From 4bfc44958e499af9a73f62201543b3a1f617cfeb Mon Sep 17 00:00:00 2001 From: KAMEZAWA Hiroyuki Date: Thu, 6 Aug 2009 15:07:33 -0700 Subject: mm: make set_mempolicy(MPOL_INTERLEAV) N_HIGH_MEMORY aware At first, init_task's mems_allowed is initialized as this. init_task->mems_allowed == node_state[N_POSSIBLE] And cpuset's top_cpuset mask is initialized as this top_cpuset->mems_allowed = node_state[N_HIGH_MEMORY] Before 2.6.29: policy's mems_allowed is initialized as this. 1. update tasks->mems_allowed by its cpuset->mems_allowed. 2. policy->mems_allowed = nodes_and(tasks->mems_allowed, user's mask) Updating task's mems_allowed in reference to top_cpuset's one. cpuset's mems_allowed is aware of N_HIGH_MEMORY, always. In 2.6.30: After commit 58568d2a8215cb6f55caf2332017d7bdff954e1c ("cpuset,mm: update tasks' mems_allowed in time"), policy's mems_allowed is initialized as this. 1. policy->mems_allowd = nodes_and(task->mems_allowed, user's mask) Here, if task is in top_cpuset, task->mems_allowed is not updated from init's one. Assume user excutes command as #numactrl --interleave=all ,.... policy->mems_allowd = nodes_and(N_POSSIBLE, ALL_SET_MASK) Then, policy's mems_allowd can includes a possible node, which has no pgdat. MPOL's INTERLEAVE just scans nodemask of task->mems_allowd and access this directly. NODE_DATA(nid)->zonelist even if NODE_DATA(nid)==NULL Then, what's we need is making policy->mems_allowed be aware of N_HIGH_MEMORY. This patch does that. But to do so, extra nodemask will be on statck. Because I know cpumask has a new interface of CPUMASK_ALLOC(), I added it to node. This patch stands on old behavior. But I feel this fix itself is just a Band-Aid. But to do fundametal fix, we have to take care of memory hotplug and it takes time. (task->mems_allowd should be N_HIGH_MEMORY, I think.) mpol_set_nodemask() should be aware of N_HIGH_MEMORY and policy's nodemask should be includes only online nodes. In old behavior, this is guaranteed by frequent reference to cpuset's code. Now, most of them are removed and mempolicy has to check it by itself. To do check, a few nodemask_t will be used for calculating nodemask. But, size of nodemask_t can be big and it's not good to allocate them on stack. Now, cpumask_t has CPUMASK_ALLOC/FREE an easy code for get scratch area. NODEMASK_ALLOC/FREE shoudl be there. [akpm@linux-foundation.org: cleanups & tweaks] Tested-by: KOSAKI Motohiro Signed-off-by: KAMEZAWA Hiroyuki Cc: Miao Xie Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Christoph Lameter Cc: Paul Menage Cc: Nick Piggin Cc: Yasunori Goto Cc: Pekka Enberg Cc: David Rientjes Cc: Lee Schermerhorn Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/nodemask.h | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) (limited to 'include/linux') diff --git a/include/linux/nodemask.h b/include/linux/nodemask.h index 829b94b156f2..b359c4a9ec9e 100644 --- a/include/linux/nodemask.h +++ b/include/linux/nodemask.h @@ -82,6 +82,12 @@ * to generate slightly worse code. So use a simple one-line #define * for node_isset(), instead of wrapping an inline inside a macro, the * way we do the other calls. + * + * NODEMASK_SCRATCH + * When doing above logical AND, OR, XOR, Remap operations the callers tend to + * need temporary nodemask_t's on the stack. But if NODES_SHIFT is large, + * nodemask_t's consume too much stack space. NODEMASK_SCRATCH is a helper + * for such situations. See below and CPUMASK_ALLOC also. */ #include @@ -473,4 +479,26 @@ static inline int num_node_state(enum node_states state) #define for_each_node(node) for_each_node_state(node, N_POSSIBLE) #define for_each_online_node(node) for_each_node_state(node, N_ONLINE) +/* + * For nodemask scrach area.(See CPUMASK_ALLOC() in cpumask.h) + */ + +#if NODES_SHIFT > 8 /* nodemask_t > 64 bytes */ +#define NODEMASK_ALLOC(x, m) struct x *m = kmalloc(sizeof(*m), GFP_KERNEL) +#define NODEMASK_FREE(m) kfree(m) +#else +#define NODEMASK_ALLOC(x, m) struct x _m, *m = &_m +#define NODEMASK_FREE(m) +#endif + +/* A example struture for using NODEMASK_ALLOC, used in mempolicy. */ +struct nodemask_scratch { + nodemask_t mask1; + nodemask_t mask2; +}; + +#define NODEMASK_SCRATCH(x) NODEMASK_ALLOC(nodemask_scratch, x) +#define NODEMASK_SCRATCH_FREE(x) NODEMASK_FREE(x) + + #endif /* __LINUX_NODEMASK_H */ -- cgit v1.2.3