On Tue, Mar 19, 2024 at 11:50 PM Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> wrote: > > Hello, bpf developers. > > syzbot is reporting circular locking dependency because bpf program is hitting > printk() path. To avoid this dependency, something like > https://syzkaller.appspot.com/text?tag=Patch&x=121c92fe180000 is needed. > > Is it possible to call printk_deferred_{enter,exit}() from the bpf side (e.g. > bpf_prog_run()) so that we don't need to add overhead on the scheduler side > when bpf programs are not registered? > > printk_deferred_{enter,exit}() requires that printk_deferred_exit() is called > on a CPU which printk_deferred_enter() was called, for percpu counter is used. > Is migrate_{disable,enable}() also needed around printk_deferred_{enter,exit}() ? > > On 2023/10/08 15:28, syzbot wrote: > > Hello, > > > > syzbot found the following issue on: > > > > HEAD commit: 7d730f1bf6f3 Add linux-next specific files for 20231005 > > git tree: linux-next > > console output: https://syzkaller.appspot.com/x/log.txt?x=172d36e9680000 This has nothing to do with bpf. bpf never calls printk().
