From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ed1-f47.google.com (mail-ed1-f47.google.com [209.85.208.47]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 01E98224FD for ; Mon, 7 Apr 2025 12:09:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.208.47 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744027792; cv=none; b=X4WE78IsgUGo3Ft3J9gffke+PshJAJrXwwokR8IEnMrWMRwjJTTF6YYSvRSmALT1ILlN29zSgRrAlH+AnolnxtJNKWE301kZg/Ha4IhseF7G+mGwTpGBeiVCI24m88fsefUQg6+GcfZ7kSIAQ9TxoZptUMTKkKUH/SlU19NtaWY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744027792; c=relaxed/simple; bh=e44SiL3bvklsDrt1HjaQIZmPJ2dv984wWJrVwVr43XM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Z+DrDazE6IePQUL66mIm76XXlpsMfeD3QgAbgyFS0VI3Dfs+Mw3omkWSUK0ArvHzCkDKUr5PVU7s95lfznoXdNPOWrQJin3ZughZi9GK8EiTTuLPr8y13n0dx1wMfFoRRDC9nz2yeL2pLCjB5ntPc6ccPmhK+XYkHD0TXLr2Fmo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=MqrCjnzW; arc=none smtp.client-ip=209.85.208.47 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="MqrCjnzW" Received: by mail-ed1-f47.google.com with SMTP id 4fb4d7f45d1cf-5eb5ecf3217so7298844a12.3 for ; Mon, 07 Apr 2025 05:09:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1744027789; x=1744632589; darn=vger.kernel.org; h=user-agent:in-reply-to:content-disposition:mime-version:references :reply-to:message-id:subject:cc:to:from:date:from:to:cc:subject:date :message-id:reply-to; bh=enARi2Z7JnPTEmDCNXEY7n8qxxK9DglFVB+3z5zSkI0=; b=MqrCjnzWuIA3k3IMVpU04YS6JGOaEgkT45/nByZmz6I5+BPvQLJH6VeDgYXIqrTTNC ircBSoaEx8KOrDUQA+wsgnSxskDspk5i9HYCBhB9TjV0ZMM6EvfnQgv0MKnGTCTt0s8Y dfXARSnYEFeLBQZjpp+C6qXUrpbVBP3JtxFpBJOk0wdUuNmVvjdlLXmSVx/qeddIlp7R KmtO1Yda2S1SlmCzi+cgBIV85bRKAuCC8zDeg5RKb/2QL8opzSYRAA/Li2nPXDyZWcjO 0oWtZ89E1OFxtENwIsrIVIynedQDDLjHRlGlmBXGuiiBnvSTkBp7/R68w21FiJkNJuCp XI7Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1744027789; x=1744632589; h=user-agent:in-reply-to:content-disposition:mime-version:references :reply-to:message-id:subject:cc:to:from:date:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=enARi2Z7JnPTEmDCNXEY7n8qxxK9DglFVB+3z5zSkI0=; b=jIgTEcBmaDXjd2fDDOhAzcbFZAbRqaWfieKxJIh9Ds59pRYW13ZbfPLzlA6NR97v4K qY4unsd1pf0jWtwKnXzNeszq+hneR9e8JafE+tFCO1xdotDzcztthy1G4cNrQRjQVVIn jYzy+41+2bwH3V1ZXmrbeL+anvVargY4LDHmNxL1WS7ChysNnv88MhMaMnWfCW4xJ+nn GqkMX6TsektsKLkR5RmMeW/3EbC3COLVtcz8mmcVNyFJPkXXBvPWa1aHaxWDgBC4btwj 2WOf6LOqjcrHchaLAXLGfnnc1kazdIa0HEKgsPrGm2anhMpfrvA/yXMegW7rhXwpzO9l fIQw== X-Forwarded-Encrypted: i=1; AJvYcCVYfPe47xRXP+xp2srlb+hD9KPkCfUlYPEWO9OSisrpIaJOSKVh1jikT8jjarrrAFMc07EhoJfH3jfp2UE=@vger.kernel.org X-Gm-Message-State: AOJu0YxeLLUs5IpZKiG8yP19XSi/m/+xY4wXEDW7Zw/nkpuHb4lduElF t0s96VYac16MtMoupwjlAHpjqtKBrvtQ1jByc1Lde6glH85vwiGf X-Gm-Gg: ASbGncsLs0ahfDe5ldHvs1g0xv3JdHJCvIgrZSOtigHXapjDNs+VrVdcznAi92zXiZD W+yQHi+zQkb9bDXYhIgPYkyjCpR2AOPaBjrFhJ1h+bp05G78/sj8verDkamhfCIcmpZoGTaVPcF Gy2MnKasA1wEW8bdF7O1Qkhq8uIuz8wdYiEzEaJduAI4NHJ9tHjT64PzSUOw2fIOaBYiLGRjA2Y D9cBrFtj+/UA7DPjiX3NEM2GMg7r1adRq6cHxTD3d5Lu1h9dzOgS4xKxzdqNOR3uzk3tIsNSdWr kwABQpjzRG7IgIKTyvbtDjxAFyWKXyIJ+tCzSZ8Vk/z43nT/8mhW5Vo= X-Google-Smtp-Source: AGHT+IGn0rEfvulogO9nsHA48Cij7KYVKJkS78aPH6qE6hVJ5Z+++CiiVGjuZNBfsfI6Ibw6sqznyQ== X-Received: by 2002:a17:907:6e88:b0:ac6:fe8c:e7bb with SMTP id a640c23a62f3a-ac7d1c66170mr1253923566b.55.1744027788976; Mon, 07 Apr 2025 05:09:48 -0700 (PDT) Received: from localhost ([185.92.221.13]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ac7bfe9adc6sm740717766b.59.2025.04.07.05.09.48 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Mon, 07 Apr 2025 05:09:48 -0700 (PDT) Date: Mon, 7 Apr 2025 12:09:48 +0000 From: Wei Yang To: Lorenzo Stoakes Cc: Wei Yang , Andrew Morton , Vlastimil Babka , Jann Horn , "Liam R . Howlett" , Suren Baghdasaryan , David Hildenbrand , Matthew Wilcox , Rik van Riel , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/3] tools/testing/selftests: assert that anon merge cases behave as expected Message-ID: <20250407120948.zb5th45e6ehxpmrm@master> Reply-To: Wei Yang References: <20250407025455.67nhchndedotn57g@master> <4a8a1163-a7f9-4368-98e1-f79b0411aac4@lucifer.local> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4a8a1163-a7f9-4368-98e1-f79b0411aac4@lucifer.local> User-Agent: NeoMutt/20170113 (1.7.2) On Mon, Apr 07, 2025 at 12:02:00PM +0100, Lorenzo Stoakes wrote: >I know you mean well Wei, > >But drive-by extremely pedantic review on minor details isn't really >useful. I can't tell you not to do this, but I can at least ask. I don't >think this is a great use of either of our time. > >Thanks. > [...] >> >+ >> >+ /* unCOWing everything does not cause the AVC to go away. */ >> ^^^ >> >> Before ptr[i] = 'x', we have unCOWed pages in vma. What we are doing here is >> COWing, right? > >Nope, it's the other way round, as commented. A 'CoW' page is one marked >for copy-on-write right? we now make it just a normal mapping by writing to >it. > Oh, I misunderstand the meaning of 'CoW' page. It is the page before copy. I thought it is the page after. Sorry for bothering. >> >> >+ for (i = 0; i < 5 * page_size; i += page_size) >> >+ ptr[i] = 'x'; >> >+ >> >+ /* >> >+ * Map in adjacent VMA in child. >> >+ * >> >+ * forked >> >+ * |-----------|-----------| >> >+ * | faulted | unfaulted | >> >+ * |-----------|-----------| >> >+ * ptr ptr2 >> >+ */ >> >+ ptr2 = mmap(&ptr[5 * page_size], 5 * page_size, PROT_READ | PROT_WRITE, >> >+ MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0); >> >+ ASSERT_NE(ptr2, MAP_FAILED); >> >+ >> >+ /* Make sure not merged. */ >> >+ ASSERT_TRUE(find_vma_procmap(procmap, ptr)); >> >+ ASSERT_EQ(procmap->query.vma_start, (unsigned long)ptr); >> >+ ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr + 5 * page_size); >> >+} >> >+ >> >+TEST_F(merge, forked_source_vma) >> >+{ >> >+ unsigned int page_size = self->page_size; >> >+ char *carveout = self->carveout; >> >+ struct procmap_fd *procmap = &self->procmap; >> >+ pid_t pid; >> >+ char *ptr, *ptr2; >> >+ int i; >> >+ >> >+ /* >> >+ * |............|-----------| >> >+ * | | unfaulted | >> >+ * |............|-----------| >> >> I am not sure "unmapped" is correct here. The range has already been mapped by >> FIXTURE_SETUP(merge). > >This is pointless and actually misleading pedantry. > >For the purposes of what we are doing here, this is unmapped. Do you truly >think mentioning a PROT_NONE mapping here would be useful, meaningful, or >add anything but noise? > >> >> >+ */ >> >+ ptr = mmap(&carveout[page_size], 5 * page_size, PROT_READ | PROT_WRITE, >> >+ MAP_ANON | MAP_PRIVATE | MAP_FIXED | MAP_NORESERVE, -1, 0); >> >+ ASSERT_NE(ptr, MAP_FAILED); >> >+ >> >+ /* >> >+ * Fault in process. >> >+ * >> >+ * |............||-----------| >> >+ * | || faulted | >> >+ * |............||-----------| >> ^ >> >> Extra line here? > >Eh? I don't understand what you mean... you mean an extra '-'? This is to >fit both unfaulted/faulted in the same size SACII 'VMA', a convention I've >kept (hopefully) consistently... > Sounds the character format is corrupted. The extra line I meant is "||" between unmapped and faulted area. Well it is trivial, just forget it. -- Wei Yang Help you, Help me