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[216.228.121.64]) by mx.google.com with ESMTPS id j66si1235852ywc.423.2019.02.22.14.42.09 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 22 Feb 2019 14:42:09 -0800 (PST) Received-SPF: pass (google.com: domain of rcampbell@nvidia.com designates 216.228.121.64 as permitted sender) client-ip=216.228.121.64; Authentication-Results: mx.google.com; dkim=pass header.i=@nvidia.com header.s=n1 header.b=Nc3wStqM; spf=pass (google.com: domain of rcampbell@nvidia.com designates 216.228.121.64 as permitted sender) smtp.mailfrom=rcampbell@nvidia.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=nvidia.com Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqemgate15.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Fri, 22 Feb 2019 14:42:06 -0800 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Fri, 22 Feb 2019 14:42:08 -0800 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Fri, 22 Feb 2019 14:42:08 -0800 Received: from rcampbell-dev.nvidia.com (172.20.13.39) by HQMAIL101.nvidia.com (172.20.187.10) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Fri, 22 Feb 2019 22:42:08 +0000 Subject: Re: [PATCH v5 8/9] mm/mmu_notifier: mmu_notifier_range_update_to_read_only() helper To: , , Andrew Morton CC: , =?UTF-8?Q?Christian_K=c3=b6nig?= , Joonas Lahtinen , Jani Nikula , Rodrigo Vivi , Jan Kara , Andrea Arcangeli , Peter Xu , Felix Kuehling , Jason Gunthorpe , Ross Zwisler , Dan Williams , Paolo Bonzini , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Michal Hocko , John Hubbard , , , , Arnd Bergmann References: <20190219200430.11130-1-jglisse@redhat.com> <20190219200430.11130-9-jglisse@redhat.com> From: Ralph Campbell Message-ID: <9da5e3b9-7f4a-49ee-bf80-024e5aed20a1@nvidia.com> Date: Fri, 22 Feb 2019 14:42:08 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.0 MIME-Version: 1.0 In-Reply-To: <20190219200430.11130-9-jglisse@redhat.com> X-Originating-IP: [172.20.13.39] X-ClientProxiedBy: HQMAIL103.nvidia.com (172.20.187.11) To HQMAIL101.nvidia.com (172.20.187.10) Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: quoted-printable DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1550875326; bh=mtXo/OgTrDWenFtgKz94DgciMW8dOaQHFFYZnjJ+Qp0=; h=X-PGP-Universal:Subject:To:CC:References:From:Message-ID:Date: User-Agent:MIME-Version:In-Reply-To:X-Originating-IP: X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=Nc3wStqMc92w+r1iPlq9rgZ+vhAdWvC7XW8dkhwHHCmx+cNeaVKN6yWaoSYkFGqvT uhymWbKVsZcyJTFIgkUtdKMW/Tsuv33gN/wOITb98h85ko32ucaIGihP8IVsWu63e+ RLiXSb3H/jUiJzFLcXYhasBMoZ4g7EP2Tp1xfl0aq1qDPn4bEwy8XsCtD5FknLXjCx S/Ipg5VGk57i+O7iRu0wRw+y7pSIDnIzcLzfrQz7q0vQ0X4njJ7g8SGd51l5tKEN25 Wioa0sixuhaYxOZPKygwhRvB0YPxY2SUyYImiqOF25igrTWAzBCLUYZ2vfJlAi2rRs M8uWU0XGYlSmQ== 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 2/19/19 12:04 PM, jglisse@redhat.com wrote: > From: J=C3=A9r=C3=B4me Glisse >=20 > Helper to test if a range is updated to read only (it is still valid > to read from the range). This is useful for device driver or anyone > who wish to optimize out update when they know that they already have > the range map read only. >=20 > Signed-off-by: J=C3=A9r=C3=B4me Glisse > Cc: Christian K=C3=B6nig > Cc: Joonas Lahtinen > Cc: Jani Nikula > Cc: Rodrigo Vivi > Cc: Jan Kara > Cc: Andrea Arcangeli > Cc: Peter Xu > Cc: Felix Kuehling > Cc: Jason Gunthorpe > Cc: Ross Zwisler > Cc: Dan Williams > Cc: Paolo Bonzini > Cc: Radim Kr=C4=8Dm=C3=A1=C5=99 > Cc: Michal Hocko > Cc: Christian Koenig > Cc: Ralph Campbell > Cc: John Hubbard > Cc: kvm@vger.kernel.org > Cc: dri-devel@lists.freedesktop.org > Cc: linux-rdma@vger.kernel.org > Cc: Arnd Bergmann > --- > include/linux/mmu_notifier.h | 4 ++++ > mm/mmu_notifier.c | 10 ++++++++++ > 2 files changed, 14 insertions(+) >=20 > diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h > index 0379956fff23..b6c004bd9f6a 100644 > --- a/include/linux/mmu_notifier.h > +++ b/include/linux/mmu_notifier.h > @@ -259,6 +259,8 @@ extern void __mmu_notifier_invalidate_range_end(struc= t mmu_notifier_range *r, > bool only_end); > extern void __mmu_notifier_invalidate_range(struct mm_struct *mm, > unsigned long start, unsigned long end); > +extern bool > +mmu_notifier_range_update_to_read_only(const struct mmu_notifier_range *= range); > =20 > static inline bool > mmu_notifier_range_blockable(const struct mmu_notifier_range *range) > @@ -568,6 +570,8 @@ static inline void mmu_notifier_mm_destroy(struct mm_= struct *mm) > { > } > =20 > +#define mmu_notifier_range_update_to_read_only(r) false > + > #define ptep_clear_flush_young_notify ptep_clear_flush_young > #define pmdp_clear_flush_young_notify pmdp_clear_flush_young > #define ptep_clear_young_notify ptep_test_and_clear_young > diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c > index abd88c466eb2..ee36068077b6 100644 > --- a/mm/mmu_notifier.c > +++ b/mm/mmu_notifier.c > @@ -395,3 +395,13 @@ void mmu_notifier_unregister_no_release(struct mmu_n= otifier *mn, > mmdrop(mm); > } > EXPORT_SYMBOL_GPL(mmu_notifier_unregister_no_release); > + > +bool > +mmu_notifier_range_update_to_read_only(const struct mmu_notifier_range *= range) > +{ > + if (!range->vma || range->event !=3D MMU_NOTIFY_PROTECTION_VMA) > + return false; > + /* Return true if the vma still have the read flag set. */ > + return range->vma->vm_flags & VM_READ; > +} > +EXPORT_SYMBOL_GPL(mmu_notifier_range_update_to_read_only); >=20 Don't you have to check for !WRITE & READ? mprotect() can change the permissions from R/O to RW and end up calling mmu_notifier_range_init() and=20 mmu_notifier_invalidate_range_start()/end(). I'm not sure how useful this is since only applies to the MMU_NOTIFY_PROTECTION_VMA case. Anyway, you can add Reviewed-by: Ralph Campbell