On Tue 03-01-17 14:37:09, Anshuman Khandual wrote: > On 01/03/2017 02:14 PM, Michal Hocko wrote: > > On Tue 03-01-17 13:57:53, Anshuman Khandual wrote: > >> node_isset can give incorrect result if the node number is beyond the > >> bitmask size (MAX_NUMNODES in this case) which is not checked inside > >> test_bit. Hence check for the bit limits (MAX_NUMNODES) inside the > >> node_isset function before calling test_bit. > > Could you be more specific when such a thing might happen? Have you seen > > any in-kernel user who would give such a bogus node? > > Have not seen this through any in-kernel use case. While rebasing the CDM > zonelist rebuilding series, Then fix this particular code path... > I came across this through an error path when > a bogus node value of 256 (MAX_NUMNODES on POWER) is received when we call > first_node() on an empty nodemask (which itself seems weird as well). Does calling first_node on an empty nodemask make any sense? If there is a risk then I would expect nodes_empty() check before doing any mask related operations. -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>