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From: Roman Gushchin To: "Liam R. Howlett" , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Jann Horn , Peter Zijlstra , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Hugh Dickins , linux-arch@vger.kernel.org Subject: Re: [PATCH v3] mmu_gather: move tlb flush for VM_PFNMAP/VM_MIXEDMAP vmas into free_pgtables() Message-ID: References: <20250123164358.2384447-1-roman.gushchin@linux.dev> <5bpibh7qkrcggyqsrathszfqrjckyaqspdons6cfkkyse4ub4b@2iu4sibbirxf> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5bpibh7qkrcggyqsrathszfqrjckyaqspdons6cfkkyse4ub4b@2iu4sibbirxf> X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 939E812000B X-Stat-Signature: k1fqpdxamqz8iunhaz4ryyritydqtd4h X-Rspam-User: X-HE-Tag: 1737667173-831394 X-HE-Meta: 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 8mAvjhze 6RXCRWTJrBi67Xd2bvHVfoYk0WFYRWz/FEh/5AAnxojx7K7KukW3b6ZSkIPoqh7iAcIU4HdJUWtHRUrZ8cZZYaqTF81vShd/EzBn2FCg4tsPQTwN10SxuNN2pZCQrTSOUiBS4BkFxihuc2deX2eQgKXI9O7UuhtCouY0RQ5mSsDMwm7m8LdmKaxpow3lUmD/T5JI6jBzPJkpBYJjGtVILluYmA+NNGqa22JcrzId6/ar/o1WLhaTHEaB+CU0aNkeQKcBrPYxUW4g3E3w= 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, Jan 23, 2025 at 02:42:56PM -0500, Liam R. Howlett wrote: > * Roman Gushchin [250123 11:44]: > > 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. > > > > --- > > Hugh didn't mean to add a ---, he meant to move the version info between > the Cc list and the patch so that it's not in the git history. Ah, ok, somehow it wasn't a problem previously for me, usually Andrew was dropping the part while merging into the mm tree. Thanks for clarifying. > > You can find examples on the ML. > > > > > v3: > > - added initialization of vma_pfn in __tlb_reset_range() (by Hugh D.) > > > > 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.) > > > > > > Suggested-by: Jann Horn > > Signed-off-by: Roman Gushchin > > Link: some email discussion url lore.kernel.org.. It was based on some non-public discussion unfortunately, so no lore link. Thank you!