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: 13184190 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2E319C6FD1C for ; Wed, 22 Mar 2023 14:56:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231569AbjCVO4R (ORCPT ); Wed, 22 Mar 2023 10:56:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59132 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230525AbjCVOzz (ORCPT ); Wed, 22 Mar 2023 10:55:55 -0400 Received: from mail-wm1-x32d.google.com (mail-wm1-x32d.google.com [IPv6:2a00:1450:4864:20::32d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6510476B8; Wed, 22 Mar 2023 07:55:34 -0700 (PDT) Received: by mail-wm1-x32d.google.com with SMTP id m35so11725440wms.4; 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=bRF7PwFOy6OtgG4PN8Bxxv7QkU0sjyl2zk2Yn8BDBxapG53qC/Omcbqhffuc+lCWb0 dyMpsdn+UhMyUlmdZ9UB8RuoGK1cUFPclLMKyqLsBOwiEzjtKo7Yx/6X17Gck0JA54ZN DccF1xhHm2Uj07fyQYozFwbUvzbuE0QdMc+9235l4OUa7XePVKwHvFnvpQi2NZlmVSzu tYUmsY33YsM3ln8i6XrjAhi+q+y/RIEZyQ/53xRUgjmr0eS0LeGOjYmCQ9PkdyZ179gL mIPzQQ2iDlnEN5ioz1zJiSVkeVjZ5jidOHAQ52NtarbppMREWxi1KKCZIJ7F0H55buBB /L3Q== X-Gm-Message-State: AO0yUKWvR8N3q6C6W7UTYjBfCVK3SPujd4MkK3AZXzZePZtWy/aFuVtQ sM6HAEwyfDAKEyKyFyrFR4k= 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 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org 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