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From: CAI Qian <caiqian@redhat.com>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Dave Chinner <david@fromorbit.com>,
	linux-xfs <linux-xfs@vger.kernel.org>,
	xfs@oss.sgi.com, Jens Axboe <axboe@kernel.dk>,
	Nick Piggin <npiggin@gmail.com>,
	linux-fsdevel@vger.kernel.org
Subject: Re: [RFC][CFT] splice_read reworked
Date: Fri, 30 Sep 2016 13:42:17 -0400 (EDT)
Message-ID: <1415238593.811146.1475257337058.JavaMail.zimbra@redhat.com> (raw)
In-Reply-To: <2131586457.763354.1475242373422.JavaMail.zimbra@redhat.com>



----- Original Message -----
> From: "CAI Qian" <caiqian@redhat.com>
> To: "Al Viro" <viro@ZenIV.linux.org.uk>
> Cc: "Linus Torvalds" <torvalds@linux-foundation.org>, "Dave Chinner" <david@fromorbit.com>, "linux-xfs"
> <linux-xfs@vger.kernel.org>, xfs@oss.sgi.com, "Jens Axboe" <axboe@kernel.dk>, "Nick Piggin" <npiggin@gmail.com>,
> linux-fsdevel@vger.kernel.org
> Sent: Friday, September 30, 2016 9:32:53 AM
> Subject: Re: [RFC][CFT] splice_read reworked
> 
> 
> 
> ----- Original Message -----
> > From: "Al Viro" <viro@ZenIV.linux.org.uk>
> > To: "Linus Torvalds" <torvalds@linux-foundation.org>
> > Cc: "Dave Chinner" <david@fromorbit.com>, "CAI Qian" <caiqian@redhat.com>,
> > "linux-xfs" <linux-xfs@vger.kernel.org>,
> > xfs@oss.sgi.com, "Jens Axboe" <axboe@kernel.dk>, "Nick Piggin"
> > <npiggin@gmail.com>, linux-fsdevel@vger.kernel.org
> > Sent: Friday, September 23, 2016 3:00:32 PM
> > Subject: [RFC][CFT] splice_read reworked
> > 
> > The series is supposed to solve the locking order problems for
> > ->splice_read() and get rid of code duplication between the read-side
> > methods.
> > 	pipe_lock is lifted out of ->splice_read() instances, along with
> > waiting for empty space in pipe, etc. - we do that stuff in callers.
> > 	A new variant of iov_iter is introduced - it's backed by a pipe,
> > copy_to_iter() results in allocating pages and copying into those,
> > copy_page_to_iter() just sticks a reference to that page into pipe.
> > Running out of space in pipe yields a short read, as a fault in
> > iovec-backed
> > iov_iter would have.  Enough primitives are implemented for normal
> > ->read_iter() instances to work.
> > 	generic_file_splice_read() switched to feeding such iov_iter to
> > ->read_iter() instance.  That turns out to be enough to kill almost all
> > ->splice_read() instances; the only ones _not_ using
> > generic_file_splice_read()
> > or default_file_splice_read() (== no zero-copy fallback) are
> > fuse_dev_splice_read(), 3 instances in kernel/{relay.c,trace/trace.c} and
> > sock_splice_read().  It's almost certainly possible to convert fuse one
> > and the same might be possible to do to socket one.  relay and tracing
> > stuff is just plain weird; might or might not be doable.
> > 
> > 	Something hopefully working is in
> > git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git
> > #work.splice_read
> Tested-by: CAI Qian <caiqian@redhat.com>

Except...

One warning just pop up while running trinity.

