* FAILED: patch "[PATCH] rust: use `#[used(compiler)]` to fix build and `modpost` with" failed to apply to 6.15-stable tree
@ 2025-07-21 9:30 gregkh
2025-07-21 19:49 ` [PATCH 6.15.y] rust: use `#[used(compiler)]` to fix build and `modpost` with Rust >= 1.89.0 Miguel Ojeda
0 siblings, 1 reply; 3+ messages in thread
From: gregkh @ 2025-07-21 9:30 UTC (permalink / raw)
To: ojeda, aliceryhl, bjorn3_gh, david, wwiser; +Cc: stable
The patch below does not apply to the 6.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.15.y
git checkout FETCH_HEAD
git cherry-pick -x 7498159226772d66f150dd406be462d75964a366
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025072101-perfume-vitalize-a08b@gregkh' --subject-prefix 'PATCH 6.15.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 7498159226772d66f150dd406be462d75964a366 Mon Sep 17 00:00:00 2001
From: Miguel Ojeda <ojeda@kernel.org>
Date: Sat, 12 Jul 2025 18:01:03 +0200
Subject: [PATCH] rust: use `#[used(compiler)]` to fix build and `modpost` with
Rust >= 1.89.0
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Starting with Rust 1.89.0 (expected 2025-08-07), the Rust compiler fails
to build the `rusttest` target due to undefined references such as:
kernel...-cgu.0:(.text....+0x116): undefined reference to
`rust_helper_kunit_get_current_test'
Moreover, tooling like `modpost` gets confused:
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/gpu/drm/nova/nova.o
ERROR: modpost: missing MODULE_LICENSE() in drivers/gpu/nova-core/nova_core.o
The reason behind both issues is that the Rust compiler will now [1]
treat `#[used]` as `#[used(linker)]` instead of `#[used(compiler)]`
for our targets. This means that the retain section flag (`R`,
`SHF_GNU_RETAIN`) will be used and that they will be marked as `unique`
too, with different IDs. In turn, that means we end up with undefined
references that did not get discarded in `rusttest` and that multiple
`.modinfo` sections are generated, which confuse tooling like `modpost`
because they only expect one.
Thus start using `#[used(compiler)]` to keep the previous behavior
and to be explicit about what we want. Sadly, it is an unstable feature
(`used_with_arg`) [2] -- we will talk to upstream Rust about it. The good
news is that it has been available for a long time (Rust >= 1.60) [3].
The changes should also be fine for previous Rust versions, since they
behave the same way as before [4].
Alternatively, we could use `#[no_mangle]` or `#[export_name = ...]`
since those still behave like `#[used(compiler)]`, but of course it is
not really what we want to express, and it requires other changes to
avoid symbol conflicts.
Cc: David Wood <david@davidtw.co>
Cc: Wesley Wiser <wwiser@gmail.com>
Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
Link: https://github.com/rust-lang/rust/pull/140872 [1]
Link: https://github.com/rust-lang/rust/issues/93798 [2]
Link: https://github.com/rust-lang/rust/pull/91504 [3]
Link: https://godbolt.org/z/sxzWTMfzW [4]
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Björn Roy Baron <bjorn3_gh@protonmail.com>
Link: https://lore.kernel.org/r/20250712160103.1244945-3-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
diff --git a/rust/Makefile b/rust/Makefile
index 27dec7904c3a..115b63b7d1e3 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -194,6 +194,7 @@ quiet_cmd_rustdoc_test = RUSTDOC T $<
RUST_MODFILE=test.rs \
OBJTREE=$(abspath $(objtree)) \
$(RUSTDOC) --test $(rust_common_flags) \
+ -Zcrate-attr='feature(used_with_arg)' \
@$(objtree)/include/generated/rustc_cfg \
$(rustc_target_flags) $(rustdoc_test_target_flags) \
$(rustdoc_test_quiet) \
diff --git a/rust/kernel/firmware.rs b/rust/kernel/firmware.rs
index 2494c96e105f..4fe621f35716 100644
--- a/rust/kernel/firmware.rs
+++ b/rust/kernel/firmware.rs
@@ -202,7 +202,7 @@ macro_rules! module_firmware {
};
#[link_section = ".modinfo"]
- #[used]
+ #[used(compiler)]
static __MODULE_FIRMWARE: [u8; $($builder)*::create(__MODULE_FIRMWARE_PREFIX)
.build_length()] = $($builder)*::create(__MODULE_FIRMWARE_PREFIX).build();
};
diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs
index 4b8cdcb21e77..b9e65905e121 100644
--- a/rust/kernel/kunit.rs
+++ b/rust/kernel/kunit.rs
@@ -302,7 +302,7 @@ macro_rules! kunit_unsafe_test_suite {
is_init: false,
};
- #[used]
+ #[used(compiler)]
#[allow(unused_unsafe)]
#[cfg_attr(not(target_os = "macos"), link_section = ".kunit_test_suites")]
static mut KUNIT_TEST_SUITE_ENTRY: *const ::kernel::bindings::kunit_suite =
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 6b4774b2b1c3..e13d6ed88fa6 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -34,6 +34,9 @@
// Expected to become stable.
