From: Juerg Haefliger <juerg.haefliger@hpe.com> To: Dave Hansen <dave.hansen@intel.com>, linux-kernel@vger.kernel.org, linux-mm@kvack.org, kernel-hardening@lists.openwall.com, linux-x86_64@vger.kernel.org Cc: vpk@cs.columbia.edu Subject: Re: [RFC PATCH v2 2/3] xpfo: Only put previous userspace pages into the hot cache Date: Mon, 5 Sep 2016 13:54:47 +0200 [thread overview] Message-ID: <e7a0789e-585c-839d-d8ea-95b1c9aef38a@hpe.com> (raw) In-Reply-To: <57C9E37A.9070805@intel.com> [-- Attachment #1.1: Type: text/plain, Size: 989 bytes --] On 09/02/2016 10:39 PM, Dave Hansen wrote: > On 09/02/2016 04:39 AM, Juerg Haefliger wrote: >> Allocating a page to userspace that was previously allocated to the >> kernel requires an expensive TLB shootdown. To minimize this, we only >> put non-kernel pages into the hot cache to favor their allocation. > > But kernel allocations do allocate from these pools, right? Yes. > Does this > just mean that kernel allocations usually have to pay the penalty to > convert a page? Only pages that are allocated for userspace (gfp & GFP_HIGHUSER == GFP_HIGHUSER) which were previously allocated for the kernel (gfp & GFP_HIGHUSER != GFP_HIGHUSER) have to pay the penalty. > So, what's the logic here? You're assuming that order-0 kernel > allocations are more rare than allocations for userspace? The logic is to put reclaimed kernel pages into the cold cache to postpone their allocation as long as possible to minimize (potential) TLB flushes. ...Juerg [-- Attachment #2: OpenPGP digital signature --] [-- Type: application/pgp-signature, Size: 819 bytes --]
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From: Juerg Haefliger <juerg.haefliger@hpe.com> To: Dave Hansen <dave.hansen@intel.com>, linux-kernel@vger.kernel.org, linux-mm@kvack.org, kernel-hardening@lists.openwall.com, linux-x86_64@vger.kernel.org Cc: vpk@cs.columbia.edu Subject: [kernel-hardening] Re: [RFC PATCH v2 2/3] xpfo: Only put previous userspace pages into the hot cache Date: Mon, 5 Sep 2016 13:54:47 +0200 [thread overview] Message-ID: <e7a0789e-585c-839d-d8ea-95b1c9aef38a@hpe.com> (raw) In-Reply-To: <57C9E37A.9070805@intel.com> [-- Attachment #1.1: Type: text/plain, Size: 989 bytes --] On 09/02/2016 10:39 PM, Dave Hansen wrote: > On 09/02/2016 04:39 AM, Juerg Haefliger wrote: >> Allocating a page to userspace that was previously allocated to the >> kernel requires an expensive TLB shootdown. To minimize this, we only >> put non-kernel pages into the hot cache to favor their allocation. > > But kernel allocations do allocate from these pools, right? Yes. > Does this > just mean that kernel allocations usually have to pay the penalty to > convert a page? Only pages that are allocated for userspace (gfp & GFP_HIGHUSER == GFP_HIGHUSER) which were previously allocated for the kernel (gfp & GFP_HIGHUSER != GFP_HIGHUSER) have to pay the penalty. > So, what's the logic here? You're assuming that order-0 kernel > allocations are more rare than allocations for userspace? The logic is to put reclaimed kernel pages into the cold cache to postpone their allocation as long as possible to minimize (potential) TLB flushes. ...Juerg [-- Attachment #2: OpenPGP digital signature --] [-- Type: application/pgp-signature, Size: 819 bytes --]
next prev parent reply other threads:[~2016-09-05 11:55 UTC|newest] Thread overview: 93+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-02-26 14:21 [RFC PATCH] Add support for eXclusive Page Frame Ownership (XPFO) Juerg Haefliger 2016-02-26 14:21 ` Juerg Haefliger 2016-03-01 1:31 ` Laura Abbott 2016-03-01 1:31 ` Laura Abbott 2016-03-21 8:37 ` Juerg Haefliger 2016-03-21 8:37 ` Juerg Haefliger 2016-03-28 19:29 ` Laura Abbott 2016-03-28 19:29 ` Laura Abbott 2016-03-01 2:10 ` Balbir Singh 2016-03-01 2:10 ` Balbir Singh 2016-03-21 8:44 ` Juerg Haefliger 2016-03-21 8:44 ` Juerg Haefliger 2016-04-01 0:21 ` Balbir Singh 2016-04-01 0:21 ` Balbir Singh 2016-09-02 