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bh=ZivJ7EerY3Vw+ercF4baigkPxVV4k6zKRN43xpFWDKk=; b=WwQosKhXcVC6nkZibORwOgdg0WbN3rgy6lV2E4zpVlgsKsRaRf1OKaI6mu1VI2ykzbVPEs xxBCSH0F3uNmrdFcvQ9zTMsL8OWzncy6uvQw2v7GAzjcSwvsTg4iH+/OO3g92I4vAhFtC3 nZZ6dYUkd9gMZs5Ghf59CEMPEC1D9/k= 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-Rspamd-Queue-Id: 3157A120021 X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: w1guj19ba9k443hf8p56gapdqf6d5hc1 X-HE-Tag: 1684497800-179836 X-HE-Meta: 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 ljE/afxb /InDISJqUBfs+NdXiAt5NEyFjbXMCIpPznI6ZN3LmIukzGZHjOT6OgqXxC9fBaUfp69IBGu/gCPxTdTYBQLREV0YpupLTqYcVRSmrJ4+BIll0xcgUj99LFEPv7ED9POHkZg+BzBPxkrA5mNNCoyTRs6MEDqUuFikNWd8pImEOH4Hz3egSL4if0kWtubsNCgn0+vnWB1j1WA9lKPVuibyELLYSTkUB/J6JylTv8euJbgGxfrqCZh9QzYxgVGlkzm9ophY3oCwpsKCG4dkdw3+b5s4jyg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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); /**