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d=hostedemail.com; s=arc-20220608; t=1675763271; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=6Vg6CNd0CR1TzkhbRRzxI4mNzdP5/NlbGyjJTK84nDE=; b=z2ksRrhJT4KrO3wv8iCL1V5HNntwK5Q3ME4v+jqxtr4hf/8KwZGi/pf3gegGnMFLYHj79+ mZDcTR3s/2e6GURN1OSmDPjZWtfZ7k5BNypo3H3B0npDi3/BYUCMbwdOmk2YR8jQsL4mqX StDt+YYIJ34Z5ajZQQOs4mHCXLlWuzM= Received: from unknown (HELO localhost.localdomain)([114.249.61.130]) by sina.com (172.16.97.35) with ESMTP id 63E21D530001D4BA; Tue, 7 Feb 2023 17:43:49 +0800 (CST) X-Sender: hdanton@sina.com X-Auth-ID: hdanton@sina.com X-SMAIL-MID: 13893915073472 From: Hillf Danton To: David Howells Cc: Jens Axboe , Christoph Hellwig , David Hildenbrand , John Hubbard , linux-mm@kvack.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: Need help tracking down a bug in the bio-FOLL_PIN patches Date: Tue, 7 Feb 2023 17:47:31 +0800 Message-Id: <20230207094731.1390-1-hdanton@sina.com> In-Reply-To: <2811508.1675724572@warthog.procyon.org.uk> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: 36CAE80008 X-Rspamd-Server: rspam01 X-Stat-Signature: ttg6zrebepnzjyn31wcum6tdiooadpxh X-HE-Tag: 1675763267-917250 X-HE-Meta: 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 i0KZDATg uQfmKjnCmAFHwlscHDVcXQNiSQPhF2rvotU6/dxlN6dsz6C6oLVNPm/KYtzYunBtv39yZweSt55CegCTY5Zf7mM8KeZGv8P9D8tf/Kh2Phi5L/cH84DVt0+Ud//Kom6vSpn7qt2/MQ5yH3iHXdpbfXC+/HYpXUS/7SA3yC1rshZV4nZr6EthhnYGuEZk+5FJ3xGbLjG+F5fnWs48hjG/mPrT2OyrCvcJ8cAmN4Lst+yHtjvywbQ3D3F/R8LZSG+c4Ielt9KEXBRoO7/I0ZrANwIVCAhSBCtL6CPJhY4CyEua0DjD2qmcDbxiYVw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000004, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, 06 Feb 2023 23:02:52 +0000 David Howells > Hi Jens, Christoph, > > I need some help tracking down a bug in the patches that make the bio usin= > g > page pinning or no pinning using iov_iter_extract_pages(). The bug causes > seemingly random memory corruption once the "block: Convert > bio_iov_iter_get_pages to use iov_iter_extract_pages" patch is applied. > > The bug was detected by a syzbot special: > > https://lore.kernel.org/r/000000000000b0b3c005f3a09383@google.com/ @@ -1342,7 +1342,8 @@ int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter) return 0; } - bio_set_flag(bio, BIO_PAGE_REFFED); + if (iov_iter_extract_will_pin(iter)) + bio_set_flag(bio, BIO_PAGE_PINNED); do { ret = __bio_iov_iter_get_pages(bio, iter); } while (!ret && iov_iter_count(iter) && !bio_full(bio, 0)); I suspect it is due to the above change, given the following call trace. pipe_buf_release include/linux/pipe_fs_i.h:183 [inline] iov_iter_revert.part.0+0x402/0x730 lib/iov_iter.c:935 iov_iter_revert+0x4c/0x60 lib/iov_iter.c:919 __iomap_dio_rw+0x16cb/0x1d80 fs/iomap/direct-io.c:610 iomap_dio_rw+0x40/0xa0 fs/iomap/direct-io.c:682 ext4_dio_read_iter fs/ext4/file.c:94 [inline] ext4_file_read_iter+0x4be/0x690 fs/ext4/file.c:145 call_read_iter include/linux/fs.h:1845 [inline] generic_file_splice_read+0x182/0x4b0 fs/splice.c:309 do_splice_to+0x1b9/0x240 fs/splice.c:793 splice_direct_to_actor+0x2ab/0x8a0 fs/splice.c:865 do_splice_direct+0x1ab/0x280 fs/splice.c:974 do_sendfile+0xb19/0x12c0 fs/read_write.c:1255 __do_sys_sendfile64 fs/read_write.c:1323 [inline] __se_sys_sendfile64 fs/read_write.c:1309 [inline] __x64_sys_sendfile64+0x1d0/0x210 fs/read_write.c:1309 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80