#![feature(arbitrary_self_types)]
//
+// To be determined.
+#![feature(used_with_arg)]
+//
// `feature(derive_coerce_pointee)` is expected to become stable. Before Rust
// 1.84.0, it did not exist, so enable the predecessor features.
#![cfg_attr(CONFIG_RUSTC_HAS_COERCE_POINTEE, feature(derive_coerce_pointee))]
diff --git a/rust/macros/module.rs b/rust/macros/module.rs
index 2ddd2eeb2852..75efc6eeeafc 100644
--- a/rust/macros/module.rs
+++ b/rust/macros/module.rs
@@ -57,7 +57,7 @@ fn emit_base(&mut self, field: &str, content: &str, builtin: bool) {
{cfg}
#[doc(hidden)]
#[cfg_attr(not(target_os = \"macos\"), link_section = \".modinfo\")]
- #[used]
+ #[used(compiler)]
pub static __{module}_{counter}: [u8; {length}] = *{string};
",
cfg = if builtin {
@@ -249,7 +249,7 @@ mod __module_init {{
// key or a new section. For the moment, keep it simple.
#[cfg(MODULE)]
#[doc(hidden)]
- #[used]
+ #[used(compiler)]
static __IS_RUST_MODULE: () = ();
static mut __MOD: ::core::mem::MaybeUninit<{type_}> =
@@ -273,7 +273,7 @@ mod __module_init {{
#[cfg(MODULE)]
#[doc(hidden)]
- #[used]
+ #[used(compiler)]
#[link_section = \".init.data\"]
static __UNIQUE_ID___addressable_init_module: unsafe extern \"C\" fn() -> i32 = init_module;
@@ -293,7 +293,7 @@ mod __module_init {{
#[cfg(MODULE)]
#[doc(hidden)]
- #[used]
+ #[used(compiler)]
#[link_section = \".exit.data\"]
static __UNIQUE_ID___addressable_cleanup_module: extern \"C\" fn() = cleanup_module;
@@ -303,7 +303,7 @@ mod __module_init {{
#[cfg(not(CONFIG_HAVE_ARCH_PREL32_RELOCATIONS))]
#[doc(hidden)]
#[link_section = \"{initcall_section}\"]
- #[used]
+ #[used(compiler)]
pub static __{ident}_initcall: extern \"C\" fn() ->
::kernel::ffi::c_int = __{ident}_init;
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index a6461ea411f7..ba71b27aa363 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -312,10 +312,11 @@ $(obj)/%.lst: $(obj)/%.c FORCE
# - Stable since Rust 1.82.0: `feature(asm_const)`, `feature(raw_ref_op)`.
# - Stable since Rust 1.87.0: `feature(asm_goto)`.
# - Expected to become stable: `feature(arbitrary_self_types)`.
+# - To be determined: `feature(used_with_arg)`.
