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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3EA6CC61DA4 for ; Thu, 23 Feb 2023 20:30:13 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id CFA296B0073; Thu, 23 Feb 2023 15:30:12 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id CAA3D6B0074; Thu, 23 Feb 2023 15:30:12 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B72C76B0075; Thu, 23 Feb 2023 15:30:12 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id A75056B0073 for ; Thu, 23 Feb 2023 15:30:12 -0500 (EST) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 64D8C1A099C for ; Thu, 23 Feb 2023 20:30:12 +0000 (UTC) X-FDA: 80499698664.08.5E1FB0B Received: from mail-yw1-f170.google.com (mail-yw1-f170.google.com [209.85.128.170]) by imf01.hostedemail.com (Postfix) with ESMTP id B7BF340019 for ; Thu, 23 Feb 2023 20:30:10 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b="B6/JiBkD"; spf=pass (imf01.hostedemail.com: domain of surenb@google.com designates 209.85.128.170 as permitted sender) smtp.mailfrom=surenb@google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1677184210; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=CMGzsrET5qE4cm3wL58ElWUmfAVE8Lnnb4W08Pj10+A=; b=zr1boPwBJr5PNJ7XNGdYx1WA3xBTCaQI0CVlF72X2ZsRHq3QoYTZwxzrtMWPOeOh3kYI1U e8HCDdqu6VJa0al1WiNM6aDtfn6cmrbg4EjPyddMhBUp/AZChBlZjm2VmKV6cy6boR7v2F tkNruf2Kc36XKyEAKOFliEyT49nM4S4= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b="B6/JiBkD"; spf=pass (imf01.hostedemail.com: domain of surenb@google.com designates 209.85.128.170 as permitted sender) smtp.mailfrom=surenb@google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1677184210; a=rsa-sha256; cv=none; b=2pstYZTXTU63l6HfA3OC9N6E3s1jk4P6KVEfqgN3G6lSKXiYH6JKxkpQlVTzYISKsoKwc6 aXeqM3nCVHYJRm/xR9VR1TrT2aX/iJkgRjgSWI3U/ulU+2lbcdQT5D5krIDIUGVU2qsnRi vtZ8Nl3oQPEBQ3nqQxNdh54A9yhjJi8= Received: by mail-yw1-f170.google.com with SMTP id 00721157ae682-536af432ee5so225660807b3.0 for ; Thu, 23 Feb 2023 12:30:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=to:subject:message-id:date:from:in-reply-to:references:mime-version :from:to:cc:subject:date:message-id:reply-to; bh=CMGzsrET5qE4cm3wL58ElWUmfAVE8Lnnb4W08Pj10+A=; b=B6/JiBkDjmKqddTlJFlMqnXK40lAYeDPRS4a3wigdEoxFsz1HP3cZ41O2hEXZV9Xol /rRDg2EuqZr4nqAPsi+Nqp2tUvIVu5sXgAPgl2d3pY56FfrlQvdNgLF/0el1elZs0sps MYpEft32MAnfenBesVLm9ejdsXPSP8e1VBVq6nYjBaNpd9GqxoaAZyXTGGniZgTblELz aIQNB7x2h1Hx32Nv4l8q7wdnu57zyoEQ2TTJOtjZY8xTfiqT5z8Xw6B3ZCMWWL/3u7Hg BvGhZFvkbFjcdYBCz+sycnQ5JDiZlEU9TnDAbdR8CsKpngdVEMtZfy5CmGVJkpie5XAW fKLQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=to:subject:message-id:date:from:in-reply-to:references:mime-version :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=CMGzsrET5qE4cm3wL58ElWUmfAVE8Lnnb4W08Pj10+A=; b=bzsoEZE+9z/1bJ9UsP3IIOe1UTo/epdA1Z1rpvr1kvlTB1Gki2WHeCGKLzY1DZwLsg DMk4c6auilL6HaSyM3dNstDWQoKRDkO9EjgBRMPIG4xzxfYvPfKcnMqZkMduhCKhF9T8 xVs0X36lLo7TE2n/QRZ09089MKiVD7/YDYth4qPt1yEuu+tLgTkv+d9AVucDYeFt0GcK xEkxw5AtHwqQ9I0iLR898sA9DHADgVES40Ifj8QmRL9UIztI7ttuEb2CCsztbDh+FVst 9qFBN0sBtxXi6UnAZ9YQnJIvXSMgswh+V4wjVG6dFWab5QbWciLTOjgBF7mBYq7LG6rn 4AHg== X-Gm-Message-State: AO0yUKXSxEU1QrcOqkgbKr4Ji7Kw0/QbjmCvpLTHni4mmTjGsKADX1yu OSEMnQMm00Hqtxj1LJzioakiiDAnN+rEUZBipxXzWg== X-Google-Smtp-Source: AK7set8a9nd1M3o5gtKjXRBIHs8kxt28mAUZ8uoVHl5ofJl5gBClpfYNWL1FfQgENoI8c6BT919QQlLsb6LhXxWAFZ8= X-Received: by 2002:a05:6902:1449:b0:a06:538f:265f with SMTP id a9-20020a056902144900b00a06538f265fmr3251368ybv.4.1677184209550; Thu, 23 Feb 2023 12:30:09 -0800 (PST) MIME-Version: 1.0 References: <20230216051750.3125598-1-surenb@google.com> <20230216051750.3125598-24-surenb@google.com> <20230223200616.kfnwwpuzuwq5hr7j@revolver> In-Reply-To: <20230223200616.kfnwwpuzuwq5hr7j@revolver> From: Suren Baghdasaryan Date: Thu, 23 Feb 2023 12:29:58 -0800 Message-ID: Subject: Re: [PATCH v3 23/35] mm/mmap: prevent pagefault handler from racing with mmu_notifier registration To: "Liam R. Howlett" , Suren Baghdasaryan , akpm@linux-foundation.org, michel@lespinasse.org, jglisse@google.com, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, mgorman@techsingularity.net, dave@stgolabs.net, willy@infradead.org, peterz@infradead.org, ldufour@linux.ibm.com, paulmck@kernel.org, mingo@redhat.com, will@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, chriscli@google.com, axelrasmussen@google.com, joelaf@google.com, minchan@google.com, rppt@kernel.org, jannh@google.com, shakeelb@google.com, tatashin@google.com, edumazet@google.com, gthelen@google.com, gurua@google.com, arjunroy@google.com, soheil@google.com, leewalsh@google.com, posk@google.com, michalechner92@googlemail.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 Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: B7BF340019 X-Stat-Signature: sqwhmorc3hezj7475k3iwsqxrmsg385k X-Rspam-User: X-HE-Tag: 1677184210-363727 X-HE-Meta: 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 0FAfo/7g MGNPZ3VsFqdKsnDHhBRUlqdsAj4U2dkIR9T+nhXuPMR4lIOG9b85mCiStRd0XjqBrd7O4VkyED7WK7WyX9aMQAnc+9dgNbmnKx/HLuzTN3Y0RVR8pTLQP2kVSB/pzo8H9IK/7ysWUghd07Qqrg3zYASUwNr233HH+bPac7k0ElUMSHHRfIQiQZhBuigObrmnpWSf3EsdW8rFMMDRdAt5dClJcKtGiG0vWQxvmLlIy8NF0/atv+38CLFAH1QvW9K9JgUZyq5FJh+7mSdDfz/k6xqSYjljCXwnMhQiCPXUW+a/Fzg0mF2CYBvWWX8ZRTn5iDgOaQPOyxPwoW9ZTpEVcmf7tDcnGWdRV4yX2DmffIri0Bol9all2s0xPX9Yg88Hov5tV0E5rYuLomiaihhe/EOoJtsewgbk/Y91QjqT/NeLwXJukXf5zrZSZlCea9i3mU4Z7kKkEv+gySZHkwSMgCmWsYQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Feb 23, 2023 at 12:06 PM Liam R. Howlett wrote: > > * Suren Baghdasaryan [230216 00:18]: > > Page fault handlers might need to fire MMU notifications while a new > > notifier is being registered. Modify mm_take_all_locks to write-lock all > > VMAs and prevent this race with page fault handlers that would hold VMA > > locks. VMAs are locked before i_mmap_rwsem and anon_vma to keep the same > > locking order as in page fault handlers. > > > > Signed-off-by: Suren Baghdasaryan > > --- > > mm/mmap.c | 9 +++++++++ > > 1 file changed, 9 insertions(+) > > > > diff --git a/mm/mmap.c b/mm/mmap.c > > index 00f8c5798936..801608726be8 100644 > > --- a/mm/mmap.c > > +++ b/mm/mmap.c > > @@ -3501,6 +3501,7 @@ static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping) > > * of mm/rmap.c: > > * - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for > > * hugetlb mapping); > > + * - all vmas marked locked > > * - all i_mmap_rwsem locks; > > * - all anon_vma->rwseml > > * > > @@ -3523,6 +3524,13 @@ int mm_take_all_locks(struct mm_struct *mm) > > > > mutex_lock(&mm_all_locks_mutex); > > > > + mas_for_each(&mas, vma, ULONG_MAX) { > > + if (signal_pending(current)) > > + goto out_unlock; > > + vma_start_write(vma); > > + } > > + > > + mas_set(&mas, 0); > > mas_for_each(&mas, vma, ULONG_MAX) { > > if (signal_pending(current)) > > goto out_unlock; > > Do we need a vma_end_write_all(mm) in the out_unlock unrolling? We can't really do that because some VMAs might have been locked before mm_take_all_locks() got called. So, we will have to wait until mmap write lock is dropped and vma_end_write_all() is called from there. Getting a signal while executing mm_take_all_locks() is probably not too common and won't pose a performance issue. > > Also, does this need to honour the strict locking order that we have to > add an entire new loop? This function is...suboptimal today, but if we > could get away with not looping through every VMA for a 4th time, that > would be nice. That's what I used to do until Jann pointed out the locking order requirement to avoid deadlocks in here: https://lore.kernel.org/all/CAG48ez3EAai=1ghnCMF6xcgUebQRm-u2xhwcpYsfP9=r=oVXig@mail.gmail.com/. > > > @@ -3612,6 +3620,7 @@ void mm_drop_all_locks(struct mm_struct *mm) > > if (vma->vm_file && vma->vm_file->f_mapping) > > vm_unlock_mapping(vma->vm_file->f_mapping); > > } > > + vma_end_write_all(mm); > > > > mutex_unlock(&mm_all_locks_mutex); > > } > > -- > > 2.39.1 > > > > -- > To unsubscribe from this group and stop receiving emails from it, send an email to kernel-team+unsubscribe@android.com. >