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Date:   Fri, 15 Jul 2022 01:55:02 +0100
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Liu Xinpeng <liuxp11@chinatelecom.cn>
Cc:     linux-kernel@vger.kernel.org
Subject: Re: [PATCH] iov_iter: Fix repeated minus operation
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On Wed, Jul 13, 2022 at 06:23:40PM +0800, Liu Xinpeng wrote:
> After executing command 'cat /proc/cpuinfo', got a message:
> 
> [    6.909745] ------------[ cut here ]------------
> [    6.910267] WARNING: CPU: 0 PID: 76 at lib/iov_iter.c:1026
> iov_iter_pipe+0x34/0x40
> [    6.910951] Modules linked in:
> [    6.911584] CPU: 0 PID: 76 Comm: cat Not tainted 5.19.0-rc6-next-20220711 #9
> [    6.911916] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
> [    6.912668] RIP: 0010:iov_iter_pipe+0x34/0x40
> [    6.913062] Code: 72 54 39 72 5c 76 23 48 c7 07 00 00 00 00 48 c7 47 08 00 00
> 00 00 c6 07 03 48 89 4f 10 48 89 57 18 89 47 20 89 47 24 c3 0f 0b <0f> 7
> [    6.914341] RSP: 0018:ffffc900001c7d48 EFLAGS: 00000246
> [    6.914647] RAX: 0000000000000010 RBX: ffff888004988700 RCX: 0000000000000000
> [    6.914893] RDX: ffff88800490bc00 RSI: 0000000000000010 RDI: ffffc900001c7d58
> [    6.915302] RBP: ffffc900001c7e00 R08: 0000000000000000 R09: ffff888004cafad8
> [    6.915609] R10: 0000000000020000 R11: 0000000000001000 R12: ffff88800490bc00
> [    6.915856] R13: ffffc900001c7e48 R14: 00000000000002d5 R15: ffff88800490bc00
> [    6.916352] FS:  00000000016df8c0(0000) GS:ffff88800f600000(0000)
> 
> Checking the code, need to delete the duplicate minus in a loop.

Nice catch.  Fix folded in...