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 69C8BC67871 for ; Mon, 9 Jan 2023 20:58:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237950AbjAIU6r (ORCPT ); Mon, 9 Jan 2023 15:58:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34734 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237782AbjAIU5f (ORCPT ); Mon, 9 Jan 2023 15:57:35 -0500 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C27E58CD03 for ; Mon, 9 Jan 2023 12:55:01 -0800 (PST) Received: by mail-yb1-xb4a.google.com with SMTP id z17-20020a25e311000000b00719e04e59e1so10333479ybd.10 for ; Mon, 09 Jan 2023 12:55:01 -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=kEbjJObwF3X8F3sFkf3mioj7FiTBVSLxL3AOZVg1QSY=; b=b707Zl9+U9/mZ9c+XkHaueCkegKOCNYI/oVAEusRFU63I3srOxecFlDkxyKx//4mW5 JwP5obEgccip2H4R9+fiuFL4CW2k5fc/GSQhSK1HsVxo3ZKjTR0Lux66eUg0E3PQlBTw wXh6GkCABKuopnTH7q3BfoKfyBQ/HE6fsvI1JacGKFSqz7wW0ul/c07mqYyM4k4N+tIJ sPYdgU87tyvftSSm83lgw37DswrvUBJMsShqXbiuQjXDGVNwSgoByZHvozZ1Xmfis7g3 cB964lLozfT6WEMDCdFsl0vR2EiUHB+3pHP9fkmg+z92l6SffusdjR7B04cQIU05PEZE 4Ang== 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=kEbjJObwF3X8F3sFkf3mioj7FiTBVSLxL3AOZVg1QSY=; b=On5XH7T/XztBTIHK1F0jbT3+7EpKtly/sB/VELy5QXD64CES6fsN4Df0fL6okyF+sS cm8TpIp+16HIV2IAmsYDzfFra/o1/rO9Ivt8WkYS+ylN7Frx+hZAW+FjH/qeQ9nw0lt9 yU+qIWO8ZEZmeOehDze2kSA6MImtN65Cz0M3rv+cJBXSGEQaO7qxTO/VCX56KQ3OcYGR k7IPUzZMH0P3CmUqcwIu2YX6DESYCCHF+ZmZ/z/HS9YFEChTsHDD9dl6nmqPMvJR76Ui zEn57ofBgclev2pSkbePmANZpd1XidywhVOOEeZWyjD5UCyHeWX9+PgKCMhjYQm+5OfG mwiQ== X-Gm-Message-State: AFqh2kpezNhwfZi/psI2KulaQFNumhrpEUXU/e2Un16i3JiAyyLH5NmZ w7SukcgcjZuk8lUTpsf9Bn/1QmgQWGU= X-Google-Smtp-Source: AMrXdXuMlfQ+hsH5bYnRbFVRQKfHDnoMxNv1bo1mLunTWqhQUT5+3qxDxTtfm+RaU7eYfnfY1D8yBkPOjiE= X-Received: from surenb-desktop.mtv.corp.google.com ([2620:15c:211:200:9393:6f7a:d410:55ca]) (user=surenb job=sendgmr) by 2002:a25:9304:0:b0:7bf:ffcb:79d7 with SMTP id f4-20020a259304000000b007bfffcb79d7mr163411ybo.446.1673297701437; Mon, 09 Jan 2023 12:55:01 -0800 (PST) Date: Mon, 9 Jan 2023 12:53:27 -0800 In-Reply-To: <20230109205336.3665937-1-surenb@google.com> Mime-Version: 1.0 References: <20230109205336.3665937-1-surenb@google.com> X-Mailer: git-send-email 2.39.0.314.g84b9a713c41-goog Message-ID: <20230109205336.3665937-33-surenb@google.com> Subject: [PATCH 32/41] mm: prevent userfaults to be handled under per-vma lock From: Suren Baghdasaryan To: akpm@linux-foundation.org Cc: michel@lespinasse.org, jglisse@google.com, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, mgorman@techsingularity.net, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, peterz@infradead.org, ldufour@linux.ibm.com, laurent.dufour@fr.ibm.com, paulmck@kernel.org, luto@kernel.org, songliubraving@fb.com, peterx@redhat.com, david@redhat.com, dhowells@redhat.com, hughd@google.com, bigeasy@linutronix.de, kent.overstreet@linux.dev, punit.agrawal@bytedance.com, lstoakes@gmail.com, peterjung1337@gmail.com, rientjes@google.com, axelrasmussen@google.com, joelaf@google.com, minchan@google.com, jannh@google.com, shakeelb@google.com, tatashin@google.com, edumazet@google.com, gthelen@google.com, gurua@google.com, arjunroy@google.com, soheil@google.com, hughlynch@google.com, leewalsh@google.com, posk@google.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-kernel@vger.kernel.org, kernel-team@android.com, surenb@google.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Due to the possibility of handle_userfault dropping mmap_lock, avoid fault handling under VMA lock and retry holding mmap_lock. This can be handled more gracefully in the future. Signed-off-by: Suren Baghdasaryan Suggested-by: Peter Xu --- mm/memory.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/mm/memory.c b/mm/memory.c index 20806bc8b4eb..12508f4d845a 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -5273,6 +5273,13 @@ struct vm_area_struct *lock_vma_under_rcu(struct mm_struct *mm, if (!vma->anon_vma) goto inval; + /* + * Due to the possibility of userfault handler dropping mmap_lock, avoid + * it for now and fall back to page fault handling under mmap_lock. + */ + if (userfaultfd_armed(vma)) + goto inval; + if (!vma_read_trylock(vma)) goto inval; -- 2.39.0