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 X-Spam-Level: X-Spam-Status: No, score=-15.1 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5BD82C433E2 for ; Mon, 31 Aug 2020 14:41:20 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 1B35320767 for ; Mon, 31 Aug 2020 14:41:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="aH/j8WKX" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1B35320767 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id AE9DE6B005C; Mon, 31 Aug 2020 10:41:19 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id AC1B76B005D; Mon, 31 Aug 2020 10:41:19 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9D6AE6B0062; Mon, 31 Aug 2020 10:41:19 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0183.hostedemail.com [216.40.44.183]) by kanga.kvack.org (Postfix) with ESMTP id 78C5B6B005C for ; Mon, 31 Aug 2020 10:41:19 -0400 (EDT) Received: from smtpin20.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 1EC32180AD806 for ; Mon, 31 Aug 2020 14:41:19 +0000 (UTC) X-FDA: 77211126678.20.boat70_410a77327090 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin20.hostedemail.com (Postfix) with ESMTP id E378C180C07A3 for ; Mon, 31 Aug 2020 14:41:18 +0000 (UTC) X-HE-Tag: boat70_410a77327090 X-Filterd-Recvd-Size: 3869 Received: from mail-lf1-f67.google.com (mail-lf1-f67.google.com [209.85.167.67]) by imf37.hostedemail.com (Postfix) with ESMTP for ; Mon, 31 Aug 2020 14:41:18 +0000 (UTC) Received: by mail-lf1-f67.google.com with SMTP id w11so1632753lfn.2 for ; Mon, 31 Aug 2020 07:41:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=5jdf7Yr1a6XX4TRwS1JHRRHr0CFyp0wrlJUOIn8FHr8=; b=aH/j8WKXZPdvikd5WEObfSDw9GR1wJDjg8Q3jQu4nRVY9eQMhZVxWM6/5we9KIEqbG dEL/W1lGnc4l5SckXCn8cshObUaR3qEffqA4aJ1jnqH+OHCZQA0TjM7SyTFMRscUPOqU p9+/ggGI6gxE5rfLwBkj2Pd9U7EfrTXd7A2ff4+FhWHr8PSG+gcNWLoibjGbSQTcHBNt kLxaT7IxEGAYoT1p4dkzBiY9HqNaZ3YL4qctWQ8QDjbfiqLje6MQtdUr0x5L25/dXVDw xx8fbfrVbGopBll7Hf8nNsmdFOuFyWnUA8itQlXufL86bh3cM9BfEEF1jBSp4pnucC7Y 18FA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=5jdf7Yr1a6XX4TRwS1JHRRHr0CFyp0wrlJUOIn8FHr8=; b=k2/b5CNdhb7zmgPLpDG3EEOw4wgDiJA6Zy5UYjtQPrXykQvWMMfVA5OrzxfyZUBTET 0YQR31cfqjjsnn+P0dlz0x0N6DcEXxxxokPDsG46Lngy72UCi2h3Fc+6mxijUzs8tf7n OPXX9swSbtrTcfsBM0/Ya6oq2q3nqKF1sFE6hkY4hwAjcvzhr7aszKlq+kh6hpU7auxo OMH0ZN1ZKZmkMDWaxeclqJV7kkd7lF9/u5GJAGsMNP0tUo8A/8pwkJdOL+prjOdccIEd rSjpptaiCGHK4Jk1v/wiobhbZh5b10fRyDiJ+EXdD3rFf02LwrdTSJJijnmskncdNDlJ SeFw== X-Gm-Message-State: AOAM530RQYjST+sHSMJ2EotBjgywLI15j2maAc8W811RnAy8r/keh7Fe ZV2/+FzZwB1G4KXMUjSXDDSM81OxwKGD17kbJbg7SQ== X-Google-Smtp-Source: ABdhPJzyliB5lE1nzTQObWc+yrnVQDwbEMzPDyzwKQjR4ExISbfjpW4peJBU8buMyH9dXJeEg+86459vcjM6z2maAYI= X-Received: by 2002:ac2:47ec:: with SMTP id b12mr889283lfp.124.1598884876690; Mon, 31 Aug 2020 07:41:16 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Shakeel Butt Date: Mon, 31 Aug 2020 07:41:05 -0700 Message-ID: Subject: Re: [PATCH 3/5] shmem: shmem_writepage() split unlikely i915 THP To: Hugh Dickins Cc: Andrew Morton , Alex Shi , Johannes Weiner , Michal Hocko , Mike Kravetz , Matthew Wilcox , Qian Cai , Chris Wilson , Kuo-Hsin Yang , LKML , Linux MM Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: E378C180C07A3 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 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 Sun, Aug 30, 2020 at 2:04 PM Hugh Dickins wrote: > > drivers/gpu/drm/i915/gem/i915_gem_shmem.c contains a shmem_writeback() > which calls shmem_writepage() from a shrinker: that usually works well > enough; but if /sys/kernel/mm/transparent_hugepage/shmem_enabled has > been set to "force" (documented as "Force the huge option on for all - > very useful for testing"), shmem_writepage() is surprised to be called > with a huge page, and crashes on the VM_BUG_ON_PAGE(PageCompound) (I > did not find out where the crash happens when CONFIG_DEBUG_VM is off). > > LRU page reclaim always splits the shmem huge page first: I'd prefer not > to demand that of i915, so check and split compound in shmem_writepage(). > > Fixes: 2d6692e642e7 ("drm/i915: Start writeback from the shrinker") > Signed-off-by: Hugh Dickins > Cc: stable@vger.kernel.org # v5.3+ Reviewed-by: Shakeel Butt