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Mon, 30 Mar 2026 05:27:24 -0700 (PDT) Received: from milan ([2001:9b1:d5a0:a500::24b]) by smtp.gmail.com with ESMTPSA id 38308e7fff4ca-38c8389202asm14847641fa.24.2026.03.30.05.27.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 Mar 2026 05:27:24 -0700 (PDT) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Mon, 30 Mar 2026 14:27:22 +0200 To: Alice Ryhl , Andrew Morton Cc: Andrew Morton , shivamkalra98@zohomail.in, Shivam Kalra via B4 Relay , Uladzislau Rezki , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Danilo Krummrich Subject: Re: [PATCH v8 0/6] mm/vmalloc: free unused pages on vrealloc() shrink Message-ID: References: <20260327-vmalloc-shrink-v8-0-cc6b57059ed7@zohomail.in> <20260327113758.75f04588310a707b4d4b1aac@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 26A6240007 X-Stat-Signature: brecqi19kaoke1xh5jkunne37w6a57xd X-HE-Tag: 1774873646-135143 X-HE-Meta: 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 SQ86kJvl 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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 Mon, Mar 30, 2026 at 08:05:44AM +0000, Alice Ryhl wrote: > 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 Agree, let's postpone this, so i have a chance to check it one more time even though it seems ready. -- Uladzislau Rezki