From patchwork Fri May 19 12:03:09 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Baoquan He X-Patchwork-Id: 13248268 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C2A12C77B7A for ; Fri, 19 May 2023 12:03:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=kq4nSx2UFTr7UuSJhl9LVfArKl/f+2d5lxeIhR4dLqY=; b=afB7POlHsOuyM0 yidmk/cvCf+IgidfSK5ANG95zi3m5qTd9Ul13zTiORWTdX1oQIJeN1o8kAsX/ym6bE4JIMmP1Ame+ OMnh5ls/g2u7yZMVbJ6CHVODiQwWimrVq7rOTvfOnQoRoGHNTC276+nj+axRVmEIgxf5mnWoQ0UCl yMUAXp9muJfaOGPCNoRoAX0eGbzi8KG1xC1Q0abEQ74aGb1/Wskr6qM0u3YZ9aBhQ1jiL1C7gb5Eq UPWoSz71+Z3fnfcH9TWDTaFV1HUeyWn+nyyAUHHKT0Gs+zLMOqxJHhVJgz/vV4h9qqo+F7KFjTYUB TjJWAlZZu+E5yrp5m8Kg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1pzypT-00GBJT-15; Fri, 19 May 2023 12:03:27 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1pzypQ-00GBIk-2F for linux-arm-kernel@lists.infradead.org; Fri, 19 May 2023 12:03:26 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1684497803; 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=ZivJ7EerY3Vw+ercF4baigkPxVV4k6zKRN43xpFWDKk=; b=FaJjicGr2mIpUq5eqjma19aB6m6C5c5oDbJS4KHMAhd0K+PzRLxxI2NOG1M86vw5KE8Jim Hki1Jp2lgS8xXYKa9LfTCqfQmmpSDyjPizbtkFnAXra2msezTkWxqhoTI3t+mAriLl62te 1kTPPzaXzMGHVajloLqks80VnxNk+7E= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-562-Z7r5N1YRPJyifeXJHy-YsA-1; Fri, 19 May 2023 08:03:17 -0400 X-MC-Unique: Z7r5N1YRPJyifeXJHy-YsA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 1A20C800159; Fri, 19 May 2023 12:03:14 +0000 (UTC) Received: from localhost (ovpn-12-79.pek2.redhat.com [10.72.12.79]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 63AD140CFD45; Fri, 19 May 2023 12:03:13 +0000 (UTC) Date: Fri, 19 May 2023 20:03:09 +0800 From: Baoquan He To: Thomas Gleixner Cc: "Russell King (Oracle)" , Andrew Morton , linux-mm@kvack.org, Christoph Hellwig , Uladzislau Rezki , Lorenzo Stoakes , Peter Zijlstra , John Ogness , linux-arm-kernel@lists.infradead.org, Mark Rutland , Marc Zyngier , x86@kernel.org Subject: [RFC PATCH 3/3] mm/vmalloc.c: change _vm_unmap_aliases() to do purge firstly Message-ID: References: <87zg658fla.ffs@tglx> <87r0rg93z5.ffs@tglx> <87ilcs8zab.ffs@tglx> <87fs7w8z6y.ffs@tglx> <874joc8x7d.ffs@tglx> <87r0rg73wp.ffs@tglx> <87edng6qu8.ffs@tglx> MIME-Version: 1.0 In-Reply-To: <87edng6qu8.ffs@tglx> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230519_050324_812365_00D817F2 X-CRM114-Status: GOOD ( 19.70 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org After vb_free() invocation, the va will be purged and put into purge tree/list if the entire vmap_block is dirty. If not entirely dirty, the vmap_block is still in percpu vmap_block_queue list, just like below two graphs: (1) |-----|------------|-----------|-------| |dirty|still mapped| dirty | free | 2) |------------------------------|-------| | dirty | free | In the current _vm_unmap_aliases(), to reclaim those unmapped range and flush, it will iterate percpu vbq to calculate the range from vmap_block like above two cases. Then call purge_fragmented_blocks_allcpus() to purge the vmap_block in case 2 since no mapping exists right now, and put these purged vmap_block va into purge tree/list. Then in __purge_vmap_area_lazy(), it will continue calculating the flush range from purge list. Obviously, this will take vmap_block va in the 2nd case into account twice. So here just move purge_fragmented_blocks_allcpus() up to purge the vmap_block va of case 2 firstly, then only need iterate and count in the dirty range in above 1st case. With the change, counting in the dirty region of vmap_block in 1st case is now inside vmap_purge_lock protection region, which makes the flush range calculation more reasonable and accurate by avoiding concurrent operation in other cpu. And also rename _vm_unmap_aliases() to vm_unmap_aliases(), since no other caller except of the old vm_unmap_aliases(). Signed-off-by: Baoquan He --- mm/vmalloc.c | 45 ++++++++++++++++++++------------------------- 1 file changed, 20 insertions(+), 25 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 87134dd8abc3..9f7cbd6182ad 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -2236,8 +2236,23 @@ static void vb_free(unsigned long addr, unsigned long size) spin_unlock(&vb->lock); } -static void _vm_unmap_aliases(unsigned long start, unsigned long end, int flush) +/** + * vm_unmap_aliases - unmap outstanding lazy aliases in the vmap layer + * + * The vmap/vmalloc layer lazily flushes kernel virtual mappings primarily + * to amortize TLB flushing overheads. What this means is that any page you + * have now, may, in a former life, have been mapped into kernel virtual + * address by the vmap layer and so there might be some CPUs with TLB entries + * still referencing that page (additional to the regular 1:1 kernel mapping). + * + * vm_unmap_aliases flushes all such lazy mappings. After it returns, we can + * be sure that none of the pages we have control over will have any aliases + * from the vmap layer. + */ +void vm_unmap_aliases(void) { + unsigned long start = ULONG_MAX, end = 0; + bool flush = false; int cpu; if (unlikely(!vmap_initialized)) @@ -2245,6 +2260,9 @@ static void _vm_unmap_aliases(unsigned long start, unsigned long end, int flush) might_sleep(); + mutex_lock(&vmap_purge_lock); + purge_fragmented_blocks_allcpus(); + for_each_possible_cpu(cpu) { struct vmap_block_queue *vbq = &per_cpu(vmap_block_queue, cpu); struct vmap_block *vb; @@ -2262,40 +2280,17 @@ static void _vm_unmap_aliases(unsigned long start, unsigned long end, int flush) start = min(s, start); end = max(e, end); - flush = 1; + flush = true; } spin_unlock(&vb->lock); } rcu_read_unlock(); } - mutex_lock(&vmap_purge_lock); - purge_fragmented_blocks_allcpus(); if (!__purge_vmap_area_lazy(start, end) && flush) flush_tlb_kernel_range(start, end); mutex_unlock(&vmap_purge_lock); } - -/** - * vm_unmap_aliases - unmap outstanding lazy aliases in the vmap layer - * - * The vmap/vmalloc layer lazily flushes kernel virtual mappings primarily - * to amortize TLB flushing overheads. What this means is that any page you - * have now, may, in a former life, have been mapped into kernel virtual - * address by the vmap layer and so there might be some CPUs with TLB entries - * still referencing that page (additional to the regular 1:1 kernel mapping). - * - * vm_unmap_aliases flushes all such lazy mappings. After it returns, we can - * be sure that none of the pages we have control over will have any aliases - * from the vmap layer. - */ -void vm_unmap_aliases(void) -{ - unsigned long start = ULONG_MAX, end = 0; - int flush = 0; - - _vm_unmap_aliases(start, end, flush); -} EXPORT_SYMBOL_GPL(vm_unmap_aliases); /**