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AJvYcCWUGMV7+XB3tAbRrkddnsyJNtx/BXKXlmWNUTIJ+iWj4alRGTu6hyozkPdyyqgXMzm5FCmV1C+sxg==@kvack.org X-Gm-Message-State: AOJu0YzVliPp3e9PxQN1xbmcP7Z1VL566KTlBK9Xy/LKRpMzkFE7Pj6N wLaupUKMh6A48Zh7EEQaGEyiwTAmM9LNLqfZpxLrS9/0OxwRSROCP7zOTnbXAY8szdYPPyM4/6z cwi/ef+ZHQygQoXqP+Q== X-Received: from wmby6.prod.google.com ([2002:a05:600c:c046:b0:485:3a2f:2f7e]) (user=aliceryhl job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:810b:b0:487:219e:41c with SMTP id 5b1f17b1804b1-48727f36da5mr169791385e9.28.1774857945322; Mon, 30 Mar 2026 01:05:45 -0700 (PDT) Date: Mon, 30 Mar 2026 08:05:44 +0000 In-Reply-To: <20260327113758.75f04588310a707b4d4b1aac@linux-foundation.org> Mime-Version: 1.0 References: <20260327-vmalloc-shrink-v8-0-cc6b57059ed7@zohomail.in> <20260327113758.75f04588310a707b4d4b1aac@linux-foundation.org> Message-ID: Subject: Re: [PATCH v8 0/6] mm/vmalloc: free unused pages on vrealloc() shrink From: Alice Ryhl To: Andrew Morton Cc: shivamkalra98@zohomail.in, Shivam Kalra via B4 Relay , Uladzislau Rezki , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Danilo Krummrich Content-Type: text/plain; charset="utf-8" X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 2C40540010 X-Stat-Signature: j6k66d1pkdkkyaah6g5cg9qzdsqczy8w X-HE-Tag: 1774857946-945500 X-HE-Meta: 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 MTNJbgwb 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Mar 27, 2026 at 11:37:58AM -0700, Andrew Morton wrote: > On Fri, 27 Mar 2026 15:18:36 +0530 Shivam Kalra via B4 Relay wrote: > > > This series implements the TODO in vrealloc() to unmap and free unused > > pages when shrinking across a page boundary. > > Thanks. I'd prefer to defer this until the next -rc cycle > (https://lkml.kernel.org/r/20260323202941.08ddf2b0411501cae801ab4c@linux-foundation.org). > If Ulad would prefer that we push ahead then OK. That's fine. No rush from my side. > Are we able to describe how much memory this change might save under > various scenarios? If the savings are impressively large then that > would get attention. The primary purpose of this is to ensure that this scenario is not possible: * There is a global list in the Binder driver. It's an array allocated using kvmalloc and resized on demand using kvrealloc. * A process decides to add a bajillion elements to that global list. * The process exits, taking its entries with it. * The global list now remains extremely large for no good reason. I don't know if it would save a significant amount of memory for well-behaved programs. Alice