Messages in this thread Patch in this message | | | Date | Thu, 13 Jun 2019 12:07:13 -0700 | From | tip-bot for Christoph Hellwig <> | Subject | [tip:x86/urgent] x86/fpu: Don't use current->mm to check for a kthread |
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Commit-ID: 8d3289f2fa1e0c7e2f72c7352f1efb75d2ad7c76 Gitweb: https://git.kernel.org/tip/8d3289f2fa1e0c7e2f72c7352f1efb75d2ad7c76 Author: Christoph Hellwig <hch@lst.de> AuthorDate: Tue, 4 Jun 2019 19:54:12 +0200 Committer: Borislav Petkov <bp@suse.de> CommitDate: Thu, 13 Jun 2019 20:57:49 +0200
x86/fpu: Don't use current->mm to check for a kthread
current->mm can be non-NULL if a kthread calls use_mm(). Check for PF_KTHREAD instead to decide when to store user mode FP state.
Fixes: 2722146eb784 ("x86/fpu: Remove fpu->initialized") Reported-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Borislav Petkov <bp@suse.de> Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Aubrey Li <aubrey.li@intel.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Nicolai Stange <nstange@suse.de> Cc: Rik van Riel <riel@surriel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: x86-ml <x86@kernel.org> Link: https://lkml.kernel.org/r/20190604175411.GA27477@lst.de --- arch/x86/include/asm/fpu/internal.h | 6 +++--- arch/x86/kernel/fpu/core.c | 2 +- 2 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h index 9e27fa05a7ae..4c95c365058a 100644 --- a/arch/x86/include/asm/fpu/internal.h +++ b/arch/x86/include/asm/fpu/internal.h @@ -536,7 +536,7 @@ static inline void __fpregs_load_activate(void) struct fpu *fpu = ¤t->thread.fpu; int cpu = smp_processor_id(); - if (WARN_ON_ONCE(current->mm == NULL)) + if (WARN_ON_ONCE(current->flags & PF_KTHREAD)) return; if (!fpregs_state_valid(fpu, cpu)) { @@ -567,11 +567,11 @@ static inline void __fpregs_load_activate(void) * otherwise. * * The FPU context is only stored/restored for a user task and - * ->mm is used to distinguish between kernel and user threads. + * PF_KTHREAD is used to distinguish between kernel and user threads. */ static inline void switch_fpu_prepare(struct fpu *old_fpu, int cpu) { - if (static_cpu_has(X86_FEATURE_FPU) && current->mm) { + if (static_cpu_has(X86_FEATURE_FPU) && !(current->flags & PF_KTHREAD)) { if (!copy_fpregs_to_fpstate(old_fpu)) old_fpu->last_cpu = -1; else diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index 466fca686fb9..649fbc3fcf9f 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -102,7 +102,7 @@ static void __kernel_fpu_begin(void) kernel_fpu_disable(); - if (current->mm) { + if (!(current->flags & PF_KTHREAD)) { if (!test_thread_flag(TIF_NEED_FPU_LOAD)) { set_thread_flag(TIF_NEED_FPU_LOAD); /*
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