From nobody Wed Apr 8 12:12:34 2026 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 26104FA3740 for ; Tue, 25 Oct 2022 18:22:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232559AbiJYSV7 (ORCPT ); Tue, 25 Oct 2022 14:21:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50890 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232227AbiJYSV4 (ORCPT ); Tue, 25 Oct 2022 14:21:56 -0400 Received: from mail-yw1-x114a.google.com (mail-yw1-x114a.google.com [IPv6:2607:f8b0:4864:20::114a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1C7F5DD89D for ; Tue, 25 Oct 2022 11:21:56 -0700 (PDT) Received: by mail-yw1-x114a.google.com with SMTP id 00721157ae682-360a7ff46c3so124889277b3.12 for ; Tue, 25 Oct 2022 11:21:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=PjNoCfBC/CKwMAwiLtsnaqEW9HWbqcvaYiZFCHqhX1A=; b=cUt63EGPJ5XLXHEiRR83p6e5nk3wF+EccI3J2Nj4Hz7sd+o45EdjHmClaVdJS7D6Qt SRVj8/gV7ow6GDJ8o9U0wqDQuR4bhJD648XzGLZIF6bPN1Sdx3E6Rg7CDPlZWdwOkQgp AldXSSSnsZD7zLMgOdb0Vfa/h8JHe098M+X4gSZKtZWQWp5p15UcDWhAiMMLrjUjhkcY KC0eBsTNKsCRaOvTdGIHQ6ESz+Ix1YWpg7YnPKEM4Ti4Gz2qXJY47W47EziC/8C/dDfo 8xbZi5AbaDJ/hjFTwNPbJswDGS8yutCtZxwos1qagpx/I6fIYQdakdLMhuiTDm8H//iZ 9INg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=PjNoCfBC/CKwMAwiLtsnaqEW9HWbqcvaYiZFCHqhX1A=; b=MZ1EczwRbEvklu/vGvd5kF3H8qeGl/Ud9T+4TZ0SXwp+EyucTM2bKPng1d2tcSQpg6 ZhNvKz+zKTgHNfsffUJZJ5ZtxF/Ob/6MveoHGErMuy/i4mRE7buSTG5gtmodXFDugpPg Y2UUgOs+V+k0i/L68Kr4PWW+AuAE7G9/UK26Jw25bMA/batsR1IhdvlBv7CZqAFbvi9e CXFLJFaTltbmUQ9qmzPcZacfst5KHrbYNAlrxzsh4dEZ+1Vw6A8lPBw96t6jNJTC4m7J 3p3hr+1rCDJy8ONI54DHmoTfRhXmS4ruFtwyUlrBSEyiyPkGkn+0BBdoTHMwcf2faOZL RlHQ== X-Gm-Message-State: ACrzQf32zVUZLwulFsItbE5jwasJhJX4RGj5odRl8tO2M+BJ+ZUwfy7q PT2tlUbGMHYRANM29i1hnpKm9x/dEsuC2714s9yd X-Google-Smtp-Source: AMsMyM4O87oXuKbv1CK6ykDEbUdHUhv03vaFJfj6qvi2cGjc27L1Ng0hWt6v43WJjuwTFmjgJpiMHYC0BIw0H/MfKP8n X-Received: from ajr0.svl.corp.google.com ([2620:15c:2d4:203:9558:df20:7923:f362]) (user=axelrasmussen job=sendgmr) by 2002:a0d:cc51:0:b0:36c:98b0:dc38 with SMTP id o78-20020a0dcc51000000b0036c98b0dc38mr12308042ywd.275.1666722115408; Tue, 25 Oct 2022 11:21:55 -0700 (PDT) Date: Tue, 25 Oct 2022 11:21:49 -0700 Mime-Version: 1.0 X-Mailer: git-send-email 2.38.0.135.g90850a2211-goog Message-ID: <20221025182149.3076870-1-axelrasmussen@google.com> Subject: [PATCH] userfaultfd: wake on unregister for minor faults as well as missing From: Axel Rasmussen To: Alexander Viro , Andrew Morton , Peter Xu , Mike Kravetz Cc: Axel Rasmussen , Lokesh Gidra , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" This was an overlooked edge case when minor faults were added. In general, minor faults have the same rough edge here as missing faults: if we unregister while there are waiting threads, they will just remain waiting forever, as there is no way for userspace to wake them after unregistration. To work around this, userspace needs to carefully wake everything before unregistering. So, wake for minor faults just like we already do for missing faults as part of the unregistration process. Cc: stable@vger.kernel.org Fixes: 7677f7fd8be7 ("userfaultfd: add minor fault registration mode") Reported-by: Lokesh Gidra Signed-off-by: Axel Rasmussen --- fs/userfaultfd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 07c81ab3fd4d..7daee4b9481c 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -1606,7 +1606,7 @@ static int userfaultfd_unregister(struct userfaultfd_= ctx *ctx, start =3D vma->vm_start; vma_end =3D min(end, vma->vm_end); =20 - if (userfaultfd_missing(vma)) { + if (userfaultfd_missing(vma) || userfaultfd_minor(vma)) { /* * Wake any concurrent pending userfault while * we unregister, so they will not hang --=20 2.38.0.135.g90850a2211-goog