Hi Andre, On Thu, Oct 23, 2014 at 10:00 AM, Andre Przywara <andre.przyw...@arm.com> wrote: > Hi, > > I see a crash with 3.18-rc1 on a Juno board related to bpf_jit (see dump > below). Userland tries to carry on afterwards, but eventually hangs in > RCU stalls. > The kernel has just CONFIG_BPF_JIT enabled, I guess Ubuntu enables this > automatically if detected. >
When net-next and arm64-next merged in mainline, a silent failure is introduced due to new enhancements in net/bpf. This was actually uncovered before 3.18 merge window, and Daniel's patch to fix this was discussed here [1]. I see that Catalin has queued up this patch in fixes/core [2]. [1] https://lkml.org/lkml/2014/9/16/73 [2] https://git.kernel.org/cgit/linux/kernel/git/arm64/linux.git/commit/?h=fixes/core&id=b569c1c622c5e60c960a6ae5bd0880e0cdbd56b1) > The backtrace doesn't make too much sense to me: > > void bpf_jit_free(struct bpf_prog *prog) > { > if (prog->jited) > module_free(NULL, prog->bpf_func); > > kfree(prog); > } > It crashes in kfree, but has survived the dereference before. > > I have no clue about BPF, so if anyone could help me debug this, I'd be > grateful. > > Cheers, > Andre. > > > * Starting Signal sysvinit that local filesystems are mounted [ OK ] > * Starting configure network device security [ OK ] > Unable to handle kernel paging request at virtual address 37fffbd21c02290 > pgd = ffffffc976538000 > [37fffbd21c02290] *pgd=0000000000000000, *pud=0000000000000000 > Internal error: Oops: 96000004 [#1] PREEMPT SMP > Modules linked in: > CPU: 3 PID: 737 Comm: kworker/3:1 Not tainted 3.18.0-rc1+ #1666 > Workqueue: events bpf_prog_free_deferred > task: ffffffc977a89580 ti: ffffffc976494000 task.ti: ffffffc976494000 > PC is at kfree+0x70/0x260 > LR is at bpf_jit_free+0x34/0x40 > pc : [<ffffffc0001b0634>] lr : [<ffffffc000099290>] pstate: a0000145 > sp : ffffffc976497ca0 > x29: ffffffc976497ca0 x28: 0000000000000000 > x27: ffffffc97feff400 x26: ffffffc0009b0000 > x25: 0000000000000000 x24: 0000000000000000 > x23: ffffffc97ff03900 x22: ffffffc97feff400 > x21: ffffffc000099290 x20: ffffff800009e000 > x19: ffffff800009e000 x18: 0000007feb492820 > x17: 0000007fb71c6980 x16: ffffffc0001fcc14 > x15: 003b9aca00000000 x14: 0027947614000000 > x13: ffffffffabb6d0e3 x12: 0000000000000018 > x11: 0000000033c2a168 x10: 0000000000000006 > x9 : ffffffc976497bd0 x8 : ffffffc977a89a90 > x7 : ffffffc97736c4d0 x6 : 00000000000009be > x5 : 0000000000000000 x4 : 0000000000000001 > x3 : ffffffc97feff7c0 x2 : 03ffffff02002780 > x1 : 037fffff21c02290 x0 : ffffffbe00000000 > > Process kworker/3:1 (pid: 737, stack limit = 0xffffffc976494058) > Stack: (0xffffffc976497ca0 to 0xffffffc976498000) > .... -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
