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authorGuoju Fang <fangguoju@gmail.com>2018-09-27 23:41:46 +0800
committerJens Axboe <axboe@kernel.dk>2018-09-27 09:47:01 -0600
commit0f843e65d9eef4936929bb036c5f771fb261eea4 (patch)
treeb02f7ba31960169e8789a54b3c546d50834b0da9 /drivers/md
parentf151ba989d149bbdfc90e5405724bbea094f9b17 (diff)
downloadlinux-0f843e65d9eef4936929bb036c5f771fb261eea4.tar.bz2
bcache: add separate workqueue for journal_write to avoid deadlock
After write SSD completed, bcache schedules journal_write work to system_wq, which is a public workqueue in system, without WQ_MEM_RECLAIM flag. system_wq is also a bound wq, and there may be no idle kworker on current processor. Creating a new kworker may unfortunately need to reclaim memory first, by shrinking cache and slab used by vfs, which depends on bcache device. That's a deadlock. This patch create a new workqueue for journal_write with WQ_MEM_RECLAIM flag. It's rescuer thread will work to avoid the deadlock. Signed-off-by: Guoju Fang <fangguoju@gmail.com> Cc: stable@vger.kernel.org Signed-off-by: Coly Li <colyli@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/bcache/bcache.h1
-rw-r--r--drivers/md/bcache/journal.c6
-rw-r--r--drivers/md/bcache/super.c8
3 files changed, 12 insertions, 3 deletions
diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
index 83504dd8100a..954dad29e6e8 100644
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -965,6 +965,7 @@ void bch_prio_write(struct cache *ca);
void bch_write_bdev_super(struct cached_dev *dc, struct closure *parent);
extern struct workqueue_struct *bcache_wq;
+extern struct workqueue_struct *bch_journal_wq;
extern struct mutex bch_register_lock;
extern struct list_head bch_cache_sets;
diff --git a/drivers/md/bcache/journal.c b/drivers/md/bcache/journal.c
index 6116bbf870d8..522c7426f3a0 100644
--- a/drivers/md/bcache/journal.c
+++ b/drivers/md/bcache/journal.c
@@ -485,7 +485,7 @@ static void do_journal_discard(struct cache *ca)
closure_get(&ca->set->cl);
INIT_WORK(&ja->discard_work, journal_discard_work);
- schedule_work(&ja->discard_work);
+ queue_work(bch_journal_wq, &ja->discard_work);
}
}
@@ -592,7 +592,7 @@ static void journal_write_done(struct closure *cl)
: &j->w[0];
__closure_wake_up(&w->wait);
- continue_at_nobarrier(cl, journal_write, system_wq);
+ continue_at_nobarrier(cl, journal_write, bch_journal_wq);
}
static void journal_write_unlock(struct closure *cl)
@@ -627,7 +627,7 @@ static void journal_write_unlocked(struct closure *cl)
spin_unlock(&c->journal.lock);
btree_flush_write(c);
- continue_at(cl, journal_write, system_wq);
+ continue_at(cl, journal_write, bch_journal_wq);
return;
}
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 94c756c66bd7..30ba9aeb5ee8 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -47,6 +47,7 @@ static int bcache_major;
static DEFINE_IDA(bcache_device_idx);
static wait_queue_head_t unregister_wait;
struct workqueue_struct *bcache_wq;
+struct workqueue_struct *bch_journal_wq;
#define BTREE_MAX_PAGES (256 * 1024 / PAGE_SIZE)
/* limitation of partitions number on single bcache device */
@@ -2341,6 +2342,9 @@ static void bcache_exit(void)
kobject_put(bcache_kobj);
if (bcache_wq)
destroy_workqueue(bcache_wq);
+ if (bch_journal_wq)
+ destroy_workqueue(bch_journal_wq);
+
if (bcache_major)
unregister_blkdev(bcache_major, "bcache");
unregister_reboot_notifier(&reboot);
@@ -2370,6 +2374,10 @@ static int __init bcache_init(void)
if (!bcache_wq)
goto err;
+ bch_journal_wq = alloc_workqueue("bch_journal", WQ_MEM_RECLAIM, 0);
+ if (!bch_journal_wq)
+ goto err;
+
bcache_kobj = kobject_create_and_add("bcache", fs_kobj);
if (!bcache_kobj)
goto err;