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 1DDB5C10F1B for ; Sat, 24 Dec 2022 08:12:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230323AbiLXIMX (ORCPT ); Sat, 24 Dec 2022 03:12:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55824 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230307AbiLXIMU (ORCPT ); Sat, 24 Dec 2022 03:12:20 -0500 Received: from mail-pg1-x54a.google.com (mail-pg1-x54a.google.com [IPv6:2607:f8b0:4864:20::54a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CB01DDF3A for ; Sat, 24 Dec 2022 00:12:18 -0800 (PST) Received: by mail-pg1-x54a.google.com with SMTP id l63-20020a639142000000b0047942953738so3502691pge.15 for ; Sat, 24 Dec 2022 00:12:18 -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=ItQBUrV0EvZiYOjtPn9RtcHJwdM5uCOC63vNEO/Cgn4=; b=IQNrJhCRWbch37b0zxiQ63klwB/GGCz0T3Ti+BnTbJFnWDAuKxZuxygKiPLeM+O0AR w/T2lFf+mrPfJE/QEm2dA04gLVnrUB0sjvh4mOGQ0L26Qki+z+qwi+gk41DAtyORCPyd xTjFieSO7GBH4ut5SB0J3jEXfQ7FMh3pxSwPoz/OHCGFw8TSmZKZxwP/JCiLOnektegW Vmxhwp1NU8QaK6s+ZiVaZ0vSUG4se+Ch/6vOTg54/jZg8pz+Dwnszf0rzMCW3udUjA4S 5zQdWNFo64+OlvLPScP5CEMif/f89OuQZi8ioPTgb23fkNwP4zciNWW7SJXWpZ/mQDF8 0MUQ== 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=ItQBUrV0EvZiYOjtPn9RtcHJwdM5uCOC63vNEO/Cgn4=; b=0frACKyDLZbTch2WHlZd/0uK1WDAuN663mnBn+ndXRCF71PWUnUL6Vvp6mDlUW2uJW daQSnKTqdxghihEh9BjYF8Wnazkawb73zSLhu7X8YQvcdu+g/Jf8azDDS8Tsdajhd20r 5hMm7+cvODiKL2VW/SQL6issuf+lMN/4tM7RJL6IA6lY9dThJ9Ap/X7TIOrdKZkIII1q CWWCDVGldMnxkw7f53KNsG+hvEbe5qd1c5d7rZBYRL8qnFmI0WBTVur1pmrDhbSFomAd WixAK78+JKfONFFOwIozxWNpRRsDlnDP4fQWOhjsoOkBssEwRnEOt33FHdFGoAk4SRhe ce2w== X-Gm-Message-State: AFqh2koboXz82cS+mKNaN6kdoXZq1BUpmtq70x8tvOPA7ns+cDjGZPA4 kWhxlR3YDQRACIZdDrftDuAyiZc/U1+4 X-Google-Smtp-Source: AMrXdXsO97Tf6V+s4D4bpX/S6mjRj56+jxyaaHemqoaz8G5Nwc8Bqz8Sa7QxAErbsdzR57ehavEIxWJ9q3OD X-Received: from zokeefe3.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:1b6]) (user=zokeefe job=sendgmr) by 2002:a17:902:c10a:b0:189:cf7a:b564 with SMTP id 10-20020a170902c10a00b00189cf7ab564mr893175pli.8.1671869538392; Sat, 24 Dec 2022 00:12:18 -0800 (PST) Date: Sat, 24 Dec 2022 00:12:03 -0800 In-Reply-To: <20221224081203.3193960-1-zokeefe@google.com> Mime-Version: 1.0 References: <20221224081203.3193960-1-zokeefe@google.com> X-Mailer: git-send-email 2.39.0.314.g84b9a713c41-goog Message-ID: <20221224081203.3193960-2-zokeefe@google.com> Subject: [PATCH v2 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 --- 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