#
# Please see https://github.com/Rust-for-Linux/linux/issues/2 for details on
# the unstable features in use.
-rust_allowed_features := asm_const,asm_goto,arbitrary_self_types,lint_reasons,raw_ref_op
+rust_allowed_features := asm_const,asm_goto,arbitrary_self_types,lint_reasons,raw_ref_op,used_with_arg
# `--out-dir` is required to avoid temporaries being created by `rustc` in the
# current working directory, which may be not accessible in the out-of-tree
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [PATCH 6.15.y] rust: use `#[used(compiler)]` to fix build and `modpost` with Rust >= 1.89.0
2025-07-21 9:30 FAILED: patch "[PATCH] rust: use `#[used(compiler)]` to fix build and `modpost` with" failed to apply to 6.15-stable tree gregkh
@ 2025-07-21 19:49 ` Miguel Ojeda
2025-07-23 4:34 ` Sasha Levin
0 siblings, 1 reply; 3+ messages in thread
From: Miguel Ojeda @ 2025-07-21 19:49 UTC (permalink / raw)
To: stable
Cc: Miguel Ojeda, David Wood, Wesley Wiser, Alice Ryhl,
Björn Roy Baron
Starting with Rust 1.89.0 (expected 2025-08-07), the Rust compiler fails
to build the `rusttest` target due to undefined references such as:
kernel...-cgu.0:(.text....+0x116): undefined reference to
`rust_helper_kunit_get_current_test'
Moreover, tooling like `modpost` gets confused:
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/gpu/drm/nova/nova.o
ERROR: modpost: missing MODULE_LICENSE() in drivers/gpu/nova-core/nova_core.o
The reason behind both issues is that the Rust compiler will now [1]
treat `#[used]` as `#[used(linker)]` instead of `#[used(compiler)]`
for our targets. This means that the retain section flag (`R`,
`SHF_GNU_RETAIN`) will be used and that they will be marked as `unique`
too, with different IDs. In turn, that means we end up with undefined
references that did not get discarded in `rusttest` and that multiple
`.modinfo` sections are generated, which confuse tooling like `modpost`
because they only expect one.
Thus start using `#[used(compiler)]` to keep the previous behavior
and to be explicit about what we want. Sadly, it is an unstable feature
(`used_with_arg`) [2] -- we will talk to upstream Rust about it. The good
news is that it has been available for a long time (Rust >= 1.60) [3].
The changes should also be fine for previous Rust versions, since they
behave the same way as before [4].
Alternatively, we could use `#[no_mangle]` or `#[export_name = ...]`
since those still behave like `#[used(compiler)]`, but of course it is
not really what we want to express, and it requires other changes to
avoid symbol conflicts.
Cc: David Wood <david@davidtw.co>
Cc: Wesley Wiser <wwiser@gmail.com>
Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
Link: https://github.com/rust-lang/rust/pull/140872 [1]
Link: https://github.com/rust-lang/rust/issues/93798 [2]
Link: https://github.com/rust-lang/rust/pull/91504 [3]
Link: https://godbolt.org/z/sxzWTMfzW [4]
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Björn Roy Baron <bjorn3_gh@protonmail.com>
Link: https://lore.kernel.org/r/20250712160103.1244945-3-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
(cherry picked from commit 7498159226772d66f150dd406be462d75964a366)
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
rust/Makefile | 1 +
rust/kernel/firmware.rs | 2 +-
rust/kernel/kunit.rs | 2 +-
rust/kernel/lib.rs | 2 ++
rust/macros/module.rs | 10 +++++-----
scripts/Makefile.build | 2 +-
6 files changed, 11 insertions(+), 8 deletions(-)
diff --git a/rust/Makefile b/rust/Makefile
index d62b58d0a55c..913b31d25bc4 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -194,6 +194,7 @@ quiet_cmd_rustdoc_test = RUSTDOC T $<
RUST_MODFILE=test.rs \
OBJTREE=$(abspath $(objtree)) \
$(RUSTDOC) --test $(rust_common_flags) \
+ -Zcrate-attr='feature(used_with_arg)' \
@$(objtree)/include/generated/rustc_cfg \
$(rustc_target_flags) $(rustdoc_test_target_flags) \
$(rustdoc_test_quiet) \
diff --git a/rust/kernel/firmware.rs b/rust/kernel/firmware.rs
index 2494c96e105f..4fe621f35716 100644
--- a/rust/kernel/firmware.rs
+++ b/rust/kernel/firmware.rs
@@ -202,7 +202,7 @@ macro_rules! module_firmware {
};
#[link_section = ".modinfo"]
- #[used]
+ #[used(compiler)]
static __MODULE_FIRMWARE: [u8; $($builder)*::create(__MODULE_FIRMWARE_PREFIX)
.build_length()] = $($builder)*::create(__MODULE_FIRMWARE_PREFIX).build();
};
diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs
index 1604fb6a5b1b..cf95700c8612 100644
--- a/rust/kernel/kunit.rs
+++ b/rust/kernel/kunit.rs
@@ -278,7 +278,7 @@ macro_rules! kunit_unsafe_test_suite {
is_init: false,
};
- #[used]
+ #[used(compiler)]
#[allow(unused_unsafe)]
#[cfg_attr(not(target_os = "macos"), link_section = ".kunit_test_suites")]
static mut KUNIT_TEST_SUITE_ENTRY: *const ::kernel::bindings::kunit_suite =
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index de07aadd1ff5..2bdf9d14ec43 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -26,6 +26,8 @@
#![feature(const_mut_refs)]
#![feature(const_ptr_write)]
#![feature(const_refs_to_cell)]
+// To be determined.
