Bug 42630 - memtest=n kernel parameter tests only low memory on 32-bit x86
memtest=n kernel parameter tests only low memory on 32-bit x86
Status: RESOLVED WILL_NOT_FIX
Product: Memory Management
Classification: Unclassified
Component: Other
All Linux
: P1 low
Assigned To: Andrew Morton
:
Depends on:
Blocks:
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Reported: 2012-01-22 14:08 UTC by Maxim Kammerer
Modified: 2012-08-30 13:59 UTC (History)
1 user (show)

See Also:
Kernel Version: 3.0.4
Tree: Mainline
Regression: No


Attachments

Description Maxim Kammerer 2012-01-22 14:08:58 UTC
On 3.0.4 (and probably all other recent kernel versions), HIGHMEM memory (HIGHMEM64G in my tests) is apparently ignored during memtest.

Looking at arch/x86/mm/memtest.c, no special mapping is performed (kmap/kunmap?), so it seems that at most ~895 MiB can be tested in 32-bit x86 kernels.

This might not appear like an important issue (as there are other memory testing tools available), but memtest is extremely useful for anti-forensic memory wiping on shutdown/reboot in security-oriented distributions like Liberté Linux and Tails, and there is no other good substitute.

See, for instance, some background in Debian bug
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=646361.

I tried posting to the linux-mm mailing list, but the mails were ignored.
Comment 1 Alan 2012-08-30 13:59:47 UTC
If you want it fixed I think you will need to write the code and submit it. Nobody else seems to be concerned about it.

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