[PATCH v2] riscv: signal: protect regs->status RMW from concurrent preemption

[patchwork-bot+linux-riscv at kernel.org]

Hello:

This patch was applied to riscv/linux.git (fixes)
by Paul Walmsley <pjw at kernel.org>:

On Tue, 20 Oct 2026 19:24:25 +0800 you wrote:
> __fstate_clean() performs a non-atomic read-modify-write (RMW) on
> task_pt_regs(current)->status to clear the FS bits. This RMW is
> unprotected - it runs with preemption enabled and IRQs on during
> signal delivery (setup_rt_frame -> fstate_save) and sigreturn
> (restore_fp_state -> fstate_restore).
> 
> If a reschedule IPI or timer interrupt triggers preemption between
> the load and store of this RMW, __switch_to_vector() calls
> riscv_v_vstate_set_restore() which modifies the VS bits of the
> same regs->status. When the preempted task resumes, it stores back
> the stale value captured before preemption, overwriting the VS
> update and restoring VS=DIRTY while TIF_RISCV_V_DEFER_RESTORE
> remains set - a combination that should never occur and leads to
> vector state corruption.
> 
> [...]

Here is the summary with links:
  - [v2] riscv: signal: protect regs->status RMW from concurrent preemption
    https://git.kernel.org/riscv/c/d1a8d411533d

You are awesome, thank you!
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