forked from luck/tmp_suning_uos_patched
[PATCH] CFQ io scheduler: scheduler switch oops
If cfq is managing a queue and a new scheduler is later selected, it is possible for the cfqd unplug_work work to be queued after the kblockd work struct has been flushed. The problem is the ordering of cfq_shutdown_timer_wq() and blk_put_queue() in cfq_put_cfqd(). The latter may rearm the work, leaving cfq_kick_queue() with dead data. Signed-off-by: Jens Axboe <axboe@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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@ -2249,10 +2249,11 @@ static void cfq_put_cfqd(struct cfq_data *cfqd)
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if (!atomic_dec_and_test(&cfqd->ref))
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return;
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cfq_shutdown_timer_wq(cfqd);
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blk_put_queue(q);
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cfq_shutdown_timer_wq(cfqd);
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q->elevator->elevator_data = NULL;
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mempool_destroy(cfqd->crq_pool);
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kfree(cfqd->crq_hash);
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kfree(cfqd->cfq_hash);
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