Messages in this thread Patch in this message | | | Date | Wed, 03 Sep 2008 15:33:53 +0800 | From | Li Zefan <> | Subject | [PATCH] cpuset: avoid changing cpuset's cpus when -errno returned |
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After the patch:
commit 0b2f630a28d53b5a2082a5275bc3334b10373508 Author: Miao Xie <miaox@cn.fujitsu.com> Date: Fri Jul 25 01:47:21 2008 -0700
cpusets: restructure the function update_cpumask() and update_nodemask()
It might happen that 'echo 0 > /cpuset/sub/cpus' returns failure but 'cpus' has been changed, because cpus was changed before calling heap_init() which may return -ENOMEM.
This patch restores the orginal behavior.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> --- kernel/cpuset.c | 32 ++++++++++++++------------------ 1 files changed, 14 insertions(+), 18 deletions(-)
diff --git a/kernel/cpuset.c b/kernel/cpuset.c index d5ab79c..817f8ac 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -774,36 +774,27 @@ static void cpuset_change_cpumask(struct task_struct *tsk, /** * update_tasks_cpumask - Update the cpumasks of tasks in the cpuset. * @cs: the cpuset in which each task's cpus_allowed mask needs to be changed + * @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks() * * Called with cgroup_mutex held * * The cgroup_scan_tasks() function will scan all the tasks in a cgroup, * calling callback functions for each. * - * Return 0 if successful, -errno if not. + * Always return 0 if @heap != NULL, may return -errno if @heap == NULL */ -static int update_tasks_cpumask(struct cpuset *cs) +static int update_tasks_cpumask(struct cpuset *cs, struct ptr_heap *heap) { struct cgroup_scanner scan; - struct ptr_heap heap; int retval; - /* - * cgroup_scan_tasks() will initialize heap->gt for us. - * heap_init() is still needed here for we should not change - * cs->cpus_allowed when heap_init() fails. - */ - retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL); - if (retval) - return retval; - scan.cg = cs->css.cgroup; scan.test_task = cpuset_test_cpumask; scan.process_task = cpuset_change_cpumask; - scan.heap = &heap; + scan.heap = heap; retval = cgroup_scan_tasks(&scan); + BUG_ON(heap != NULL && retval); - heap_free(&heap); return retval; } @@ -814,6 +805,7 @@ static int update_tasks_cpumask(struct cpuset *cs) */ static int update_cpumask(struct cpuset *cs, const char *buf) { + struct ptr_heap heap; struct cpuset trialcs; int retval; int is_load_balanced; @@ -848,6 +840,10 @@ static int update_cpumask(struct cpuset *cs, const char *buf) if (cpus_equal(cs->cpus_allowed, trialcs.cpus_allowed)) return 0; + retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL); + if (retval) + return retval; + is_load_balanced = is_sched_load_balance(&trialcs); mutex_lock(&callback_mutex); @@ -858,9 +854,9 @@ static int update_cpumask(struct cpuset *cs, const char *buf) * Scan tasks in the cpuset, and update the cpumasks of any * that need an update. */ - retval = update_tasks_cpumask(cs); - if (retval < 0) - return retval; + update_tasks_cpumask(cs, &heap); + + heap_free(&heap); if (is_load_balanced) rebuild_sched_domains(); @@ -1896,7 +1892,7 @@ static void scan_for_empty_cpusets(const struct cpuset *root) nodes_empty(cp->mems_allowed)) remove_tasks_in_empty_cpuset(cp); else { - update_tasks_cpumask(cp); + update_tasks_cpumask(cp, NULL); update_tasks_nodemask(cp, &oldmems); } } -- 1.5.4.rc3
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