tree 13337f2be30164b30f22eea832c04c40a90781ad
parent 267a4c76bbdb950688d3aeb020976c2918064584
author Seth Jennings <sjennings@variantweb.net> 1449870057 -0800
committer Linus Torvalds <torvalds@linux-foundation.org> 1449944134 -0800

drivers/base/memory.c: prohibit offlining of memory blocks with missing sections

Commit bdee237c0343 ("x86: mm: Use 2GB memory block size on large-memory
x86-64 systems") and 982792c782ef ("x86, mm: probe memory block size for
generic x86 64bit") introduced large block sizes for x86.  This made it
possible to have multiple sections per memory block where previously,
there was a only every one section per block.

Since blocks consist of contiguous ranges of section, there can be holes
in the blocks where sections are not present.  If one attempts to
offline such a block, a crash occurs since the code is not designed to
deal with this.

This patch is a quick fix to gaurd against the crash by not allowing
blocks with non-present sections to be offlined.

Addresses https://bugzilla.kernel.org/show_bug.cgi?id=107781

Signed-off-by: Seth Jennings <sjennings@variantweb.net>
Reported-by: Andrew Banman <abanman@sgi.com>
Cc: Daniel J Blueman <daniel@numascale.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Greg KH <greg@kroah.com>
Cc: Russ Anderson <rja@sgi.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>