From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wr1-f47.google.com (mail-wr1-f47.google.com [209.85.221.47]) (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 BED2F2DCBEC for ; Tue, 23 Jun 2026 18:45:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=pass smtp.client-ip=209.85.221.47 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782240342; cv=pass; b=NXVUHPKguzYIke3gfImBlJM+GHTih+C50BIP47QaEzWZf59YJx3c+nxE8u8ob5hbn43E9c2WDZv7UTO53KuS9U1A4z/Z6IEcEGk6dwoXFD3XhzRx+TOBpMpW0Tdf7EZMb4aXqvV2nec5RR+TmI3QX/2hvpSAyHjukCAybzVrhuY= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782240342; c=relaxed/simple; bh=LVwncB4caCHuMDpKbFeo4MHlTUSmtwWDgRh+YGNPGK0=; h=MIME-Version:References:In-Reply-To:From:Date:Message-ID:Subject: To:Cc:Content-Type; b=uiMbyhp5VHHLKxMD8EYwYSEvWz53M3XeTozqzcKC+WmkzPVMMbbBKKY3pmdz3P9R3nXQTRdZ4wjEtAIIz+vL6fC9pQoFCFAARpWpRNfZLtkcn+vj2Vgoq6b9I0zNudj/SXWF1QFRmVoC80K5/8Mk29Qpx0DDXCRhyHSxHYHA24k= ARC-Authentication-Results:i=2; 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=kFTrXaGr; arc=pass smtp.client-ip=209.85.221.47 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="kFTrXaGr" Received: by mail-wr1-f47.google.com with SMTP id ffacd0b85a97d-45fd464d51fso132573f8f.3 for ; Tue, 23 Jun 2026 11:45:40 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1782240339; cv=none; d=google.com; s=arc-20240605; b=XaXY/cSQ+uulaePERP/PTVO/6kfcPeB2ckkgqXzuFdXx5by+Jy028drSw41Z/pm4Jn IHtj+zKW3n9v4xvAMJShsNirUCADDzmNWeXN7OpYLS53f+HaSxiHqEAj6YHJwWZrqMxM tttYqPz7wiu24beC3ZRv5mDfc3BQHvc/ueAjyHlXFznPQEGz/orXI+eAYuA56KTZp4GW MOZT9jy4FSh747LD8qfmYFC2oKRAvPRP3sJn/srKvVUfnVqY9um+zFy5X60h6UEUivs/ 8gNmNauQRbv/OffsnmdqEy02Gw+rYZy+28+Mbe9eP0jXUcIZ83I5J49auwXRMGe2+iYo uj+Q== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20240605; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:dkim-signature; bh=LVwncB4caCHuMDpKbFeo4MHlTUSmtwWDgRh+YGNPGK0=; fh=Pty5epKtGkRnJJn5MdUwHnOxZOkMMqKiGILLZ2j/7Us=; b=aq4L5drvUXUOWqz2a1/Bx+be4/j1arvirrWozr4tw9me27yAg7gtbsWKRfa0xh8ZLG ERlLervsfbWei8yTjOCASqr/A8JCMF+NKPR7k7v7pXekCKx1U9rREJX4MtkjpvuKskBK ec1jaZ3vuiYvGLfEvnO0JE00UIydjq6qVM21ge/ZnRa98dPHkSLPiMapH3HW8UZ6mFLf kaWzG7CR+961qr2zWvt4C2dBe8hPDdK9Wd6CSqEQO7tUhKfk3NSAMW9OWwQ3klM+SD7E URKT/lUsX9YwejaIuXuwZJErua8zd+wSUupxKSVIhHDACD9l1ysiLvtf0zHwiF3F/QEr v2VQ==; darn=vger.kernel.org ARC-Authentication-Results: i=1; mx.google.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1782240339; x=1782845139; darn=vger.kernel.org; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=LVwncB4caCHuMDpKbFeo4MHlTUSmtwWDgRh+YGNPGK0=; b=kFTrXaGrBG7wuIVkIV/FxMkwUyGBZjtOJfEw0tLnwFBG3AjOStWaBy4TkxYmcbD2/3 f0QBf6xVPzvx39yM4ANzHt0nLdoZ+iCzDDk12Fejh1o4/4IyQ4MK/AcVSqLXFYI00sQk UvFwRCDUtGfZutDxhWGKptLk3rdLTUXc9M72WHTi2tY9Uh8emya1W1/6rbyKrFie3f9x PX9nghHMyM9lc0Vf3xU1pUPxMWkv05hu0ld1wYg05hmQ2IKNnz2cZwFowsN7ZMcfCVE8 1jLPu5P1npsnu6eMQcroEzZZlNI02xKsDZ42jGYCsHFJtNqPBR2pouDPJinbIwGd3UpQ p6xw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1782240339; x=1782845139; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=LVwncB4caCHuMDpKbFeo4MHlTUSmtwWDgRh+YGNPGK0=; b=nXNhX40V5jHhifspeqXuR20Lt3KAe9gRZC/6jIuTCFyyG30jziFe0WLI1tQ7ikGUYO 