https://github.com/torvalds/linux
Revision d5c9fde3dae750889168807038243ff36431d276 authored by Rik van Riel on 06 May 2014, 19:50:01 UTC, committed by Linus Torvalds on 06 May 2014, 20:04:58 UTC
It is possible for "limit - setpoint + 1" to equal zero, after getting
truncated to a 32 bit variable, and resulting in a divide by zero error.

Using the fully 64 bit divide functions avoids this problem.  It also
will cause pos_ratio_polynom() to return the correct value when
(setpoint - limit) exceeds 2^32.

Also uninline pos_ratio_polynom, at Andrew's request.

Signed-off-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 457c1b2
History
Tip revision: d5c9fde3dae750889168807038243ff36431d276 authored by Rik van Riel on 06 May 2014, 19:50:01 UTC
mm/page-writeback.c: fix divide by zero in pos_ratio_polynom
Tip revision: d5c9fde
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