| Message ID | alpine.LRH.2.02.1807092300520.24277@file01.intranet.prod.int.rdu2.redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Jul 09, 2018 at 11:04:33PM -0400, Mikulas Patocka wrote: > On Thu, 28 Jun 2018, Dave Martin wrote: > > Alternatively, if someone wants to pick up my patch and take it forward, > > I'm happy to comment. > > > > Cheers > > ---Dave > > Or - what about this patch? It doesn't guarantee that infinite loop won't > happen, but it at least catches the most obvious loop on the same address. > > > From: Mikulas Patocka <mpatocka@redhat.com> > Subject: [PATCH] arm64: fix infinite stacktrace > > I've got this infinite stacktrace when debugging another problem: > [ 908.795225] INFO: rcu_preempt detected stalls on CPUs/tasks: > [ 908.796176] 1-...!: (1 GPs behind) idle=952/1/4611686018427387904 softirq=1462/1462 fqs=355 > [ 908.797692] 2-...!: (1 GPs behind) idle=f42/1/4611686018427387904 softirq=1550/1551 fqs=355 > [ 908.799189] (detected by 0, t=2109 jiffies, g=130, c=129, q=235) > [ 908.800284] Task dump for CPU 1: > [ 908.800871] kworker/1:1 R running task 0 32 2 0x00000022 > [ 908.802127] Workqueue: writecache-writeabck writecache_writeback [dm_writecache] > [ 908.820285] Call trace: > [ 908.824785] __switch_to+0x68/0x90 > [ 908.837661] 0xfffffe00603afd90 > [ 908.844119] 0xfffffe00603afd90 > [ 908.850091] 0xfffffe00603afd90 > [ 908.854285] 0xfffffe00603afd90 > [ 908.863538] 0xfffffe00603afd90 > [ 908.865523] 0xfffffe00603afd90 > > The machine just locked up and kept on printing the same line over and > over again. This patch fixes it. > > Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> > Cc: stable@vger.kernel.org > > --- > arch/arm64/kernel/stacktrace.c | 3 +++ > 1 file changed, 3 insertions(+) > > Index: linux-2.6/arch/arm64/kernel/stacktrace.c > =================================================================== > --- linux-2.6.orig/arch/arm64/kernel/stacktrace.c 2018-07-10 05:01:56.990000000 +0200 > +++ linux-2.6/arch/arm64/kernel/stacktrace.c 2018-07-10 05:02:51.650000000 +0200 > @@ -56,6 +56,9 @@ int notrace unwind_frame(struct task_str > frame->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp)); > frame->pc = READ_ONCE_NOCHECK(*(unsigned long *)(fp + 8)); > > + if (frame->fp == fp) > + return -EINVAL; I've already queued your previous patch using '<=' (it's in -next). If you want to change it, please send patches on top of the arm64 for-next/core branch. Will
On Tue, 10 Jul 2018, Will Deacon wrote: > On Mon, Jul 09, 2018 at 11:04:33PM -0400, Mikulas Patocka wrote: > > On Thu, 28 Jun 2018, Dave Martin wrote: > > > Alternatively, if someone wants to pick up my patch and take it forward, > > > I'm happy to comment. > > > > > > Cheers > > > ---Dave > > > > Or - what about this patch? It doesn't guarantee that infinite loop won't > > happen, but it at least catches the most obvious loop on the same address. > > > > > > From: Mikulas Patocka <mpatocka@redhat.com> > > Subject: [PATCH] arm64: fix infinite stacktrace > > > > I've got this infinite stacktrace when debugging another problem: > > [ 908.795225] INFO: rcu_preempt detected stalls on CPUs/tasks: > > [ 908.796176] 1-...!: (1 GPs behind) idle=952/1/4611686018427387904 softirq=1462/1462 fqs=355 > > [ 908.797692] 2-...!: (1 GPs behind) idle=f42/1/4611686018427387904 softirq=1550/1551 fqs=355 > > [ 908.799189] (detected by 0, t=2109 jiffies, g=130, c=129, q=235) > > [ 908.800284] Task dump for CPU 1: > > [ 908.800871] kworker/1:1 R running task 0 32 2 0x00000022 > > [ 908.802127] Workqueue: writecache-writeabck writecache_writeback [dm_writecache] > > [ 908.820285] Call trace: > > [ 908.824785] __switch_to+0x68/0x90 > > [ 908.837661] 0xfffffe00603afd90 > > [ 908.844119] 0xfffffe00603afd90 > > [ 908.850091] 0xfffffe00603afd90 > > [ 908.854285] 0xfffffe00603afd90 > > [ 908.863538] 0xfffffe00603afd90 > > [ 908.865523] 0xfffffe00603afd90 > > > > The machine just locked up and kept on printing the same line over and > > over again. This patch fixes it. > > > > Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> > > Cc: stable@vger.kernel.org > > > > --- > > arch/arm64/kernel/stacktrace.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > Index: linux-2.6/arch/arm64/kernel/stacktrace.c > > =================================================================== > > --- linux-2.6.orig/arch/arm64/kernel/stacktrace.c 2018-07-10 05:01:56.990000000 +0200 > > +++ linux-2.6/arch/arm64/kernel/stacktrace.c 2018-07-10 05:02:51.650000000 +0200 > > @@ -56,6 +56,9 @@ int notrace unwind_frame(struct task_str > > frame->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp)); > > frame->pc = READ_ONCE_NOCHECK(*(unsigned long *)(fp + 8)); > > > > + if (frame->fp == fp) > > + return -EINVAL; > > I've already queued your previous patch using '<=' (it's in -next). If you > want to change it, please send patches on top of the arm64 for-next/core > branch. > > Will I don't know - is this function supposed to backtrace against more discontiguous stacks? If yes, then the patch with (frame->fp <= fp) is incorrect. If no, then the condition (frame->fp <= fp) could be there. Mikulas
On Tue, Jul 10, 2018 at 02:10:04PM -0400, Mikulas Patocka wrote: > On Tue, 10 Jul 2018, Will Deacon wrote: > > On Mon, Jul 09, 2018 at 11:04:33PM -0400, Mikulas Patocka wrote: > > > Index: linux-2.6/arch/arm64/kernel/stacktrace.c > > > =================================================================== > > > --- linux-2.6.orig/arch/arm64/kernel/stacktrace.c 2018-07-10 05:01:56.990000000 +0200 > > > +++ linux-2.6/arch/arm64/kernel/stacktrace.c 2018-07-10 05:02:51.650000000 +0200 > > > @@ -56,6 +56,9 @@ int notrace unwind_frame(struct task_str > > > frame->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp)); > > > frame->pc = READ_ONCE_NOCHECK(*(unsigned long *)(fp + 8)); > > > > > > + if (frame->fp == fp) > > > + return -EINVAL; > > > > I've already queued your previous patch using '<=' (it's in -next). If you > > want to change it, please send patches on top of the arm64 for-next/core > > branch. > > > > Will > > I don't know - is this function supposed to backtrace against more > discontiguous stacks? If yes, then the patch with (frame->fp <= fp) is > incorrect. If no, then the condition (frame->fp <= fp) could be there. Ah yes, your original patch breaks with irqstacks, so I'll need to revert it. Using '==' feels like a big hack to me. Will
Index: linux-2.6/arch/arm64/kernel/stacktrace.c =================================================================== --- linux-2.6.orig/arch/arm64/kernel/stacktrace.c 2018-07-10 05:01:56.990000000 +0200 +++ linux-2.6/arch/arm64/kernel/stacktrace.c 2018-07-10 05:02:51.650000000 +0200 @@ -56,6 +56,9 @@ int notrace unwind_frame(struct task_str frame->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp)); frame->pc = READ_ONCE_NOCHECK(*(unsigned long *)(fp + 8)); + if (frame->fp == fp) + return -EINVAL; + #ifdef CONFIG_FUNCTION_GRAPH_TRACER if (tsk->ret_stack && (frame->pc == (unsigned long)return_to_handler)) {