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160 lines
4.0 KiB
160 lines
4.0 KiB
From: Russ Anderson <rja@sgi.com>
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Subject: ia64: cpe_migrate.ko causes deadlock.
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References: bnc#464676
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Patch-mainline: not yet, depends on patches.arch/ia64-page-migration
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schedule_on_each_cpu() deadlocks when called from an event thread.
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Change cpe_migrate to use a kthread to avoid the problem.
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Signed-off-by: Russ Anderson <rja@sgi.com>
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Acked-by: Raymund Will <rw@suse.de>
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---
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arch/ia64/kernel/cpe_migrate.c | 72 +++++++++++++++++++++++++++++++----------
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1 file changed, 56 insertions(+), 16 deletions(-)
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--- a/arch/ia64/kernel/cpe_migrate.c
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+++ b/arch/ia64/kernel/cpe_migrate.c
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@@ -22,6 +22,7 @@
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#include <linux/page-isolation.h>
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#include <linux/memcontrol.h>
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#include <linux/kobject.h>
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+#include <linux/kthread.h>
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#include <asm/page.h>
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#include <asm/system.h>
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@@ -40,12 +41,15 @@ static struct cpe_info cpe[CE_HISTORY_LE
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static int cpe_polling_enabled = 1;
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static int cpe_head;
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static int cpe_tail;
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-static int work_scheduled;
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static int mstat_cannot_isolate;
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static int mstat_failed_to_discard;
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static int mstat_already_marked;
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static int mstat_already_on_list;
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+/* IRQ handler notifies this wait queue on receipt of an IRQ */
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+DECLARE_WAIT_QUEUE_HEAD(cpe_activate_IRQ_wq);
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+static DECLARE_COMPLETION(kthread_cpe_migrated_exited);
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+int cpe_active;
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DEFINE_SPINLOCK(cpe_migrate_lock);
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static void
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@@ -160,12 +164,12 @@ ia64_mca_cpe_move_page(u64 paddr, u32 no
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}
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/*
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- * ia64_mca_cpe_migrate
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- * The worker that does the actual migration. It pulls a
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- * physical address off the list and calls the migration code.
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+ * cpe_process_queue
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+ * Pulls the physical address off the list and calls the migration code.
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+ * Will process all the addresses on the list.
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*/
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-static void
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-ia64_mca_cpe_migrate(struct work_struct *unused)
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+void
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+cpe_process_queue(void)
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{
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int ret;
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u64 paddr;
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@@ -193,10 +197,36 @@ ia64_mca_cpe_migrate(struct work_struct
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cpe_tail = 0;
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} while (cpe_tail != cpe_head);
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- work_scheduled = 0;
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+ return;
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+}
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+
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+inline int
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+cpe_list_empty(void)
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+{
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+ return (cpe_head == cpe_tail) && (!cpe[cpe_head].paddr);
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+}
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+
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+/*
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+ * kthread_cpe_migrate
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+ * kthread_cpe_migrate is created at module load time and lives
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+ * until the module is removed. When not active, it will sleep.
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+ */
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+static int
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+kthread_cpe_migrate(void *ignore)
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+{
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+ while (cpe_active) {
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+ /*
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+ * wait for work
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+ */
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+ (void)wait_event_interruptible(cpe_activate_IRQ_wq,
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+ (!cpe_list_empty() ||
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+ !cpe_active));
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+ cpe_process_queue(); /* process work */
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+ }
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+ complete(&kthread_cpe_migrated_exited);
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+ return 0;
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}
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-static DECLARE_WORK(cpe_enable_work, ia64_mca_cpe_migrate);
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DEFINE_SPINLOCK(cpe_list_lock);
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/*
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@@ -228,10 +258,7 @@ cpe_setup_migrate(void *rec)
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if (ret < 0)
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return -EINVAL;
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- if ((cpe_head != cpe_tail) || (cpe[cpe_head].paddr != 0))
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- /*
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- * List not empty
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- */
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+ if (!cpe_list_empty())
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for (i = 0; i < CE_HISTORY_LENGTH; i++) {
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if (PAGE_ALIGN(cpe[i].paddr) == PAGE_ALIGN(paddr)) {
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mstat_already_on_list++;
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@@ -256,10 +283,7 @@ cpe_setup_migrate(void *rec)
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}
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spin_unlock(&cpe_list_lock);
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- if (!work_scheduled) {
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- work_scheduled = 1;
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- schedule_work(&cpe_enable_work);
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- }
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+ wake_up_interruptible(&cpe_activate_IRQ_wq);
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return 1;
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}
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@@ -396,12 +420,23 @@ static int __init
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cpe_migrate_external_handler_init(void)
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{
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int error;
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+ struct task_struct *kthread;
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error = sysfs_create_file(kernel_kobj, &badram_attr.attr);
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if (error)
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return -EINVAL;
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/*
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+ * set up the kthread
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+ */
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+ cpe_active = 1;
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+ kthread = kthread_run(kthread_cpe_migrate, NULL, "cpe_migrate");
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+ if (IS_ERR(kthread)) {
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+ complete(&kthread_cpe_migrated_exited);
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+ return -EFAULT;
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+ }
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+
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+ /*
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* register external ce handler
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*/
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if (ia64_reg_CE_extension(cpe_setup_migrate)) {
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@@ -420,6 +455,11 @@ cpe_migrate_external_handler_exit(void)
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/* unregister external mca handlers */
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ia64_unreg_CE_extension();
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+ /* Stop kthread */
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+ cpe_active = 0; /* tell kthread_cpe_migrate to exit */
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+ wake_up_interruptible(&cpe_activate_IRQ_wq);
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+ wait_for_completion(&kthread_cpe_migrated_exited);
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+
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sysfs_remove_file(kernel_kobj, &badram_attr.attr);
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}
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