linux-kernel - RE: [patch 2/14] x86, mm: add release_locked_buffer_on

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <928CFBE8E7CB0040959E56B4EA41A77E9266B6C0@irsmsx504.ger.corp.intel.com>
Date:	Fri, 27 Mar 2009 15:18:40 +0000
From:	"Metzger, Markus T" <markus.t.metzger@...el.com>
To:	Oleg Nesterov <oleg@...hat.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"mingo@...e.hu" <mingo@...e.hu>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"hpa@...or.com" <hpa@...or.com>,
	"markus.t.metzger@...il.com" <markus.t.metzger@...il.com>,
	"roland@...hat.com" <roland@...hat.com>,
	"eranian@...glemail.com" <eranian@...glemail.com>,
	"Villacis, Juan" <juan.villacis@...el.com>,
	"ak@...ux.jf.intel.com" <ak@...ux.jf.intel.com>
Subject: RE: [patch 2/14] x86, mm: add release_locked_buffer_on_behalf

>-----Original Message-----
>From: Oleg Nesterov [mailto:oleg@...hat.com]
>Sent: Friday, March 27, 2009 3:22 PM
>To: Metzger, Markus T
>Cc: linux-kernel@...r.kernel.org; mingo@...e.hu; tglx@...utronix.de; hpa@...or.com;
>markus.t.metzger@...il.com; roland@...hat.com; eranian@...glemail.com; Villacis, Juan;
>ak@...ux.jf.intel.com
>Subject: Re: [patch 2/14] x86, mm: add release_locked_buffer_on_behalf
>
>On 03/27, Markus Metzger wrote:
>>
>> -void release_locked_buffer(void *buffer, size_t size)
>> +void release_locked_buffer_on_behalf(struct mm_struct *mm,
>> +				     void *buffer, size_t size)
>>  {
>>  	unsigned long pgsz = PAGE_ALIGN(size) >> PAGE_SHIFT;
>>
>> -	down_write(&current->mm->mmap_sem);
>> +	down_write(&mm->mmap_sem);
>>
>> -	current->mm->total_vm  -= pgsz;
>> -	current->mm->locked_vm -= pgsz;
>> +	mm->total_vm  -= pgsz;
>> +	mm->locked_vm -= pgsz;
>>
>> -	up_write(&current->mm->mmap_sem);
>> +	up_write(&mm->mmap_sem);
>>  }
>
>If you change this helper, perhaps you can remove the "void *buffer"
>argument? It is not used. Actually, this helper should be renamed.
>It doesn't free the memory, it only updates mm->xxx_vm.

OK.

There's an alloc/free pair. This one is in between to allow another task to free
the buffer and get the memory correctly refunded.

How about refund_locked_buffer_memory(struct mm_struct *, size_t)?

regards,
markus.

---------------------------------------------------------------------
Intel GmbH
Dornacher Strasse 1
85622 Feldkirchen/Muenchen Germany
Sitz der Gesellschaft: Feldkirchen bei Muenchen
Geschaeftsfuehrer: Douglas Lusk, Peter Gleissner, Hannes Schwaderer
Registergericht: Muenchen HRB 47456 Ust.-IdNr.
VAT Registration No.: DE129385895
Citibank Frankfurt (BLZ 502 109 00) 600119052

This e-mail and any attachments may contain confidential material for
the sole use of the intended recipient(s). Any review or distribution
by others is strictly prohibited. If you are not the intended
recipient, please contact the sender and delete all copies.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/