* + atomic-add-option-for-weaker-alignment-check.patch added to mm-nonmm-unstable branch
@ 2025-12-16 19:50 Andrew Morton
0 siblings, 0 replies; 3+ messages in thread
From: Andrew Morton @ 2025-12-16 19:50 UTC (permalink / raw)
To: mm-commits, ysato, yonghong.song, will, stefan.kristiansson, song,
shorne, sdf, peterz, martin.lau, mark.rutland, kpsingh, jonas,
jolsa, john.fastabend, haoluo, guoren, glaubitz, geert, gary,
eddyz87, dinguyen, daniel, dalias, boqun.feng, ast, arnd, andrii,
fthain, akpm
The patch titled
Subject: atomic: add option for weaker alignment check
has been added to the -mm mm-nonmm-unstable branch. Its filename is
atomic-add-option-for-weaker-alignment-check.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/atomic-add-option-for-weaker-alignment-check.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days
------------------------------------------------------
From: Finn Thain <fthain@linux-m68k.org>
Subject: atomic: add option for weaker alignment check
Date: Tue, 16 Dec 2025 17:31:05 +1100
Add a new Kconfig symbol to make CONFIG_DEBUG_ATOMIC more useful on those
architectures which do not align dynamic allocations to 8-byte boundaries.
Without this, CONFIG_DEBUG_ATOMIC produces excessive WARN splats.
Link: https://lkml.kernel.org/r/ff38f3d6c7a3e5b8c680013de15540f3ef903522.1765866665.git.fthain@linux-m68k.org
Signed-off-by: Finn Thain <fthain@linux-m68k.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Boqun Feng <boqun.feng@gmail.com>
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: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Hao Luo <haoluo@google.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: 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: Will Deacon <will@kernel.org>
Cc: Yonghong Song <yonghong.song@linux.dev>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
include/linux/instrumented.h | 17 ++++++++++++++---
lib/Kconfig.debug | 8 ++++++++
2 files changed, 22 insertions(+), 3 deletions(-)
--- a/include/linux/instrumented.h~atomic-add-option-for-weaker-alignment-check
+++ a/include/linux/instrumented.h
@@ -56,6 +56,17 @@ static __always_inline void instrument_r
kcsan_check_read_write(v, size);
}
+static __always_inline void instrument_atomic_check_alignment(const volatile void *v, size_t size)
+{
+ if (IS_ENABLED(CONFIG_DEBUG_ATOMIC)) {
+ unsigned int mask = size - 1;
+
+ if (IS_ENABLED(CONFIG_DEBUG_ATOMIC_LARGEST_ALIGN))
+ mask &= sizeof(struct { long x; } __aligned_largest) - 1;
+ WARN_ON_ONCE((unsigned long)v & mask);
+ }
+}
+
/**
* instrument_atomic_read - instrument atomic read access
* @v: address of access
@@ -68,7 +79,7 @@ static __always_inline void instrument_a
{
kasan_check_read(v, size);
kcsan_check_atomic_read(v, size);
- WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_ATOMIC) && ((unsigned long)v & (size - 1)));
+ instrument_atomic_check_alignment(v, size);
}
/**
@@ -83,7 +94,7 @@ static __always_inline void instrument_a
{
kasan_check_write(v, size);
kcsan_check_atomic_write(v, size);
- WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_ATOMIC) && ((unsigned long)v & (size - 1)));
+ instrument_atomic_check_alignment(v, size);
}
/**
@@ -98,7 +109,7 @@ static __always_inline void instrument_a
{
kasan_check_write(v, size);
kcsan_check_atomic_read_write(v, size);
- WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_ATOMIC) && ((unsigned long)v & (size - 1)));
+ instrument_atomic_check_alignment(v, size);
}
/**
--- a/lib/Kconfig.debug~atomic-add-option-for-weaker-alignment-check
+++ a/lib/Kconfig.debug
@@ -1370,6 +1370,14 @@ config DEBUG_ATOMIC
This option has potentially significant overhead.
+config DEBUG_ATOMIC_LARGEST_ALIGN
+ bool "Check alignment only up to __aligned_largest"
+ depends on DEBUG_ATOMIC
+ help
+ If you say Y here then the check for natural alignment of
+ atomic accesses will be constrained to the compiler's largest
+ alignment for scalar types.