+#![feature(used_with_arg)]
// Ensure conditional compilation based on the kernel configuration works;
// otherwise we may silently break things like initcall handling.
diff --git a/rust/macros/module.rs b/rust/macros/module.rs
index 44e5cb108cea..b19ce62f6af1 100644
--- a/rust/macros/module.rs
+++ b/rust/macros/module.rs
@@ -57,7 +57,7 @@ fn emit_base(&mut self, field: &str, content: &str, builtin: bool) {
{cfg}
#[doc(hidden)]
#[cfg_attr(not(target_os = \"macos\"), link_section = \".modinfo\")]
- #[used]
+ #[used(compiler)]
pub static __{module}_{counter}: [u8; {length}] = *{string};
",
cfg = if builtin {
@@ -247,7 +247,7 @@ mod __module_init {{
// key or a new section. For the moment, keep it simple.
#[cfg(MODULE)]
#[doc(hidden)]
- #[used]
+ #[used(compiler)]
static __IS_RUST_MODULE: () = ();
static mut __MOD: core::mem::MaybeUninit<{type_}> =
@@ -271,7 +271,7 @@ mod __module_init {{
#[cfg(MODULE)]
#[doc(hidden)]
- #[used]
+ #[used(compiler)]
#[link_section = \".init.data\"]
static __UNIQUE_ID___addressable_init_module: unsafe extern \"C\" fn() -> i32 = init_module;
@@ -291,7 +291,7 @@ mod __module_init {{
#[cfg(MODULE)]
#[doc(hidden)]
- #[used]
+ #[used(compiler)]
#[link_section = \".exit.data\"]
static __UNIQUE_ID___addressable_cleanup_module: extern \"C\" fn() = cleanup_module;
@@ -301,7 +301,7 @@ mod __module_init {{
#[cfg(not(CONFIG_HAVE_ARCH_PREL32_RELOCATIONS))]
#[doc(hidden)]
#[link_section = \"{initcall_section}\"]
- #[used]
+ #[used(compiler)]
pub static __{name}_initcall: extern \"C\" fn() -> kernel::ffi::c_int = __{name}_init;
#[cfg(not(MODULE))]
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 13dcd86e74ca..eb0d27812aec 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -222,7 +222,7 @@ $(obj)/%.lst: $(obj)/%.c FORCE
# Compile Rust sources (.rs)
# ---------------------------------------------------------------------------
-rust_allowed_features := asm_const,asm_goto,arbitrary_self_types,lint_reasons,raw_ref_op
+rust_allowed_features := asm_const,asm_goto,arbitrary_self_types,lint_reasons,raw_ref_op,used_with_arg
# `--out-dir` is required to avoid temporaries being created by `rustc` in the
# current working directory, which may be not accessible in the out-of-tree
--
2.50.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH 6.15.y] rust: use `#[used(compiler)]` to fix build and `modpost` with Rust >= 1.89.0
2025-07-21 19:49 ` [PATCH 6.15.y] rust: use `#[used(compiler)]` to fix build and `modpost` with Rust >= 1.89.0 Miguel Ojeda
@ 2025-07-23 4:34 ` Sasha Levin
0 siblings, 0 replies; 3+ messages in thread
From: Sasha Levin @ 2025-07-23 4:34 UTC (permalink / raw)
To: stable; +Cc: Sasha Levin
[ Sasha's backport helper bot ]
Hi,
✅ All tests passed successfully. No issues detected.
