On Tue, Sep 14, 2021 at 08:54:02PM +0800, Yu Kuai wrote:
> If blk-throttle is enabled and io is issued before
> blk_throtl_register_queue() is done. Divide by zero crash will be
> triggered in tg_may_dispatch() because 'throtl_slice' is uninitialized.
>
> The problem is fixed in commit 75f4dca59694 ("block: call
> blk_register_queue earlier in device_add_disk") from mainline, however
> it's too hard to backport this patch due to lots of refactoring.
>
> Thus introduce a new flag QUEUE_FLAG_THROTL_INIT_DONE. It will be set
> after blk_throtl_register_queue() is done, and will be checked before
> applying any config.
>
> Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
> ---
> block/blk-sysfs.c | 2 ++
> block/blk-throttle.c | 41 +++++++++++++++++++++++++++++++++++++++--
> include/linux/blkdev.h | 1 +
> 3 files changed, 42 insertions(+), 2 deletions(-)
The commit you reference above is in 5.15-rc1. What about all of the
other stable kernel releases newer than 4.19.y? You do not want to move
to a newer release and have a regression.
And I would _REALLY_ like to take the identical commits that are
upstream if at all possible. What is needed to backport instead of
doing this one-off patch instead?
When we take changes that are not upstream, almost always they are
broken so we almost never want to do that.
thanks,
greg k-h
