From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2BBA2C433FE for ; Wed, 27 Apr 2022 23:16:57 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4A6446B0071; Wed, 27 Apr 2022 19:16:57 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4571D6B0073; Wed, 27 Apr 2022 19:16:57 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2F6A36B0074; Wed, 27 Apr 2022 19:16:57 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.26]) by kanga.kvack.org (Postfix) with ESMTP id 19D276B0071 for ; Wed, 27 Apr 2022 19:16:57 -0400 (EDT) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id CE8F5CAE for ; Wed, 27 Apr 2022 23:16:56 +0000 (UTC) X-FDA: 79404221232.15.3CDA7F6 Received: from mail-pl1-f173.google.com (mail-pl1-f173.google.com [209.85.214.173]) by imf22.hostedemail.com (Postfix) with ESMTP id AD3CDC002F for ; Wed, 27 Apr 2022 23:16:55 +0000 (UTC) Received: by mail-pl1-f173.google.com with SMTP id h12so2822411plf.12 for ; Wed, 27 Apr 2022 16:16:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=HA2iOZcTH9xcoVq+fhYi3f+JG1jZPj5iAWQGBU6dxYk=; b=M100Rgh1scYfFJVKHX6QedUDxXFHqefXLnvT4SqpUd/oHlGHbb/oobYGJFfZlvRt1M 95u5K/iCnx6NQ7kgK7bkszLk8x7ofF3bQKGcGV45CNFuq4OUGo/RYoEh4F3EVIvemdEx yOFupPUtEIQR2vhi+lhYq1DTpri8x/xGnjCBCf1N36k55KMSggE7TSA7G5uRqI1wT1zO J7cNpB211LLtBzO2XzHUH5cdVhbLWGjq+bDG09a3GHhMkBuqZls7iw92MiCcPd+FGFvc Z2TGRypKxvKunQrWePC0n4oj+29gCKwlaf54Vbgu4O74ohCNVv39Omp0RAR38diwNweB 9igQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=HA2iOZcTH9xcoVq+fhYi3f+JG1jZPj5iAWQGBU6dxYk=; b=8Rzttkm83kcUoUUnmDIw/0+hq8V+gpxgrzwXRPoyDg2UsCVfI5IrNZfiadzP39+u9k n1ZptalfoP4N4WG6s8+e3ejz8EVshscVx7rdEx/KAsqE2oYMNJZn1Y6MxkxMcrc6KS62 axBOCsSMGJxNw8LNX2bOjZ3JRKNZumayHb7UVHUlayRWOQWw+CBMWwKb2QzR0MYH9uAJ NNq+PMR9Bx2renq4PvIgp5IBbXxhX3REmk07w1siabmwslv1so3Y1q38V5q9am8HgJQa WAwZOil88s2GVYmJTohnlYo6V/uw12Y/9jfJ0IjcuZe077Vmtm1d9d2ZdbE76mxckBLT ILfw== X-Gm-Message-State: AOAM530C0uTft0Zv+JbNaQwYuFscf31fx8Mmyizguwmf3LahhOSH8F8u K+cK0ts6lDnNSKzRvDO7gzOTGhpoRcJDWiCaiic= X-Google-Smtp-Source: ABdhPJwQD/s4Wm0t1d5fd85VE3pA75rhD0V4WeNDy9GUto3y7CAzPGk0OO4/YD3GwumzVQoz/fYfJTWJroTeWij17TU= X-Received: by 2002:a17:90b:4b07:b0:1db:c488:7394 with SMTP id lx7-20020a17090b4b0700b001dbc4887394mr2634716pjb.21.1651101415382; Wed, 27 Apr 2022 16:16:55 -0700 (PDT) MIME-Version: 1.0 References: <20220404200250.321455-1-shy828301@gmail.com> In-Reply-To: From: Yang Shi Date: Wed, 27 Apr 2022 16:16:41 -0700 Message-ID: Subject: Re: [v3 PATCH 0/8] Make khugepaged collapse readonly FS THP more consistent To: Matthew Wilcox Cc: Vlastimil Babka , "Kirill A. Shutemov" , Miaohe Lin , Song Liu , Rik van Riel , Zi Yan , "Theodore Ts'o" , Andrew Morton , Linux MM , Linux FS-devel Mailing List , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" X-Stat-Signature: iep664k147g1ms5po4gityh564gbnemi Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=M100Rgh1; spf=pass (imf22.hostedemail.com: domain of shy828301@gmail.com designates 209.85.214.173 as permitted sender) smtp.mailfrom=shy828301@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: AD3CDC002F X-HE-Tag: 1651101415-698333 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Apr 27, 2022 at 1:59 PM Matthew Wilcox wrote: > > On Mon, Apr 04, 2022 at 05:48:49PM -0700, Yang Shi wrote: > > When khugepaged collapses file THPs, its behavior is not consistent. > > It is kind of "random luck" for khugepaged to see the file vmas (see > > report: https://lore.kernel.org/linux-mm/00f195d4-d039-3cf2-d3a1-a2c88de397a0@suse.cz/) > > since currently the vmas are registered to khugepaged when: > > - Anon huge pmd page fault > > - VMA merge > > - MADV_HUGEPAGE > > - Shmem mmap > > > > If the above conditions are not met, even though khugepaged is enabled > > it won't see any file vma at all. MADV_HUGEPAGE could be specified > > explicitly to tell khugepaged to collapse this area, but when > > khugepaged mode is "always" it should scan suitable vmas as long as > > VM_NOHUGEPAGE is not set. > > I don't see that as being true at all. The point of this hack was that > applications which really knew what they were doing could enable it. > It makes no sense to me that setting "always" by the sysadmin for shmem > also force-enables ROTHP, even for applications which aren't aware of it. > > Most telling, I think, is that Song Liu hasn't weighed in on this at > all. It's clearly not important to the original author. Song Liu already acked the series, please see https://lore.kernel.org/linux-mm/96F2D93B-2043-44C3-8062-C639372A0212@fb.com/