This is a note to let you know that I've just added the patch titled
blk-mq: free hctx->ctxs in queue's release handler
to the 4.0-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:
blk-mq-free-hctx-ctxs-in-queue-s-release-handler.patch
and it can be found in the queue-4.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From c3b4afca7023b5aa0531912364246e67f79b3010 Mon Sep 17 00:00:00 2001
From: Ming Lei <tom.leiming@xxxxxxxxx>
Date: Thu, 4 Jun 2015 22:25:04 +0800
Subject: blk-mq: free hctx->ctxs in queue's release handler
From: Ming Lei <tom.leiming@xxxxxxxxx>
commit c3b4afca7023b5aa0531912364246e67f79b3010 upstream.
Now blk_cleanup_queue() can be called before calling
del_gendisk()[1], inside which hctx->ctxs is touched
from blk_mq_unregister_hctx(), but the variable has
been freed by blk_cleanup_queue() at that time.
So this patch moves freeing of hctx->ctxs into queue's
release handler for fixing the oops reported by Stefan.
[1], 6cd18e711dd8075 (block: destroy bdi before blockdev is
unregistered)
Reported-by: Stefan Seyfried <stefan.seyfried@xxxxxxxxxxxxxx>
Cc: NeilBrown <neilb@xxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Ming Lei <tom.leiming@xxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
block/blk-mq.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1589,6 +1589,7 @@ static int blk_mq_hctx_notify(void *data
return NOTIFY_OK;
}
+/* hctx->ctxs will be freed in queue's release handler */
static void blk_mq_exit_hctx(struct request_queue *q,
struct blk_mq_tag_set *set,
struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
@@ -1607,7 +1608,6 @@ static void blk_mq_exit_hctx(struct requ
blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
blk_free_flush_queue(hctx->fq);
- kfree(hctx->ctxs);
blk_mq_free_bitmap(&hctx->ctx_map);
}
@@ -1873,8 +1873,12 @@ void blk_mq_release(struct request_queue
unsigned int i;
/* hctx kobj stays in hctx */
- queue_for_each_hw_ctx(q, hctx, i)
+ queue_for_each_hw_ctx(q, hctx, i) {
+ if (!hctx)
+ continue;
+ kfree(hctx->ctxs);
kfree(hctx);
+ }
kfree(q->queue_hw_ctx);
Patches currently in stable-queue which might be from tom.leiming@xxxxxxxxx are
queue-4.0/blk-mq-free-hctx-ctxs-in-queue-s-release-handler.patch
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