From 5fcbb23050936d69de8087d4b311eaf55cb42740 Mon Sep 17 00:00:00 2001 From: Christoph Lameter <clameter@engr.sgi.com> Date: Sat, 29 Oct 2005 18:17:00 -0700 Subject: [PATCH] [PATCH] Remove policy contextualization from mbind Policy contextualization is only useful for task based policies and not for vma based policies. It may be useful to define allowed nodes that are not accessible from this thread because other threads may have access to these nodes. Without this patch strange memory policy situations may cause an application to fail with out of memory. Example: Let's say we have two threads A and B that share the same address space and a huge array computational array X. Thread A is restricted by its cpuset to nodes 0 and 1 and thread B is restricted by its cpuset to nodes 2 and 3. Thread A now wants to restrict allocations to the first node and thus applies a BIND policy on X to node 0 and 2. The cpuset limits this to node 0. Thus pages for X must be allocated on node 0 now. Thread B now touches a page that has never been used in X and faults in a page. According to the BIND policy of the vma for X the page must be allocated on page 0. However, the cpuset of B does not allow allocation on 0 and 1. Now the application fails in alloc_pages with out of memory. Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Andi Kleen <ak@muc.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org> --- mm/mempolicy.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 123925f50f86..2076b1542b8a 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -370,7 +370,7 @@ long do_mbind(unsigned long start, unsigned long len, return -EINVAL; if (end == start) return 0; - if (contextualize_policy(mode, nmask)) + if (mpol_check_policy(mode, nmask)) return -EINVAL; new = mpol_new(mode, nmask); if (IS_ERR(new))