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=-7.0 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 9E5D8C43381 for ; Tue, 26 Feb 2019 15:55:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6DFDF20C01 for ; Tue, 26 Feb 2019 15:55:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="g3w7aOEl" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726478AbfBZPyN (ORCPT ); Tue, 26 Feb 2019 10:54:13 -0500 Received: from mail-it1-f195.google.com ([209.85.166.195]:38268 "EHLO mail-it1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726624AbfBZPyN (ORCPT ); Tue, 26 Feb 2019 10:54:13 -0500 Received: by mail-it1-f195.google.com with SMTP id l66so4806840itg.3 for ; Tue, 26 Feb 2019 07:54:12 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:from:to:cc:references:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=PSfp7jby7bJf7Iq0yet+thJT0mZpXiOS1xz90ywbKnQ=; b=g3w7aOEl/L8KtnvvAEkZow1u+ovK7RNvgH76lEn/RMgVPU2QVwU4hBegehn/LWbgtD PbedU/C6ytZXIkdP2lx4GrHFCtLDNcbMK1MB3Vte9AjS/JAF8HXFkUCrFFw7sN2SO2hY 2OGBIiiLN/p9fI5eDTcWhtp37IGDCUSC/CgTTUzAizbJxxAm0ssN7cOnL/wTHkOYkW+2 +OCLxwaTq+t5m9qwFVtTN0JnQFV6Cadd8C16nbKVxC09CsegmrB+RFZpykTslriix9PP 21GZvR++Ou/FhI38fIM8CPEixRNF/whQLAOS6czplMUSQvhLlrfEJ4jUwxD5eAGPQ9o7 FBTA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:from:to:cc:references:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=PSfp7jby7bJf7Iq0yet+thJT0mZpXiOS1xz90ywbKnQ=; b=M0L5TZRXQKzdbXtNZ7c22a5cw2VHHWakaEJT54iCfVcktesjHh1ZY81akfTdS70zzM LnE+2l5fEa+SIW56dqEaND02tteHm/5AKaZ2jr9yOssbEibXam9d/C7ICPPUSvthzwLU tw9Mwh6KJ8JrqnG2yRm2kkA92i55DoXa5qvOoRK4gtkKNzBWoW7ug8F2kGtJIB1cV32o zKwE8RzoTTnW2BUuyN1d4EdZDQh5K6Pp+Ain+ntZuSt1jjgcdcGTy+MCTETjUG11JUCM VrqbQhx2fKPYO3L5TN7ctHPVJFl/207ZM0zaOKy6gLCuCvJM1hoIK6516nvhjxNd2OYG +uhg== X-Gm-Message-State: AHQUAubaakyDzDdhxbdGSLzihDk1uIi+K84TIX9yK0PrJoTDMSwi00xs Fg0ZlYy+jakxowvmvHwQ81ZQSQ== X-Google-Smtp-Source: APXvYqz5rGLSbIxoYYivRzVrhhUs6j9sM+/1pDFzmQjk2XEongI2L4ZOA2r3ktY5Q95W0DCCPkMcUQ== X-Received: by 2002:a24:30e:: with SMTP id e14mr2647634ite.111.1551196452273; Tue, 26 Feb 2019 07:54:12 -0800 (PST) Received: from [192.168.1.158] ([216.160.245.98]) by smtp.gmail.com with ESMTPSA id q133sm4761202itb.19.2019.02.26.07.54.10 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 26 Feb 2019 07:54:11 -0800 (PST) Subject: Re: [PATCH 11/19] block: implement bio helper to add iter bvec pages to bio From: Jens Axboe To: Eric Biggers Cc: Ming Lei , linux-aio@kvack.org, linux-block@vger.kernel.org, linux-api@vger.kernel.org, hch@lst.de, jmoyer@redhat.com, avi@scylladb.com, jannh@google.com, viro@zeniv.linux.org.uk References: <20190211190049.7888-1-axboe@kernel.dk> <20190211190049.7888-13-axboe@kernel.dk> <20190220225856.GB28313@ming.t460p> <20190226034613.GA676@sol.localdomain> Message-ID: <1652577e-787b-638e-625d-c200fb144a9d@kernel.dk> Date: Tue, 26 Feb 2019 08:54:10 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 2/25/19 9:34 PM, Jens Axboe wrote: > On 2/25/19 8:46 PM, Eric Biggers wrote: >> Hi