Messages in this thread | | | Date | Sun, 3 May 2015 19:39:17 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH v2] x86/fpu: always restore_xinit_state() when use_eager_cpu() |
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On 05/02, Bobby Powers wrote: > > 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?
Yes, please, 4.1 needs this patch.
Borislav, perhaps you can help ?
> > 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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