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 F110DC25B06 for ; Wed, 10 Aug 2022 23:40:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232420AbiHJXkq (ORCPT ); Wed, 10 Aug 2022 19:40:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36514 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233360AbiHJXkh (ORCPT ); Wed, 10 Aug 2022 19:40:37 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A35A7B8F for ; Wed, 10 Aug 2022 16:40:36 -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 ams.source.kernel.org (Postfix) with ESMTPS id 5AAD1B81D92 for ; Wed, 10 Aug 2022 23:40:35 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0ED9EC433C1; Wed, 10 Aug 2022 23:40:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1660174834; bh=pHFNFWeAzlHRyqxWatl8iWNdTvC4DWXlz+FpHmmbuKk=; h=Date:To:From:Subject:From; b=THdeIUExXe9ty959TiNpXXpYX27XMuKUAgQ+BJloZR7t4zVPWHJXKcyAfn89XnPkF 4/tJc9sbWqO8FtIQgDWAFMBkAn2+vbPdVrMlnTmlMQItacyKPkVj6j6ok7QdNyMs8S RozvOSFVCd8aRbIRI/MRY1RMeFlwOf9VIS3hVgA8= Date: Wed, 10 Aug 2022 16:40:33 -0700 To: mm-commits@vger.kernel.org, willy@infradead.org, songmuchun@bytedance.com, slava@dubeyko.com, keescook@chromium.org, ira.weiny@intel.com, bvanassche@acm.org, axboe@kernel.dk, fmdefrancesco@gmail.com, akpm@linux-foundation.org From: Andrew Morton Subject: + hfsplus-convert-kmap-to-kmap_local_page-in-bitmapc.patch added to mm-nonmm-unstable branch Message-Id: <20220810234034.0ED9EC433C1@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: hfsplus: convert kmap() to kmap_local_page() in bitmap.c has been added to the -mm mm-nonmm-unstable branch. Its filename is hfsplus-convert-kmap-to-kmap_local_page-in-bitmapc.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/hfsplus-convert-kmap-to-kmap_local_page-in-bitmapc.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: hfsplus: convert kmap() to kmap_local_page() in bitmap.c Date: Tue, 9 Aug 2022 22:31:04 +0200 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). It is faster than kmap() in kernels with HIGHMEM enabled. Furthermore, the tasks can be preempted and, when they are scheduled to run again, the kernel virtual addresses are restored and are still valid. Since its use in bitmap.c is safe everywhere, it should be preferred. Therefore, replace kmap() with kmap_local_page() in bitmap.c. Tested in a QEMU/KVM x86_32 VM, 6GB RAM, booting a kernel with HIGHMEM64GB enabled. Link: https://lkml.kernel.org/r/20220809203105.26183-4-fmdefrancesco@gmail.com Signed-off-by: Fabio M. De Francesco Suggested-by: Ira Weiny Reviewed-by: Ira Weiny Reviewed-by: Viacheslav Dubeyko Cc: Bart Van Assche Cc: Jens Axboe Cc: Kees Cook Cc: Matthew Wilcox Cc: Muchun Song Signed-off-by: Andrew Morton --- fs/hfsplus/bitmap.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) --- a/fs/hfsplus/bitmap.c~hfsplus-convert-kmap-to-kmap_local_page-in-bitmapc +++ a/fs/hfsplus/bitmap.c @@ -39,7 +39,7 @@ int hfsplus_block_allocate(struct super_ start = size; goto out; } - pptr = kmap(page); + pptr = kmap_local_page(page); curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32; i = offset % 32; offset &= ~(PAGE_CACHE_BITS - 1); @@ -74,7 +74,7 @@ int hfsplus_block_allocate(struct super_ } curr++; } - kunmap(page); + kunmap_local(pptr); offset += PAGE_CACHE_BITS; if (offset >= size) break; @@ -84,7 +84,7 @@ int hfsplus_block_allocate(struct super_ start = size; goto out; } - curr = pptr = kmap(page); + curr = pptr = kmap_local_page(page); if ((size ^ offset) / PAGE_CACHE_BITS) end = pptr + PAGE_CACHE_BITS / 32; else @@ -127,7 +127,7 @@ found: len -= 32; } set_page_dirty(page); - kunmap(page); + kunmap_local(pptr); offset += PAGE_CACHE_BITS; page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS, NULL); @@ -135,7 +135,7 @@ found: start = size; goto out; } - pptr = kmap(page); + pptr = kmap_local_page(page); curr = pptr; end = pptr + PAGE_CACHE_BITS / 32; } @@ -151,7 +151,7 @@ last: done: *curr = cpu_to_be32(n); set_page_dirty(page); - kunmap(page); + kunmap_local(pptr); *max = offset + (curr - pptr) * 32 + i - start; sbi->free_blocks -= *max; hfsplus_mark_mdb_dirty(sb); @@ -185,7 +185,7 @@ int hfsplus_block_free(struct super_bloc page = read_mapping_page(mapping, pnr, NULL); if (IS_ERR(page)) goto kaboom; - pptr = kmap(page); + pptr = kmap_local_page(page); curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32; end = pptr + PAGE_CACHE_BITS / 32; len = count; @@ -215,11 +215,11 @@ int hfsplus_block_free(struct super_bloc if (!count) break; set_page_dirty(page); - kunmap(page); + kunmap_local(pptr); page = read_mapping_page(mapping, ++pnr, NULL); if (IS_ERR(page)) goto kaboom; - pptr = kmap(page); + pptr = kmap_local_page(page); curr = pptr; end = pptr + PAGE_CACHE_BITS / 32; } @@ -231,7 +231,7 @@ done: } out: set_page_dirty(page); - kunmap(page); + kunmap_local(pptr); sbi->free_blocks += len; hfsplus_mark_mdb_dirty(sb); mutex_unlock(&sbi->alloc_mutex); _ 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