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Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1uKvjt-0000000FeW1-1Dxy; Fri, 30 May 2025 09:09:21 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id A5B2030066A; Fri, 30 May 2025 11:09:20 +0200 (CEST) Date: Fri, 30 May 2025 11:09:20 +0200 From: Peter Zijlstra To: Roman Gushchin Cc: Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, Jann Horn , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Hugh Dickins Subject: Re: [PATCH v6] mmu_gather: move tlb flush for VM_PFNMAP/VM_MIXEDMAP vmas into free_pgtables() Message-ID: <20250530090920.GB21197@noisy.programming.kicks-ass.net> References: <20250522012838.163876-1-roman.gushchin@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250522012838.163876-1-roman.gushchin@linux.dev> X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: BE1041A0004 X-Stat-Signature: 6j4uz8bzjx1rnm6ef57ahgzhsixbwd5s X-Rspam-User: X-HE-Tag: 1748596165-238217 X-HE-Meta: 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 +1ihsRMj smceHftxoOYeDZYZphD+wmfU6hsHFEV09ujSeBLXHv09kqUlxFxSTz/1YdA1dugHcsLgqSZ49ukHyzDHH3F4t4f4OwLagS1sORlPQQdrL+yRdRGmgqYVRt5Di/NVZhQOpwuLrQBCfKZS/YEwN/UOMYz68QsZYj+FOeQn+8SooKO8xPwW8WjvvV4DdE6+KkAPmA+le9oT+XXb5SHv1lm+BM+Pmmp8EJ6+MTy24sgGAMP3TUmeX2oV/TxKBqHbf0zKfEMZqdRxiHgFxLq6k0UYtkFG25sgsQTOCNAPZxwksJuyi4VqJ42tLx/DWqtxXZoVcRrMX 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: List-Subscribe: List-Unsubscribe: On Thu, May 22, 2025 at 01:28:38AM +0000, Roman Gushchin wrote: > Commit b67fbebd4cf9 ("mmu_gather: Force tlb-flush VM_PFNMAP vmas") > added a forced tlbflush to tlb_vma_end(), which is required to avoid a > race between munmap() and unmap_mapping_range(). However it added some > overhead to other paths where tlb_vma_end() is used, but vmas are not > removed, e.g. madvise(MADV_DONTNEED). > > Fix this by moving the tlb flush out of tlb_end_vma() into new > tlb_flush_vmas() called from free_pgtables(), somewhat similar to the > stable version of the original commit: > commit 895428ee124a ("mm: Force TLB flush for PFNMAP mappings before > unlink_file_vma()"). > > Note, that if tlb->fullmm is set, no flush is required, as the whole > mm is about to be destroyed. > > Signed-off-by: Roman Gushchin Acked-by: Peter Zijlstra (Intel)