From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 E3CDF364EBE; Wed, 4 Mar 2026 03:24:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772594677; cv=none; b=hP8j3Q1k6kLu9Sxtex+CVa8JyBoBtNs25mTCKPuDrn37JPNbyQEXgXyzqLS7ttIIvecnJslCthEdRf9uII5Z6zzxGaFd3IDE9XzvpPjI/ZI5gNxdp9DXBA5Fl9BcX+2MUKeNixAkpC7P3QRCP7Q2ATiQFhOQyew2OcIf9Sbwh2Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772594677; c=relaxed/simple; bh=+XUB+cPb6apo0xYcEzw+Ryc3ukmRfySainPZItfuUyU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ZCFMjiby4GROcixkyvuD4hyIeyBbX/sO2+3BMus8853p6pgVW1XgTPzfHZsPoWkXOHicl6zRI7l/rL/dblumFVvQXt4xJurG+cIhRkDuPJIIRjjfK603foM1piQhJY4CHUVGzOguzUN6Tz0fy5FsUxsg/rTsr24oLMflRoLsqNc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=Y55ilsFI; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="Y55ilsFI" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Transfer-Encoding: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=uwaew1TASwLFpWF0VG/+hJg8qwclvjQWd4Xpfif75xM=; b=Y55ilsFIY2uEBOFXIvrtEYMcxx V/JrCLDxgjkhM/9AmmOM6p2YDvZEp3at1c81Mie4L08hbvdW5XczTSkOpKUYldRXpbRkzcpST75rE JSYtWs4lPnRkwt7VLpWnZS8EYTQrG9i0BWDSDV+inn6J4BRublQVBcsZz3JeLdeZOhCHNoqKY6jbX slhEqOeUTLTlm9sVqBgehi2kNsWbfS4dhEWJs3o+XtyJnOKyJLFluQ6KxU+iVO6wjIpviTd1Jv27X wgrr6MdnWMKHkAWtXiFA2/xvfrUlXJBSn38A1vOyJKFa1OXMKd+jiad+JQnbO2GJUwecYvLglkRKO MBiTn2xw==; Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1vxcqD-0000000Cdoe-3gHX; Wed, 04 Mar 2026 03:24:05 +0000 Date: Wed, 4 Mar 2026 03:24:05 +0000 From: Matthew Wilcox To: Suren Baghdasaryan Cc: Lorenzo Stoakes , akpm@linux-foundation.org, david@kernel.org, ziy@nvidia.com, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net, ying.huang@linux.alibaba.com, apopple@nvidia.com, baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, vbabka@suse.cz, jannh@google.com, rppt@kernel.org, mhocko@suse.com, pfalcato@suse.de, kees@kernel.org, maddy@linux.ibm.com, npiggin@gmail.com, mpe@ellerman.id.au, chleroy@kernel.org, borntraeger@linux.ibm.com, frankja@linux.ibm.com, imbrenda@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, svens@linux.ibm.com, gerald.schaefer@linux.ibm.com, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, "Ritesh Harjani (IBM)" Subject: Re: [PATCH v3 2/3] mm: replace vma_start_write() with vma_start_write_killable() Message-ID: References: <20260226070609.3072570-1-surenb@google.com> <20260226070609.3072570-3-surenb@google.com> <74bffc7a-2b8c-40ae-ab02-cd0ced082e18@lucifer.local> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Tue, Mar 03, 2026 at 04:02:50PM -0800, Suren Baghdasaryan wrote: > On Tue, Mar 3, 2026 at 2:18 PM Matthew Wilcox wrote: > > > > On Tue, Mar 03, 2026 at 02:11:31PM -0800, Suren Baghdasaryan wrote: > > > On Mon, Mar 2, 2026 at 6:53 AM Lorenzo Stoakes > > > wrote: > > > > Overall I'm a little concerned about whether callers can handle -EINTR in all > > > > cases, have you checked? Might we cause some weirdness in userspace if a syscall > > > > suddenly returns -EINTR when before it didn't? > > > > > > I did check the kernel users and put the patchset through AI reviews. > > > I haven't checked if any of the affected syscalls do not advertise > > > -EINTR as a possible error. Adding that to my todo list for the next > > > respin. > > > > This only allows interruption by *fatal* signals. ie there's no way > > that userspace will see -EINTR because it's dead before the syscall > > returns to userspace. That was the whole point of killable instead of > > interruptible. > > Ah, I see. So, IIUC, that means any syscall can potentially fail with > -EINTR and this failure code doesn't need to be documented. Is that > right? We could literally return any error code -- it never makes it to userspace. I forget where it is, but if you follow the syscall return to user path, a dying task never makes it to running a single instruction.