Re: [PATCH 2.6.24-mm1] Mempolicy: silently restrict nodemask to allowed nodes V3

KOSAKI Motohiro
2008-02-10T05:31:33Z

CC'd Greg KH <greg@kroah.com>

I tested this patch on fujitsu memoryless node.
(2.6.24 + silently-restrict-nodemask-to-allowed-nodes-V3 insted 2.6.24-mm1)
it seems works good.

Tested-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>

Greg, I hope this patch merge to 2.6.24.x stable tree because
this patch is regression fixed patch.
Please tell me what do i doing for it.

[intentional full quote]

> Was "Re: [2.6.24 regression][BUGFIX] numactl --interleave=all doesn't
> works on memoryless node."
>
> [Aside: I noticed there were two slightly different distributions for
> this topic. I've unified the distribution lists w/o dropping anyone, I
> think. Apologies if you'd rather have been dropped...]
>
> Here's V3 of the patch, accomodating Kosaki Motohiro's suggestion for
> folding contextualize_policy() into mpol_check_policy() [because my
> "was_empty" argument "was ugly" ;-)]. It does seem to clean up the
> code.
>
> I'm still deferring David Rientjes' suggestion to fold
> mpol_check_policy() into mpol_new(). We need to sort out whether
> mempolicies specified for tmpfs and hugetlbfs mounts always need the
> same "contextualization" as user/application installed policies. I
> don't want to hold up this bug fix for that discussion. This is
> something Paul J will need to address with his cpuset/mempolicy rework,
> so we can sort it out in that context.
>
> Again, tested with "numactl --interleave=all" and memtoy on ia64 using
> mem= command line argument to simulate memoryless node.
>
>
> Lee
>
> ============================
> [PATCH] 2.6.24-mm1 - mempolicy: silently restrict nodemask to allowed nodes
>
> V2 -> V3:
> + As suggested by Kosaki Motohito, fold the "contextualization"
> of policy nodemask into mpol_check_policy(). Looks a little
> cleaner.
>
> V1 -> V2:
> + Communicate whether or not incoming node mask was empty to
> mpol_check_policy() for better error checking.
> + As suggested by David Rientjes, remove the now unused
> cpuset_nodes_subset_current_mems_allowed() from cpuset.h
>
> Kosaki Motohito noted that "numactl --interleave=all ..." failed in the
> presence of memoryless nodes. This patch attempts to fix that problem.
>
> Some background:
>
> numactl --interleave=all calls set_mempolicy(2) with a fully
> populated [out to MAXNUMNODES] nodemask. set_mempolicy()
> [in do_set_mempolicy()] calls contextualize_policy() which
> requires that the nodemask be a subset of the current task's
> mems_allowed; else EINVAL will be returned. A task's
> mems_allowed will always be a subset of node_states[N_HIGH_MEMORY]--
> i.e., nodes with memory. So, a fully populated nodemask will
> be declared invalid if it includes memoryless nodes.
>
> NOTE: the same thing will occur when running in a cpuset
> with restricted mem_allowed--for the same reason:
> node mask contains dis-allowed nodes.
>
> mbind(2), on the other hand, just masks off any nodes in the
> nodemask that are not included in the caller's mems_allowed.
>
> In each case [mbind() and set_mempolicy()], mpol_check_policy()
> will complain [again, resulting in EINVAL] if the nodemask contains
> any memoryless nodes. This is somewhat redundant as mpol_new()
> will remove memoryless nodes for interleave policy, as will
> bind_zonelist()--called by mpol_new() for BIND policy.
>
> Proposed fix:
>
> 1) modify contextualize_policy logic to:
> a) remember whether the incoming node mask is empty.
> b) if not, restrict the nodemask to allowed nodes, as is
> currently done in-line for mbind(). This guarantees
> that the resulting mask includes only nodes with memory.
>
> NOTE: this is a [benign, IMO] change in behavior for
> set_mempolicy(). Dis-allowed nodes will be
> silently ignored, rather than returning an error.
>
> c) fold this code into mpol_check_policy(), replace 2 calls to
> contextualize_policy() to call mpol_check_policy() directly
> and remove contextualize_policy().
>
> 2) In existing mpol_check_policy() logic, after "contextualization":
> a) MPOL_DEFAULT: require that in coming mask "was_empty"
> b) MPOL_{BIND|INTERLEAVE}: require that contextualized nodemask
> contains at least one node.
> c) add a case for MPOL_PREFERRED: if in coming was not empty
> and resulting mask IS empty, user specified invalid nodes.
> Return EINVAL.
> c) remove the now redundant check for memoryless nodes
>
> 3) remove the now redundant masking of policy nodes for interleave
> policy from mpol_new().
>
> 4) Now that mpol_check_policy() contextualizes the nodemask, remove
> the in-line nodes_and() from sys_mbind(). I believe that this
> restores mbind() to the behavior before the memoryless-nodes
