From patchwork Tue Oct 25 18:21:49 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Axel Rasmussen X-Patchwork-Id: 13019688 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 B9B19FA373E for ; Tue, 25 Oct 2022 18:21:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232533AbiJYSV6 (ORCPT ); Tue, 25 Oct 2022 14:21:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50894 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229544AbiJYSV5 (ORCPT ); Tue, 25 Oct 2022 14:21:57 -0400 Received: from mail-yw1-x1149.google.com (mail-yw1-x1149.google.com [IPv6:2607:f8b0:4864:20::1149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1E350DD8A9 for ; Tue, 25 Oct 2022 11:21:56 -0700 (PDT) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-36b7cfda276so77261157b3.1 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=5ovnUH0cShQDYdgG59szmxOcLex2XfwZikif8OHkY/zBy7XmBSkHecwwMvErTVr7ra BRR/E/7XAkhvU4VGCR+0WJE+eFHztxEKsyi8MyjELaHcsfIc9IGwErw3PfU1RGsODQww jSISJuwAidxRYbppSakAp+5vYS4pnf0bZ92WSnUjr5xwotdjbkcCRLcMpC+nnp4Ipbrp KhkjqJk/ODxluw+BEYT+e+hz56rr6gn8PVAGqzeoD+hhixrEk0r1H3v7Wt1DLUO1K2PI mjxbua5lihLcaf8RS+Xs9rOkDhTw6Dh3sukPGnSVw18c/C1RiHVrinx54VuYgCIazWmN WXaA== X-Gm-Message-State: ACrzQf0i+ijAIm/iVbvxCjTOSfR3m7GCHEaxzHQFnMu/sIqtNY+B6bK7 JF25NJSbVAWyOyJS25d9IAcDj8hC8Fs9H6NDGNeS 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-fsdevel@vger.kernel.org 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 = vma->vm_start; vma_end = min(end, vma->vm_end); - if (userfaultfd_missing(vma)) { + if (userfaultfd_missing(vma) || userfaultfd_minor(vma)) { /* * Wake any concurrent pending userfault while * we unregister, so they will not hang