From patchwork Wed Mar 22 14:55:24 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lorenzo Stoakes X-Patchwork-Id: 13184195 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id B24ECC6FD1C for ; Wed, 22 Mar 2023 14:55:37 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 2561B6B0071; Wed, 22 Mar 2023 10:55:37 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 206806B0072; Wed, 22 Mar 2023 10:55:37 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0CE0F6B0075; Wed, 22 Mar 2023 10:55:37 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id F2F146B0071 for ; Wed, 22 Mar 2023 10:55:36 -0400 (EDT) Received: from smtpin19.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 740831603F7 for ; Wed, 22 Mar 2023 14:55:36 +0000 (UTC) X-FDA: 80596833072.19.47545A4 Received: from mail-wm1-f52.google.com (mail-wm1-f52.google.com [209.85.128.52]) by imf21.hostedemail.com (Postfix) with ESMTP id A7E3B1C0029 for ; Wed, 22 Mar 2023 14:55:34 +0000 (UTC) Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=QGIdPC+a; spf=pass (imf21.hostedemail.com: domain of lstoakes@gmail.com designates 209.85.128.52 as permitted sender) smtp.mailfrom=lstoakes@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1679496934; 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:references:dkim-signature; bh=S0jzfl8zYgnt4u77SA/RKleSL52i8/7auCWoYemv5LQ=; b=MzVCxaJS2P59bSUHLjyxxqJWRjkqZkvzpXGnRhe6b8LdnI/eObZ97Iw+ZDKTBDbEURThH+ 06xUwUeQ8l/o5nSIONWhJ1OZ6UKaeaV0AcdNbia+BgC9eygP3ibkpmoKqGMuk04HMWOu6i OFrRrZVbuVZ6qZwvxGXLRfixkRvJXsQ= ARC-Authentication-Results: i=1; imf21.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=QGIdPC+a; spf=pass (imf21.hostedemail.com: domain of lstoakes@gmail.com designates 209.85.128.52 as permitted sender) smtp.mailfrom=lstoakes@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1679496934; a=rsa-sha256; cv=none; b=r4kLLXtYMwDK0INK1e55zKM7iyFznCSC1htx+cr7Hi02HCeUDUn1JJoZLvZ0ZB1EdBhtuI cASMuKvTrxRbQ5MnZrnG6Kw+XQbB0AK4+NW+RDGMg7f6Unn632mESRPo1odWvHW6AEqa9X c8d6LXsDd5Py+1yqfl2pcKo+pF103HY= Received: by mail-wm1-f52.google.com with SMTP id m6-20020a05600c3b0600b003ee6e324b19so915062wms.1 for ; Wed, 22 Mar 2023 07:55:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; t=1679496933; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=S0jzfl8zYgnt4u77SA/RKleSL52i8/7auCWoYemv5LQ=; b=QGIdPC+aai08tzMB75tJBk5h5rw0YfB4Hu59Nebsl30NRcDrEE2RPuoU4Z0qQxaiGg 63eso4kAHq7v5w/8B+nWXbQiCrusXBTaO/S8rFVW1gLebge4EeTreG17HinOYDWCFdRA b58oceYeN5p4Yau4AOSaF7lVoIpyortoEulOJ4C8e2MesjuAPGSxY2uqZ7Uh+YqmQfq5 CVzECfeNq5yU/+xfM/BmreN46P7Y3Z+7X1z0DKHUfCJI+RIe6z75rQCs3qkB9dzgwJ8g f4YmrjScouZT3ypPFhw7HMX6dUvmC1kHUXwacOFz1LdbC8ob1MzZluIv9kfTFrCiqMLi R6Tg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1679496933; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=S0jzfl8zYgnt4u77SA/RKleSL52i8/7auCWoYemv5LQ=; b=giB0KUnTiVHGCeykCXHU7AA/yBItDv0FAHoreXNQtObr/iNGGiMyS4v0ps75pzv/+m amRjYbUBshXpknqmPEXnSu5mupHzqmMBTNTGTlgK4rxLNufJlV00HmYabRzNz3k+X9SU cXagtwLx8RFy6APk3ZNwAFKCAFGVJRclVCMGJZztdl2i/3+16FAiRK8RpNKA0fQd+rFv 8TLqNaXQH8EdqshQqLRRUmZjWLXhun/z55PfpcfmmZAynXPPn1Bd2UM5KJoScM5gUjZb vcl8qWg/lY0EyzhNNpeXtRBe9dz+Y//LMWhU0/9zwqi7myy82mfWGE/k8RoQLd9kH5tw sJ0g== X-Gm-Message-State: AO0yUKUbEygCvWTlxE6qBFnFceyUnwGpVcvUTn8MEVJWwOfLN4ajMD5M bu5ZpI/EAT2M9/UF9AGm/dw+j9DjwSE= X-Google-Smtp-Source: AK7set+BvPRQcF2S+lEhoUuE5DF64BfRAwgDpCTEMyODUlMPjxVuKCtt+SKVaYDDMUYFQYqc4IldDA== X-Received: by 2002:a05:600c:35cd:b0:3ee:534:9eba with SMTP id r13-20020a05600c35cd00b003ee05349ebamr1909798wmq.6.1679496932905; Wed, 22 Mar 2023 07:55:32 -0700 (PDT) Received: from lucifer.home ([2a00:23c5:dc8c:8701:1663:9a35:5a7b:1d76]) by smtp.googlemail.com with ESMTPSA id n23-20020a7bcbd7000000b003ed243222adsm16812246wmi.42.2023.03.22.07.55.