Patch "[PATCH 031/135] lightnvm: fix locking and mempool in rrpc_lun_gc" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

[PATCH 031/135] lightnvm: fix locking and mempool in rrpc_lun_gc

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
0031-lightnvm-fix-locking-and-mempool-in-rrpc_lun_gc.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Wenwei Tao <[email protected]>
Date: Tue, 12 Jan 2016 07:49:25 +0100
Subject: [PATCH 031/135] lightnvm: fix locking and mempool in rrpc_lun_gc
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[ Upstream commit b262924be03d5d2ae735bc9a4b37eb2c613f61f8 ]

This patch fix two issues in rrpc_lun_gc

1. prio_list is protected by rrpc_lun's lock not nvm_lun's, so acquire rlun's lock instead of lun's before operate on the list.

2. we delete block from prio_list before allocating gcb, but gcb allocation may fail, we end without putting it back to the list, this makes the block won't get reclaimed in the future. To solve this issue, delete block after gcb allocation.

---
 drivers/lightnvm/rrpc.c |   12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

@@ -429,7 +429,7 @@ static void rrpc_lun_gc(struct work_stru
 	if (nr_blocks_need < rrpc->nr_luns)
 		nr_blocks_need = rrpc->nr_luns;
 
-	spin_lock(&lun->lock);
+	spin_lock(&rlun->lock);
 	while (nr_blocks_need > lun->nr_free_blocks &&
 					!list_empty(&rlun->prio_list)) {
 		struct rrpc_block *rblock = block_prio_find_max(rlun);

@@ -438,16 +438,16 @@ static void rrpc_lun_gc(struct work_stru
 		if (!rblock->nr_invalid_pages)
 			break;
 
+		gcb = mempool_alloc(rrpc->gcb_pool, GFP_ATOMIC);
+		if (!gcb)
+			break;
+
 		list_del_init(&rblock->prio);
 
 		BUG_ON(!block_is_full(rrpc, rblock));
 
 		pr_debug("rrpc: selected block '%lu' for GC\n", block->id);
 
-		gcb = mempool_alloc(rrpc->gcb_pool, GFP_ATOMIC);
-		if (!gcb)
-			break;
-
 		gcb->rrpc = rrpc;
 		gcb->rblk = rblock;
 		INIT_WORK(&gcb->ws_gc, rrpc_block_gc);

@@ -456,7 +456,7 @@ static void rrpc_lun_gc(struct work_stru
 
 		nr_blocks_need--;
 	}
-	spin_unlock(&lun->lock);
+	spin_unlock(&rlun->lock);
 
 	/* TODO: Hint that request queue can be started again */
 }

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/0030-lightnvm-unlock-rq-and-free-ppa_list-on-submission-f.patch queue-4.4/0033-NVMe-fix-build-with-CONFIG_NVM-enabled.patch queue-4.4/0031-lightnvm-fix-locking-and-mempool-in-rrpc_lun_gc.patch queue-4.4/0027-lightnvm-fix-bio-submission-issue.patch