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From: Igor Stoppa <igor.stoppa@gmail.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: Mimi Zohar <zohar@linux.vnet.ibm.com>,
	Kees Cook <keescook@chromium.org>,
	Dave Chinner <david@fromorbit.com>,
	James Morris <jmorris@namei.org>,
	Michal Hocko <mhocko@kernel.org>,
	kernel-hardening@lists.openwall.com,
	linux-integrity@vger.kernel.org,
	linux-security-module@vger.kernel.org, igor.stoppa@huawei.com,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Laura Abbott <labbott@redhat.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Pavel Tatashin <pasha.tatashin@oracle.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 08/17] prmem: struct page: track vmap_area
Date: Thu, 25 Oct 2018 02:01:02 +0300
Message-ID: <ffb887e1-2029-42d5-3a97-54546e4d28d8@gmail.com> (raw)
In-Reply-To: <20181024031200.GC25444@bombadil.infradead.org>



On 24/10/2018 06:12, Matthew Wilcox wrote:
> On Wed, Oct 24, 2018 at 12:34:55AM +0300, Igor Stoppa wrote:
>> The connection between each page and its vmap_area avoids more expensive
>> searches through the btree of vmap_areas.
> 
> Typo -- it's an rbtree.

ack

>> +++ b/include/linux/mm_types.h
>> @@ -87,13 +87,24 @@ struct page {
>>   			/* See page-flags.h for PAGE_MAPPING_FLAGS */
>>   			struct address_space *mapping;
>>   			pgoff_t index;		/* Our offset within mapping. */
>> -			/**
>> -			 * @private: Mapping-private opaque data.
>> -			 * Usually used for buffer_heads if PagePrivate.
>> -			 * Used for swp_entry_t if PageSwapCache.
>> -			 * Indicates order in the buddy system if PageBuddy.
>> -			 */
>> -			unsigned long private;
>> +			union {
>> +				/**
>> +				 * @private: Mapping-private opaque data.
>> +				 * Usually used for buffer_heads if
>> +				 * PagePrivate.
>> +				 * Used for swp_entry_t if PageSwapCache.
>> +				 * Indicates order in the buddy system if
>> +				 * PageBuddy.
>> +				 */
>> +				unsigned long private;
>> +				/**
>> +				 * @area: reference to the containing area
>> +				 * For pages that are mapped into a virtually
>> +				 * contiguous area, avoids performing a more
>> +				 * expensive lookup.
>> +				 */
>> +				struct vmap_area *area;
>> +			};
> 
> Not like this.  Make it part of a different struct in the existing union,
> not a part of the pagecache struct.  And there's no need to use ->private
> explicitly.

Ok, I'll have a look at the googledoc you made

>> @@ -1747,6 +1750,10 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align,
>>   	if (!addr)
>>   		return NULL;
>>   
>> +	va = __find_vmap_area((unsigned long)addr);
>> +	for (i = 0; i < va->vm->nr_pages; i++)
>> +		va->vm->pages[i]->area = va;
> 
> I don't like it that you're calling this for _every_ vmalloc() caller
> when most of them will never use this.  Perhaps have page->va be initially
> NULL and then cache the lookup in it when it's accessed for the first time.
> 

If __find_vmap_area() was part of the API, this loop could be left out 
from __vmalloc_node_range() and the user of the allocation could 
initialize the field, if needed.

What is the reason for keeping __find_vmap_area() private?

