On Fri, 03 Oct 2014 00:50:13 -0400 Sasha Levin <sasha.le...@oracle.com> wrote:
> On 09/24/2014 11:02 AM, tip-bot for Oleg Nesterov wrote: > > Commit-ID: 0ad6e3c5199be12c9745da8f8b9e3c9f8066c235 > > Gitweb: > > http://git.kernel.org/tip/0ad6e3c5199be12c9745da8f8b9e3c9f8066c235 > > Author: Oleg Nesterov <o...@redhat.com> > > AuthorDate: Sun, 21 Sep 2014 20:41:53 +0200 > > Committer: Ingo Molnar <mi...@kernel.org> > > CommitDate: Wed, 24 Sep 2014 15:15:38 +0200 > > > > x86: Speed up ___preempt_schedule*() by using THUNK helpers > > > > ___preempt_schedule() does SAVE_ALL/RESTORE_ALL but this is > > suboptimal, we do not need to save/restore the callee-saved > > register. And we already have arch/x86/lib/thunk_*.S which > > implements the similar asm wrappers, so it makes sense to > > redefine ___preempt_schedule() as "THUNK ..." and remove > > preempt.S altogether. > > > > Signed-off-by: Oleg Nesterov <o...@redhat.com> > > Reviewed-by: Andy Lutomirski <l...@amacapital.net> > > Cc: Denys Vlasenko <dvlas...@redhat.com> > > Cc: Peter Zijlstra <pet...@infradead.org> > > Cc: Linus Torvalds <torva...@linux-foundation.org> > > Link: http://lkml.kernel.org/r/20140921184153.ga23...@redhat.com > > Signed-off-by: Ingo Molnar <mi...@kernel.org> > > --- > > Hi Oleg, > > I *think* that this patch is causing the following trace > (arch/x86/lib/thunk_64.S:44 > is new code introduced by this patch): > > > [ 921.908530] kernel BUG at kernel/sched/core.c:2702! > [ 921.909159] invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC > [ 921.910084] Dumping ftrace buffer: > [ 921.910626] (ftrace buffer empty) > [ 921.911178] Modules linked in: > [ 921.915690] CPU: 18 PID: 9489 Comm: trinity-c195 Not tainted > 3.17.0-rc7-next-20141002-sasha-00031-gbdb4244 #1273 > [ 921.917016] task: ffff8802bd748000 ti: ffff8802bda3c000 task.ti: > ffff8802bda3c000 > [ 921.917752] RIP: __schedule (kernel/sched/core.c:2702 > kernel/sched/core.c:2808) > [ 921.917752] RSP: 0018:ffff8802bda3c360 EFLAGS: 00010297 > [ 921.917752] RAX: ffff8802bda3c000 RBX: ffff8808501e2a00 RCX: > 0000000000000001 > [ 921.917752] RDX: 0000000000000000 RSI: 0000000000000000 RDI: > 0000000000000286 > [ 921.917752] RBP: ffff8802bda3c3c0 R08: 000000000001aa50 R09: > 0000000000000000 > [ 921.917752] R10: 0000000000000000 R11: 0000000000000001 R12: > 0000000000000012 > [ 921.917752] R13: ffff8808501e2a00 R14: 0000000000000002 R15: > ffff8802bda3c428 > [ 921.917752] FS: 00007f5475cc2700(0000) GS:ffff880850000000(0000) > knlGS:0000000000000000 > [ 921.917752] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b > [ 921.917752] CR2: 00007f5475abe60c CR3: 00000002bebab000 CR4: > 00000000000006a0 > [ 921.917752] DR0: 00000000006f0000 DR1: 0000000000000000 DR2: > 0000000000000000 > [ 921.917752] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: > 0000000000000600 > [ 921.917752] Stack: > [ 921.917752] 000000000001aa50 ffff8802bd748000 ffff8802bda3ffd8 > 00000000001e2a00 > [ 921.917752] 00000000001e2a00 ffff8802bd748000 ffff8802bda3c3a0 > 00000000001e2a00 > [ 921.917752] ffff8802bd748000 000000000001a9ea 0000000000000002 > ffff8802bda3c428 > [ 921.917752] Call Trace: > [ 921.917752] schedule_user (kernel/sched/core.c:2894 > include/linux/jump_label.h:114 include/linux/context_tracking_state.h:27 > include/linux/context_tracking.h:20 kernel/sched/core.c:2909) > [ 921.917752] int_careful (arch/x86/kernel/entry_64.S:560) > [ 921.917752] ? retint_careful (arch/x86/kernel/entry_64.S:889) > [ 921.917752] ? preempt_schedule (./arch/x86/include/asm/preempt.h:80 > (discriminator 1) kernel/sched/core.c:2943 (discriminator 1)) > [ 921.917752] ? preempt_schedule_context > (./arch/x86/include/asm/preempt.h:75 kernel/context_tracking.c:143) > [ 921.917752] ? ___preempt_schedule_context (arch/x86/lib/thunk_64.S:44) > [ 921.917752] ? preempt_schedule_context (kernel/context_tracking.c:145) > [ 921.917752] ? ___preempt_schedule_context (arch/x86/lib/thunk_64.S:44) > [ 921.917752] ? preempt_schedule_context (kernel/context_tracking.c:145) > [ 921.917752] ? ___preempt_schedule_context (arch/x86/lib/thunk_64.S:44) > [ 921.917752] ? preempt_schedule_context (kernel/context_tracking.c:145) > [ 921.917752] ? ___preempt_schedule_context (arch/x86/lib/thunk_64.S:44) > [ 921.917752] ? preempt_schedule_context (kernel/context_tracking.c:145) > [ 921.917752] ? ___preempt_schedule_context (arch/x86/lib/thunk_64.S:44) > [ 921.917752] ? preempt_schedule_context (kernel/context_tracking.c:145) <snip lots of repeats of this> I *think* this is because RBP isn't being saved across task switch anymore? Without CONFIG_FRAME_POINTERS that night not be a problem... -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
