Re: arm64: allmodconfig: BUG: KCSAN: data-race in p9_client_cb / p9_client_rpc

[Naresh Kamboju]

On Thu, 1 Dec 2022 at 01:35, Dominique Martinet <asmadeus@xxxxxxxxxxxxx> wrote:
>
> Naresh Kamboju wrote on Wed, Nov 30, 2022 at 09:34:45PM +0530:
> > > > [  424.418214] write to 0xffff00000a753000 of 4 bytes by interrupt on cpu 0:
> > > > [  424.422437]  p9_client_cb+0x84/0x100
> > >
> > > Then we can look at git blame of the lines and see if it's new code.
> >
> > True.
> > Hope that tree and tag could help you get git details.
>
> Even with the git tag, if we don't build for the same arch with the same
> compiler version/options and the same .config we aren't likely to have
> identical binaries, so we cannot make sense of these offsets without
> much work.
>
> As much as I'd like to investigate a data race in 9p (and geez that code
> has been such a headache from syzbot already so I don't doubt there are
> more), having line numbers is really not optional if we want to scale at
> all.
> If you still have the vmlinux binary from that build (or if you can
> rebuild with the same options), running this text through addr2line
> should not take you too long.

Please find build artifacts in this link,
 - config
 - vmlinux
 - System.map
https://people.linaro.org/~anders.roxell/next-20221130-allmodconfig-arm64-tuxmake-build/

And

 # aarch64-linux-gnu-objdump -D vmlinux|less search for p9_client_cb

Attached objdump log and here is the link.
    - http://ix.io/4hk1

> (You might need to build with at least CONFIG_DEBUG_INFO_REDUCED (or not
> reduced), but that is on by default for aarch64)

Thanks for the suggestions.
The Kconfig is enabled now.
CONFIG_DEBUG_INFO_REDUCED=y

> --
> Dominique


- Naresh
ffff80000a46cac0 <p9_client_cb>:
ffff80000a46cac0:       d503201f        nop
ffff80000a46cac4:       d503201f        nop
ffff80000a46cac8:       d503233f        paciasp
ffff80000a46cacc:       a9bc7bfd        stp     x29, x30, [sp, #-64]!
ffff80000a46cad0:       910003fd        mov     x29, sp
ffff80000a46cad4:       a90153f3        stp     x19, x20, [sp, #16]
ffff80000a46cad8:       aa0103f3        mov     x19, x1
ffff80000a46cadc:       aa1e03f4        mov     x20, x30
ffff80000a46cae0:       a9025bf5        stp     x21, x22, [sp, #32]
ffff80000a46cae4:       2a0203f6        mov     w22, w2
ffff80000a46cae8:       aa0003f5        mov     x21, x0
ffff80000a46caec:       f9001bf7        str     x23, [sp, #48]
ffff80000a46caf0:       aa1403fe        mov     x30, x20
ffff80000a46caf4:       d50320ff        xpaclri
ffff80000a46caf8:       9101ba77        add     x23, x19, #0x6e
ffff80000a46cafc:       aa1e03e0        mov     x0, x30
ffff80000a46cb00:       97834b20        bl      ffff80000853f780 <__tsan_func_entry>
ffff80000a46cb04:       f0003614        adrp    x20, ffff80000ab2f000 <event_type_size+0x8>
ffff80000a46cb08:       aa1703e0        mov     x0, x23
ffff80000a46cb0c:       97835cad        bl      ffff800008543dc0 <__tsan_read2>
ffff80000a46cb10:       7940de63        ldrh    w3, [x19, #110]
ffff80000a46cb14:       911c8294        add     x20, x20, #0x720
ffff80000a46cb18:       91384294        add     x20, x20, #0xe10
ffff80000a46cb1c:       52800400        mov     w0, #0x20                       // #32
ffff80000a46cb20:       aa1403e1        mov     x1, x20
ffff80000a46cb24:       b0006a22        adrp    x2, ffff80000b1b1000 <kallsyms_token_index+0x20f070>
ffff80000a46cb28:       910a8042        add     x2, x2, #0x2a0
ffff80000a46cb2c:       97fff345        bl      ffff80000a469840 <_p9_debug>
ffff80000a46cb30:       52800080        mov     w0, #0x4                        // #4
ffff80000a46cb34:       97834de3        bl      ffff8000085402c0 <__tsan_atomic_signal_fence>
ffff80000a46cb38:       d5033abf        dmb     ishst
ffff80000a46cb3c:       aa1303e0        mov     x0, x19
ffff80000a46cb40:       97835ac0        bl      ffff800008543640 <__tsan_unaligned_write4>
ffff80000a46cb44:       aa1303e0        mov     x0, x19
ffff80000a46cb48:       d2800003        mov     x3, #0x0                        // #0
ffff80000a46cb4c:       52800022        mov     w2, #0x1                        // #1
ffff80000a46cb50:       52800061        mov     w1, #0x3                        // #3