Peter, Guenter is reporting that the patch below breaks all non-x86 builds with: include/asm-generic/preempt.h: In function '__preempt_count_dec_and_test': include/asm-generic/preempt.h:71:2: error: implicit declaration of function 'tif_need_resched' [-Werror=implicit-function-declaration] return !--*preempt_count_ptr() && tif_need_resched(); Any ideas? thanks, greg k-h On Tue, May 13, 2014 at 04:57:15PM -0700, gregkh@xxxxxxxxxxxxxxxxxxx wrote: > > This is a note to let you know that I've just added the patch titled > > x86,preempt: Fix preemption for i386 > > to the 3.14-stable tree which can be found at: > http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary > > The filename of the patch is: > x86-preempt-fix-preemption-for-i386.patch > and it can be found in the queue-3.14 subdirectory. > > If you, or anyone else, feels it should not be added to the stable tree, > please let <stable@xxxxxxxxxxxxxxx> know about it. > > > >From peterz@xxxxxxxxxxxxx Tue May 13 16:56:21 2014 > From: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > Date: Wed, 9 Apr 2014 16:24:47 +0200 > Subject: x86,preempt: Fix preemption for i386 > To: Stefan Bader <stefan.bader@xxxxxxxxxxxxx> > Cc: Toralf Förster <toralf.foerster@xxxxxx>, Michele Ballabio <barra_cuda@xxxxxxxxxxxx>, linux-kernel@xxxxxxxxxxxxxxx, fweisbec@xxxxxxxxx, mingo@xxxxxxxxxx, Steven Rostedt <rostedt@xxxxxxxxxxx>, David Cohen <david.a.cohen@xxxxxxxxxxxxxxx>, Paolo Bonzini <pbonzini@xxxxxxxxxx>, Borislav Petkov <bp@xxxxxxxxx>, Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>, Greg KH <greg@xxxxxxxxx> > Message-ID: <20140409142447.GD13658@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> > Content-Disposition: inline > > > From: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > > Many people reported preemption/reschedule problems with i386 kernels > for .13 and .14. After Michele bisected this to a combination of > > 3e8e42c69bb ("sched: Revert need_resched() to look at TIF_NEED_RESCHED") > ded79754754 ("irq: Force hardirq exit's softirq processing on its own stack") > > it finally dawned on me that i386's current_thread_info() was to > blame. > > When we are on interrupt/exception stacks, we fail to observe the > right TIF_NEED_RESCHED bit and therefore the PREEMPT_NEED_RESCHED > folding malfunctions. > > Current upstream fixes this by making i386 behave the same as x86_64 > already did: > > 2432e1364bbe ("x86: Nuke the supervisor_stack field in i386 thread_info") > b807902a88c4 ("x86: Nuke GET_THREAD_INFO_WITH_ESP() macro for i386") > 0788aa6a23cb ("x86: Prepare removal of previous_esp from i386 thread_info structure") > 198d208df437 ("x86: Keep thread_info on thread stack in x86_32") > > However, that is far too much to stuff into -stable. Therefore I > propose we merge the below patch which uses task_thread_info(current) > for tif_need_resched() instead of the ESP based current_thread_info(). > > This makes sure we always observe the one true TIF_NEED_RESCHED bit > and things will work as expected again. > > Cc: fweisbec@xxxxxxxxx > Cc: mingo@xxxxxxxxxx > Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> > Cc: David Cohen <david.a.cohen@xxxxxxxxxxxxxxx> > Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> > Cc: Borislav Petkov <bp@xxxxxxxxx> > Tested-by: Stefan Bader <stefan.bader@xxxxxxxxxxxxx> > Tested-by: Toralf Förster <toralf.foerster@xxxxxx> > Tested-by: Michele Ballabio <barra_cuda@xxxxxxxxxxxx> > Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > --- > arch/x86/include/asm/preempt.h | 11 +++++++++++ > include/linux/preempt.h | 4 ++++ > include/linux/thread_info.h | 2 -- > 3 files changed, 15 insertions(+), 2 deletions(-) > > --- a/arch/x86/include/asm/preempt.h > +++ b/arch/x86/include/asm/preempt.h > @@ -5,6 +5,17 @@ > #include <asm/percpu.h> > #include <linux/thread_info.h> > > +#ifdef CONFIG_X86_32 > +/* > + * i386's current_thread_info() depends on ESP and for interrupt/exception > + * stacks this doesn't yield the actual task thread_info. > + * > + * We hard rely on the fact that all the TIF_NEED_RESCHED bits are > + * the same, therefore use the slightly more expensive version below. > + */ > +#define tif_need_resched() test_tsk_thread_flag(current, TIF_NEED_RESCHED) > +#endif > + > DECLARE_PER_CPU(int, __preempt_count); > > /* > --- a/include/linux/preempt.h > +++ b/include/linux/preempt.h > @@ -17,6 +17,10 @@ > > #include <asm/preempt.h> > > +#ifndef tif_need_resched > +#define tif_need_resched() test_thread_flag(TIF_NEED_RESCHED) > +#endif > + > #if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_PREEMPT_TRACER) > extern void preempt_count_add(int val); > extern void preempt_count_sub(int val); > --- a/include/linux/thread_info.h > +++ b/include/linux/thread_info.h > @@ -118,8 +118,6 @@ static inline __deprecated void set_need > */ > } > > -#define tif_need_resched() test_thread_flag(TIF_NEED_RESCHED) > - > #if defined TIF_RESTORE_SIGMASK && !defined HAVE_SET_RESTORE_SIGMASK > /* > * An arch can define its own version of set_restore_sigmask() to get the > > > Patches currently in stable-queue which might be from peterz@xxxxxxxxxxxxx are > > queue-3.14/x86-preempt-fix-preemption-for-i386.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html