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x86/fpu: Don't set TIF_NEED_FPU_LOAD for PF_IO_WORKER threads

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We don't set it on PF_KTHREAD threads as they never return to userspace,
and PF_IO_WORKER threads are identical in that regard. As they keep
running in the kernel until they die, skip setting the FPU flag on them.

More of a cosmetic thing that was found while debugging and
issue and pondering why the FPU flag is set on these threads.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/560c844c-f128-555b-40c6-31baff27537f@kernel.dk
This commit is contained in:
Jens Axboe 2023-01-24 08:23:20 -07:00 committed by Ingo Molnar
parent aa81cb9d97
commit cb3ea4b767
3 changed files with 3 additions and 3 deletions
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2
arch/x86/include/asm/fpu/sched.h
View File

@ -39,7 +39,7 @@ extern void fpu_flush_thread(void);
static inline void switch_fpu_prepare(struct fpu *old_fpu, int cpu)
{
if (cpu_feature_enabled(X86_FEATURE_FPU) &&
!(current->flags & PF_KTHREAD)) {
!(current->flags & (PF_KTHREAD | PF_IO_WORKER))) {
save_fpregs_to_fpstate(old_fpu);
/*
* The save operation preserved register state, so the

2
arch/x86/kernel/fpu/context.h
View File

@ -57,7 +57,7 @@ static inline void fpregs_restore_userregs(void)
struct fpu *fpu = &current->thread.fpu;
int cpu = smp_processor_id();
if (WARN_ON_ONCE(current->flags & PF_KTHREAD))
if (WARN_ON_ONCE(current->flags & (PF_KTHREAD | PF_IO_WORKER)))
return;
if (!fpregs_state_valid(fpu, cpu)) {

2
arch/x86/kernel/fpu/core.c
View File

@ -426,7 +426,7 @@ void kernel_fpu_begin_mask(unsigned int kfpu_mask)
this_cpu_write(in_kernel_fpu, true);
if (!(current->flags & PF_KTHREAD) &&
if (!(current->flags & (PF_KTHREAD | PF_IO_WORKER)) &&
!test_thread_flag(TIF_NEED_FPU_LOAD)) {
set_thread_flag(TIF_NEED_FPU_LOAD);
save_fpregs_to_fpstate(&current->thread.fpu);