On Fri, 2016-07-01 at 16:10 +0800, Ding Tianhong wrote: > On 2016/7/1 15:57, Eric Dumazet wrote: > > On Fri, 2016-07-01 at 15:38 +0800, Ding Tianhong wrote: > > ... > >> net/ipv6/addrconf.c | 6 ++++++ > >> 1 file changed, 6 insertions(+) > >> > >> diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c > >> index f555f4f..e294a3d 100644 > >> --- a/net/ipv6/addrconf.c > >> +++ b/net/ipv6/addrconf.c > >> @@ -3284,6 +3284,12 @@ restart: > >> spin_unlock_bh(&addrconf_hash_lock); > >> } > >> > >> + /* > >> + * It is safe here to schedule out to avoid softlocking if preempt > >> + * is disabled. > >> + */ > >> + cond_resched(); > >> + > >> write_lock_bh(&idev->lock); > >> > >> addrconf_del_rs_timer(idev); > > > > Seeing you apparently cooked your patch against an old kernel (which > > one ?) ... > > > > I tried vanilla net-next kernel, and apparently I could not trigger the > > softlockup you mentioned. > > > > Are you sure current kernel has a bug to begin with ? > > > have you disable the preempt? The problem will disappear if you enable the > preempt voluntary or preempt. > CONFIG_PREEMPT_NONE=y > # CONFIG_PREEMPT_VOLUNTARY is not set > # CONFIG_PREEMPT is not set > > I test the 4.1 lts kernel and found this problem, and I didn't found any > patch to fix this from linux 4.1, but I will try to test in 4.7 kernel > version.
I usually do not have PREEMPT enabled in my kernels. $ grep PREEMPT .config CONFIG_PREEMPT_NOTIFIERS=y CONFIG_PREEMPT_NONE=y # CONFIG_PREEMPT_VOLUNTARY is not set # CONFIG_PREEMPT is not set Also the whole script is quite fast on latest kernels. I am guessing you are chasing an already fixed problem.
