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Fri, 02 Oct 2026 14:15:45 +0000 X-Mizu-Trace-ID: ae4e3d5f1d27fd0b X-Migadu-Flow: FLOW_OUT Message-ID: <28f2c85c-d45c-46af-bd2f-e97696f42f7c@linux.dev> Date: Fri, 2 Oct 2026 22:15:36 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] mm/vma: don't remove VMA from rmap if pgoff unchanged Content-Language: en-US To: "Lorenzo Stoakes (ARM)" Cc: akpm@linux-foundation.org, david@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, riel@surriel.com, harry@kernel.org, jannh@google.com, pfalcato@suse.de, linux-mm@kvack.org, linux-kernel@vger.kernel.org, pan.deng@intel.com References: <20260930-speed-up-inplace-rmap-v2-1-ac1aa19708aa@kernel.org> <20261001154511.23931-1-lance.yang@linux.dev> From: Lance Yang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 62A92140008 X-Rspam-User: X-Rspamd-Server: rspam07 X-Stat-Signature: zw3shj3n9x3q37463pms74bnr41gxu38 X-HE-Tag: 1790950547-176480 X-HE-Meta: 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 9IsJ26dM O8y1q191WwAYbZbg2CNASbA5v9x2R5JffNRCEodH8jDppje5c3GEuTlwoih1F9Ouq1jC6sGiO0j8uNCcDgqXOFTzKRQaJ9U08v+Us5ryB69gcNpVdW4ncVzBaRFdXh0UdaF8jJn/G2ce6FB/uzkyA1N5h6Z2jLICJw8hdgqPjLusvkagB6XY7vvTWehFYMPRuxzMPgmWeHyQ26Vd7TovIIVYHqbkD1sEDJqvCSFZJ8MszHTzkdEzw6+Q6D1rnIxr2xeipR8moeP6i1CskQl3fWVl94I41pJ23qyFj6/CTGxnizug= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2026/10/2 22:05, Lorenzo Stoakes (ARM) wrote: > On Thu, Oct 01, 2026 at 11:45:11PM +0800, Lance Yang wrote: [...] >>> +static void anon_rmap_tree_update_inplace(struct anon_vma_chain *avc) >>> +{ >>> +#ifdef CONFIG_DEBUG_VM_RB >>> + avc->cached_vma_last = avc_last_pgoff(avc); >>> +#endif >>> + /* Propagate all the way up the tree. */ >> >> Nit: propagate() can stop early when rb_subtree_last is unchanged ... >> >> Maybe: >> >> /* Update the subtree maximum and propagate any changes up the tree. */ > > I think in this case it's ok to be a bit blurry about it :P it deciding not to > unnecessary work is fine but I don't want to put too much in there. > > The point is as a simple sign or pointer to help somebody wondering wtf that's > for even if it's not quite the full story! > > Hopefully that's ok? :) Fair enough. Let’s leave it as-is ;) > >> >>> + __anon_rmap_tree_augment.propagate(&avc->rb, NULL); >>> +} >>> + >> [...] >> >> Acked-by: Lance Yang > > Thanks :) > >> >> Hammered it with VMA churn (split/merge/mremap/madvise/fork) + concurrent >> rmap walks + hwpoison injection. Nothing complained :D >> >> Tested-by: Lance Yang > > Thanks, very much appreciated! :) Cheers!