From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lamorak.hansenpartnership.com (lamorak.hansenpartnership.com [198.37.111.173]) (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 0CD8313C816; Fri, 21 Mar 2025 17:00:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.37.111.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742576427; cv=none; b=jkiGS+RePihBFB0zSWBXr913gcaG7xx0XA31W1+tVRgIKiiLnjgIuizkCv3SX5Ck1XdX5UbY1DPWqpzTjm0m88/zv40hl8myLbR3AMrmf4hxDWU25/gvthbLN5kbZYPHlcpDJYS/oR/9wLUl1IPL/YmbjC9v5O5caId+wzZYn1I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742576427; c=relaxed/simple; bh=rg3MbuOKDm/Gk/PotzEpTnKaY2FHNg0kGGwO5K1Z9Ds=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=pByB+MI1fyzEa4MIPmTmkFQp391POfgHChBgE0vBqDOhp9PUcbz/CrSF3tc2YdLQvVCujTmLewOGe4mAjTFXL/vtkvha1pV9cJj/V9jZR5Ldl2H1feCao1/kUKYoUrDzk0YS2o6WLk8Sgf2ImpDhfaO0tjjsiPPHMkPbdx951ck= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=HansenPartnership.com; spf=pass smtp.mailfrom=HansenPartnership.com; dkim=pass (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b=oLjtlAf5; arc=none smtp.client-ip=198.37.111.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=HansenPartnership.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=HansenPartnership.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b="oLjtlAf5" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1742576425; bh=rg3MbuOKDm/Gk/PotzEpTnKaY2FHNg0kGGwO5K1Z9Ds=; h=Message-ID:Subject:From:To:Date:In-Reply-To:References:From; b=oLjtlAf5YWry6+HNQifHopRCvZuzZszi/aiW2mCZ9L48Uo0pSDP7JcEVdwjUipHwH K5Rmd37C/vzywkBQFiHtA/TPHmicLAS/hRiG/nJiqXL8+DM4RWlkelB/Os0Pc/IytY xl/ImOv3O9g5FA4NaFzb5EX8yE4bY1C9wdZ0bMnk= Received: from lingrow.int.hansenpartnership.com (unknown [IPv6:2601:5c4:4302:c21::a774]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519) (No client certificate requested) by lamorak.hansenpartnership.com (Postfix) with ESMTPSA id BFFA21C0396; Fri, 21 Mar 2025 13:00:24 -0400 (EDT) Message-ID: <62bfd49bc06a58e435431610256e722651e1e5ca.camel@HansenPartnership.com> Subject: Re: [LSF/MM/BPF TOPIC] Filesystem Suspend Resume From: James Bottomley To: Christoph Hellwig Cc: linux-fsdevel@vger.kernel.org, lsf-pc@lists.linux-foundation.org, "Rafael J. Wysocki" , Pavel Machek , Len Brown , linux-pm@vger.kernel.org Date: Fri, 21 Mar 2025 13:00:24 -0400 In-Reply-To: <576418420308d2511a4c155cc57cf0b1420c273b.camel@HansenPartnership.com> References: <0a76e074ef262ca857c61175dd3d0dc06b67ec42.camel@HansenPartnership.com> <576418420308d2511a4c155cc57cf0b1420c273b.camel@HansenPartnership.com> Autocrypt: addr=James.Bottomley@HansenPartnership.com; prefer-encrypt=mutual; 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 8mT2Eh9SkH+YVOmaKsajgZgrBxA7fWmGoxXswEVxJIFj3vW7yNc0C5HaUdYa5iGOMs4kg2ht4s7yy7NRQuh7BifWjo6BQ6k4S1H+6axZucxhSV1L6zN9d+lr3Xo/vy1unzA== Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.50.3 Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Fri, 2025-03-21 at 08:34 -0400, James Bottomley wrote: [...] > Let me digest all that and see if we have more hope this time around. OK, I think I've gone over it all. The biggest problem with resurrecting the patch was bugs in ext3, which isn't a problem now.=20 Most of the suspend system has been rearchitected to separate suspending user space processes from kernel ones. The sync it currently does occurs before even user processes are frozen. I think (as most of the original proposals did) that we just do freeze all supers (using the reverse list) after user processes are frozen but just before kernel threads are (this shouldn't perturb the image allocation in hibernate, which was another source of bugs in xfs). There's a final wrinkle in that if I plumb efivarfs into all this, it needs to know whether it was a hibernate or suspend, but I can add that as an extra freeze_holder flag. This looked like such a tiny can of worms when I opened it; now it seems to be a lot bigger on the inside than it was on the outside, sigh. Regards, James