This is a note to let you know that I've just added the patch titled
blk-throttle: prevent overflow while calculating wait time
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
blk-throttle-prevent-overflow-while-calculating-wait.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit f7d3731607fdd8ec30b4568ca2734691ba307fca
Author: Yu Kuai <yukuai3@xxxxxxxxxx>
Date: Mon Aug 29 10:22:38 2022 +0800
blk-throttle: prevent overflow while calculating wait time
[ Upstream commit 8d6bbaada2e0a65f9012ac4c2506460160e7237a ]
There is a problem found by code review in tg_with_in_bps_limit() that
'bps_limit * jiffy_elapsed_rnd' might overflow. Fix the problem by
calling mul_u64_u64_div_u64() instead.
Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
Acked-by: Tejun Heo <tj@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20220829022240.3348319-3-yukuai1@xxxxxxxxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 7c4e7993ba97..68cf8dbb4c67 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -950,7 +950,7 @@ static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio,
u64 bps_limit, unsigned long *wait)
{
bool rw = bio_data_dir(bio);
- u64 bytes_allowed, extra_bytes, tmp;
+ u64 bytes_allowed, extra_bytes;
unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;
unsigned int bio_size = throtl_bio_data_size(bio);
@@ -967,10 +967,8 @@ static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio,
jiffy_elapsed_rnd = tg->td->throtl_slice;
jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, tg->td->throtl_slice);
-
- tmp = bps_limit * jiffy_elapsed_rnd;
- do_div(tmp, HZ);
- bytes_allowed = tmp;
+ bytes_allowed = mul_u64_u64_div_u64(bps_limit, (u64)jiffy_elapsed_rnd,
+ (u64)HZ);
if (tg->bytes_disp[rw] + bio_size <= bytes_allowed) {
if (wait)
