From: Sasha Levin <sashal@kernel.org>
To: Nathan Chancellor <nathan@kernel.org>
Cc: patches@lists.linux.dev, stable@vger.kernel.org,
"Borislav Petkov (AMD)" <bp@alien8.de>,
tglx@linutronix.de, mingo@redhat.com,
dave.hansen@linux.intel.com, x86@kernel.org,
linux-kernel@vger.kernel.org, llvm@lists.linux.dev
Subject: Re: [PATCH AUTOSEL 6.17-5.4] x86/build: Remove cc-option from stack alignment flags
Date: Mon, 6 Oct 2025 19:13:39 -0400 [thread overview]
Message-ID: <aORNI3nnm5PRvNuT@laps> (raw)
In-Reply-To: <20251006215505.GB3234160@ax162>
On Mon, Oct 06, 2025 at 02:55:05PM -0700, Nathan Chancellor wrote:
>On Mon, Oct 06, 2025 at 02:17:33PM -0400, Sasha Levin wrote:
>> From: Nathan Chancellor <nathan@kernel.org>
>>
>> [ Upstream commit d87208128a3330c0eab18301ab39bdb419647730 ]
>>
>> '-mpreferred-stack-boundary' (the GCC option) and '-mstack-alignment'
>> (the clang option) have been supported in their respective compilers for
>> some time, so it is unnecessary to check for support for them via
>> cc-option. '-mpreferred-stack-boundary=3' had a restriction on
>> '-mno-sse' until GCC 7.1 but that is irrelevant for most of the kernel,
>> which includes '-mno-sse'.
>>
>> Move to simple Kconfig checks to avoid querying the compiler for the
>> flags that it supports.
>>
>> Signed-off-by: Nathan Chancellor <nathan@kernel.org>
>> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
>> Link: https://lore.kernel.org/20250814-x86-min-ver-cleanups-v1-2-ff7f19457523@kernel.org
>> Signed-off-by: Sasha Levin <sashal@kernel.org>
>...
>> ## Backport Status: NO
>...
>> **Dependency Analysis:**
>> - Requires minimum GCC 8.1 for x86 (introduced in v6.15 via commit
>> a3e8fe814ad1)
>> - Requires minimum Clang 15.0.0 for x86 (commit 7861640aac52b)
>> - Both requirements are satisfied in 6.17 stable tree (verified via
>> scripts/min-tool-version.sh)
>> - GCC 7.1+ supports `-mpreferred-stack-boundary=3` with `-msse` (per GCC
>> commit 34fac449e121)
>...
>> ### Conclusion
>>
>> While this commit is technically safe and provides a marginal build-time
>> performance improvement by eliminating unnecessary runtime compiler
>> checks, **it does not meet the fundamental requirement for stable kernel
>> backporting**: it does not fix a bug that affects users.
>>
>> The commit is purely a cleanup that removes obsolete code after compiler
>> minimum version requirements were raised. Such cleanups belong in
>> mainline development, not stable trees, which should focus exclusively
>> on fixing bugs that impact users.
>>
>> The fact that it was auto-selected by AUTOSEL does not override the
>> documented stable kernel rules. This commit should be **rejected** from
>> stable backporting or **reverted** if already applied.
>
>Based on all of this, I would agree that it is not really suitable for
>backporting (at least not beyond 6.15, whereas the subject says back to
>5.4), so why was this still sent for review?