No action required from the submitter.
The upstream commit SHA1 provided is correct: 7498159226772d66f150dd406be462d75964a366
Note: The patch differs from the upstream commit:
---
1: 749815922677 ! 1: a3a4555a1d32 rust: use `#[used(compiler)]` to fix build and `modpost` with Rust >= 1.89.0
@@ Commit message
Acked-by: Björn Roy Baron <bjorn3_gh@protonmail.com>
Link: https://lore.kernel.org/r/20250712160103.1244945-3-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
+ (cherry picked from commit 7498159226772d66f150dd406be462d75964a366)
+ Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
## rust/Makefile ##
@@ rust/Makefile: quiet_cmd_rustdoc_test = RUSTDOC T $<
@@ rust/kernel/kunit.rs: macro_rules! kunit_unsafe_test_suite {
## rust/kernel/lib.rs ##
@@
- // Expected to become stable.
- #![feature(arbitrary_self_types)]
- //
+ #![feature(const_mut_refs)]
+ #![feature(const_ptr_write)]
+ #![feature(const_refs_to_cell)]
+// To be determined.
+#![feature(used_with_arg)]
-+//
- // `feature(derive_coerce_pointee)` is expected to become stable. Before Rust
- // 1.84.0, it did not exist, so enable the predecessor features.
- #![cfg_attr(CONFIG_RUSTC_HAS_COERCE_POINTEE, feature(derive_coerce_pointee))]
+
+ // Ensure conditional compilation based on the kernel configuration works;
+ // otherwise we may silently break things like initcall handling.
## rust/macros/module.rs ##
@@ rust/macros/module.rs: fn emit_base(&mut self, field: &str, content: &str, builtin: bool) {
@@ rust/macros/module.rs: mod __module_init {{
+ #[used(compiler)]
static __IS_RUST_MODULE: () = ();
- static mut __MOD: ::core::mem::MaybeUninit<{type_}> =
+ static mut __MOD: core::mem::MaybeUninit<{type_}> =
@@ rust/macros/module.rs: mod __module_init {{
#[cfg(MODULE)]
@@ rust/macros/module.rs: mod __module_init {{
#[link_section = \"{initcall_section}\"]
- #[used]
+ #[used(compiler)]
- pub static __{ident}_initcall: extern \"C\" fn() ->
- ::kernel::ffi::c_int = __{ident}_init;
+ pub static __{name}_initcall: extern \"C\" fn() -> kernel::ffi::c_int = __{name}_init;
+ #[cfg(not(MODULE))]
## scripts/Makefile.build ##
@@ scripts/Makefile.build: $(obj)/%.lst: $(obj)/%.c FORCE
- # - Stable since Rust 1.82.0: `feature(asm_const)`, `feature(raw_ref_op)`.
- # - Stable since Rust 1.87.0: `feature(asm_goto)`.
- # - Expected to become stable: `feature(arbitrary_self_types)`.
-+# - To be determined: `feature(used_with_arg)`.
- #
- # Please see https://github.com/Rust-for-Linux/linux/issues/2 for details on
- # the unstable features in use.
+ # Compile Rust sources (.rs)
+ # ---------------------------------------------------------------------------
+
-rust_allowed_features := asm_const,asm_goto,arbitrary_self_types,lint_reasons,raw_ref_op
+rust_allowed_features := asm_const,asm_goto,arbitrary_self_types,lint_reasons,raw_ref_op,used_with_arg
---
Results of testing on various branches:
| Branch | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| origin/linux-6.15.y | Success | Success |
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2025-07-23 4:34 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
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2025-07-21 9:30 FAILED: patch "[PATCH] rust: use `#[used(compiler)]` to fix build and `modpost` with" failed to apply to 6.15-stable tree gregkh
2025-07-21 19:49 ` [PATCH 6.15.y] rust: use `#[used(compiler)]` to fix build and `modpost` with Rust >= 1.89.0 Miguel Ojeda
2025-07-23 4:34 ` Sasha Levin
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