Re: [stable request < 4.1] signal: remove warning about using SI_TKILL in rt_[tg]sigqueueinfo

[Greg KH <greg@kroah.com>]

On Wed, Jul 13, 2016 at 11:41:35AM -0700, Vinson Lee wrote:
> Hi.
> 
> I would like to nominate 4.1 commit
> 69828dce7af2cb6d08ef5a03de687d422fb7ec1f for backport to stable
> branches.

How far back do you want this to go, and have you tested it for?

Are people hitting this on 3.14?  Does anyone care about this for 3.14?

thanks,

greg k-h

> 
> commit 69828dce7af2cb6d08ef5a03de687d422fb7ec1f
> Author: Vladimir Davydov <vdavydov@parallels.com>
> Date:   Thu Apr 16 12:47:35 2015 -0700
> 
>     signal: remove warning about using SI_TKILL in rt_[tg]sigqueueinfo
> 
>     Sending SI_TKILL from rt_[tg]sigqueueinfo was deprecated, so now we issue
>     a warning on the first attempt of doing it.  We use WARN_ON_ONCE, which is
>     not informative and, what is worse, taints the kernel, making the trinity
>     syscall fuzzer complain false-positively from time to time.
> 
>     It does not look like we need this warning at all, because the behaviour
>     changed quite a long time ago (2.6.39), and if an application relies on
>     the old API, it gets EPERM anyway and can issue a warning by itself.
> 
>     So let us zap the warning in kernel.
> 
>     Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
>     Acked-by: Oleg Nesterov <oleg@redhat.com>
>     Cc: Richard Weinberger <richard@nod.at>
>     Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
>     Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
>     Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
> 
> 
> I trigger this warning with trinity as well on older kernels. For
> example, this is a warning from a trinity run on a Ubuntu 3.16 kernel.
> 
> ------------[ cut here ]------------
> WARNING: CPU: 9 PID: 27056 at
> /build/buildd/linux-lts-utopic-3.16.0/kernel/signal.c:3035
> do_rt_tgsigqueueinfo+0xac/0xc0()
> Modules linked in: l2tp_ppp(E) l2tp_netlink(E) l2tp_core(E) dccp_ipv4
> dccp dlci(E) ipt_ULOG dn_rtmsg cmtp(E) kernelcapi(E) nfnetlink bnep(E)
> sctp scsi_transport_iscsi rfcomm(E) hidp(E) can_bcm af_alg irda
> af_rxrpc phonet ipx p8022 p8023 can_raw can appletalk psnap xfrm_user
> bluetooth(E) 6lowpan_iphc nfc(E) pppoe pppox caif_socket(E) caif(E)
> crc_ccitt llc2 vmw_vsock_vmci_transport vsock vmw_vmci atm af_key
> xfrm_algo hfs(E) ip6table_filter ip6_tables xt_comment xt_state xt_LOG
> xt_limit xt_tcpudp xt_addrtype iptable_filter iptable_mangle
> iptable_raw iptable_nat nf_nat_ipv4 nf_nat ip_tables x_tables 8021q
> mrp garp bridge stp llc squashfs nf_conntrack_ipv4 nf_defrag_ipv4
> nf_conntrack xfs libcrc32c intel_rapl(E) x86_pkg_temp_thermal(E)
> intel_powerclamp(E) coretemp(E) kvm_intel kvm crct10dif_pclmul
> crc32_pclmul ghash_clmulni_intel aesni_intel ablk_helper cryptd lrw
> gf128mul glue_helper aes_x86_64 ioatdma(E) sb_edac(E) lpc_ich(E)
> edac_core(E) joydev mei_me(E) mei(E) shpchp(E) ipmi_si(E) mac_hid(E)
> ipmi_devintf(E) ipmi_msghandler lp parport ses(E) enclosure(E) raid10
> raid456 async_raid6_recov async_pq raid6_pq igb(E) hid_generic(E)
> async_xor ixgbe(E) isci(E) xor mpt2sas(E) libsas dca(E)
> i2c_algo_bit(E) async_memcpy usbhid(E) ptp async_tx mdio(E)
> scsi_transport_sas hid(E) pps_core raid_class raid1 raid0 multipath
> linear
> CPU: 9 PID: 27056 Comm: trinity-c32 Tainted: G            E
> 3.16.0-33-generic #44~14.04.1-Ubuntu
>  0000000000000009 ffff88080ebffe48 ffffffff81763720 0000000000000000
>  ffff88080ebffe80 ffffffff8106dd7d 0000000000000001 0000000000000101
>  00000000ffffffff 0000000000000129 0000000000000000 ffff88080ebffe90
> Call Trace:
>  [<ffffffff81763720>] dump_stack+0x45/0x56
>  [<ffffffff8106dd7d>] warn_slowpath_common+0x7d/0xa0
>  [<ffffffff8106de5a>] warn_slowpath_null+0x1a/0x20
>  [<ffffffff8107f6dc>] do_rt_tgsigqueueinfo+0xac/0xc0
>  [<ffffffff8107f739>] SYSC_rt_tgsigqueueinfo+0x49/0x60
>  [<ffffffff8108174e>] SyS_rt_tgsigqueueinfo+0xe/0x10
>  [<ffffffff8176be6d>] system_call_fastpath+0x1a/0x1f
> ---[ end trace 87e1749467efbe95 ]---
> 
> Cheers,
> Vinson
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