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 68833C64ED6 for ; Mon, 27 Feb 2023 21:44:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229649AbjB0VoH (ORCPT ); Mon, 27 Feb 2023 16:44:07 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52346 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229535AbjB0VoG (ORCPT ); Mon, 27 Feb 2023 16:44:06 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DD46E1BEA for ; Mon, 27 Feb 2023 13:44:05 -0800 (PST) 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 9CB28B80D9A for ; Mon, 27 Feb 2023 21:44:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3C356C433EF; Mon, 27 Feb 2023 21:44:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1677534243; bh=2Oyz55UiJ8nBfLmssVbhXolDOq/JrosJrbxvV54QZr0=; h=Date:To:From:Subject:From; b=hdSawq2S+dTa8Fr0j05IqlXSBWq42tPvOfMLDqYTF2Mbgtae2sqgOEWZ7InYNlujn GL7B02XeTwbm7mx2Ln1DblXusG5fRVHBdkaTLK8Cc7NfUxNE/kUTT1nJae2XZen9h7 JPoIus3+kY5UUkocLuanPMkOp05pBFV+gSTHwqgw= Date: Mon, 27 Feb 2023 13:44:02 -0800 To: mm-commits@vger.kernel.org, ubizjak@gmail.com, akpm@linux-foundation.org From: Andrew Morton Subject: + mm-rmap-use-atomic_try_cmpxchg-in-set_tlb_ubc_flush_pending.patch added to mm-unstable branch Message-Id: <20230227214403.3C356C433EF@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/rmap: use atomic_try_cmpxchg in set_tlb_ubc_flush_pending has been added to the -mm mm-unstable branch. Its filename is mm-rmap-use-atomic_try_cmpxchg-in-set_tlb_ubc_flush_pending.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-rmap-use-atomic_try_cmpxchg-in-set_tlb_ubc_flush_pending.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: Uros Bizjak Subject: mm/rmap: use atomic_try_cmpxchg in set_tlb_ubc_flush_pending Date: Mon, 27 Feb 2023 22:42:28 +0100 Use atomic_try_cmpxchg instead of atomic_cmpxchg (*ptr, old, new) == old in set_tlb_ubc_flush_pending. 86 CMPXCHG instruction returns success in ZF flag, so this change saves a compare after cmpxchg (and related move instruction in front of cmpxchg). Also, try_cmpxchg implicitly assigns old *ptr value to "old" when cmpxchg fails. No functional change intended. Link: https://lkml.kernel.org/r/20230227214228.3533299-1-ubizjak@gmail.com Signed-off-by: Uros Bizjak Signed-off-by: Andrew Morton --- --- a/mm/rmap.c~mm-rmap-use-atomic_try_cmpxchg-in-set_tlb_ubc_flush_pending +++ a/mm/rmap.c @@ -644,7 +644,7 @@ void try_to_unmap_flush_dirty(void) static void set_tlb_ubc_flush_pending(struct mm_struct *mm, bool writable) { struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc; - int batch, nbatch; + int batch; arch_tlbbatch_add_mm(&tlb_ubc->arch, mm); tlb_ubc->flush_required = true; @@ -662,11 +662,8 @@ retry: * overflow. Reset `pending' and `flushed' to be 1 and 0 if * `pending' becomes large. */ - nbatch = atomic_cmpxchg(&mm->tlb_flush_batched, batch, 1); - if (nbatch != batch) { - batch = nbatch; + if (!atomic_try_cmpxchg(&mm->tlb_flush_batched, &batch, 1)) goto retry; - } } else { atomic_inc(&mm->tlb_flush_batched); } _ Patches currently in -mm which might be from ubizjak@gmail.com are mm-rmap-use-atomic_try_cmpxchg-in-set_tlb_ubc_flush_pending.patch nfs-remove-empty-if-statement-from-nfs3_prepare_get_acl.patch