From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 2791135E1C5; Fri, 9 Oct 2026 18:47:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791571660; cv=none; b=B0L6mRTeTC4CQMLW9WeeqYRhiJG3o0iH9sD50ftVwggXbh83nuOghHxgfihxKgW7jBBTLdyJgyu0jQ62VISPd91dGn6Lqz9uW8ppfUSBMDlPIVhD8pS27y7zM09TdhfeOmMK6Yey/y3Jo2r7lnatvTdXLgHPAhfvMdPTzAZU/Ss= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791571660; c=relaxed/simple; bh=mLlOFaw/IlJZnvJ/4xxpVCtKs3elyFr6/EuYxK+WsAw=; h=Message-ID:From:Subject:To:Cc:In-Reply-To:References:Content-Type: Date; b=O+D5m1WQ+8GBV1dYDOI+X4mTBJTNpa0qxwC+CSQ7Ab7i4A0hMrIQ6rHu5GUhE2VPzuRkmK44beGzRdmnenO98mhs6Zoy8kziMkomA+F6S7QUSMj50eTvY44zbYirC49p+gVXtt72M5Mlb8o+Vzt3pf+7nH709lpg3cwdh4jf8k4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=HLqJTBNT; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="HLqJTBNT" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B6C861F000FF; Fri, 9 Oct 2026 18:47:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791571658; bh=mLlOFaw/IlJZnvJ/4xxpVCtKs3elyFr6/EuYxK+WsAw=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=HLqJTBNTQI+DMSuFOj7AqNFJPmjCsLNI/umMw+QNgwVgaLZlsBcDqiHahrE2PcNv1 kqZkhRrN/kDmCtQnsXSSaaT8ga6dT9tFJAwfV+9f9oMuHy1If9uuX5es7diAu3W8sS +dX1b9JMhQMPVlCpbrM9xmL0xp21DKimVpTg3G5OhakXTY1xmjiJLKfJN1P1Gpv6gA fcJ5Kd61r/ENOVuDCagyA/i/laFHRXNNqUrsrrK66WagciziwnY8mjSrpZ0kIkaWLz j/rSdVYAxJ2/0Z+IB0s22fCLlfKRymRSVJ+4l2ouCDQYA97/B+pGwrUdIwcFFRY2qd WWZ6k9ekmOWkA== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH v5 32/38] mm/madvise: use predicates for madvise(..., MADV_DOFORK) Reply-To: sashiko-reviews@lists.linux.dev To: =?utf-8?b?TG9yZW56byBTdG9ha2VzIChBUk0p?= Cc: linux-usb@vger.kernel.org, "Vasily Gorbik" , "Alexander Gordeev" , linux-scsi@vger.kernel.org, "Christian Borntraeger" , kvmarm@lists.linux.dev, selinux@vger.kernel.org, linux-s390@vger.kernel.org, linux-trace-kernel@vger.kernel.org, kvm@vger.kernel.org, "Marc Zyngier" , "Heiko Carstens" , "Oliver Upton" , bpf@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-rdma@vger.kernel.org, linux-perf-users@vger.kernel.org In-Reply-To: <20261009-b4-mmap-prepare-vma-flag-sanify-v5-32-923b70125b1e@kernel.org> References: <20261009-b4-mmap-prepare-vma-flag-sanify-v5-0-923b70125b1e@kernel.org> <20261009-b4-mmap-prepare-vma-flag-sanify-v5-32-923b70125b1e@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Fri, 09 Oct 2026 18:47:37 +0000 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: > Make it clear what we're blocking in MADV_DOFORK. Previously we simply > disallowed VM_SPECIAL i.e. mappings not managed by core mm, fixed mappings > and > VMA_IO_BIT. >=20 > Now the invariant is established that mm-managed mappings may not set > VMA_IO_BIT, the VMA_IO_BIT check is redundant. >=20 > The rest is equivalent to testing for a fixed or non-mm-managed mapping, > i.e. exactly the same check as whether the VMA is permitted to be merged. >=20 > This was established by commit 0b2758f48f22 ("Require (reasonably) normal > mappings for MADV_DOFORK") containing my hands-down favourite call out of > all time. >=20 > Express the same thing differently - if we wouldn't be allowed to merge i= t, > then we aren't allowed to manipulate CoW behaviour on fork. >=20 > No functional change intended. >=20 > Acked-by: Zi Yan > Signed-off-by: Lorenzo Stoakes (ARM) Sashiko has reviewed this patch and found no issues. It looks great! --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261009-b4-mmap-pr= epare-vma-flag-sanify-v5-0-923b70125b1e@kernel.org?part=3D32