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    Subject[PATCH 2/3] x86, xsave: remove thread_has_fpu() bug check in __sanitize_i387_state()
    Date
    Code paths like fork(), exit() and signal handling flush the fpu
    state explicitly to the structures in memory.

    BUG_ON() in __sanitize_i387_state() is checking that the fpu state
    is not live any more. But for preempt kernels, task can be scheduled
    out and in at any place and the preload_fpu logic during context switch
    can make the fpu registers live again.

    Similarly during core dump, thread dumping the core can schedule out
    and in for page-allocations etc in non-preempt case.

    So remove the paranoid check, even though it caught a bug in the
    multi-threaded core dump case (fixed in the previous patch).

    Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
    ---
    arch/x86/kernel/xsave.c | 2 --
    1 files changed, 0 insertions(+), 2 deletions(-)

    diff --git a/arch/x86/kernel/xsave.c b/arch/x86/kernel/xsave.c
    index e62728e..bd18149 100644
    --- a/arch/x86/kernel/xsave.c
    +++ b/arch/x86/kernel/xsave.c
    @@ -48,8 +48,6 @@ void __sanitize_i387_state(struct task_struct *tsk)
    if (!fx)
    return;

    - BUG_ON(__thread_has_fpu(tsk));
    -
    xstate_bv = tsk->thread.fpu.state->xsave.xsave_hdr.xstate_bv;

    /*
    --
    1.7.6.5


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