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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BF8A4C25B06 for ; Thu, 11 Aug 2022 23:13:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236081AbiHKXNX (ORCPT ); Thu, 11 Aug 2022 19:13:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46016 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236385AbiHKXNU (ORCPT ); Thu, 11 Aug 2022 19:13:20 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CDEFDA0639 for ; Thu, 11 Aug 2022 16:13:19 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 643F061449 for ; Thu, 11 Aug 2022 23:13:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B734EC433C1; Thu, 11 Aug 2022 23:13:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1660259598; bh=3GcOL2Nz8jkx/4y6H2w+x0xnvmdcD0U0kVLhd2SkRTw=; h=Date:To:From:Subject:From; b=1RAUSwuuhmp3Drt7w0YP9nN3cnSqGAzOQN/VhH/4Z4CERRlr44mAtNG6CuoOhged4 wAJVUPXKyl5gsFFKTaeY6EDxOS0CMnpwWE/fBWZSRsuNVCBQwbvROG9bktkQOP5pta tggyKdvzmhKweHy91c38KME+vXNgHnk9iti5F/YY= Date: Thu, 11 Aug 2022 16:13:18 -0700 To: mm-commits@vger.kernel.org, willy@infradead.org, tytso@mit.edu, songmuchun@bytedance.com, roman.gushchin@linux.dev, pali@kernel.org, jack@suse.cz, ira.weiny@intel.com, fmdefrancesco@gmail.com, akpm@linux-foundation.org From: Andrew Morton Subject: + fs-isofs-replace-kmap-with-kmap_local_page.patch added to mm-nonmm-unstable branch Message-Id: <20220811231318.B734EC433C1@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: fs/isofs: replace kmap() with kmap_local_page() has been added to the -mm mm-nonmm-unstable branch. Its filename is fs-isofs-replace-kmap-with-kmap_local_page.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/fs-isofs-replace-kmap-with-kmap_local_page.patch This patch will later appear in the mm-nonmm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: "Fabio M. De Francesco" Subject: fs/isofs: replace kmap() with kmap_local_page() Date: Mon, 1 Aug 2022 14:27:09 +0200 The use of kmap() is being deprecated in favor of kmap_local_page(). There are two main problems with kmap(): (1) It comes with an overhead as mapping space is restricted and protected by a global lock for synchronization and (2) it also requires global TLB invalidation when the kmap's pool wraps and it might block when the mapping space is fully utilized until a slot becomes available. With kmap_local_page() the mappings are per thread, CPU local, can take page faults, and can be called from any context (including interrupts). Tasks can be preempted and, when scheduled to run again, the kernel virtual addresses are restored and still valid. It is faster than kmap() in kernels with HIGHMEM enabled. Since kmap_local_page() can be safely used in compress.c, it should be called everywhere instead of kmap(). Therefore, replace kmap() with kmap_local_page() in compress.c. Where it is needed, use memzero_page() instead of open coding kmap_local_page() plus memset() to fill the pages with zeros. Delete the redundant flush_dcache_page() in the two call sites of memzero_page(). Tested with mkisofs on a QEMU/KVM x86_32 VM, 6GB RAM, booting a kernel with HIGHMEM64GB enabled. Link: https://lkml.kernel.org/r/20220801122709.8164-1-fmdefrancesco@gmail.com Signed-off-by: Fabio M. De Francesco Suggested-by: Ira Weiny Cc: Jan Kara Cc: Matthew Wilcox (Oracle) Cc: Roman Gushchin Cc: Pali Rohár Cc: Muchun Song Cc: Theodore Ts'o Signed-off-by: Andrew Morton --- fs/isofs/compress.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) --- a/fs/isofs/compress.c~fs-isofs-replace-kmap-with-kmap_local_page +++ a/fs/isofs/compress.c @@ -67,8 +67,7 @@ static loff_t zisofs_uncompress_block(st for ( i = 0 ; i < pcount ; i++ ) { if (!pages[i]) continue; - memset(page_address(pages[i]), 0, PAGE_SIZE); - flush_dcache_page(pages[i]); + memzero_page(pages[i], 0, PAGE_SIZE); SetPageUptodate(pages[i]); } return ((loff_t)pcount) << PAGE_SHIFT; @@ -120,7 +119,7 @@ static loff_t zisofs_uncompress_block(st zerr != Z_STREAM_END) { if (!stream.avail_out) { if (pages[curpage]) { - stream.next_out = page_address(pages[curpage]) + stream.next_out = kmap_local_page(pages[curpage]) + poffset; stream.avail_out = PAGE_SIZE - poffset; poffset = 0; @@ -176,6 +175,10 @@ static loff_t zisofs_uncompress_block(st flush_dcache_page(pages[curpage]); SetPageUptodate(pages[curpage]); } + if (stream.next_out != (unsigned char *)zisofs_sink_page) { + kunmap_local(stream.next_out); + stream.next_out = NULL; + } curpage++; } if (!stream.avail_in) @@ -183,6 +186,8 @@ static loff_t zisofs_uncompress_block(st } inflate_out: zlib_inflateEnd(&stream); + if (stream.next_out && stream.next_out != (unsigned char *)zisofs_sink_page) + kunmap_local(stream.next_out); z_eio: mutex_unlock(&zisofs_zlib_lock); @@ -283,9 +288,7 @@ static int zisofs_fill_pages(struct inod } if (poffset && *pages) { - memset(page_address(*pages) + poffset, 0, - PAGE_SIZE - poffset); - flush_dcache_page(*pages); + memzero_page(*pages, poffset, PAGE_SIZE - poffset); SetPageUptodate(*pages); } return 0; @@ -343,10 +346,8 @@ static int zisofs_read_folio(struct file for (i = 0; i < pcount; i++, index++) { if (i != full_page) pages[i] = grab_cache_page_nowait(mapping, index); - if (pages[i]) { + if (pages[i]) ClearPageError(pages[i]); - kmap(pages[i]); - } } err = zisofs_fill_pages(inode, full_page, pcount, pages); @@ -357,7 +358,6 @@ static int zisofs_read_folio(struct file flush_dcache_page(pages[i]); if (i == full_page && err) SetPageError(pages[i]); - kunmap(pages[i]); unlock_page(pages[i]); if (i != full_page) put_page(pages[i]); _ Patches currently in -mm which might be from fmdefrancesco@gmail.com are hfsplus-unmap-the-page-in-the-fail_page-label.patch hfsplus-convert-kmap-to-kmap_local_page-in-bnodec.patch hfsplus-convert-kmap-to-kmap_local_page-in-bitmapc.patch hfsplus-convert-kmap-to-kmap_local_page-in-btreec.patch fs-isofs-replace-kmap-with-kmap_local_page.patch