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 09F59C2BB3F for ; Mon, 20 Nov 2023 18:52:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229637AbjKTSwc (ORCPT ); Mon, 20 Nov 2023 13:52:32 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32906 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229676AbjKTSwb (ORCPT ); Mon, 20 Nov 2023 13:52:31 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4D502C9 for ; Mon, 20 Nov 2023 10:52:28 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DA727C433C8; Mon, 20 Nov 2023 18:52:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1700506347; bh=LNfmugjSgLN2q/2FgjNbRGAqqlvCoyOJMhfNEfFX5fE=; h=Date:To:From:Subject:From; b=Ere6hIt2ip7kH7JGl+UCblcjA5sWuYX7vq7ovYgOwK+gZTyVS6xvFFeeoz+qo7Iuc OhDqzdXOvrzaecHuBearAsaSl55fXZTjr1Bf5OHeLHCO1FxOlpyHQrAcEgdwbjIhDs LevOTtesixSKhX5ieFLl4PI3hE8KaHYKWOMcXA1o= Date: Mon, 20 Nov 2023 10:52:27 -0800 To: mm-commits@vger.kernel.org, ira.weiny@intel.com, fabio.maria.de.francesco@linux.intel.com, fabio.maria.de.francesco@intel.com, akpm@linux-foundation.org From: Andrew Morton Subject: + mm-ksm-use-kmap_local_page-in-calc_checksum.patch added to mm-unstable branch Message-Id: <20231120185227.DA727C433C8@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: mm/ksm: use kmap_local_page() in calc_checksum() has been added to the -mm mm-unstable branch. Its filename is mm-ksm-use-kmap_local_page-in-calc_checksum.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-ksm-use-kmap_local_page-in-calc_checksum.patch This patch will later appear in the mm-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: mm/ksm: use kmap_local_page() in calc_checksum() Date: Mon, 20 Nov 2023 15:18:44 +0100 kmap_atomic() has been deprecated in favor of kmap_local_page(). Therefore, replace kmap_atomic() with kmap_local_page() in calc_checksum(). kmap_atomic() is implemented like a kmap_local_page() which also disables page-faults and preemption (the latter only in !PREEMPT_RT kernels). The kernel virtual addresses returned by these two API are only valid in the context of the callers (i.e., they cannot be handed to other threads). With kmap_local_page() the mappings are per thread and CPU local like in kmap_atomic(); however, they can handle page-faults and can be called from any context (including interrupts). The tasks that call kmap_local_page() can be preempted and, when they are scheduled to run again, the kernel virtual addresses are restored and are still valid. In calc_checksum(), the block of code between the mapping and un-mapping does not depend on the above-mentioned side effects of kmap_aatomic(), so that a mere replacements of the old API with the new one is all that is required (i.e., there is no need to explicitly call pagefault_disable() and/or preempt_disable()). Link: https://lkml.kernel.org/r/20231120141855.6761-1-fmdefrancesco@gmail.com Signed-off-by: Fabio M. De Francesco Cc: Ira Weiny Signed-off-by: Andrew Morton --- mm/ksm.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/mm/ksm.c~mm-ksm-use-kmap_local_page-in-calc_checksum +++ a/mm/ksm.c @@ -1099,9 +1099,9 @@ error: static u32 calc_checksum(struct page *page) { u32 checksum; - void *addr = kmap_atomic(page); + void *addr = kmap_local_page(page); checksum = xxhash(addr, PAGE_SIZE, 0); - kunmap_atomic(addr); + kunmap_local(addr); return checksum; } _ Patches currently in -mm which might be from fabio.maria.de.francesco@intel.com are mm-util-use-kmap_local_page-in-memcmp_pages.patch mm-ksm-use-kmap_local_page-in-calc_checksum.patch