When the mbind() syscall implementation processes the node mask provided by the user, the last node is accidentally masked out. This is present since the dawn of time (aka Before Git), I guess nobody realized that because libnuma as the most prominent user of mbind() uses large masks (sizeof(long)) and nobody cared if the 64th node is not handled properly. But if the user application defers the masking to the kernel and provides the number of valid bits in maxnodes, there is always the last node missing. However this also affect the special case with maxnodes=0, the manpage reads that mbind(ptr, len, MPOL_DEFAULT, &some_long, 0, 0); should reset the policy to the default one, but in fact it returns EINVAL. This patch just removes the decrease-by-one statement, I hope that there is no workaround code in the wild that relies on the bogus behavior. Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx> --- mm/mempolicy.c | 1 - 1 files changed, 0 insertions(+), 1 deletions(-) diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 5bc0a96..e70025b 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -1174,7 +1174,6 @@ static int get_nodes(nodemask_t *nodes, const unsigned long __user *nmask, unsigned long nlongs; unsigned long endmask; - --maxnode; nodes_clear(*nodes); if (maxnode == 0 || !nmask) return 0; -- 1.6.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>