[ 1599.151286] ------------[ cut here ]------------
[ 1599.156457] WARNING: CPU: 37 PID: 95143 at lib/iov_iter.c:316 sanity+0x75/0x80
[ 1599.164818] Modules linked in: af_key ieee802154_socket ieee802154 vmw_vsock_vmci_transport vsock vmw_vmci hidp cmtp kernelcapi bnep rfcomm bluetooth rfkill can_bcm can_raw can pptp gre l2tp_ppp l2tp_netlink l2tp_core ip6_udp_tunnel udp_tunnel pppoe pppox ppp_generic slhc nfnetlink scsi_transport_iscsi atm sctp ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 xt_addrtype iptable_filter xt_conntrack nf_nat nf_conntrack br_netfilter bridge stp llc overlay intel_rapl sb_edac edac_core x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm irqbypass crct10dif_pclmul crc32_pclmul ghash_clmulni_intel aesni_intel lrw gf128mul glue_helper ablk_helper cryptd iTCO_wdt iTCO_vendor_support pcspkr mei_me sg i2c_i801 mei shpchp lpc_ich i2c_smbus ipmi_ssif wmi ipmi_si ipmi_msghandler acpi_power_meter acpi_pad nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables xfs libcrc32c sd_mod sr_mod cdrom mgag200 i2c_algo_bit drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops crc32c_intel ttm ixgbe drm ahci mdio libahci ptp libata i2c_core pps_core dca fjes dm_mirror dm_region_hash dm_log dm_mod
[ 1599.278669] CPU: 50 PID: 95143 Comm: trinity-c142 Not tainted 4.8.0-rc8-usrns-scale+ #8
[ 1599.287604] Hardware name: Intel Corporation S2600WTT/S2600WTT, BIOS GRNDSDP1.86B.0044.R00.1501191641 01/19/2015
[ 1599.298962]  0000000000000286 000000007794c41e ffff8803c6c7fbb0 ffffffff813d5e93
[ 1599.307259]  0000000000000000 0000000000000000 ffff8803c6c7fbf0 ffffffff8109c87b
[ 1599.315553]  0000013c00000000 0000000000000efe ffffea001de95240 ffff8802e1aca600
[ 1599.323847] Call Trace:
[ 1599.326580]  [<ffffffff813d5e93>] dump_stack+0x85/0xc2
[ 1599.332315]  [<ffffffff8109c87b>] __warn+0xcb/0xf0
[ 1599.337660]  [<ffffffff8109c9ad>] warn_slowpath_null+0x1d/0x20
[ 1599.344171]  [<ffffffff813e9b45>] sanity+0x75/0x80
[ 1599.349518]  [<ffffffff813ec739>] copy_page_to_iter+0xf9/0x1e0
[ 1599.356027]  [<ffffffff8120691f>] shmem_file_read_iter+0x9f/0x340
[ 1599.362829]  [<ffffffff812bbeb9>] generic_file_splice_read+0xb9/0x1b0
[ 1599.370015]  [<ffffffff812bc206>] do_splice_to+0x76/0x90
[ 1599.375941]  [<ffffffff812bc2db>] splice_direct_to_actor+0xbb/0x220
[ 1599.382935]  [<ffffffff812bba80>] ? generic_pipe_buf_nosteal+0x10/0x10
[ 1599.390220]  [<ffffffff812bc4d8>] do_splice_direct+0x98/0xd0
[ 1599.396537]  [<ffffffff81281dd1>] do_sendfile+0x1d1/0x3b0
[ 1599.402563]  [<ffffffff81282973>] SyS_sendfile64+0x73/0xd0
[ 1599.408685]  [<ffffffff81003f8c>] do_syscall_64+0x6c/0x1e0
[ 1599.414820]  [<ffffffff817d927f>] entry_SYSCALL64_slow_path+0x25/0x25
[ 1599.422087] ---[ end trace a3fb2953df356f80 ]---

