Re: [PATCH v4 3/7] blk-mq: Fix use after of free q->mq_map

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From	Akinobu Mita <akinobu.mita@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v4 3/7] blk-mq: Fix use after of free q->mq_map
Date	Tue, 06 Oct 2015 02:00:02 +0200
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2015-09-29 15:52 GMT+09:00 Christoph Hellwig <hch@lst.de>:
> Looks good,
>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
>
> Can you also add a patch that renames blk_mq_free_queue to
> blk_mq_cleaup_queue and adds a comment that we should not free any memory
> here?  We had  way too many bugs of this kinds unfortunately.

Renaming blk_mq_free_queue to blk_mq_cleaup_queue sounds good because
it is called from blk_cleanup_queue().

How about adding comment like below?

/*
 * The resources allocated by blk_mq_init_allocated_queue() are released
 * by blk_mq_cleanup_queue() and blk_mq_release().
 *
 * blk_mq_cleanup_queue() is called from blk_cleanup_queue(), so
 * the resources which may be used after blk_cleanup_queue() shouldn't
 * be released here.  Instead, those should be released by blk_mq_release()
 * which is called from blk_release_queue().
 *
 * For example, loop and md drivers call del_gendisk() after
 * blk_cleanup_queue(), so the resources used when accessing sysfs entries
 * for blk-mq shouldn't be released by blk_mq_cleanup_queue() as these sysfs
 * entries can be accessible before del_gendisk() is called.
 */
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Thread

[PATCH v4 0/7] blk-mq: fix race conditions on cpu hotplug handling Akinobu Mita <akinobu.mita@gmail.com> - 2015-09-26 19:10 +0200
  [PATCH v4 4/7] blk-mq: fix q->mq_usage_counter access race Akinobu Mita <akinobu.mita@gmail.com> - 2015-09-26 19:20 +0200
  [PATCH v4 5/7] blk-mq: avoid inserting requests before establishing new mapping Akinobu Mita <akinobu.mita@gmail.com> - 2015-09-26 19:20 +0200
    Re: [PATCH v4 5/7] blk-mq: avoid inserting requests before  establishing new mapping Christoph Hellwig <hch@lst.de> - 2015-09-29 09:00 +0200
  [PATCH v4 2/7] blk-mq: fix sysfs registration/unregistration race Akinobu Mita <akinobu.mita@gmail.com> - 2015-09-26 19:20 +0200
  [PATCH v4 1/7] blk-mq: avoid setting hctx->tags->cpumask before allocation Akinobu Mita <akinobu.mita@gmail.com> - 2015-09-26 19:20 +0200
    Re: [PATCH v4 1/7] blk-mq: avoid setting hctx->tags->cpumask  before allocation Christoph Hellwig <hch@lst.de> - 2015-09-26 20:20 +0200
  [PATCH v4 7/7] blk-mq: fix deadlock when reading cpu_list Akinobu Mita <akinobu.mita@gmail.com> - 2015-09-26 19:20 +0200
  [PATCH v4 6/7] blk-mq: fix freeze queue race Akinobu Mita <akinobu.mita@gmail.com> - 2015-09-26 19:20 +0200
    Re: [PATCH v4 6/7] blk-mq: fix freeze queue race Tejun Heo <tj@kernel.org> - 2015-09-26 19:40 +0200
      Re: [PATCH v4 6/7] blk-mq: fix freeze queue race Akinobu Mita <akinobu.mita@gmail.com> - 2015-09-27 15:10 +0200
        Re: [PATCH v4 6/7] blk-mq: fix freeze queue race Tejun Heo <tj@kernel.org> - 2015-09-28 16:50 +0200
          Re: [PATCH v4 6/7] blk-mq: fix freeze queue race Christoph Hellwig <hch@lst.de> - 2015-09-29 09:00 +0200
          Re: [PATCH v4 6/7] blk-mq: fix freeze queue race Tejun Heo <tj@kernel.org> - 2015-09-29 17:10 +0200
            Re: [PATCH v4 6/7] blk-mq: fix freeze queue race Tejun Heo <tj@kernel.org> - 2015-09-30 00:00 +0200
              Re: [PATCH v4 6/7] blk-mq: fix freeze queue race Akinobu Mita <akinobu.mita@gmail.com> - 2015-09-30 12:40 +0200
          Re: [PATCH v4 6/7] blk-mq: fix freeze queue race Jens Axboe <axboe@kernel.dk> - 2015-09-29 17:10 +0200
  [PATCH v4 3/7] blk-mq: Fix use after of free q->mq_map Akinobu Mita <akinobu.mita@gmail.com> - 2015-09-26 19:20 +0200
    Re: [PATCH v4 3/7] blk-mq: Fix use after of free q->mq_map Christoph Hellwig <hch@lst.de> - 2015-09-29 09:00 +0200
      Re: [PATCH v4 3/7] blk-mq: Fix use after of free q->mq_map Akinobu Mita <akinobu.mita@gmail.com> - 2015-10-06 02:00 +0200
        Re: [PATCH v4 3/7] blk-mq: Fix use after of free q->mq_map Christoph Hellwig <hch@lst.de> - 2015-10-06 11:50 +0200
  Re: [PATCH v4 0/7] blk-mq: fix race conditions on cpu hotplug  handling Jens Axboe <axboe@kernel.dk> - 2015-09-29 19:40 +0200

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