+
menu "Lock Debugging (spinlocks, mutexes, etc...)"
config LOCK_DEBUGGING_SUPPORT
_
Patches currently in -mm which might be from fthain@linux-m68k.org are
bpf-explicitly-align-bpf_res_spin_lock.patch
atomic-specify-alignment-for-atomic_t-and-atomic64_t.patch
atomic-add-option-for-weaker-alignment-check.patch
^ permalink raw reply [flat|nested] 3+ messages in thread
* + atomic-add-option-for-weaker-alignment-check.patch added to mm-nonmm-unstable branch
@ 2025-12-27 15:09 Andrew Morton
0 siblings, 0 replies; 3+ messages in thread
From: Andrew Morton @ 2025-12-27 15:09 UTC (permalink / raw)
To: mm-commits, ysato, yonghong.song, will, tglx, stefan.kristiansson,
song, shorne, sdf, sashal, peterz, mingo, martin.lau,
mark.rutland, kpsingh, jonas, jolsa, john.fastabend, hpa, haoluo,
guoren, glaubitz, geert, gary, eddyz87, dinguyen, dave.hansen,
daniel, dalias, bp, boqun.feng, ast, arnd, ardb, andrii, fthain,
akpm
The patch titled
Subject: atomic: add option for weaker alignment check
has been added to the -mm mm-nonmm-unstable branch. Its filename is
atomic-add-option-for-weaker-alignment-check.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/atomic-add-option-for-weaker-alignment-check.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days
------------------------------------------------------
From: Finn Thain <fthain@linux-m68k.org>
Subject: atomic: add option for weaker alignment check
Date: Wed, 31 Dec 2025 19:25:42 +1100
Add a new Kconfig symbol to make CONFIG_DEBUG_ATOMIC more useful on those
architectures which do not align dynamic allocations to 8-byte boundaries.
Without this, CONFIG_DEBUG_ATOMIC produces excessive WARN splats.
Link: https://lkml.kernel.org/r/0c8ef95ea5e9a949a28412a3c791b2167592ae80.1767169542.git.fthain@linux-m68k.org
Signed-off-by: Finn Thain <fthain@linux-m68k.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Borislav Betkov <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: Geert Uytterhoeven <geert@linux-m68k.org>
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 Gleinxer <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>
---
include/linux/instrumented.h | 25 ++++++++++++++++---------
lib/Kconfig.debug | 8 ++++++++
2 files changed, 24 insertions(+), 9 deletions(-)
--- a/include/linux/instrumented.h~atomic-add-option-for-weaker-alignment-check
+++ a/include/linux/instrumented.h
@@ -56,6 +56,19 @@ static __always_inline void instrument_r
kcsan_check_read_write(v, size);
}
+static __always_inline void instrument_atomic_check_alignment(const volatile void *v, size_t size)
+{
+#ifndef __DISABLE_BUG_TABLE
+ if (IS_ENABLED(CONFIG_DEBUG_ATOMIC)) {
+ unsigned int mask = size - 1;
+
+ if (IS_ENABLED(CONFIG_DEBUG_ATOMIC_LARGEST_ALIGN))
+ mask &= sizeof(struct { long x; } __aligned_largest) - 1;
+ WARN_ON_ONCE((unsigned long)v & mask);
+ }
+#endif
+}
+
/**
* instrument_atomic_read - instrument atomic read access
* @v: address of access
@@ -68,9 +81,7 @@ static __always_inline void instrument_a
{
kasan_check_read(v, size);
kcsan_check_atomic_read(v, size);
-#ifndef __DISABLE_BUG_TABLE
- WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_ATOMIC) && ((unsigned long)v & (size - 1)));
-#endif
+ instrument_atomic_check_alignment(v, size);
}
/**
@@ -85,9 +96,7 @@ static __always_inline void instrument_a
{
kasan_check_write(v, size);
kcsan_check_atomic_write(v, size);
-#ifndef __DISABLE_BUG_TABLE
- WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_ATOMIC) && ((unsigned long)v & (size - 1)));
-#endif
+ instrument_atomic_check_alignment(v, size);
}
/**
@@ -102,9 +111,7 @@ static __always_inline void instrument_a
{
kasan_check_write(v, size);
kcsan_check_atomic_read_write(v, size);
-#ifndef __DISABLE_BUG_TABLE
- WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_ATOMIC) && ((unsigned long)v & (size - 1)));
-#endif
+ instrument_atomic_check_alignment(v, size);
}
/**
--- a/lib/Kconfig.debug~atomic-add-option-for-weaker-alignment-check
+++ a/lib/Kconfig.debug
@@ -1370,6 +1370,14 @@ config DEBUG_ATOMIC
This option has potentially significant overhead.
