From: Lee Schermerhorn This patch augments the MPOL_MF_LAZY feature by adding a "NOOP" policy to mbind(). When the NOOP policy is used with the 'MOVE and 'LAZY flags, mbind() [check_range()] will walk the specified range and unmap eligible pages so that they will be migrated on next touch. This allows an application to prepare for a new phase of operation where different regions of shared storage will be assigned to worker threads, w/o changing policy. Note that we could just use "default" policy in this case. However, this also allows an application to request that pages be migrated, only if necessary, to follow any arbitrary policy that might currently apply to a range of pages, without knowing the policy, or without specifying multiple mbind()s for ranges with different policies. Signed-off-by: Lee Schermerhorn Signed-off-by: Peter Zijlstra --- include/linux/mempolicy.h | 1 + mm/mempolicy.c | 8 ++++---- 2 files changed, 5 insertions(+), 4 deletions(-) --- a/include/linux/mempolicy.h +++ b/include/linux/mempolicy.h @@ -20,6 +20,7 @@ enum { MPOL_PREFERRED, MPOL_BIND, MPOL_INTERLEAVE, + MPOL_NOOP, /* retain existing policy for range */ MPOL_MAX, /* always last member of enum */ }; --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -251,10 +251,10 @@ static struct mempolicy *mpol_new(unsign pr_debug("setting mode %d flags %d nodes[0] %lx\n", mode, flags, nodes ? nodes_addr(*nodes)[0] : -1); - if (mode == MPOL_DEFAULT) { + if (mode == MPOL_DEFAULT || mode == MPOL_NOOP) { if (nodes && !nodes_empty(*nodes)) return ERR_PTR(-EINVAL); - return NULL; /* simply delete any existing policy */ + return NULL; } VM_BUG_ON(!nodes); @@ -1121,7 +1121,7 @@ static long do_mbind(unsigned long start if (start & ~PAGE_MASK) return -EINVAL; - if (mode == MPOL_DEFAULT) + if (mode == MPOL_DEFAULT || mode == MPOL_NOOP) flags &= ~MPOL_MF_STRICT; len = (len + PAGE_SIZE - 1) & PAGE_MASK; @@ -1173,7 +1173,7 @@ static long do_mbind(unsigned long start flags | MPOL_MF_INVERT, &pagelist); err = PTR_ERR(vma); /* maybe ... */ - if (!IS_ERR(vma)) + if (!IS_ERR(vma) && mode != MPOL_NOOP) err = mbind_range(mm, start, end, new); if (!err) { -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/