Jens, >> >> On Thu, Feb 21, 2019 at 10:45:27AM -0700, Jens Axboe wrote: >>> On 2/20/19 3:58 PM, Ming Lei wrote: >>>> On Mon, Feb 11, 2019 at 12:00:41PM -0700, Jens Axboe wrote: >>>>> For an ITER_BVEC, we can just iterate the iov and add the pages >>>>> to the bio directly. This requires that the caller doesn't releases >>>>> the pages on IO completion, we add a BIO_NO_PAGE_REF flag for that. >>>>> >>>>> The current two callers of bio_iov_iter_get_pages() are updated to >>>>> check if they need to release pages on completion. This makes them >>>>> work with bvecs that contain kernel mapped pages already. >>>>> >>>>> Reviewed-by: Hannes Reinecke >>>>> Reviewed-by: Christoph Hellwig >>>>> Signed-off-by: Jens Axboe >>>>> --- >>>>> block/bio.c | 59 ++++++++++++++++++++++++++++++++------- >>>>> fs/block_dev.c | 5 ++-- >>>>> fs/iomap.c | 5 ++-- >>>>> include/linux/blk_types.h | 1 + >>>>> 4 files changed, 56 insertions(+), 14 deletions(-) >>>>> >>>>> diff --git a/block/bio.c b/block/bio.c >>>>> index 4db1008309ed..330df572cfb8 100644 >>>>> --- a/block/bio.c >>>>> +++ b/block/bio.c >>>>> @@ -828,6 +828,23 @@ int bio_add_page(struct bio *bio, struct page *page, >>>>> } >>>>> EXPORT_SYMBOL(bio_add_page); >>>>> >>>>> +static int __bio_iov_bvec_add_pages(struct bio *bio, struct iov_iter *iter) >>>>> +{ >>>>> + const struct bio_vec *bv = iter->bvec; >>>>> + unsigned int len; >>>>> + size_t size; >>>>> + >>>>> + len = min_t(size_t, bv->bv_len, iter->count); >>>>> + size = bio_add_page(bio, bv->bv_page, len, >>>>> + bv->bv_offset + iter->iov_offset); >>>> >>>> iter->iov_offset needs to be subtracted from 'len', looks >>>> the following delta change[1] is required, otherwise memory corruption >>>> can be observed when running xfstests over loop/dio. >>> >>> Thanks, I folded this in. >>> >>> -- >>> Jens Axboe >>> >> >> syzkaller started hitting a crash on linux-next starting with this commit, and >> it still occurs even with your latest version that has Ming's fix folded in. >> Specifically, commit a566653ab5ab80a from your io_uring branch with commit date >> Sun Feb 24 08:20:53 2019 -0700. >> >> Reproducer: >> >> #define _GNU_SOURCE >> #include >> #include >> #include >> #include >> #include >> #include >> >> int main(void) >> { >> int memfd, loopfd; >> >> memfd = syscall(__NR_memfd_create, "foo", 0); >> >> pwrite(memfd, "\xa8", 1, 4096); >> >> loopfd = open("/dev/loop0", O_RDWR|O_DIRECT); >> >> ioctl(loopfd, LOOP_SET_FD, memfd); >> >> sendfile(loopfd, loopfd, NULL, 1000000); >> } >> >> >> Crash: >> >> page:ffffea0001a6aab8 count:0 mapcount:0 mapping:0000000000000000 index:0x0 >> flags: 0x100000000000000() >> raw: 0100000000000000 ffffea0001ad2c50 ffff88807fca49d0 0000000000000000 >> raw: 0000000000000000 0000000000000000 00000000ffffffff >> page dumped because: VM_BUG_ON_PAGE(page_ref_count(page) == 0) > > I see what this is, I'll cut a fix for this tomorrow. Folded in a fix for this, it's in my current io_uring branch and my for-next branch. -- Jens Axboe