From bbe373f2c60b2aa36c3231734a5afc5271a06718 Mon Sep 17 00:00:00 2001 From: David Rientjes Date: Tue, 16 Oct 2007 23:25:58 -0700 Subject: [PATCH] oom: compare cpuset mems_allowed instead of exclusive ancestors Instead of testing for overlap in the memory nodes of the the nearest exclusive ancestor of both current and the candidate task, it is better to simply test for intersection between the task's mems_allowed in their task descriptors. This does not require taking callback_mutex since it is only used as a hint in the badness scoring. Tasks that do not have an intersection in their mems_allowed with the current task are not explicitly restricted from being OOM killed because it is quite possible that the candidate task has allocated memory there before and has since changed its mems_allowed. Cc: Andrea Arcangeli Acked-by: Christoph Lameter Signed-off-by: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/cpuset.h | 6 ++++-- kernel/cpuset.c | 43 +++++++++++------------------------------- mm/oom_kill.c | 2 +- 3 files changed, 16 insertions(+), 35 deletions(-) diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h index 9e633ea103ce..ea44d2e768a0 100644 --- a/include/linux/cpuset.h +++ b/include/linux/cpuset.h @@ -45,7 +45,8 @@ static int inline cpuset_zone_allowed_hardwall(struct zone *z, gfp_t gfp_mask) __cpuset_zone_allowed_hardwall(z, gfp_mask); } -extern int cpuset_excl_nodes_overlap(const struct task_struct *p); +extern int cpuset_mems_allowed_intersects(const struct task_struct *tsk1, + const struct task_struct *tsk2); #define cpuset_memory_pressure_bump() \ do { \ @@ -113,7 +114,8 @@ static inline int cpuset_zone_allowed_hardwall(struct zone *z, gfp_t gfp_mask) return 1; } -static inline int cpuset_excl_nodes_overlap(const struct task_struct *p) +static inline int cpuset_mems_allowed_intersects(const struct task_struct *tsk1, + const struct task_struct *tsk2) { return 1; } diff --git a/kernel/cpuset.c b/kernel/cpuset.c index 0864f4097930..2eb2e50db0d6 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -2506,41 +2506,20 @@ int cpuset_mem_spread_node(void) EXPORT_SYMBOL_GPL(cpuset_mem_spread_node); /** - * 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. - * - * Call while holding callback_mutex. + * cpuset_mems_allowed_intersects - Does @tsk1's mems_allowed intersect @tsk2's? + * @tsk1: pointer to task_struct of some task. + * @tsk2: pointer to task_struct of some other task. + * + * Description: Return true if @tsk1's mems_allowed intersects the + * mems_allowed of @tsk2. Used by the OOM killer to determine if + * one of the task's memory usage might impact the memory available + * to the other. **/ -int cpuset_excl_nodes_overlap(const struct task_struct *p) +int cpuset_mems_allowed_intersects(const struct task_struct *tsk1, + const struct task_struct *tsk2) { - const struct cpuset *cs1, *cs2; /* my and p's cpuset ancestors */ - int overlap = 1; /* do cpusets overlap? */ - - task_lock(current); - if (current->flags & PF_EXITING) { - task_unlock(current); - goto done; - } - cs1 = nearest_exclusive_ancestor(current->cpuset); - task_unlock(current); - - task_lock((struct task_struct *)p); - if (p->flags & PF_EXITING) { - task_unlock((struct task_struct *)p); - goto done; - } - cs2 = nearest_exclusive_ancestor(p->cpuset); - task_unlock((struct task_struct *)p); - - overlap = nodes_intersects(cs1->mems_allowed, cs2->mems_allowed); -done: - return overlap; + return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed); } /* diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 5c5aa7380bd1..d9bba82923d5 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -143,7 +143,7 @@ unsigned long badness(struct task_struct *p, unsigned long uptime) * because p may have allocated or otherwise mapped memory on * this node before. However it will be less likely. */ - if (!cpuset_excl_nodes_overlap(p)) + if (!cpuset_mems_allowed_intersects(current, p)) points /= 8; /* -- 2.20.1