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 [thread overview]
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
next prev parent reply other threads:[~2018-10-24 23:01 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20181023213504.28905-1-igor.stoppa@huawei.com>
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
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