linux-kernel - memory allocation: smap large "Size", but unused

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <k930p2$8br$1@ger.gmane.org>
Date:	Tue, 27 Nov 2012 19:28:52 +0100
From:	Bernd Schubert <bernd.schubert@...m.fraunhofer.de>
To:	linux-kernel@...r.kernel.org
Subject: memory allocation: smap large "Size", but unused

Hello,

I'm just investigating why a user space program has a rather large 
VmSize, but small VmRSS size. Looking into /proc/$pid/smaps I notice 
several areas with an size of about 64MB, but otherwise that area is 
unused. So far I did not find a way how to reproduce that with malloc() 
calls.

7ffd34021000-7ffd38000000 ---p 00000000 00:00 0
Size:              65404 kB
Rss:                   0 kB
Pss:                   0 kB
Shared_Clean:          0 kB
Shared_Dirty:          0 kB
Private_Clean:         0 kB
Private_Dirty:         0 kB
Referenced:            0 kB
Anonymous:             0 kB
AnonHugePages:         0 kB
Swap:                  0 kB
KernelPageSize:        4 kB
MMUPageSize:           4 kB


Any idea how to do such an allocation from user space?


Thanks,
Bernd

--
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/