11:39 ` [RFC PATCH v2 0/3] " Juerg Haefliger 2016-09-02 11:39 ` [kernel-hardening] " Juerg Haefliger 2016-09-02 11:39 ` Juerg Haefliger 2016-09-02 11:39 ` [RFC PATCH v2 1/3] " Juerg Haefliger 2016-09-02 11:39 ` [kernel-hardening] " Juerg Haefliger 2016-09-02 11:39 ` Juerg Haefliger 2016-09-02 11:39 ` [RFC PATCH v2 2/3] xpfo: Only put previous userspace pages into the hot cache Juerg Haefliger 2016-09-02 11:39 ` [kernel-hardening] " Juerg Haefliger 2016-09-02 11:39 ` Juerg Haefliger 2016-09-02 20:39 ` Dave Hansen 2016-09-02 20:39 ` [kernel-hardening] " Dave Hansen 2016-09-02 20:39 ` Dave Hansen 2016-09-05 11:54 ` Juerg Haefliger [this message] 2016-09-05 11:54 ` [kernel-hardening] " Juerg Haefliger 2016-09-02 11:39 ` [RFC PATCH v2 3/3] block: Always use a bounce buffer when XPFO is enabled Juerg Haefliger 2016-09-02 11:39 ` [kernel-hardening] " Juerg Haefliger 2016-09-02 11:39 ` Juerg Haefliger 2016-09-14 7:18 ` [RFC PATCH v2 0/3] Add support for eXclusive Page Frame Ownership (XPFO) Juerg Haefliger 2016-09-14 7:18 ` [kernel-hardening] " Juerg Haefliger 2016-09-14 7:18 ` Juerg Haefliger 2016-09-14 7:18 ` [RFC PATCH v2 1/3] " Juerg Haefliger 2016-09-14 7:18 ` [kernel-hardening] " Juerg Haefliger 2016-09-14 7:18 ` Juerg Haefliger 2016-09-14 7:19 ` [RFC PATCH v2 2/3] xpfo: Only put previous userspace pages into the hot cache Juerg Haefliger 2016-09-14 7:19 ` [kernel-hardening] " Juerg Haefliger 2016-09-14 7:19 ` Juerg Haefliger 2016-09-14 14:33 ` [kernel-hardening] " Dave Hansen 2016-09-14 14:33 ` Dave Hansen 2016-09-14 14:40 ` Juerg Haefliger 2016-09-14 14:48 ` Dave Hansen 2016-09-14 14:48 ` Dave Hansen 2016-09-21 5:32 ` Juerg Haefliger 2016-09-14 7:19 ` [RFC PATCH v2 3/3] block: Always use a bounce buffer when XPFO is enabled Juerg Haefliger 2016-09-14 7:19 ` [kernel-hardening] " Juerg Haefliger 2016-09-14 7:19 ` Juerg Haefliger 2016-09-14 7:33 ` Christoph Hellwig 2016-09-14 7:33 ` [kernel-hardening] " Christoph Hellwig 2016-09-14 7:33 ` Christoph Hellwig 2016-09-14 7:23 ` [RFC PATCH v2 0/3] Add support for eXclusive Page Frame Ownership (XPFO) Juerg Haefliger 2016-09-14 7:23 ` [kernel-hardening] " Juerg Haefliger 2016-09-14 9:36 ` [kernel-hardening] " Mark Rutland 2016-09-14 9:36 ` Mark Rutland 2016-09-14 9:49 ` Mark Rutland 2016-09-14 9:49 ` Mark Rutland 2016-11-04 14:45 ` [RFC PATCH v3 0/2] " Juerg Haefliger 2016-11-04 14:45 ` [kernel-hardening] " Juerg Haefliger 2016-11-04 14:45 ` Juerg Haefliger 2016-11-04 14:45 ` [RFC PATCH v3 1/2] " Juerg Haefliger 2016-11-04 14:45 ` [kernel-hardening] " Juerg Haefliger 2016-11-04 14:45 ` Juerg Haefliger 2016-11-04 14:50 ` Christoph Hellwig 2016-11-04 14:50 ` [kernel-hardening] " Christoph Hellwig 2016-11-04 14:50 ` Christoph Hellwig 2016-11-10 5:53 ` [kernel-hardening] " ZhaoJunmin Zhao(Junmin) 2016-11-10 5:53 ` ZhaoJunmin Zhao(Junmin) 2016-11-10 5:53 ` ZhaoJunmin Zhao(Junmin) 2016-11-10 19:11 ` Kees Cook 2016-11-10 19:11 ` [kernel-hardening] " Kees Cook 2016-11-10 19:11 ` Kees Cook 2016-11-15 11:15 ` Juerg Haefliger 2016-11-15 11:15 ` [kernel-hardening] " Juerg Haefliger 2016-11-15 11:15 ` Juerg Haefliger 2016-11-10 19:24 ` Kees Cook 2016-11-10 19:24 ` [kernel-hardening] " Kees Cook 2016-11-10 19:24 ` Kees Cook 2016-11-15 11:18 ` Juerg Haefliger 2016-11-15 11:18 ` [kernel-hardening] " Juerg Haefliger 2016-11-15 11:18 ` Juerg Haefliger 2016-11-24 10:56 ` AKASHI Takahiro 2016-11-24 10:56 ` [kernel-hardening] " AKASHI Takahiro 2016-11-24 10:56 ` AKASHI Takahiro 2016-11-28 11:15 ` Juerg Haefliger 2016-11-28 11:15 ` [kernel-hardening] " Juerg Haefliger 2016-12-09 9:02 ` AKASHI Takahiro 2016-12-09 9:02 ` [kernel-hardening] " AKASHI Takahiro 2016-12-09 9:02 ` AKASHI Takahiro 2016-11-04 14:45 ` [RFC PATCH v3 2/2] xpfo: Only put previous userspace pages into the hot cache Juerg Haefliger 2016-11-04 14:45 ` [kernel-hardening] " Juerg Haefliger 2016-11-04 14:45 ` Juerg Haefliger
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