Hello list,

On my most recent update, I had some build failures that led me to
find that some files on my root partition have been corrupted.  This
is a new Asus N550JK laptop, a mostly-stable amd64 install with
gentoo-sources-4.0.5 and ext4-root-in-LVM-in-LUKS-on-HDD, and Debian
lives in there too (no problems showed up verifying Debian's packages;
I installed Debian on Jul 1 and used it for a week before getting time
to set up Gentoo).

These are the package merge times, package names, and files that I
found to be corrupted via qcheck (there were also a couple Python
headers that I fixed by rebuilding).  They appear to be filled with
random data.  The binpkg contents in /usr/portage/packages are okay,
so I don't know when the files were corrupted; their mtimes haven't
been updated since the packages were installed.

Thu-Jul-30-22:40:23-2015 app-arch/p7zip-9.20.1-r5 /usr/lib64/p7zip/Lang/va.txt
Thu-Jul-30-22:40:23-2015 app-arch/p7zip-9.20.1-r5 /usr/lib64/p7zip/help/cmdline/switches/large_pages.htm
Sun-Jul-19-22:34:30-2015 dev-libs/libzip-1.0.1 /usr/share/man/man3/zip_error_get_sys_type.3.bz2
Sun-Jul-26-22:35:28-2015 dev-python/pygments-2.0.1-r1 /usr/lib64/python2.7/site-packages/pygments/styles/pastie.pyc
Wed-Jul-08-23:34:56-2015 media-libs/tiff-4.0.3-r6 /usr/share/man/man3/TIFFGetField.3tiff.bz2
Thu-Jul-30-10:05:31-2015 sci-mathematics/scilab-5.5.2 /usr/share/scilab/modules/compatibility_functions/macros/%b_l_s.bin
-(from-stage3-on-Jul-8)- sys-apps/acl-2.2.52-r1 /usr/share/man/man3/acl_set_file.3.bz2

I haven't had any unclean shutdowns, it looks like OpenRC is
unmounting things cleanly on shutdown, and suspend appears to work
fine.

After I make a fresh backup of my files, how would you recommend
troubleshooting this?  Run memtest or a hard drive tester?  Since the
files seemingly corrupted themselves after install without being
touched, I'm highly suspicious of the hard drive, but would like to
rule other things out (if say for example that CONFIG_X86_INTEL_PSTATE
CPU clock booster is dangerous, or nvidia-drivers, or ...).  Haven't
checked for corruption on /home yet.

This is the disk:

  *-disk
    description: ATA Disk
    product: ST1000LM024 HN-M
    vendor: Seagate
    physical id: 0.0.0
    bus info: scsi@4:0.0.0
    logical name: /dev/sda
    version: 0001
    size: 931GiB (1TB)
    capabilities: gpt-1.00 partitioned partitioned:gpt
    configuration: ansiversion=5
    guid=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx sectorsize=4096

Thanks for any help you can provide,
Bryan