From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 78252186294 for ; Tue, 15 Apr 2025 14:38:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744727936; cv=none; b=tBNhM4tR5Iv2nvZJSFuKCzbOyZHTTLns/XRaazmDwmcKdaWUYF5QiPFnrmOb5ddl+8RD5KTe6QMdTSG+vq6n7qSO2vMRCee08sRz3O25/mX4UkYTfrQmme5absWcI8NjZiSxcFVsUxwSCy2odBtxFXIof+pUoTQA95K/lihC3HQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744727936; c=relaxed/simple; bh=kYi/G7DS8yucADl/KkyCY0+Cn23HSPgimqEVlmD5PT8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=AfOXWhRvke4gr3783DNFleKSWu9W+2B+a+PJ9rC25pTcUf4ZCW5RYy01RgXSuowrcHEK0FO7Z/4ueVhj9iE45e/tCQu4+ndlkiqG1hnfPRgFvEvvJ3rYd7yPQRUGMn9SxXAmaS2NKGW5kKuLXpirDwEWnXyrOi4ehxDyT3OgQAY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=hM4WdmUE; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="hM4WdmUE" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1744727933; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=yWIjLbUYw25/PQVcItxs9iUgezbC0x0pYB89p458ZAQ=; b=hM4WdmUEJtu71CZ5wZtoN6DHyIhIx62ViLXrIACURqlRVMJCE+CHc4uLlnA/twnRKqdbzL nPPVTnu3Cv8pd1tRqhhYy/0iVgQ6FDKd2wF8ORnpNkP3FGCLge+fp4qTZSp2pBrp7l5y81 4VsjjyQ5qEO9zfiIMoIHQIdVjKpGggA= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-671-cl1ikxPrO7WSHGtsHXvuJQ-1; Tue, 15 Apr 2025 10:38:50 -0400 X-MC-Unique: cl1ikxPrO7WSHGtsHXvuJQ-1 X-Mimecast-MFC-AGG-ID: cl1ikxPrO7WSHGtsHXvuJQ_1744727929 Received: from mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.40]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id A23DE19560B7; Tue, 15 Apr 2025 14:38:48 +0000 (UTC) Received: from localhost (unknown [10.72.112.38]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 193C019560AD; Tue, 15 Apr 2025 14:38:46 +0000 (UTC) Date: Tue, 15 Apr 2025 22:38:38 +0800 From: Baoquan He To: "Uladzislau Rezki (Sony)" Cc: Andrew Morton , linux-mm@kvack.org, LKML , Christoph Hellwig , Oleksiy Avramchenko Subject: Re: [PATCH] vmalloc: Use atomic_long_add_return_relaxed() Message-ID: References: <20250415112646.113091-1-urezki@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250415112646.113091-1-urezki@gmail.com> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 On 04/15/25 at 01:26pm, Uladzislau Rezki (Sony) wrote: > Switch from the atomic_long_add_return() to its relaxed version. > > We do not need a full memory barrier or any memory ordering during > increasing the "vmap_lazy_nr" variable. What we only need is to do it > atomically. This is what atomic_long_add_return_relaxed() guarantees. > > AARCH64: > > > Default: > 40ec: d34cfe94 lsr x20, x20, #12 > 40f0: 14000044 b 4200 > 40f4: 94000000 bl 0 <__sanitizer_cov_trace_pc> > 40f8: 90000000 adrp x0, 0 <__traceiter_alloc_vmap_area> > 40fc: 91000000 add x0, x0, #0x0 > 4100: f8f40016 ldaddal x20, x22, [x0] > 4104: 8b160296 add x22, x20, x22 > > Relaxed: > 40ec: d34cfe94 lsr x20, x20, #12 > 40f0: 14000044 b 4200 > 40f4: 94000000 bl 0 <__sanitizer_cov_trace_pc> > 40f8: 90000000 adrp x0, 0 <__traceiter_alloc_vmap_area> > 40fc: 91000000 add x0, x0, #0x0 > 4100: f8340016 ldadd x20, x22, [x0] > 4104: 8b160296 add x22, x20, x22 > > > Signed-off-by: Uladzislau Rezki (Sony) > --- > mm/vmalloc.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index 7bb32f498d39..9d4027041a3f 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -2370,7 +2370,7 @@ static void free_vmap_area_noflush(struct vmap_area *va) > if (WARN_ON_ONCE(!list_empty(&va->list))) > return; > > - nr_lazy = atomic_long_add_return(va_size(va) >> PAGE_SHIFT, > + nr_lazy = atomic_long_add_return_relaxed(va_size(va) >> PAGE_SHIFT, > &vmap_lazy_nr); LGTM, Reviewed-by: Baoquan He