From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1FADBC48BCF for ; Wed, 9 Jun 2021 13:01:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F264961108 for ; Wed, 9 Jun 2021 13:01:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233210AbhFINDh (ORCPT ); Wed, 9 Jun 2021 09:03:37 -0400 Received: from alexa-out.qualcomm.com ([129.46.98.28]:22160 "EHLO alexa-out.qualcomm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231231AbhFINDg (ORCPT ); Wed, 9 Jun 2021 09:03:36 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=quicinc.com; i=@quicinc.com; q=dns/txt; s=qcdkim; t=1623243702; x=1654779702; h=subject:to:cc:references:from:message-id:date: mime-version:in-reply-to:content-transfer-encoding; bh=VZlcXVEwmFnY01mwIlUZHeuNKUjGhrs1lJFRi8gIe4I=; b=CQZPlia7HKeWBKg/W7M298F5CBHAhQKFvDu0sGePVEJeK5Ch3zLXR2kp NVD3olzD4bF1NhB3+XvpEbZpdH9yI9MarDhv0Prjvcil4MxGEQ0PFKb9Q iTqAX6DpGKuquZaiRkjT1vGPnjhWts4ov6wz7TunVtfyAoadlrG5/54Kw 8=; Received: from ironmsg08-lv.qualcomm.com ([10.47.202.152]) by alexa-out.qualcomm.com with ESMTP; 09 Jun 2021 06:01:41 -0700 X-QCInternal: smtphost Received: from nalasexr03e.na.qualcomm.com ([10.49.195.114]) by ironmsg08-lv.qualcomm.com with ESMTP/TLS/AES256-SHA; 09 Jun 2021 06:01:40 -0700 Received: from [10.38.245.103] (10.80.80.8) by nalasexr03e.na.qualcomm.com (10.49.195.114) with Microsoft SMTP Server (TLS) id 15.0.1497.18; Wed, 9 Jun 2021 06:01:38 -0700 Subject: Re: [RFC PATCH 16/37] iov_iter_gap_alignment(): get rid of iterate_all_kinds() To: Al Viro , Linus Torvalds CC: , , David Sterba , Miklos Szeredi , Anton Altaparmakov , David Howells , Matthew Wilcox , Pavel Begunkov References: <20210606191051.1216821-1-viro@zeniv.linux.org.uk> <20210606191051.1216821-16-viro@zeniv.linux.org.uk> From: Qian Cai Message-ID: Date: Wed, 9 Jun 2021 09:01:36 -0400 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210606191051.1216821-16-viro@zeniv.linux.org.uk> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.80.80.8] X-ClientProxiedBy: nasanex01a.na.qualcomm.com (10.52.223.231) To nalasexr03e.na.qualcomm.com (10.49.195.114) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/6/2021 3:10 PM, Al Viro wrote: > For one thing, it's only used for iovec (and makes sense only for those). > For another, here we don't care about iov_offset, since the beginning of > the first segment and the end of the last one are ignored. So it makes > a lot more sense to just walk through the iovec array... > > We need to deal with the case of truncated iov_iter, but unlike the > situation with iov_iter_alignment() we don't care where the last > segment ends - just which segment is the last one. > > Signed-off-by: Al Viro Al, today's linux-next started to give a boot warning. I looked at the code and noticed this series is new. Any thoughts? [ 70.060822][ T1286] WARNING: CPU: 26 PID: 1286 at lib/iov_iter.c:1320 iov_iter_gap_alignment+0x144/0x1a8 [ 70.070323][ T1286] Modules linked in: loop cppc_cpufreq processor efivarfs ip_tables x_tables ext4 mbcache jbd2 dm_mod igb i2c_algo_bit nvme mlx5_core i2c_core nvme_core firmware_class [ 70.086922][ T1286] CPU: 26 PID: 1286 Comm: fwupd Tainted: G W 5.13.0-rc5-next-20210609+ #19 [ 70.096668][ T1286] Hardware name: MiTAC RAPTOR EV-883832-X3-0001/RAPTOR, BIOS 1.6 06/28/2020 [ 70.105196][ T1286] pstate: 10000005 (nzcV daif -PAN -UAO -TCO BTYPE=--) [ 70.111902][ T1286] pc : iov_iter_gap_alignment+0x144/0x1a8 [ 70.117485][ T1286] lr : blk_rq_map_user_iov+0xd00/0xff0 [ 70.122808][ T1286] sp : ffff80002360f680 [ 70.126821][ T1286] x29: ffff80002360f680 x28: 0000000000000000 x27: ffff00005dc8d620 [ 70.134670][ T1286] x26: 0000000000001000 x25: ffff80002360f980 x24: 0000000000001000 [ 70.142518][ T1286] x23: 0000000000000000 x22: 0000000000000007 x21: 1ffff000046c1f30 [ 70.150365][ T1286] x20: 0000000000000fff x19: ffff80002360f980 x18: 0000000000000000 [ 70.158214][ T1286] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000 [ 70.166067][ T1286] x14: 0000000000000045 x13: 0000000000000000 x12: 000000000000f1f1 [ 70.173915][ T1286] x11: ffff00093d700040 x10: 000000000000f2f2 x9 : 00000000f3000000 [ 70.181763][ T1286] x8 : dfff800000000000 x7 : 00000000f3f3f3f3 x6 : 00000000f2000000 [ 70.189610][ T1286] x5 : 0000000000000000 x4 : 0000000000000cc0 x3 : 1ffff000046c1f30 [ 70.197459][ T1286] x2 : 1ffff000046c1f30 x1 : 0000000000000000 x0 : 0000000000000000 [ 70.205307][ T1286] Call trace: [ 70.208453][ T1286] iov_iter_gap_alignment+0x144/0x1a8 [ 70.213693][ T1286] blk_rq_map_user_iov+0xd00/0xff0 [ 70.218668][ T1286] blk_rq_map_user+0xf4/0x190 [ 70.223209][ T1286] nvme_submit_user_cmd.isra.0+0x150/0x4e0 [nvme_core] [ 70.229943][ T1286] nvme_user_cmd.isra.0+0x298/0x3d0 [nvme_core] [ 70.236063][ T1286] nvme_dev_ioctl+0x19c/0x3c8 [nvme_core] [ 70.241661][ T1286] __arm64_sys_ioctl+0x114/0x180 [ 70.246463][ T1286] invoke_syscall.constprop.0+0xdc/0x1d8 [ 70.251959][ T1286] do_el0_svc+0x1f8/0x298 [ 70.256151][ T1286] el0_svc+0x20/0x30 [ 70.259910][ T1286] el0t_64_sync_handler+0xb0/0xb8 [ 70.264796][ T1286] el0t_64_sync+0x178/0x17c [ 70.269161][ T1286] irq event stamp: 254526 [ 70.273348][ T1286] hardirqs last enabled at (254525): [] seqcount_lockdep_reader_access.constprop.0+0x138/0x190 [ 70.285183][ T1286] hardirqs last disabled at (254526): [] el1_dbg+0x28/0x80 [ 70.293805][ T1286] softirqs last enabled at (250668): [] _stext+0xa90/0x1114 [ 70.302597][ T1286] softirqs last disabled at (250661): [] irq_exit+0x53c/0x610 > --- > lib/iov_iter.c | 25 ++++++++++++++----------- > 1 file changed, 14 insertions(+), 11 deletions(-) > > diff --git a/lib/iov_iter.c b/lib/iov_iter.c > index bb7089cd0cf7..a6947301b9a0 100644 > --- a/lib/iov_iter.c > +++ b/lib/iov_iter.c > @@ -1409,23 +1409,26 @@ EXPORT_SYMBOL(iov_iter_alignment); > unsigned long iov_iter_gap_alignment(const struct iov_iter *i) > { > unsigned long res = 0; > + unsigned long v = 0; > size_t size = i->count; > + unsigned k; > > - if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) { > + if (unlikely(iter_is_iovec(i))) { > WARN_ON(1); > return ~0U; > } > > - iterate_all_kinds(i, size, v, > - (res |= (!res ? 0 : (unsigned long)v.iov_base) | > - (size != v.iov_len ? size : 0), 0), > - (res |= (!res ? 0 : (unsigned long)v.bv_offset) | > - (size != v.bv_len ? size : 0)), > - (res |= (!res ? 0 : (unsigned long)v.iov_base) | > - (size != v.iov_len ? size : 0)), > - (res |= (!res ? 0 : (unsigned long)v.bv_offset) | > - (size != v.bv_len ? size : 0)) > - ); > + for (k = 0; k < i->nr_segs; k++) { > + if (i->iov[k].iov_len) { > + unsigned long base = (unsigned long)i->iov[k].iov_base; > + if (v) // if not the first one > + res |= base | v; // this start | previous end > + v = base + i->iov[k].iov_len; > + if (size <= i->iov[k].iov_len) > + break; > + size -= i->iov[k].iov_len; > + } > + } > return res; > } > EXPORT_SYMBOL(iov_iter_gap_alignment); >