--
igor

  reply index

Thread overview: 140+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-23 21:34 [RFC v1 PATCH 00/17] prmem: protected memory Igor Stoppa
2018-10-23 21:34 ` [PATCH 01/17] prmem: linker section for static write rare Igor Stoppa
2018-10-23 21:34 ` [PATCH 02/17] prmem: write rare for static allocation Igor Stoppa
2018-10-25  0:24   ` Dave Hansen
2018-10-29 18:03     ` Igor Stoppa
2018-10-26  9:41   ` Peter Zijlstra
2018-10-29 20:01     ` Igor Stoppa
2018-10-23 21:34 ` [PATCH 03/17] prmem: vmalloc support for dynamic allocation Igor Stoppa
2018-10-25  0:26   ` Dave Hansen
2018-10-29 18:07     ` Igor Stoppa
2018-10-23 21:34 ` [PATCH 04/17] prmem: " Igor Stoppa
2018-10-23 21:34 ` [PATCH 05/17] prmem: shorthands for write rare on common types Igor Stoppa
2018-10-25  0:28   ` Dave Hansen
2018-10-29 18:12     ` Igor Stoppa
2018-10-23 21:34 ` [PATCH 06/17] prmem: test cases for memory protection Igor Stoppa
2018-10-24  3:27   ` Randy Dunlap
2018-10-24 14:24     ` Igor Stoppa
2018-10-25 16:43   ` Dave Hansen
2018-10-29 18:16     ` Igor Stoppa
2018-10-23 21:34 ` [PATCH 07/17] prmem: lkdtm tests " Igor Stoppa
2018-10-23 21:34 ` [PATCH 08/17] prmem: struct page: track vmap_area Igor Stoppa
2018-10-24  3:12   ` Matthew Wilcox
2018-10-24 23:01     ` Igor Stoppa [this message]
2018-10-25  2:13       ` Matthew Wilcox
2018-10-29 18:21         ` Igor Stoppa
2018-10-23 21:34 ` [PATCH 09/17] prmem: hardened usercopy Igor Stoppa
2018-10-29 11:45   ` Chris von Recklinghausen
2018-10-29 18:24     ` Igor Stoppa
2018-10-23 21:34 ` [PATCH 10/17] prmem: documentation Igor Stoppa
2018-10-24  3:48   ` Randy Dunlap
2018-10-24 14:30     ` Igor Stoppa
2018-10-24 23:04   ` Mike Rapoport
2018-10-29 19:05     ` Igor Stoppa
2018-10-26  9:26   ` Peter Zijlstra
2018-10-26 10:20     ` Matthew Wilcox
2018-10-29 19:28       ` Igor Stoppa
2018-10-26 10:46     ` Kees Cook
2018-10-28 18:31       ` Peter Zijlstra
2018-10-29 21:04         ` Igor Stoppa
2018-10-30 15:26           ` Peter Zijlstra
2018-10-30 16:37             ` Kees Cook
2018-10-30 17:06               ` Andy Lutomirski
2018-10-30 17:58                 ` Matthew Wilcox
2018-10-30 18:03                   ` Dave Hansen
2018-10-31  9:18                     ` Peter Zijlstra
2018-10-30 18:28                   ` Tycho Andersen
2018-10-30 19:20                     ` Matthew Wilcox
2018-10-30 20:43                       ` Igor Stoppa
2018-10-30 21:02                         ` Andy Lutomirski
2018-10-30 21:07                           ` Kees Cook
2018-10-30 21:25                             ` Igor Stoppa
2018-10-30 22:15                           ` Igor Stoppa
2018-10-31 10:11                             ` Peter Zijlstra
2018-10-31 20:38                               ` Andy Lutomirski
2018-10-31 20:53                                 ` Andy Lutomirski
2018-10-31  9:45                           ` Peter Zijlstra
2018-10-30 21:35                         ` Matthew Wilcox
2018-10-30 21:49                           ` Igor Stoppa
2018-10-31  4:41                           ` Andy Lutomirski
2018-10-31  9:08                             ` Igor Stoppa
2018-10-31 19:38                               ` Igor Stoppa
2018-10-31 10:02                             ` Peter Zijlstra
2018-10-31 20:36                               ` Andy Lutomirski
2018-10-31 21:00                                 ` Peter Zijlstra
2018-10-31 22:57                                   ` Andy Lutomirski
2018-10-31 23:10                                     ` Igor Stoppa
2018-10-31 23:19                                       ` Andy Lutomirski
2018-10-31 23:26                                         ` Igor Stoppa
2018-11-01  8:21                                           ` Thomas Gleixner
2018-11-01 15:58                                             ` Igor Stoppa
