From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sender-of-o58.zoho.eu (sender-of-o58.zoho.eu [136.143.169.58]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 178473B8BBB; Thu, 6 Aug 2026 15:42:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=pass smtp.client-ip=136.143.169.58 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786030942; cv=pass; b=ZTe33I8WmGZ2gjR2+Lyij82c9beuDX5j4F5egkhaSW1F8XRm+1zJKwfUUspaujJiyIAVVK8b5BNx8x2xfAbKl4dH2g4mUywAHI+We8xmiF9ZRoln4LsLIc8z3B2YeCOYbLIHwfVOBcXa+l0XNOcJOxaGL62HfJFXEvJPbF5XgFQ= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786030942; c=relaxed/simple; bh=/oW3er4sqRCc1h2LisJaGMPNfRF7QTJMp6Eo8XT2dqk=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=KGszpLE5ROks+CL9QjDgChpRVP3LRd8/XLrt68FD9p8j1SYndm9THT384zguDUGTWJmzc0Zlr1PCGFt6faPydB9zhBfnk0KpNwusNftRq9NpLOHDnLn29LprG3XTxC6x9qjmNKo94BS/5Mqf2pEw0IMvsaJiFj3s1JUlkpdWZTk= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=iusegentoo.com; spf=pass smtp.mailfrom=iusegentoo.com; dkim=pass (1024-bit key) header.d=iusegentoo.com header.i=ali@iusegentoo.com header.b=CQ0J6ufO; arc=pass smtp.client-ip=136.143.169.58 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=iusegentoo.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=iusegentoo.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=iusegentoo.com header.i=ali@iusegentoo.com header.b="CQ0J6ufO" ARC-Seal: i=1; a=rsa-sha256; t=1786030935; cv=none; d=zohomail.eu; s=zohoarc; b=in/m0RkusI3Y7gcx6h+VukHX9gvSeMQhHEri+pIq65Sl27Mt0LFDVEPuD8BP2JdEq9rOyDCdEPppTNEooTdTOuSXDMd777WrJ6W+U6zFPe26RJuTEj9hHv8r9yn8f7naFCDTVW7/zOrl6JuU33mG9RUao8oHpGFiUPxcHJPn4XQ= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.eu; s=zohoarc; t=1786030935; h=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:MIME-Version:Message-ID:Subject:Subject:To:To:Message-Id:Reply-To; bh=/oW3er4sqRCc1h2LisJaGMPNfRF7QTJMp6Eo8XT2dqk=; b=HkK+zjXXX8uT7J+9H3DmO7Y33Brquoqkdz7Po4918YHVayidNuaTBALrJIywmztFPeTrAtHnE5AOTfxtso1g7J1KqdHxxU5uefQ1mSfVZ9EoG4Ht6CEv9cseqQPaPMe0krmWZBDb2G422WKRNZA0yVvk+QHmjIFwKC0qMUirjZI= ARC-Authentication-Results: i=1; mx.zohomail.eu; dkim=pass header.i=iusegentoo.com; spf=pass smtp.mailfrom=ali@iusegentoo.com; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1786030935; s=zmail; d=iusegentoo.com; i=ali@iusegentoo.com; h=From:From:To:To:Cc:Cc:Subject:Subject:Date:Date:Message-ID:MIME-Version:Content-Transfer-Encoding:Message-Id:Reply-To; bh=/oW3er4sqRCc1h2LisJaGMPNfRF7QTJMp6Eo8XT2dqk=; b=CQ0J6ufO4CARcZOq9bGjNxL1cV2sfYQyVYXqXePKIedZT4oXcgeZ2EssZWRR7FxB vEGa0ETLBfIcB2BolaLU62BWS2Ru2GSXdHZRDSPR+BxHRRL6FhyNDx4wB6Tl0Nwy6yU hdIbbFUX5SIei5HalCq7kS/1xiUp/WGpILAqkm0Q= Received: by mx.zoho.eu with SMTPS id 1786030932797290.52232199042635; Thu, 6 Aug 2026 17:42:12 +0200 (CEST) From: Ali Ahmet Memis To: Jens Axboe Cc: Pavel Begunkov , io-uring@vger.kernel.org, linux-kernel@vger.kernel.org Subject: io_uring/memmap: compound allocation larger than accounted region Date: Thu, 6 Aug 2026 15:42:00 +0000 Message-ID: <20260806154200.183725-1-ali@iusegentoo.com> X-Mailer: git-send-email 2.55.0 Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-ZohoMailClient: External io_mem_alloc_compound() allocates get_order(size) pages, while io_create_region() accounts reg->size >> PAGE_SHIFT. For a ring with 4096 SQ entries and the default CQ size that is 64 pages allocated against 37 accounted. Is that intentional? memcg charges the full allocation, so only RLIMIT_MEMLOCK undercounts, and the gap is bounded by 2x. I did not want to send a patch for something that may well be a deliberate trade for the single folio. Thanks, Ali