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For instance, with Rust 1.97.1: > > With the version that I applied of that series, this was not strictly > needed anymore. I am seeing this function causing issue on my 1.85.1 -Os build, although th= e error message is different this time: rust/kernel.o: warning: objtool: _RNvXs2_NtNtCsaNryh1j6xD7_4core3str6traits= eINtNtNtB9_3ops5index5IndexINtNtBJ_5range9RangeFromjEE5indexCsldbe0TGTmNx_6= kernel+0x1d: stack state mismatch: cfa1=3D4+8 cfa2=3D4+16 Disassembly shows that the function call before the warning location is a c= all to _4core3str16slice_error_fail, and objtool thought it can return (which w= ill end up with a unbalanced stack if it does return). Applying the patch fixes the issue. Best, Gary