Re: [PATCH bpf-next 2/4] bpf: fix lockdep false positive in stackmap

2019-02-05 Thread Eric Dumazet
On 02/05/2019 07:30 PM, Alexei Starovoitov wrote: > Thanks for the reminder :) > > I've been waiting for Peter's direction on this one. > Happy to fix it whichever way. > > To recap: > Approach 1: > s/up_read/up_read_non_owner/ from irq_work + rwsem_release as Longman > proposed. > > Appora

Re: [PATCH bpf-next 2/4] bpf: fix lockdep false positive in stackmap

2019-02-05 Thread Alexei Starovoitov
On Tue, Feb 05, 2019 at 07:21:08PM -0800, Eric Dumazet wrote: > >>> > >>> diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c > >>> index d43b145..79eef9d 100644 > >>> --- a/kernel/bpf/stackmap.c > >>> +++ b/kernel/bpf/stackmap.c > >>> @@ -338,6 +338,13 @@ static void stack_map_get_build_id_

Re: [PATCH bpf-next 2/4] bpf: fix lockdep false positive in stackmap

2019-02-05 Thread Eric Dumazet
On 01/30/2019 06:48 PM, Waiman Long wrote: > On 01/30/2019 09:01 PM, Alexei Starovoitov wrote: >> On Wed, Jan 30, 2019 at 04:32:12PM -0500, Waiman Long wrote: >>> On 01/30/2019 04:11 PM, Waiman Long wrote: On 01/30/2019 03:10 PM, Alexei Starovoitov wrote: > On Wed, Jan 30, 2019 at 02:42

Re: [PATCH bpf-next 2/4] bpf: fix lockdep false positive in stackmap

2019-01-30 Thread Waiman Long
On 01/30/2019 09:01 PM, Alexei Starovoitov wrote: > On Wed, Jan 30, 2019 at 04:32:12PM -0500, Waiman Long wrote: >> On 01/30/2019 04:11 PM, Waiman Long wrote: >>> On 01/30/2019 03:10 PM, Alexei Starovoitov wrote: On Wed, Jan 30, 2019 at 02:42:23PM -0500, Waiman Long wrote: > On 01/30/2019

Re: [PATCH bpf-next 2/4] bpf: fix lockdep false positive in stackmap

2019-01-30 Thread Alexei Starovoitov
On Wed, Jan 30, 2019 at 04:32:12PM -0500, Waiman Long wrote: > On 01/30/2019 04:11 PM, Waiman Long wrote: > > On 01/30/2019 03:10 PM, Alexei Starovoitov wrote: > >> On Wed, Jan 30, 2019 at 02:42:23PM -0500, Waiman Long wrote: > >>> On 01/30/2019 02:30 PM, Alexei Starovoitov wrote: > On Wed, Ja

Re: [PATCH bpf-next 2/4] bpf: fix lockdep false positive in stackmap

2019-01-30 Thread Waiman Long
On 01/30/2019 04:11 PM, Waiman Long wrote: > On 01/30/2019 03:10 PM, Alexei Starovoitov wrote: >> On Wed, Jan 30, 2019 at 02:42:23PM -0500, Waiman Long wrote: >>> On 01/30/2019 02:30 PM, Alexei Starovoitov wrote: On Wed, Jan 30, 2019 at 11:15:30AM +0100, Peter Zijlstra wrote: > On Tue, Jan

Re: [PATCH bpf-next 2/4] bpf: fix lockdep false positive in stackmap

2019-01-30 Thread Waiman Long
On 01/30/2019 03:10 PM, Alexei Starovoitov wrote: > On Wed, Jan 30, 2019 at 02:42:23PM -0500, Waiman Long wrote: >> On 01/30/2019 02:30 PM, Alexei Starovoitov wrote: >>> On Wed, Jan 30, 2019 at 11:15:30AM +0100, Peter Zijlstra wrote: On Tue, Jan 29, 2019 at 08:04:56PM -0800, Alexei Starovoitov

Re: [PATCH bpf-next 2/4] bpf: fix lockdep false positive in stackmap

2019-01-30 Thread Alexei Starovoitov
On Wed, Jan 30, 2019 at 02:42:23PM -0500, Waiman Long wrote: > On 01/30/2019 02:30 PM, Alexei Starovoitov wrote: > > On Wed, Jan 30, 2019 at 11:15:30AM +0100, Peter Zijlstra wrote: > >> On Tue, Jan 29, 2019 at 08:04:56PM -0800, Alexei Starovoitov wrote: > >>> Lockdep warns about false positive: > >

Re: [PATCH bpf-next 2/4] bpf: fix lockdep false positive in stackmap

2019-01-30 Thread Waiman Long
On 01/30/2019 02:44 PM, Peter Zijlstra wrote: > On Wed, Jan 30, 2019 at 11:30:41AM -0800, Alexei Starovoitov wrote: >> On Wed, Jan 30, 2019 at 11:15:30AM +0100, Peter Zijlstra wrote: >>> On Tue, Jan 29, 2019 at 08:04:56PM -0800, Alexei Starovoitov wrote: Lockdep warns about false positive: >>>

Re: [PATCH bpf-next 2/4] bpf: fix lockdep false positive in stackmap

2019-01-30 Thread Peter Zijlstra
On Wed, Jan 30, 2019 at 11:30:41AM -0800, Alexei Starovoitov wrote: > On Wed, Jan 30, 2019 at 11:15:30AM +0100, Peter Zijlstra wrote: > > On Tue, Jan 29, 2019 at 08:04:56PM -0800, Alexei Starovoitov wrote: > > > Lockdep warns about false positive: > > > > This is not a false positive, and you prob

Re: [PATCH bpf-next 2/4] bpf: fix lockdep false positive in stackmap

2019-01-30 Thread Waiman Long
On 01/30/2019 02:30 PM, Alexei Starovoitov wrote: > On Wed, Jan 30, 2019 at 11:15:30AM +0100, Peter Zijlstra wrote: >> On Tue, Jan 29, 2019 at 08:04:56PM -0800, Alexei Starovoitov wrote: >>> Lockdep warns about false positive: >> This is not a false positive, and you probably also need to use >> do

Re: [PATCH bpf-next 2/4] bpf: fix lockdep false positive in stackmap

2019-01-30 Thread Alexei Starovoitov
On Wed, Jan 30, 2019 at 11:15:30AM +0100, Peter Zijlstra wrote: > On Tue, Jan 29, 2019 at 08:04:56PM -0800, Alexei Starovoitov wrote: > > Lockdep warns about false positive: > > This is not a false positive, and you probably also need to use > down_read_non_owner() to match this up_read_non_owner(

Re: [PATCH bpf-next 2/4] bpf: fix lockdep false positive in stackmap

2019-01-30 Thread Peter Zijlstra
On Tue, Jan 29, 2019 at 08:04:56PM -0800, Alexei Starovoitov wrote: > Lockdep warns about false positive: This is not a false positive, and you probably also need to use down_read_non_owner() to match this up_read_non_owner(). {up,down}_read() and {up,down}_read_non_owner() are not only different

[PATCH bpf-next 2/4] bpf: fix lockdep false positive in stackmap

2019-01-29 Thread Alexei Starovoitov
Lockdep warns about false positive: [ 11.211460] [ cut here ] [ 11.211936] DEBUG_LOCKS_WARN_ON(depth <= 0) [ 11.211985] WARNING: CPU: 0 PID: 141 at ../kernel/locking/lockdep.c:3592 lock_release+0x1ad/0x280 [ 11.213134] Modules linked in: [ 11.213413] CPU: 0 PID: 1