Messages in this thread | | | Date | Sat, 2 May 2015 16:42:59 -0400 | Subject | Re: [PATCH v2] x86/fpu: always restore_xinit_state() when use_eager_cpu() | From | Bobby Powers <> |
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Hello,
Oleg Nesterov <oleg@redhat.com> wrote: > Thanks!
Dave gave this his:
Tested-By: Dave Hansen <dave.hansen@intel.com>
over under v1 of this patch: https://lkml.kernel.org/g/5543C277.9070208@intel.com
Anything else anyone sees, or anyone in particular I have to poke at to get this in? Ingo?
yours, Bobby
On Mon, Apr 27, 2015 at 11:19 AM, Oleg Nesterov <oleg@redhat.com> wrote: > Thanks! > > On 04/27, Bobby Powers wrote: >> >> v2: switch used_math() -> tsk_used_math(tsk) to consistently use the >> grabbed tsk instead of current, like in the rest of flush_thread(). >> >> 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). >> >> 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() - apply the same logic here. >> >> Fixes: f893959b ("x86/fpu: Don't abuse drop_init_fpu() in flush_thread()") >> Signed-off-by: Bobby Powers <bobbypowers@gmail.com> >> Acked-by: Oleg Nesterov <oleg@redhat.com> >> Cc: Andi Kleen <ak@linux.intel.com> >> Cc: Borislav Petkov <bp@suse.de> >> Cc: Ingo Molnar <mingo@kernel.org> >> Cc: Andy Lutomirski <luto@amacapital.net> >> Cc: Dave Hansen <dave.hansen@intel.com> >> Cc: Fenghua Yu <fenghua.yu@intel.com> >> Cc: Linus Torvalds <torvalds@linux-foundation.org> >> Cc: Pekka Riikonen <priikone@iki.fi> >> Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com> >> Cc: Rik van Riel <riel@redhat.com> >> Cc: Suresh Siddha <sbsiddha@gmail.com> >> --- >> 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..1a6fcf8 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 (!tsk_used_math(tsk)) { >> + /* 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 >> >
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