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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 74C23C4332F for ; Sat, 24 Dec 2022 08:20:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230431AbiLXIUt (ORCPT ); Sat, 24 Dec 2022 03:20:49 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58902 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229487AbiLXIUl (ORCPT ); Sat, 24 Dec 2022 03:20:41 -0500 Received: from mail-pf1-x44a.google.com (mail-pf1-x44a.google.com [IPv6:2607:f8b0:4864:20::44a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 13A32BC31 for ; Sat, 24 Dec 2022 00:20:40 -0800 (PST) Received: by mail-pf1-x44a.google.com with SMTP id x33-20020a056a0018a100b00577808a75c9so3616285pfh.13 for ; Sat, 24 Dec 2022 00:20:40 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=qHBgmM5FyY8tFESb+UZtZ7YHBNCfgMkVXvmSjVkn95c=; b=YIdgdTDlm/0rnNXmV/Ouxem7vSavubkjE/mlXtu3l2VNJp+VcHRwcxAqLRlRCht33T RjLRwnMH+83r29SKKJIBeQCmhsdRiiPnHm5RybHePQWkJtrnUBA8wvZoTReit57ZSQgj rb79t5GaIQFUYM+TelnB/YDfk3efw2LoXwE83oTT7NsNN0yVZUilRddaPER0eHid1zOn rFXxu33AQ1X9TIKISEarvlDOHXaIVzVHkuQDAvEdPao9/mUtIRnGOziez9pbYJtslSrk 9oofFPc8G704Z1XNJl+3ESz0Xb773tj4avam3C858QsEl+9wi5oCzl9RAxGV4CrpOS/U Na7w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=qHBgmM5FyY8tFESb+UZtZ7YHBNCfgMkVXvmSjVkn95c=; b=LgLOrDcLkSppSqOdr7+pgeuWSwjJxcnu7PBWud5qU0aUS4J3A7Gd+FV6OeFEb4O/Fu Zio//6Ud97Jn0KFSx7VIdSHysBNwaNftdknwf1QipwLlRBd6Lc6SH1/VquhblFJWJcWS qicP8apOaZO1M9Aey4g+Dbg3dEhD/vdLrAbINhEb8oFOjMTp0aFan4IchKciaGpki+wY AGkbDWXqHWNDRKHbwncOq7JHGBWB9+a1wgVlkmLP4AJ4xK8lxE2zXpyGmb95yKlbjUjv hbd/+3rIKI9d6NNARefKm3d1pw6TPA+GvRHTalIGix63jK3Zf8UBOXEIZ6sQvezmSbMI RpPg== X-Gm-Message-State: AFqh2koJfN5coKfsq4P6YZJszl6KgJ6MD56AtDwa9d/8o8oTbgKOhYf4 98YrsDiltAWHWLj6cvZlbyZxQWcszZ51 X-Google-Smtp-Source: AMrXdXtpnA9oa+kcg8UCtzsH2+zbPi8cE8h5FFqA3g8bAXygXEp5KA+R6LlQvnatJIrsuUCVCjwgqNmjUsVJ X-Received: from zokeefe3.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:1b6]) (user=zokeefe job=sendgmr) by 2002:a17:90a:f018:b0:21a:150d:fe63 with SMTP id bt24-20020a17090af01800b0021a150dfe63mr1313517pjb.73.1671870039401; Sat, 24 Dec 2022 00:20:39 -0800 (PST) Date: Sat, 24 Dec 2022 00:20:35 -0800 In-Reply-To: <20221224082035.3197140-1-zokeefe@google.com> Mime-Version: 1.0 References: <20221224082035.3197140-1-zokeefe@google.com> X-Mailer: git-send-email 2.39.0.314.g84b9a713c41-goog Message-ID: <20221224082035.3197140-2-zokeefe@google.com> Subject: [PATCH v3 2/2] mm/shmem: restore SHMEM_HUGE_DENY precedence over MADV_COLLAPSE From: "Zach O'Keefe" To: linux-mm@kvack.org Cc: stable@vger.kernel.org, linux-kernel@vger.kernel.org, Andrew Morton , Hugh Dickins , Yang Shi , "Zach O'Keefe" Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org SHMEM_HUGE_DENY is for emergency use by the admin, to disable allocation of shmem huge pages if, for example, a dangerous bug is found in their usage: see "deny" in Documentation/mm/transhuge.rst. An app using madvise(,,MADV_COLLAPSE) should not be allowed to override it: restore its precedence over shmem_huge_force. Restore SHMEM_HUGE_DENY precedence over MADV_COLLAPSE. Fixes: 7c6c6cc4d3a2 ("mm/shmem: add flag to enforce shmem THP in hugepage_vma_check()") Suggested-by: Hugh Dickins Signed-off-by: Zach O'Keefe Cc: Yang Shi Cc: stable@vger.kernel.org --- v2->v3: Add 'Cc: stable@vger.kernel.org' as per stable-kernel-rules. v1->v2: Update changelog, and add note explaining rationale for backporting (Andrew Morton). Request to backport this to 6.1.X stable. We'd like SHMEM_HUGE_DENY to take precedence over MADV_COLLAPSE. If we make this change later, it will be a userspace API change. As such, 6.1 cannot be allowed to continue as-is, and we should fix up the code there. --- mm/shmem.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/mm/shmem.c b/mm/shmem.c index c301487be5fb..0005ab2c29af 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -478,12 +478,10 @@ bool shmem_is_huge(struct vm_area_struct *vma, struct inode *inode, if (vma && ((vma->vm_flags & VM_NOHUGEPAGE) || test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))) return false; - if (shmem_huge_force) - return true; - if (shmem_huge == SHMEM_HUGE_FORCE) - return true; if (shmem_huge == SHMEM_HUGE_DENY) return false; + if (shmem_huge_force || shmem_huge == SHMEM_HUGE_FORCE) + return true; switch (SHMEM_SB(inode->i_sb)->huge) { case SHMEM_HUGE_ALWAYS: -- 2.39.0.314.g84b9a713c41-goog