding atomic_pool_dma32, dma_guess_pool() may return the NULL
value of that and fail a GFP_DMA32 allocation without trying to fall
back to other pools which may exist. Furthermore, if no GFP_DMA pool
exists, it is preferable to try GFP_DMA32 rather than immediately fall
back to GFP_KERNEL with even less chance of success. Improve matters
by encoding an explicit order of pool preference for each flag.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Tested-by: Vladimir Kondratiev <vladimir.kondratiev@mobileye.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/c846b1a2f43295cac926c7af2ce907f62baec518.1768230104.git.robin.murphy@arm.com
The deadline server can currently stop due to idle although fair tasks
are runnable. This happens essentially when:
* the server is set to idle, a task wakes up, the server stops
* a task wakes up, the server sets itself to idle and stops right away
Address both cases by clearing the server idle flag whenever a fair task
wakes up and accounting also for pending tasks in the definition of idle.
Fixes: f5a538c07d ("sched/deadline: Fix dl_server stop condition")
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260113085159.114226-3-gmonaco@redhat.com
A fix for the dl_server 'requires' idle_cpu() usage, which made me
note that it and available_idle_cpu() are extern function calls.
And while idle_cpu() is used outside of kernel/sched/,
available_idle_cpu() is not.
This makes it hard to make idle_cpu() an inline helper, so provide
idle_rq() and implement idle_cpu() and available_idle_cpu() using
that.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