2018-11-01 17:08                                     ` Peter Zijlstra
2018-10-30 18:51                   ` Andy Lutomirski
2018-10-30 19:14                     ` Kees Cook
2018-10-30 21:25                     ` Matthew Wilcox
2018-10-30 21:55                       ` Igor Stoppa
2018-10-30 22:08                         ` Matthew Wilcox
2018-10-31  9:29                       ` Peter Zijlstra
2018-10-30 23:18                     ` Nadav Amit
2018-10-31  9:08                       ` Peter Zijlstra
2018-11-01 16:31                         ` Nadav Amit
2018-11-02 21:11                           ` Nadav Amit
2018-10-31  9:36                   ` Peter Zijlstra
2018-10-31 11:33                     ` Matthew Wilcox
2018-11-13 14:25                 ` Igor Stoppa
2018-11-13 17:16                   ` Andy Lutomirski
2018-11-13 17:43                     ` Nadav Amit
2018-11-13 17:47                       ` Andy Lutomirski
2018-11-13 18:06                         ` Nadav Amit
2018-11-13 18:31                         ` Igor Stoppa
2018-11-13 18:33                           ` Igor Stoppa
2018-11-13 18:36                             ` Andy Lutomirski
2018-11-13 19:03                               ` Igor Stoppa
2018-11-21 16:34                               ` Igor Stoppa
2018-11-21 17:36                                 ` Nadav Amit
2018-11-21 18:01                                   ` Igor Stoppa
2018-11-21 18:15                                 ` Andy Lutomirski
2018-11-22 19:27                                   ` Igor Stoppa
2018-11-22 20:04                                     ` Matthew Wilcox
2018-11-22 20:53                                       ` Andy Lutomirski
2018-12-04 12:34                                         ` Igor Stoppa
2018-11-13 18:48                           ` Andy Lutomirski
2018-11-13 19:35                             ` Igor Stoppa
2018-11-13 18:26                     ` Igor Stoppa
2018-11-13 18:35                       ` Andy Lutomirski
2018-11-13 19:01                         ` Igor Stoppa
2018-10-31  9:27               ` Igor Stoppa
2018-10-26 11:09     ` Markus Heiser
2018-10-29 19:35       ` Igor Stoppa
2018-10-26 15:05     ` Jonathan Corbet
2018-10-29 19:38       ` Igor Stoppa
2018-10-29 20:35     ` Igor Stoppa
2018-10-23 21:34 ` [PATCH 11/17] prmem: llist: use designated initializer Igor Stoppa
2018-10-23 21:34 ` [PATCH 12/17] prmem: linked list: set alignment Igor Stoppa
2018-10-26  9:31   ` Peter Zijlstra
2018-10-23 21:35 ` [PATCH 13/17] prmem: linked list: disable layout randomization Igor Stoppa
2018-10-24 13:43   ` Alexey Dobriyan
2018-10-29 19:40     ` Igor Stoppa
2018-10-26  9:32   ` Peter Zijlstra
2018-10-26 10:17     ` Matthew Wilcox
2018-10-30 15:39       ` Peter Zijlstra
2018-10-23 21:35 ` [PATCH 14/17] prmem: llist, hlist, both plain and rcu Igor Stoppa
2018-10-24 11:37   ` Mathieu Desnoyers
2018-10-24 14:03     ` Igor Stoppa
2018-10-24 14:56       ` Tycho Andersen
2018-10-24 22:52         ` Igor Stoppa
2018-10-25  8:11           ` Tycho Andersen
2018-10-28  9:52       ` Steven Rostedt
2018-10-29 19:43         ` Igor Stoppa
2018-10-26  9:38   ` Peter Zijlstra
2018-10-23 21:35 ` [PATCH 15/17] prmem: test cases for prlist and prhlist Igor Stoppa
2018-10-23 21:35 ` [PATCH 16/17] prmem: pratomic-long Igor Stoppa
2018-10-25  0:13   ` Peter Zijlstra
2018-10-29 21:17     ` Igor Stoppa
2018-10-30 15:58       ` Peter Zijlstra
2018-10-30 16:28         ` Will Deacon
2018-10-31  9:10           ` Peter Zijlstra
2018-11-01  3:28             ` Kees Cook
2018-10-23 21:35 ` [PATCH 17/17] prmem: ima: turn the measurements list write rare Igor Stoppa
2018-10-24 23:03 ` [RFC v1 PATCH 00/17] prmem: protected memory Dave Chinner
2018-10-29 19:47   ` Igor Stoppa

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