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[172.10.233.147]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-72dab9c8da5sm12254458b3a.118.2025.01.23.00.07.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 23 Jan 2025 00:07:01 -0800 (PST) Date: Thu, 23 Jan 2025 00:06:51 -0800 (PST) From: Hugh Dickins To: Roman Gushchin cc: Hugh Dickins , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Jann Horn , Peter Zijlstra , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , linux-arch@vger.kernel.org Subject: Re: [PATCH v2] mmu_gather: move tlb flush for VM_PFNMAP/VM_MIXEDMAP vmas into free_pgtables() In-Reply-To: Message-ID: References: <20250122232716.1321171-1-roman.gushchin@linux.dev> 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 On Wed, 22 Jan 2025, Hugh Dickins wrote: > On Wed, 22 Jan 2025, 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 > > free_pgtables(), somewhat similar to the stable version of the > > original commit: e.g. stable 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. > > > > v2: > > - moved vma_pfn flag handling into tlb.h (by Peter Z.) > > - added comments (by Peter Z.) > > - fixed the vma_pfn flag setting (by Hugh D.) And in v3, that changelog should be after the ---, not in the commit.