    CAI Qian

  reply index

Thread overview: 101+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20160908235521.GL2356@ZenIV.linux.org.uk>
     [not found] ` <20160909015324.GD30056@dastard>
     [not found]   ` <CA+55aFzohsUXj_3BeFNr2t50Wm=G+7toRDEz=Tk7VJqP3n1hXQ@mail.gmail.com>
     [not found]     ` <CA+55aFxrqCng2Qxasc9pyMrKUGFjo==fEaFT1vkH9Lncte3RgQ@mail.gmail.com>
     [not found]       ` <20160909023452.GO2356@ZenIV.linux.org.uk>
     [not found]         ` <CA+55aFwHQMjO4-vtfB9-ytc=o+DRo-HXVGckvXLboUxgpwb7_g@mail.gmail.com>
     [not found]           ` <20160909221945.GQ2356@ZenIV.linux.org.uk>
     [not found]             ` <CA+55aFzTOOB6oEVaaGD0N7Uznk-W9+ULPwzsxS_L_oZqGVSeLA@mail.gmail.com>
     [not found]               ` <20160914031648.GB2356@ZenIV.linux.org.uk>
     [not found]                 ` <20160914133925.2fba4629@roar.ozlabs.ibm.com>
2016-09-18  5:33                   ` xfs_file_splice_read: possible circular locking dependency detected Al Viro
2016-09-19  3:08                     ` Nicholas Piggin
2016-09-19  6:11                       ` Al Viro
2016-09-19  7:26                         ` Nicholas Piggin
     [not found]                 ` <CA+55aFznQaOWoSMNphgGJJWZ=8-odrc0DAUMzfGPQe+_N4UgNA@mail.gmail.com>
     [not found]                   ` <20160914042559.GC2356@ZenIV.linux.org.uk>
     [not found]                     ` <20160917082007.GA6489@ZenIV.linux.org.uk>
     [not found]                       ` <20160917190023.GA8039@ZenIV.linux.org.uk>
2016-09-18 19:31                         ` skb_splice_bits() and large chunks in pipe (was " Al Viro
2016-09-18 20:12                           ` Linus Torvalds
2016-09-18 22:31                             ` Al Viro
2016-09-19  0:18                               ` Linus Torvalds
2016-09-23 19:00                         ` [RFC][CFT] splice_read reworked Al Viro
2016-09-23 19:01                           ` [PATCH 01/11] fix memory leaks in tracing_buffers_splice_read() Al Viro
2016-09-23 19:02                           ` [PATCH 02/11] splice_to_pipe(): don't open-code wakeup_pipe_readers() Al Viro
2016-09-23 19:02                           ` [PATCH 03/11] splice: switch get_iovec_page_array() to iov_iter Al Viro
2016-09-23 19:03                           ` [PATCH 04/11] splice: lift pipe_lock out of splice_to_pipe() Al Viro
2016-09-23 19:45                             ` Linus Torvalds
2016-09-23 20:10                               ` Al Viro
2016-09-23 20:36                                 ` Linus Torvalds
2016-09-24  3:59                                   ` Al Viro
2016-09-24 17:29                                     ` Al Viro
2016-09-27 15:38                                       ` Nicholas Piggin
2016-09-27 15:53                                       ` Chuck Lever
2016-09-24  3:59                                   ` [PATCH 04/12] " Al Viro
2016-09-26 13:35                                     ` Miklos Szeredi
2016-09-27  4:14                                       ` Al Viro
2016-12-17 19:54                                     ` Andreas Schwab
2016-12-18 19:28                                       ` Linus Torvalds
2016-12-18 19:57                                         ` Andreas Schwab
2016-12-18 20:12                                         ` Al Viro
2016-12-18 20:30                                           ` Al Viro
2016-12-18 22:10                                             ` Linus Torvalds
2016-12-18 22:18                                               ` Al Viro
2016-12-18 22:22                                                 ` Linus Torvalds
2016-12-18 22:49                                               ` Andreas Schwab
2016-12-21 18:56                                               ` Andreas Schwab
2016-12-21 19:12                                                 ` Linus Torvalds
2016-09-24  4:00                                   ` [PATCH 06/12] new helper: add_to_pipe() Al Viro
2016-09-26 13:49                                     ` Miklos Szeredi
2016-09-24  4:01                                   ` [PATCH 10/12] new iov_iter flavour: pipe-backed Al Viro
2016-09-29 20:53                                     ` Miklos Szeredi
2016-09-29 22:50                                       ` Al Viro
2016-09-30  7:30                                         ` Miklos Szeredi
2016-10-03  3:34                                           ` [RFC] O_DIRECT vs EFAULT (was Re: [PATCH 10/12] new iov_iter flavour: pipe-backed) Al Viro
2016-10-03 17:07                                             ` Linus Torvalds
2016-10-03 18:54                                               ` Al Viro
2016-09-24  4:01                                   ` [PATCH 11/12] switch generic_file_splice_read() to use of ->read_iter() Al Viro
2016-09-24  4:02                                   ` [PATCH 12/12] switch default_file_splice_read() to use of pipe-backed iov_iter Al Viro
2016-09-23 19:03                           ` [PATCH 05/11] skb_splice_bits(): get rid of callback Al Viro
