Messages in this thread |  | | Date | Mon, 16 Feb 2015 16:30:50 -0500 | From | Rik van Riel <> | Subject | Re: [PATCH 3/8] x86, fpu: kill save_init_fpu(), change math_error() to use unlazy_fpu() |
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On 02/16/2015 04:09 PM, Borislav Petkov wrote: > On Fri, Feb 06, 2015 at 03:02:00PM -0500, riel@redhat.com wrote: >> From: Oleg Nesterov <oleg@redhat.com>
>> diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c >> index fb4cb6adf225..51c465846f06 100644 --- >> a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -663,7 >> +663,7 @@ static void math_error(struct pt_regs *regs, int >> error_code, int trapnr) /* * Save the info for the exception >> handler and clear the error. */ - save_init_fpu(task); + >> unlazy_fpu(task); > > Do I see it correctly that even with this there's a not-so-small > hole *after* conditional_sti() and *before* unlazy_fpu() where > caller can still get preempted?
That's ok, the context switch will save the register contents to memory in that case. At that point unlazy_fpu will potentially do nothing, and the task will process the FPU context that was saved to memory previously.
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