+config DEBUG_ATOMIC_LARGEST_ALIGN
+ bool "Check alignment only up to __aligned_largest"
+ depends on DEBUG_ATOMIC
+ help
+ If you say Y here then the check for natural alignment of
+ atomic accesses will be constrained to the compiler's largest
+ alignment for scalar types.
+
menu "Lock Debugging (spinlocks, mutexes, etc...)"
config LOCK_DEBUGGING_SUPPORT
_
Patches currently in -mm which might be from fthain@linux-m68k.org are
bpf-explicitly-align-bpf_res_spin_lock.patch
atomic-specify-alignment-for-atomic_t-and-atomic64_t.patch
atomic-add-option-for-weaker-alignment-check.patch
^ permalink raw reply [flat|nested] 3+ messages in thread
* + atomic-add-option-for-weaker-alignment-check.patch added to mm-nonmm-unstable branch
@ 2026-01-13 23:34 Andrew Morton
0 siblings, 0 replies; 3+ messages in thread
From: Andrew Morton @ 2026-01-13 23:34 UTC (permalink / raw)
To: mm-commits, ysato, yonghong.song, will, tglx, stefan.kristiansson,
song, shorne, sdf, sashal, peterz, mingo, martin.lau,
mark.rutland, kpsingh, jonas, jolsa, john.fastabend, hpa, haoluo,
guoren, glaubitz, geert, gary, eddyz87, dinguyen, dave.hansen,
daniel, dalias, bp, boqun.feng, ast, arnd, ardb, andrii, fthain,
akpm
The patch titled
Subject: atomic: add option for weaker alignment check
has been added to the -mm mm-nonmm-unstable branch. Its filename is
atomic-add-option-for-weaker-alignment-check.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/atomic-add-option-for-weaker-alignment-check.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days
------------------------------------------------------
From: Finn Thain <fthain@linux-m68k.org>
Subject: atomic: add option for weaker alignment check
Date: Tue, 13 Jan 2026 16:22:28 +1100
Add a new Kconfig symbol to make CONFIG_DEBUG_ATOMIC more useful on those
architectures which do not align dynamic allocations to 8-byte boundaries.
Without this, CONFIG_DEBUG_ATOMIC produces excessive WARN splats.
Link: https://lkml.kernel.org/r/6d25a12934fe9199332f4d65d17c17de450139a8.1768281748.git.fthain@linux-m68k.org
Signed-off-by: Finn Thain <fthain@linux-m68k.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Daniel Borkman <daniel@iogearbox.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: Gary Guo <gary@garyguo.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
include/linux/instrumented.h | 8 +++++++-
lib/Kconfig.debug | 8 ++++++++
2 files changed, 15 insertions(+), 1 deletion(-)
--- a/include/linux/instrumented.h~atomic-add-option-for-weaker-alignment-check
+++ a/include/linux/instrumented.h
@@ -59,7 +59,13 @@ static __always_inline void instrument_r
static __always_inline void instrument_atomic_check_alignment(const volatile void *v, size_t size)
{
#ifndef __DISABLE_EXPORTS
- WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_ATOMIC) && ((unsigned long)v & (size - 1)));
+ if (IS_ENABLED(CONFIG_DEBUG_ATOMIC)) {
+ unsigned int mask = size - 1;
+
+ if (IS_ENABLED(CONFIG_DEBUG_ATOMIC_LARGEST_ALIGN))
+ mask &= sizeof(struct { long x; } __aligned_largest) - 1;
+ WARN_ON_ONCE((unsigned long)v & mask);
+ }
#endif
}
--- a/lib/Kconfig.debug~atomic-add-option-for-weaker-alignment-check
+++ a/lib/Kconfig.debug
@@ -1370,6 +1370,14 @@ config DEBUG_ATOMIC
This option has potentially significant overhead.
+config DEBUG_ATOMIC_LARGEST_ALIGN
+ bool "Check alignment only up to __aligned_largest"
+ depends on DEBUG_ATOMIC
+ help
+ If you say Y here then the check for natural alignment of
+ atomic accesses will be constrained to the compiler's largest
+ alignment for scalar types.
+
menu "Lock Debugging (spinlocks, mutexes, etc...)"
config LOCK_DEBUGGING_SUPPORT
_
Patches currently in -mm which might be from fthain@linux-m68k.org are
bpf-explicitly-align-bpf_res_spin_lock.patch
atomic-specify-alignment-for-atomic_t-and-atomic64_t.patch
atomic-add-option-for-weaker-alignment-check.patch
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2026-01-13 23:34 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
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