2016-09-23 19:04                           ` [PATCH 06/11] new helper: add_to_pipe() Al Viro
2016-09-23 19:04                           ` [PATCH 07/11] fuse_dev_splice_read(): switch to add_to_pipe() Al Viro
2016-09-23 19:06                           ` [PATCH 08/11] cifs: don't use memcpy() to copy struct iov_iter Al Viro
2016-09-23 19:08                           ` [PATCH 09/11] fuse_ioctl_copy_user(): don't open-code copy_page_{to,from}_iter() Al Viro
2016-09-26  9:31                             ` Miklos Szeredi
2016-09-23 19:09                           ` [PATCH 10/11] new iov_iter flavour: pipe-backed Al Viro
2016-09-23 19:10                           ` [PATCH 11/11] switch generic_file_splice_read() to use of ->read_iter() Al Viro
2016-09-30 13:32                           ` [RFC][CFT] splice_read reworked CAI Qian
2016-09-30 17:42                             ` CAI Qian [this message]
2016-09-30 18:33                               ` CAI Qian
2016-10-03  1:37                                 ` Al Viro
2016-10-03 17:49                                   ` CAI Qian
2016-10-04 17:39                                     ` local DoS - systemd hang or timeout (WAS: Re: [RFC][CFT] splice_read reworked) CAI Qian
2016-10-04 21:42                                       ` tj
2016-10-05 14:09                                         ` CAI Qian
2016-10-05 15:30                                           ` tj
2016-10-05 15:54                                             ` CAI Qian
2016-10-05 18:57                                               ` CAI Qian
2016-10-05 20:05                                                 ` Al Viro
2016-10-06 12:20                                                   ` CAI Qian
2016-10-06 12:25                                                     ` CAI Qian
2016-10-06 16:11                                                       ` CAI Qian
2016-10-06 17:00                                                         ` Linus Torvalds
2016-10-06 18:12                                                           ` CAI Qian
2016-10-07  9:57                                                           ` Dave Chinner
2016-10-07 15:25                                                             ` Linus Torvalds
2016-10-07  7:08                                                       ` Jan Kara
2016-10-07 14:43                                                         ` CAI Qian
2016-10-07 15:27                                                           ` CAI Qian
2016-10-07 18:56                                                             ` CAI Qian
2016-10-09 21:54                                                               ` Dave Chinner
2016-10-10 14:10                                                                 ` CAI Qian
2016-10-10 20:14                                                                   ` CAI Qian
2016-10-10 21:57                                                                   ` Dave Chinner
2016-10-12 19:50                                                                     ` [bisected] " CAI Qian
2016-10-12 20:59                                                                       ` Dave Chinner
2016-10-13 16:25                                                                         ` CAI Qian
2016-10-13 20:49                                                                           ` Dave Chinner
2016-10-13 20:56                                                                             ` CAI Qian
2016-10-09 21:51                                                           ` Dave Chinner
2016-10-21 15:38                                                         ` [4.9-rc1+] overlayfs lockdep CAI Qian
2016-10-24 12:57                                                           ` Miklos Szeredi
2016-10-07  9:27                                                     ` local DoS - systemd hang or timeout (WAS: Re: [RFC][CFT] splice_read reworked) Dave Chinner
2016-10-03  1:42                               ` [RFC][CFT] splice_read reworked Al Viro
2016-10-03 14:06                                 ` CAI Qian
2016-10-03 15:20                                   ` CAI Qian
2016-10-03 21:12                                     ` Dave Chinner
2016-10-04 13:57                                       ` CAI Qian
2016-10-03 20:32                                   ` CAI Qian
2016-10-03 20:35                                     ` Al Viro
2016-10-04 13:29                                       ` CAI Qian
2016-10-04 14:28                                         ` Al Viro
2016-10-04 16:21                                           ` CAI Qian
2016-10-04 20:12                                             ` Al Viro
2016-10-05 14:30                                               ` CAI Qian
2016-10-05 16:07                                                 ` Al Viro
2016-09-19  0:22 skb_splice_bits() and large chunks in pipe (was Re: xfs_file_splice_read: possible circular locking dependency detected Al Viro
2016-09-20  9:51 ` Herbert Xu

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