On Mon, Jan 13, 2014 at 03:55:27PM -0800, Andrew Morton wrote: > On Mon, 13 Jan 2014 20:18:56 +0900 Minchan Kim <[email protected]> wrote: > > > Dan and Sergey reported that there is a racy between reset and > > flushing of pending work so that it could make oops by freeing > > zram->meta in reset while zram_slot_free can access zram->meta > > if new request is adding during the race window. > > > > This patch moves flush after taking init_lock so it prevents > > new request so that it closes the race. > > > > .. > > > > --- a/drivers/block/zram/zram_drv.c > > +++ b/drivers/block/zram/zram_drv.c > > @@ -553,14 +553,14 @@ static void zram_reset_device(struct zram *zram, bool > > reset_capacity) > > size_t index; > > struct zram_meta *meta; > > > > - flush_work(&zram->free_work); > > - > > down_write(&zram->init_lock); > > if (!zram->init_done) { > > up_write(&zram->init_lock); > > return; > > } > > > > + flush_work(&zram->free_work); > > + > > meta = zram->meta; > > zram->init_done = 0; > > This makes zram.lock nest inside zram.init_lock, which afaict is new > behaviour.
Originally, it was nested so it's not new. :) Look at zram_make_request which hold init_lock and then zram_bvec_rw hold zram->lock. > > That all seems OK and logical - has it been well tested with lockdep? Yeb. > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- Kind regards, Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
