diff options
Diffstat (limited to 'kernel/cpuset.c')
| -rw-r--r-- | kernel/cpuset.c | 129 |
1 files changed, 109 insertions, 20 deletions
diff --git a/kernel/cpuset.c b/kernel/cpuset.c index 8ab1b4e518b..712d0202997 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -628,13 +628,6 @@ static int validate_change(const struct cpuset *cur, const struct cpuset *trial) * lock_cpu_hotplug()/unlock_cpu_hotplug() pair. */ -/* - * Hack to avoid 2.6.13 partial node dynamic sched domain bug. - * Disable letting 'cpu_exclusive' cpusets define dynamic sched - * domains, until the sched domain can handle partial nodes. - * Remove this #if hackery when sched domains fixed. - */ -#if 0 static void update_cpu_domains(struct cpuset *cur) { struct cpuset *c, *par = cur->parent; @@ -675,11 +668,6 @@ static void update_cpu_domains(struct cpuset *cur) partition_sched_domains(&pspan, &cspan); unlock_cpu_hotplug(); } -#else -static void update_cpu_domains(struct cpuset *cur) -{ -} -#endif static int update_cpumask(struct cpuset *cs, char *buf) { @@ -984,6 +972,10 @@ static ssize_t cpuset_common_file_read(struct file *file, char __user *buf, *s++ = '\n'; *s = '\0'; + /* Do nothing if *ppos is at the eof or beyond the eof. */ + if (s - page <= *ppos) + return 0; + start = page + *ppos; n = s - start; retval = n - copy_to_user(buf, start, min(n, nbytes)); @@ -1611,17 +1603,114 @@ int cpuset_zonelist_valid_mems_allowed(struct zonelist *zl) return 0; } +/* + * nearest_exclusive_ancestor() - Returns the nearest mem_exclusive + * ancestor to the specified cpuset. Call while holding cpuset_sem. + * If no ancestor is mem_exclusive (an unusual configuration), then + * returns the root cpuset. + */ +static const struct cpuset *nearest_exclusive_ancestor(const struct cpuset *cs) +{ + while (!is_mem_exclusive(cs) && cs->parent) + cs = cs->parent; + return cs; +} + /** - * cpuset_zone_allowed - is zone z allowed in current->mems_allowed - * @z: zone in question + * cpuset_zone_allowed - Can we allocate memory on zone z's memory node? + * @z: is this zone on an allowed node? + * @gfp_mask: memory allocation flags (we use __GFP_HARDWALL) * - * Is zone z allowed in current->mems_allowed, or is - * the CPU in interrupt context? (zone is always allowed in this case) - */ -int cpuset_zone_allowed(struct zone *z) + * If we're in interrupt, yes, we can always allocate. If zone + * z's node is in our tasks mems_allowed, yes. If it's not a + * __GFP_HARDWALL request and this zone's nodes is in the nearest + * mem_exclusive cpuset ancestor to this tasks cpuset, yes. + * Otherwise, no. + * + * GFP_USER allocations are marked with the __GFP_HARDWALL bit, + * and do not allow allocations outside the current tasks cpuset. + * GFP_KERNEL allocations are not so marked, so can escape to the + * nearest mem_exclusive ancestor cpuset. + * + * Scanning up parent cpusets requires cpuset_sem. The __alloc_pages() + * routine only calls here with __GFP_HARDWALL bit _not_ set if + * it's a GFP_KERNEL allocation, and all nodes in the current tasks + * mems_allowed came up empty on the first pass over the zonelist. + * So only GFP_KERNEL allocations, if all nodes in the cpuset are + * short of memory, might require taking the cpuset_sem semaphore. + * + * The first loop over the zonelist in mm/page_alloc.c:__alloc_pages() + * calls here with __GFP_HARDWALL always set in gfp_mask, enforcing + * hardwall cpusets - no allocation on a node outside the cpuset is + * allowed (unless in interrupt, of course). + * + * The second loop doesn't even call here for GFP_ATOMIC requests + * (if the __alloc_pages() local variable 'wait' is set). That check + * and the checks below have the combined affect in the second loop of + * the __alloc_pages() routine that: + * in_interrupt - any node ok (current task context irrelevant) + * GFP_ATOMIC - any node ok + * GFP_KERNEL - any node in enclosing mem_exclusive cpuset ok + * GFP_USER - only nodes in current tasks mems allowed ok. + **/ + +int cpuset_zone_allowed(struct zone *z, unsigned int __nocast gfp_mask) +{ + int node; /* node that zone z is on */ + const struct cpuset *cs; /* current cpuset ancestors */ + int allowed = 1; /* is allocation in zone z allowed? */ + + if (in_interrupt()) + return 1; + node = z->zone_pgdat->node_id; + if (node_isset(node, current->mems_allowed)) + return 1; + if (gfp_mask & __GFP_HARDWALL) /* If hardwall request, stop here */ + return 0; + + /* Not hardwall and node outside mems_allowed: scan up cpusets */ + down(&cpuset_sem); + cs = current->cpuset; + if (!cs) + goto done; /* current task exiting */ + cs = nearest_exclusive_ancestor(cs); + allowed = node_isset(node, cs->mems_allowed); +done: + up(&cpuset_sem); + return allowed; +} + +/** + * cpuset_excl_nodes_overlap - Do we overlap @p's mem_exclusive ancestors? + * @p: pointer to task_struct of some other task. + * + * Description: Return true if the nearest mem_exclusive ancestor + * cpusets of tasks @p and current overlap. Used by oom killer to + * determine if task @p's memory usage might impact the memory + * available to the current task. + * + * Acquires cpuset_sem - not suitable for calling from a fast path. + **/ + +int cpuset_excl_nodes_overlap(const struct task_struct *p) { - return in_interrupt() || - node_isset(z->zone_pgdat->node_id, current->mems_allowed); + const struct cpuset *cs1, *cs2; /* my and p's cpuset ancestors */ + int overlap = 0; /* do cpusets overlap? */ + + down(&cpuset_sem); + cs1 = current->cpuset; + if (!cs1) + goto done; /* current task exiting */ + cs2 = p->cpuset; + if (!cs2) + goto done; /* task p is exiting */ + cs1 = nearest_exclusive_ancestor(cs1); + cs2 = nearest_exclusive_ancestor(cs2); + overlap = nodes_intersects(cs1->mems_allowed, cs2->mems_allowed); +done: + up(&cpuset_sem); + + return overlap; } /* |