Sorry for the noise, I thought I dropped this one :(
--
Thanks,
Sasha
prev parent reply other threads:[~2025-10-06 23:13 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-06 18:17 [PATCH AUTOSEL 6.17-5.4] x86/build: Remove cc-option from stack alignment flags Sasha Levin
2025-10-06 18:17 ` [PATCH AUTOSEL 6.17-6.1] btrfs: zoned: refine extent allocator hint selection Sasha Levin
2025-10-06 18:17 ` [PATCH AUTOSEL 6.17-6.1] arch: Add the macro COMPILE_OFFSETS to all the asm-offsets.c Sasha Levin
2025-10-06 18:17 ` [PATCH AUTOSEL 6.17-6.12] btrfs: abort transaction on specific error places when walking log tree Sasha Levin
2025-10-06 18:17 ` [PATCH AUTOSEL 6.17-5.4] btrfs: use smp_mb__after_atomic() when forcing COW in create_pending_snapshot() Sasha Levin
2025-10-06 18:17 ` [PATCH AUTOSEL 6.17] x86/bugs: Add attack vector controls for VMSCAPE Sasha Levin
2025-10-06 18:17 ` [PATCH AUTOSEL 6.17-6.16] sched_ext: Keep bypass on between enable failure and scx_disable_workfn() Sasha Levin
2025-10-06 18:17 ` [PATCH AUTOSEL 6.17-6.12] perf/x86/intel: Add ICL_FIXED_0_ADAPTIVE bit into INTEL_FIXED_BITS_MASK Sasha Levin
2025-10-06 18:17 ` [PATCH AUTOSEL 6.17-6.12] btrfs: abort transaction if we fail to update inode in log replay dir fixup Sasha Levin
2025-10-06 18:17 ` [PATCH AUTOSEL 6.17-6.1] EDAC/mc_sysfs: Increase legacy channel support to 16 Sasha Levin
2025-10-06 18:17 ` [PATCH AUTOSEL 6.17-6.12] btrfs: abort transaction in the process_one_buffer() log tree walk callback Sasha Levin
2025-10-06 18:17 ` [PATCH AUTOSEL 6.17-6.6] btrfs: zoned: return error from btrfs_zone_finish_endio() Sasha Levin
2025-10-06 18:17 ` [PATCH AUTOSEL 6.17-6.6] perf: Skip user unwind if the task is a kernel thread Sasha Levin
2025-10-06 18:17 ` [PATCH AUTOSEL 6.17-6.1] perf: Have get_perf_callchain() return NULL if crosstask and user are set Sasha Levin
2025-10-06 18:17 ` [PATCH AUTOSEL 6.17-6.16] EDAC: Fix wrong executable file modes for C source files Sasha Levin
2025-10-06 18:17 ` [PATCH AUTOSEL 6.17-6.6] perf: Use current->flags & PF_KTHREAD|PF_USER_WORKER instead of current->mm == NULL Sasha Levin
2025-10-06 18:17 ` [PATCH AUTOSEL 6.17-6.6] btrfs: use level argument in log tree walk callback replay_one_buffer() Sasha Levin
2025-10-06 18:17 ` [PATCH AUTOSEL 6.17-6.12] sched_ext: Make qmap dump operation non-destructive Sasha Levin
2025-10-06 18:17 ` [PATCH AUTOSEL 6.17-6.12] seccomp: passthrough uprobe systemcall without filtering Sasha Levin
2025-10-06 18:17 ` [PATCH AUTOSEL 6.17-6.12] cpuset: Use new excpus for nocpu error check when enabling root partition Sasha Levin
2025-10-06 18:17 ` [PATCH AUTOSEL 6.17-6.12] btrfs: tree-checker: add inode extref checks Sasha Levin
2025-10-06 18:17 ` [PATCH AUTOSEL 6.17] sched/fair: update_cfs_group() for throttled cfs_rqs Sasha Levin
2025-10-06 18:17 ` [PATCH AUTOSEL 6.17-5.15] btrfs: scrub: replace max_t()/min_t() with clamp() in scrub_throttle_dev_io() Sasha Levin
2025-10-06 18:17 ` [PATCH AUTOSEL 6.17-5.4] x86/bugs: Fix reporting of LFENCE retpoline Sasha Levin
2025-10-06 18:17 ` [PATCH AUTOSEL 6.17-5.10] btrfs: always drop log root tree reference in btrfs_replay_log() Sasha Levin
2025-10-06 18:17 ` [PATCH AUTOSEL 6.17-6.6] audit: record fanotify event regardless of presence of rules Sasha Levin
2025-10-06 18:17 ` [PATCH AUTOSEL 6.17] EDAC/ie31200: Add two more Intel Alder Lake-S SoCs for EDAC support Sasha Levin
2025-10-06 18:18 ` [PATCH AUTOSEL 6.17-6.6] x86/bugs: Report correct retbleed mitigation status Sasha Levin
2025-10-06 21:55 ` [PATCH AUTOSEL 6.17-5.4] x86/build: Remove cc-option from stack alignment flags Nathan Chancellor
2025-10-06 23:13 ` Sasha Levin [this message]
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