On 2018/07/09 23:29, Tetsuo Handa wrote: > On 2018/07/09 23:02, Martijn Coenen wrote: >> On Mon, Jul 9, 2018 at 3:27 PM, Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote: >>> I know almost nothing about binder. How these debug messages are >>> enabled? I don't see anything like CONFIG_BINDER_VERBOSE_DEBUG in the >>> config: >>> https://github.com/google/syzkaller/blob/master/dashboard/config/upstream-kasan.config >>> Also no mentions of binder in sysctl/cmline. >>> All binder maintainers are in CC already, perhaps they can shed some >>> light on this. >> >> Some are enabled by default here: >> https://github.com/torvalds/linux/blob/master/drivers/android/binder.c#L138 >> >> Perhaps we should revise that set then, as it can be quite noisy when >> lots of processes are dying (which also happens a lot in syzbot >> tests). >> > > OK. Then, I think we should consider disabling by default or latelimit printk(). > Repeating hundreds of (or maybe thousands of ?) similar messages is not useful > (and blocking other threads due to processing flood of printk() is not good). > I don't have benchmark data (I'm not an Android user). But an example log at https://syzkaller.appspot.com/text?tag=CrashLog&x=12f316fc400000 got about 13214 messages in 124 seconds (over 100 messages per a second). Without disabling by default or latelimit printk(), the system shall become unusable. $ grep binder: log | wc -l 13214 $ head log [ 1167.389978] binder: 15631:15631 got reply transaction with no transaction stack [ 1167.391813] binder: 15629:15629 transaction failed 29201/-71, size 0-8 line 2759 [ 1167.399282] binder: 15631:15631 transaction failed 29201/-71, size 0-8 line 2759 [ 1167.399548] binder: undelivered TRANSACTION_ERROR: 29201 [ 1167.419645] binder: 15625:15625 got reply transaction with no transaction stack [ 1167.427800] binder: 15625:15625 transaction failed 29201/-71, size 0-8 line 2759 [ 1167.461506] binder: 15634:15634 got reply transaction with no transaction stack [ 1167.469060] binder: 15634:15634 transaction failed 29201/-71, size 0-8 line 2759 [ 1167.472747] binder: 15638:15638 got reply transaction with no transaction stack [ 1167.477550] binder: 15633:15633 got reply transaction with no transaction stack $ tail log [ 1291.131046] binder: 25566:25566 transaction failed 29201/-71, size 0-8 line 2759 [ 1291.140761] binder: 25553:25553 got reply transaction with no transaction stack [ 1291.151698] binder: 25553:25553 transaction failed 29201/-71, size 0-8 line 2759 [ 1291.182362] binder: 25568:25568 got reply transaction with no transaction stack [ 1291.183361] binder: undelivered TRANSACTION_ERROR: 29201 [ 1291.189926] binder: 25568:25568 transaction failed 29201/-71, size 0-8 line 2759 [ 1291.204438] binder: 25569:25569 got reply transaction with no transaction stack [ 1291.211953] binder: 25569:25569 transaction failed 29201/-71, size 0-8 line 2759 [ 1291.213825] binder: 25572:25572 got reply transaction with no transaction stack [ 1291.227018] binder: 25572:25572 transaction failed 29201/-71, size 0-8 line 2759 _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
