Oleg's commit f893959b ("x86/fpu: Don't abuse drop_init_fpu() in
flush_thread()") removed drop_init_fpu() usage from flush_thread.
This seems to break things for me - the Go 1.4 test suite fails all
over the place with floating point comparision errors (offending
commit found through bisection).Note: used_math() looks at current, and should be switch to tsk_used_math(tsk), but even with this I see test suite breakage. The functional change was that flush_thread after f893959b only calls restore_init_xstate when both !use_eager_fpu and !used_math are true. drop_init_fpu (now fpu_reset_state) calls restore_init_xstate() regardless of whether current used_math(). There was a lot of commentary on the initial patch - not sure I understand it all. Happy to get some pointers or be pointed to a better fix. Signed-off-by: Bobby Powers <[email protected]> Cc: Oleg Nesterov <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Dave Hansen <[email protected]> Cc: Fenghua Yu <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Pekka Riikonen <[email protected]> Cc: Quentin Casasnovas <[email protected]> Cc: Rik van Riel <[email protected]> Cc: Suresh Siddha <[email protected]> --- arch/x86/kernel/process.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 8213da6..c820baf5 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -156,11 +156,13 @@ void flush_thread(void) /* FPU state will be reallocated lazily at the first use. */ drop_fpu(tsk); free_thread_xstate(tsk); - } else if (!used_math()) { - /* kthread execs. TODO: cleanup this horror. */ - if (WARN_ON(init_fpu(tsk))) - force_sig(SIGKILL, tsk); - user_fpu_begin(); + } else { + if (!used_math()) { + /* kthread execs. TODO: cleanup this horror. */ + if (WARN_ON(init_fpu(tsk))) + force_sig(SIGKILL, tsk); + user_fpu_begin(); + } restore_init_xstate(); } } -- 2.3.6 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