7pNGV6ujQLluAfCq1UsEPkQU6R7eVChTTcwr4RYcK1cevrvr5GIVL1ZZeJF3mW2LBKHf GJtpxQwrUONUPw1GLLaeDmOFKxk45dlgOaX8sulQgV1jNYoMC9pJHIJkU1Y5al3+OB9D Qo0Q1iO/OAzONSa4tAji4WWMhFB86M1sFGufQfh1/s3/XLew0mdFiDc/6KfT7XM1gMnz aShVmykwy362SeI8MPW9R6E2GPq2xvvILaV2GXEZxfeh08CNsjPnd6WLtGuHVlJRE0QE +tKg== X-Forwarded-Encrypted: i=1; AHgh+RrbyA1LQHa1e7sVeAsiLdG5XuoS1QpxpwiBSH2i1ZSszJ+YFm4qp/N0iBpCJO8jfrIFX8mFAG7E2yZHIXs=@vger.kernel.org X-Gm-Message-State: AOJu0YznIZtY4jGbRGI9Ua7QVveNwVR6Zh0dwUyY/ldmoW41uQgGOf0u IDDJRjhsIAkAUq4u3qbjj21eJNUUaVF+HzLmfOdszoWjThON4Ld1EATjJHoNlsOM6totQ6QGJ4y BGolmpJ6gBXPUv30VZpHTxzhh7+TJOo0= X-Gm-Gg: AfdE7cnhlkjT+0ulbYVWSyW8qby5bS2ZHEs5n6QZMn0lhy6BjdTRchYcJtaR2YTvcDs uTZs8WXiHjZwtmhoXG7V4xXIp9+jldDbP85gzuU/7Uftc5bOZzRjC10ekVxnqHBbTs2o04VoBFH 45jxr7EYbsOHIsj7ssTMKvb7SKGlmZ19z0DG+HEd4eVwKW90IexzOMPlrU8kyy2ENmgbEsijEuo bp5FD4BZ4kTreF2nWAa+IeFDJAoxHUUe3rQ8h49AfNsxcE8CpkksvRqOUxdY5fbl9QMZbF/g3zD +EfwCLNCyWXZlJGOdxcRS+PEJnTB X-Received: by 2002:a05:6000:22c4:b0:45e:fa38:c899 with SMTP id ffacd0b85a97d-46c084c816bmr138476f8f.4.1782240338997; Tue, 23 Jun 2026 11:45:38 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20260612193738.2183968-1-nphamcs@gmail.com> <20260612193738.2183968-4-nphamcs@gmail.com> In-Reply-To: From: Nhat Pham Date: Tue, 23 Jun 2026 11:45:27 -0700 X-Gm-Features: AVVi8CcGflRtAnYhAwHoECRZzxc8TT27o9VDjZ7vOQkQ1fmoj7wrI9DQrKaVgpE Message-ID: Subject: Re: [RFC PATCH v2 3/7] mm, swap: support physical swap as a vswap backend To: Yosry Ahmed Cc: akpm@linux-foundation.org, chrisl@kernel.org, kasong@tencent.com, hannes@cmpxchg.org, mhocko@kernel.org, roman.gushchin@linux.dev, shakeel.butt@linux.dev, david@kernel.org, muchun.song@linux.dev, shikemeng@huaweicloud.com, baoquan.he@linux.dev, baohua@kernel.org, youngjun.park@lge.com, chengming.zhou@linux.dev, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, qi.zheng@linux.dev, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, riel@surriel.com, gourry@gourry.net, haowenchao22@gmail.com, kernel-team@meta.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, Jun 22, 2026 at 5:23=E2=80=AFPM Yosry Ahmed wrot= e: > > On Fri, Jun 12, 2026 at 12:37:34PM -0700, Nhat Pham wrote: > > Add physical swap as a backend for the virtual swap layer. > > > > With physical swap backing, vswap can allocate a physical slot on > > demand when needed: as a fallback for zswap_store failures, or as > > the destination for zswap writeback. > > > > Each vswap entry's physical slot is tracked via a Pointer-tagged > > swap_table entry on the physical cluster (rmap back to the vswap > > entry). > > > > Suggested-by: Kairui Song > > Signed-off-by: Nhat Pham > > I didn't look through the rest of the series, but are there use cases > for calling folio_realloc_swap() without calling vswap_zswap_load() > first? I wonder if the realloc_swap API should take the swpentry > directly and do the load within? Something like > vswap_alloc_phys(swpentry, folio)? It's also use on the swapout fallback path! If zswap rejects the page or is disabled, and memory.zswap.writeback=3D1, then we allocate phys swap space. We probably don't wanna do zswap_load() there again :)