FAILED: patch "[PATCH] objtool/rust: add one more `noreturn` Rust function" failed to apply to 6.18-stable tree

FAILED: patch "[PATCH] objtool/rust: add one more `noreturn` Rust function" failed to apply to 6.18-stable tree

[gregkh]

The patch below does not apply to the 6.18-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-6.18.y
git checkout FETCH_HEAD
git cherry-pick -x 993f235c4af49d0e912cc28abe6d733531600237
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026090341-uncanny-legwarmer-a899@gregkh' --subject-prefix 'PATCH 6.18.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 993f235c4af49d0e912cc28abe6d733531600237 Mon Sep 17 00:00:00 2001
From: Miguel Ojeda <ojeda@kernel.org>
Date: Wed, 5 Aug 2026 16:45:24 +0200
Subject: [PATCH] objtool/rust: add one more `noreturn` Rust function

When the pointer formatting series [1] is applied and KUnit tests
are enabled, `objtool` would report an error with any of our
supported Rust versions. For instance, with Rust 1.97.1:

    rust/kernel.o: error: objtool: _R..._4core3fmt7Pointer3fmtB7_()
    falls through to next function _R..._4core7convert5AsRefNtB5_4BStrE6as_ref()

Or, with Rust 1.85.0:

    rust/kernel.o: error: objtool: _R..._4core3fmt7Pointer3fmtB7_()
    falls through to next function _R..._4core3ffi5c_str4CStrENtNtBS_3fmt7Display3fmtB7_()

This happens due to calls to the `noreturn` symbol:

    core::str::slice_error_fail

Thus add the mangled one to the list so that `objtool` knows it is
actually `noreturn`.

See commit 56d680dd23c3 ("objtool/rust: list `noreturn` Rust functions")
for more details.

[ While the series [1] mentioned above was not applied in a way
  that triggered this, Gary found another case [2]:

    I am seeing this function causing issue on my 1.85.1 -Os build, although the
    error message is different this time:

        rust/kernel.o: warning: objtool: _R..._5range9RangeFromjEE5indexCsldbe0TGTmNx_6kernel+0x1d:
        stack state mismatch: cfa1=4+8 cfa2=4+16

    Disassembly shows that the function call before the warning location
    is a call to _4core3str16slice_error_fail, and objtool thought it can
    return (which will end up with a unbalanced stack if it does return).

  Thus apply it. - Miguel ]

Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Reported-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/rust-for-linux/anLxXvCKBcAVf91_@google.com/
Link: https://lore.kernel.org/rust-for-linux/20260706-hashedptr-v13-0-377a07f2f78d@kylinos.cn/ [1]
Link: https://lore.kernel.org/rust-for-linux/DKS7U9UHY6XR.2JC0EBIPCI06Z@garyguo.net/ [2]
Link: https://patch.msgid.link/20260805144524.233362-1-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 87db9f4ed9e2..3ab5b9f1c6a4 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -195,6 +195,7 @@ static bool is_rust_noreturn(const struct symbol *func)
 	return str_ends_with(func->name, "_4core3num20from_str_radix_panic")				||
 	       str_ends_with(func->name, "_4core3num22from_ascii_radix_panic")				||
 	       str_ends_with(func->name, "_4core3num28from_ascii_bytes_radix_panic")			||
+	       str_ends_with(func->name, "_4core3str16slice_error_fail")				||
 	       str_ends_with(func->name, "_4core5sliceSp15copy_from_slice17len_mismatch_fail")		||
 	       str_ends_with(func->name, "_4core6option13expect_failed")				||
 	       str_ends_with(func->name, "_4core6option13unwrap_failed")				||

Re: FAILED: patch "[PATCH] objtool/rust: add one more `noreturn` Rust function" failed to apply to 6.18-stable tree

[Miguel Ojeda]

On Thu, Sep 3, 2026 at 2:44 PM <gregkh@linuxfoundation.org> wrote:
>
> The patch below does not apply to the 6.18-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-6.18.y
> git checkout FETCH_HEAD
> git cherry-pick -x 993f235c4af49d0e912cc28abe6d733531600237
> # <resolve conflicts, build, test, etc.>
> git commit -s
> git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026090341-uncanny-legwarmer-a899@gregkh' --subject-prefix 'PATCH 6.18.y' 'HEAD^..'

To solve this one and the related ones, please see this sequence of
cherry-picks:

  https://lore.kernel.org/stable/CANiq72kmYx5GBU7VL3z8h3bAWB=vw-TX+ptskDO0k3Ro-F450w@mail.gmail.com/

Cheers,
Miguel