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 22 Mar 2023 07:55:31 -0700 (PDT) From: Lorenzo Stoakes To: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Andrew Morton Cc: Baoquan He , Uladzislau Rezki , Matthew Wilcox , David Hildenbrand , Liu Shixin , Jiri Olsa , Jens Axboe , Alexander Viro , Lorenzo Stoakes Subject: [PATCH v6 0/4] convert read_kcore(), vread() to use iterators Date: Wed, 22 Mar 2023 14:55:24 +0000 Message-Id: X-Mailer: git-send-email 2.39.2 MIME-Version: 1.0 X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: A7E3B1C0029 X-Stat-Signature: iogzo4jx5dmi1n7zbqgf1af1j4qkq1oe X-HE-Tag: 1679496934-398351 X-HE-Meta: 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 s5D7ifkA 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: While reviewing Baoquan's recent changes to permit vread() access to vm_map_ram regions of vmalloc allocations, Willy pointed out [1] that it would be nice to refactor vread() as a whole, since its only user is read_kcore() and the existing form of vread() necessitates the use of a bounce buffer. This patch series does exactly that, as well as adjusting how we read the kernel text section to avoid the use of a bounce buffer in this case as well. This has been tested against the test case which motivated Baoquan's changes in the first place [2] which continues to function correctly, as do the vmalloc self tests. [1] https://lore.kernel.org/all/Y8WfDSRkc%2FOHP3oD@casper.infradead.org/ [2] https://lore.kernel.org/all/87ilk6gos2.fsf@oracle.com/T/#u v6: - Correct copy_page_to_iter_nofault() to handle -EFAULT case correctly. v5: - Do not rename fpos to ppos in read_kcore_iter() to avoid churn. - Fix incorrect commit messages after prior revisions altered the approach. - Replace copy_page_to_iter_atomic() with copy_page_to_iter_nofault() and adjust it to be able to handle compound pages. This uses copy_to_user_nofault() which ensures page faults are disabled during copy which kmap_local_page() was not doing. - Only try to fault in pages if we are unable to copy in the first place and try only once to avoid any risk of spinning. - Do not zero memory in aligned_vread_iter() if we couldn't copy it. - Fix mistake in zeroing missing or unpopulated blocks in vmap_ram_vread_iter(). https://lore.kernel.org/linux-mm/cover.1679494218.git.lstoakes@gmail.com/ v4: - Fixup mistake in email client which orphaned patch emails from the cover letter. https://lore.kernel.org/all/cover.1679431886.git.lstoakes@gmail.com v3: - Revert introduction of mutex/rwsem in vmalloc - Introduce copy_page_to_iter_atomic() iovec function - Update vread_iter() and descendent functions to use only this - Fault in user pages before calling vread_iter() - Use const char* in vread_iter() and descendent functions - Updated commit messages based on feedback - Extend vread functions to always check how many bytes we could copy. If at any stage we are unable to copy/zero, abort and return the number of bytes we did copy. https://lore.kernel.org/all/cover.1679354384.git.lstoakes@gmail.com/ v2: - Fix ordering of vread_iter() parameters - Fix nommu vread() -> vread_iter() https://lore.kernel.org/all/cover.1679209395.git.lstoakes@gmail.com/ v1: https://lore.kernel.org/all/cover.1679183626.git.lstoakes@gmail.com/ Lorenzo Stoakes (4): fs/proc/kcore: avoid bounce buffer for ktext data fs/proc/kcore: convert read_kcore() to read_kcore_iter() iov_iter: add copy_page_to_iter_nofault() mm: vmalloc: convert vread() to vread_iter() fs/proc/kcore.c | 78 ++++++-------- include/linux/uio.h | 2 + include/linux/vmalloc.h | 3 +- lib/iov_iter.c | 48 +++++++++ mm/nommu.c | 10 +- mm/vmalloc.c | 234 +++++++++++++++++++++++++--------------- 6 files changed, 236 insertions(+), 139 deletions(-) --- 2.39.2