4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Paul Burton <paul.burton@xxxxxxxxxx> commit bd239f1e1429e7781096bf3884bdb1b2b1bb4f28 upstream. Whilst a PR_SET_FP_MODE prctl is performed there are decisions made based upon whether the task is executing on the current CPU. This may change if we're preempted, so disable preemption to avoid such changes for the lifetime of the mode switch. Signed-off-by: Paul Burton <paul.burton@xxxxxxxxxx> Fixes: 9791554b45a2 ("MIPS,prctl: add PR_[GS]ET_FP_MODE prctl options for MIPS") Reviewed-by: Maciej W. Rozycki <macro@xxxxxxxxxx> Tested-by: Aurelien Jarno <aurelien@xxxxxxxxxxx> Cc: Adam Buchbinder <adam.buchbinder@xxxxxxxxx> Cc: James Hogan <james.hogan@xxxxxxxxxx> Cc: linux-mips@xxxxxxxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx Patchwork: https://patchwork.linux-mips.org/patch/13144/ Signed-off-by: Ralf Baechle <ralf@xxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/mips/kernel/process.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/arch/mips/kernel/process.c +++ b/arch/mips/kernel/process.c @@ -603,6 +603,9 @@ int mips_set_process_fp_mode(struct task if (!(value & PR_FP_MODE_FR) && cpu_has_fpu && cpu_has_mips_r6) return -EOPNOTSUPP; + /* Proceed with the mode switch */ + preempt_disable(); + /* Save FP & vector context, then disable FPU & MSA */ if (task->signal == current->signal) lose_fpu(1); @@ -661,6 +664,7 @@ int mips_set_process_fp_mode(struct task /* Allow threads to use FP again */ atomic_set(&task->mm->context.fp_mode_switching, 0); + preempt_enable(); return 0; } -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html