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 7C6DEC27C40 for ; Wed, 22 Nov 2023 20:04:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344324AbjKVUFB (ORCPT ); Wed, 22 Nov 2023 15:05:01 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54872 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344393AbjKVUFA (ORCPT ); Wed, 22 Nov 2023 15:05:00 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 73974D40 for ; Wed, 22 Nov 2023 12:04:54 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0CCFCC433C8; Wed, 22 Nov 2023 20:04:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1700683494; bh=cTss+wkzihN5ttg3LHLZi2QwdsrcjLk44GX0k8o+lOI=; h=Date:To:From:Subject:From; b=0oBZRTx3/bcEmlmM7bRyNuyel2FVB9ntCCTcQTtWcP00vGJH28PH2qqCHWYYOC+pm 469nCuDp8xd4D4aca0CuJJwJWNRZ5/+nauGjKeDenw/lwLFcRQoZH7Sx5DIeuV808W VOmDuP5SbFfx4hQY9sb/4JbLN0xsW5JKL/cg75K0= Date: Wed, 22 Nov 2023 12:04:53 -0800 To: mm-commits@vger.kernel.org, glider@google.com, elver@google.com, dvyukov@google.com, juntong.deng@outlook.com, akpm@linux-foundation.org From: Andrew Morton Subject: + kfence-replace-local_clock-with-ktime_get_boot_fast_ns.patch added to mm-unstable branch Message-Id: <20231122200454.0CCFCC433C8@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: kfence: replace local_clock() with ktime_get_boot_fast_ns() has been added to the -mm mm-unstable branch. Its filename is kfence-replace-local_clock-with-ktime_get_boot_fast_ns.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/kfence-replace-local_clock-with-ktime_get_boot_fast_ns.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: Juntong Deng Subject: kfence: replace local_clock() with ktime_get_boot_fast_ns() Date: Wed, 22 Nov 2023 20:00:26 +0000 The time obtained by local_clock() is the local CPU time, which may drift between CPUs and is not suitable for comparison across CPUs. It is possible for allocation and free to occur on different CPUs, and using local_clock() to record timestamps may cause confusion. ktime_get_boot_fast_ns() is based on clock sources and can be used reliably and accurately for comparison across CPUs. Link: https://lkml.kernel.org/r/VI1P193MB0752A2F21C050D701945B62799BAA@VI1P193MB0752.EURP193.PROD.OUTLOOK.COM Signed-off-by: Juntong Deng Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: Marco Elver Signed-off-by: Andrew Morton --- mm/kfence/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/kfence/core.c~kfence-replace-local_clock-with-ktime_get_boot_fast_ns +++ a/mm/kfence/core.c @@ -295,7 +295,7 @@ metadata_update_state(struct kfence_meta track->num_stack_entries = num_stack_entries; track->pid = task_pid_nr(current); track->cpu = raw_smp_processor_id(); - track->ts_nsec = local_clock(); /* Same source as printk timestamps. */ + track->ts_nsec = ktime_get_boot_fast_ns(); /* * Pairs with READ_ONCE() in _ Patches currently in -mm which might be from juntong.deng@outlook.com are kasan-improve-free-meta-storage-in-generic-kasan.patch kfence-replace-local_clock-with-ktime_get_boot_fast_ns.patch