> patch series. E.g., we'll no longer treat an invalid nodemask
> with MPOL_PREFERRED as local allocation.
>
> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
>
> include/linux/cpuset.h | 3 --
> mm/mempolicy.c | 61 ++++++++++++++++++++++++++++---------------------
> 2 files changed, 36 insertions(+), 28 deletions(-)
>
> Index: Linux/mm/mempolicy.c
> ===================================================================
> --- Linux.orig/mm/mempolicy.c 2008-02-08 11:11:34.000000000 -0500
> +++ Linux/mm/mempolicy.c 2008-02-08 13:40:40.000000000 -0500
> @@ -116,22 +116,51 @@ static void mpol_rebind_policy(struct me
> /* Do sanity checking on a policy */
> static int mpol_check_policy(int mode, nodemask_t *nodes)
> {
> - int empty = nodes_empty(*nodes);
> + int was_empty, is_empty;
> +
> + if (!nodes)
> + return 0;
> +
> + /*
> + * "Contextualize" the in-coming nodemast for cpusets:
> + * Remember whether in-coming nodemask was empty, If not,
> + * restrict the nodes to the allowed nodes in the cpuset.
> + * This is guaranteed to be a subset of nodes with memory.
> + */
> + cpuset_update_task_memory_state();
> + is_empty = was_empty = nodes_empty(*nodes);
> + if (!was_empty) {
> + nodes_and(*nodes, *nodes, cpuset_current_mems_allowed);
> + is_empty = nodes_empty(*nodes); /* after "contextualization" */
> + }
>
> switch (mode) {
> case MPOL_DEFAULT:
> - if (!empty)
> + /*
> + * require caller to specify an empty nodemask
> + * before "contextualization"
> + */
> + if (!was_empty)
> return -EINVAL;
> break;
> case MPOL_BIND:
> case MPOL_INTERLEAVE:
> - /* Preferred will only use the first bit, but allow
> - more for now. */
> - if (empty)
> + /*
> + * require at least 1 valid node after "contextualization"
> + */
> + if (is_empty)
> + return -EINVAL;
> + break;
> + case MPOL_PREFERRED:
> + /*
> + * Did caller specify invalid nodes?
> + * Don't silently accept this as "local allocation".
> + */
> + if (!was_empty && is_empty)
> return -EINVAL;
> break;
> }
> - return nodes_subset(*nodes, node_states[N_HIGH_MEMORY]) ? 0 : -EINVAL;
> + return 0;
> }
>
> /* Generate a custom zonelist for the BIND policy. */
> @@ -188,8 +217,6 @@ static struct mempolicy *mpol_new(int mo
> switch (mode) {
> case MPOL_INTERLEAVE:
> policy->v.nodes = *nodes;
> - nodes_and(policy->v.nodes, policy->v.nodes,
> - node_states[N_HIGH_MEMORY]);
> if (nodes_weight(policy->v.nodes) == 0) {
> kmem_cache_free(policy_cache, policy);
> return ERR_PTR(-EINVAL);
> @@ -421,18 +448,6 @@ static int mbind_range(struct vm_area_st
> return err;
> }
>
> -static int contextualize_policy(int mode, nodemask_t *nodes)
> -{
> - if (!nodes)
> - return 0;
> -
> - cpuset_update_task_memory_state();
> - if (!cpuset_nodes_subset_current_mems_allowed(*nodes))
> - return -EINVAL;
> - return mpol_check_policy(mode, nodes);
> -}
> -
> -
> /*
> * Update task->flags PF_MEMPOLICY bit: set iff non-default
> * mempolicy. Allows more rapid checking of this (combined perhaps
> @@ -468,7 +483,7 @@ static long do_set_mempolicy(int mode, n
> {
> struct mempolicy *new;
>
> - if (contextualize_policy(mode, nodes))
> + if (mpol_check_policy(mode, nodes))
> return -EINVAL;
> new = mpol_new(mode, nodes);
> if (IS_ERR(new))
> @@ -915,10 +930,6 @@ asmlinkage long sys_mbind(unsigned long
> err = get_nodes(&nodes, nmask, maxnode);
> if (err)
> return err;
> -#ifdef CONFIG_CPUSETS
> - /* Restrict the nodes to the allowed nodes in the cpuset */
> - nodes_and(nodes, nodes, current->mems_allowed);
> -#endif
> return do_mbind(start, len, mode, &nodes, flags);
> }
>
> Index: Linux/include/linux/cpuset.h
> ===================================================================
> --- Linux.orig/include/linux/cpuset.h 2008-02-08 11:11:34.000000000 -0500
> +++ Linux/include/linux/cpuset.h 2008-02-08 11:12:43.000000000 -0500
> @@ -26,8 +26,6 @@ extern nodemask_t cpuset_mems_allowed(st
> #define cpuset_current_mems_allowed (current->mems_allowed)
> void cpuset_init_current_mems_allowed(void);
> void cpuset_update_task_memory_state(void);
> -#define cpuset_nodes_subset_current_mems_allowed(nodes) \
> - nodes_subset((nodes), current->mems_allowed)
> int cpuset_zonelist_valid_mems_allowed(struct zonelist *zl);
>
> extern int __cpuset_zone_allowed_softwall(struct zone *z, gfp_t gfp_mask);
> @@ -103,7 +101,6 @@ static inline nodemask_t cpuset_mems_all
> #define cpuset_current_mems_allowed (node_states[N_HIGH_MEMORY])
> static inline void cpuset_init_current_mems_allowed(void) {}
> static inline void cpuset_update_task_memory_state(void) {}
> -#define cpuset_nodes_subset_current_mems_allowed(nodes) (1)
>
> static inline int cpuset_zonelist_valid_mems_allowed(struct zonelist *zl)
> {
>
>
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