Re: [PATCH 6.7 000/707] 6.7.11-rc2 review

[Sasha Levin <sashal@kernel.org>]

On Mon, Mar 25, 2024 at 01:47:40PM -0600, Daniel Díaz wrote:
>Hello!
>
>On Mon, 25 Mar 2024 at 12:14, Sami Tolvanen <samitolvanen@google.com> wrote:
>> On Mon, Mar 25, 2024 at 11:43:48AM -0600, Daniel Díaz wrote:
>> > Hello!
>> >
>> > On 25/03/24 6:00 a. m., Sasha Levin wrote:
>> > > This is the start of the stable review cycle for the 6.7.11 release.
>> > > There are 707 patches in this series, all will be posted as a response
>> > > to this one.  If anyone has any issues with these being applied, please
>> > > let me know.
>> > >
>> > > Responses should be made by Wed Mar 27 12:00:02 PM UTC 2024.
>> > > Anything received after that time might be too late.
>> > >
>> > > The whole patch series can be found in one patch at:
>> > >          https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git/patch/?id=linux-6.7.y&id2=v6.7.10
>> > > or in the git tree and branch at:
>> > >          git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git linux-6.7.y
>> > > and the diffstat can be found below.
>> > >
>> > > Thanks,
>> > > Sasha
>> >
>> > We see *lots* of new warnings in RISC-V with Clang 17. Here's one:
>> >
>> > -----8<-----
>> >   /builds/linux/mm/oom_kill.c:1195:1: warning: unused function '___se_sys_process_mrelease' [-Wunused-function]
>> >    1195 | SYSCALL_DEFINE2(process_mrelease, int, pidfd, unsigned int, flags)
>> >         | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> >   /builds/linux/include/linux/syscalls.h:221:36: note: expanded from macro 'SYSCALL_DEFINE2'
>> >     221 | #define SYSCALL_DEFINE2(name, ...) SYSCALL_DEFINEx(2, _##name, __VA_ARGS__)
>> >         |                                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> >   /builds/linux/include/linux/syscalls.h:231:2: note: expanded from macro 'SYSCALL_DEFINEx'
>> >     231 |         __SYSCALL_DEFINEx(x, sname, __VA_ARGS__)
>> >         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> >   /builds/linux/arch/riscv/include/asm/syscall_wrapper.h:81:2: note: expanded from macro '__SYSCALL_DEFINEx'
>> >      81 |         __SYSCALL_SE_DEFINEx(x, sys, name, __VA_ARGS__)                         \
>> >         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> >   /builds/linux/arch/riscv/include/asm/syscall_wrapper.h:40:14: note: expanded from macro '__SYSCALL_SE_DEFINEx'
>> >      40 |         static long ___se_##prefix##name(__MAP(x,__SC_LONG,__VA_ARGS__))
>> >         |                     ^~~~~~~~~~~~~~~~~~~~
>> >   <scratch space>:30:1: note: expanded from here
>> >      30 | ___se_sys_process_mrelease
>> >         | ^~~~~~~~~~~~~~~~~~~~~~~~~~
>> >   1 warning generated.
>> > ----->8-----
>>
>> Yup, I can reproduce this with ToT Clang. It looks like the alias
>> isn't sufficient for Clang and we need to add an explicit __used
>> attribute. Can you confirm if this patch fixes the issue for you?
>>
>> diff --git a/arch/riscv/include/asm/syscall_wrapper.h b/arch/riscv/include/asm/syscall_wrapper.h
>> index 980094c2e976..ac80216549ff 100644
>> --- a/arch/riscv/include/asm/syscall_wrapper.h
>> +++ b/arch/riscv/include/asm/syscall_wrapper.h
>> @@ -36,7 +36,8 @@ asmlinkage long __riscv_sys_ni_syscall(const struct pt_regs *);
>>                                         ulong)                                          \
>>                         __attribute__((alias(__stringify(___se_##prefix##name))));      \
>>         __diag_pop();                                                                   \
>> -       static long noinline ___se_##prefix##name(__MAP(x,__SC_LONG,__VA_ARGS__));      \
>> +       static long noinline ___se_##prefix##name(__MAP(x,__SC_LONG,__VA_ARGS__))       \
>> +                       __used;                                                         \
>>         static long ___se_##prefix##name(__MAP(x,__SC_LONG,__VA_ARGS__))
>
>It does: the hundreds of warnings are gone. Build-tested with Clang

I'm assuming this fix needs to land upstream, and isn't specific for
stable?

I'll drop the offending commit for now, thanks!

-- 
Thanks,
Sasha