| Message ID | 20170411092901.5974-1-jack@suse.cz (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 04/11/2017 03:29 AM, Jan Kara wrote: > When CFQ calls wbt_disable_default(), it will call > blk_stat_remove_callback() to stop gathering IO statistics for the > purposes of writeback throttling. Later, when request_queue is > unregistered, wbt_exit() will call blk_stat_remove_callback() again > which will try to delete callback from the list again and possibly cause > list corruption. > > Fix the problem by making wbt_disable_default() called wbt_exit() which > is properly guarded against being called multiple times. > > Signed-off-by: Jan Kara <jack@suse.cz> > --- > block/blk-wbt.c | 12 ++++-------- > 1 file changed, 4 insertions(+), 8 deletions(-) > > So this fixes the list debug errors reported by 0-day for me. It was a > pre-existing problem with wbt_disable_default(). Thanks Jan, added for 4.12.
diff --git a/block/blk-wbt.c b/block/blk-wbt.c index ffa80e11cf14..b3b79149d3a0 100644 --- a/block/blk-wbt.c +++ b/block/blk-wbt.c @@ -653,19 +653,15 @@ void wbt_set_write_cache(struct rq_wb *rwb, bool write_cache_on) rwb->wc = write_cache_on; } - /* - * Disable wbt, if enabled by default. Only called from CFQ, if we have - * cgroups enabled +/* + * Disable wbt, if enabled by default. Only called from CFQ. */ void wbt_disable_default(struct request_queue *q) { struct rq_wb *rwb = q->rq_wb; - if (rwb && rwb->enable_state == WBT_STATE_ON_DEFAULT) { - blk_stat_remove_callback(q, rwb->cb); - rwb->win_nsec = rwb->min_lat_nsec = 0; - wbt_update_limits(rwb); - } + if (rwb && rwb->enable_state == WBT_STATE_ON_DEFAULT) + wbt_exit(q); } EXPORT_SYMBOL_GPL(wbt_disable_default);
When CFQ calls wbt_disable_default(), it will call blk_stat_remove_callback() to stop gathering IO statistics for the purposes of writeback throttling. Later, when request_queue is unregistered, wbt_exit() will call blk_stat_remove_callback() again which will try to delete callback from the list again and possibly cause list corruption. Fix the problem by making wbt_disable_default() called wbt_exit() which is properly guarded against being called multiple times. Signed-off-by: Jan Kara <jack@suse.cz> --- block/blk-wbt.c | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-) So this fixes the list debug errors reported by 0-day for me. It was a pre-existing problem with wbt_disable_default().