From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755211AbdDLQ1g (ORCPT ); Wed, 12 Apr 2017 12:27:36 -0400 Received: from scorn.kernelslacker.org ([45.56.101.199]:42982 "EHLO scorn.kernelslacker.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755004AbdDLQ1P (ORCPT ); Wed, 12 Apr 2017 12:27:15 -0400 Date: Wed, 12 Apr 2017 12:27:09 -0400 From: Dave Jones To: Al Viro Cc: Linux Kernel Subject: Re: iov_iter_pipe warning. Message-ID: <20170412162709.bn5qfk4seues3yos@codemonkey.org.uk> Mail-Followup-To: Dave Jones , Al Viro , Linux Kernel References: <20170411235158.GK29622@ZenIV.linux.org.uk> <20170411235641.GL29622@ZenIV.linux.org.uk> <20170412000607.ob4cjv7vof3f64uu@codemonkey.org.uk> <20170412001746.GM29622@ZenIV.linux.org.uk> <20170412005853.vqyuo6722tmthn5u@codemonkey.org.uk> <20170412011532.GN29622@ZenIV.linux.org.uk> <20170412022911.nhefjqlnyrk3n7rr@codemonkey.org.uk> <20170412025842.GO29622@ZenIV.linux.org.uk> <20170412143519.4hh36l3egozgdrll@codemonkey.org.uk> <20170412152600.GP29622@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170412152600.GP29622@ZenIV.linux.org.uk> User-Agent: NeoMutt/20170306 (1.8.0) X-Spam-Note: SpamAssassin invocation failed Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 12, 2017 at 04:26:00PM +0100, Al Viro wrote: > On Wed, Apr 12, 2017 at 10:35:19AM -0400, Dave Jones wrote: > > > [ 4140.040002] asked to read 8, claims to have read 4 > > [ 4140.051634] actual size of data in pipe 8 > > [ 4140.063234] [0:8 > > > [ 4140.342955] ---[ end trace d074a8823fe244d4 ]--- > > [ 4140.353868] in->f_op = ffffffffa02dc980, ->splice_write = ffffffff812b2c20 > > IOW, we just had someone's ->read_iter() return 4 after having deposited 8 > bytes. The next question is which file_operations had that been, whether > it was O_DIRECT or not and where in file had we been reading from... [ 1010.008906] WARNING: CPU: 2 PID: 15216 at fs/splice.c:297 test_it+0x7d/0x120 [ 1010.021094] CPU: 2 PID: 15216 Comm: trinity-c5 Not tainted 4.11.0-rc6-think+ #13 [ 1010.045849] Call Trace: [ 1010.058136] dump_stack+0x68/0x93 [ 1010.070379] __warn+0xcb/0xf0 [ 1010.082473] warn_slowpath_null+0x1d/0x20 [ 1010.094489] test_it+0x7d/0x120 [ 1010.106443] generic_file_splice_read+0x19a/0x1e0 [ 1010.118337] do_splice_to+0x79/0x90 [ 1010.130161] splice_direct_to_actor+0xc6/0x280 [ 1010.142032] ? generic_pipe_buf_nosteal+0x10/0x10 [ 1010.153871] do_splice_direct+0x9e/0xd0 [ 1010.165687] do_sendfile+0x1d7/0x3c0 [ 1010.177442] SyS_sendfile64+0x73/0xe0 [ 1010.189128] do_syscall_64+0x66/0x1d0 [ 1010.200743] entry_SYSCALL64_slow_path+0x25/0x25 [ 1010.212287] RIP: 0033:0x7f1bda69d0f9 [ 1010.223883] RSP: 002b:00007ffede478db8 EFLAGS: 00000246 [ 1010.235516] ORIG_RAX: 0000000000000028 [ 1010.247115] RAX: ffffffffffffffda RBX: 0000000000000028 RCX: 00007f1bda69d0f9 [ 1010.258850] RDX: 00007f1bdac39000 RSI: 0000000000000186 RDI: 0000000000000186 [ 1010.270550] RBP: 00007f1bdad49000 R08: ffffe5d6e7f7c7f4 R09: 0000000092d54252 [ 1010.282174] R10: 0000000000200000 R11: 0000000000000246 R12: 0000000000000002 [ 1010.293781] R13: 00007f1bdad49048 R14: 00007f1bdad73ad8 R15: 00007f1bdad49000 [ 1010.305695] ---[ end trace 048fab9469c0948e ]--- [ 1010.317696] asked to read 2097152, claims to have read 7025 [ 1010.329471] actual size of data in pipe 65536 [ 1010.341162] [0:4096 [ 1010.353232] ,1:4096 [ 1010.364402] ,2:4096 [ 1010.375608] ,3:4096 [ 1010.386346] ,4:4096 [ 1010.397027] ,5:4096 [ 1010.407611] ,6:4096 [ 1010.418010] ,7:4096 [ 1010.428533] ,8:4096 [ 1010.438885] ,9:4096 [ 1010.449269] ,10:4096 [ 1010.459462] ,11:4096 [ 1010.469519] ,12:4096 [ 1010.479326] ,13:4096 [ 1010.489093] ,14:4096 [ 1010.498711] ,15:4096 [ 1010.508217] ] [ 1010.517570] f_op: ffffffffa0242980, f_flags: 311298, pos: 11/7036, size: 7036