diff options
| author | Li Nan <linan122@huawei.com> | 2023-01-17 15:08:05 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-03-11 16:43:54 +0100 |
| commit | 9e8bf9f95f7a299fa9ea45b678d001806ad5e12c (patch) | |
| tree | dbb74f4050338446c5dfee39c0429606395043e6 /block | |
| parent | f10001af0f7246cf3e43530d25f8d59a8db10df6 (diff) | |
blk-iocost: fix divide by 0 error in calc_lcoefs()
[ Upstream commit 984af1e66b4126cf145153661cc24c213e2ec231 ]
echo max of u64 to cost.model can cause divide by 0 error.
# echo 8:0 rbps=18446744073709551615 > /sys/fs/cgroup/io.cost.model
divide error: 0000 [#1] PREEMPT SMP
RIP: 0010:calc_lcoefs+0x4c/0xc0
Call Trace:
<TASK>
ioc_refresh_params+0x2b3/0x4f0
ioc_cost_model_write+0x3cb/0x4c0
? _copy_from_iter+0x6d/0x6c0
? kernfs_fop_write_iter+0xfc/0x270
cgroup_file_write+0xa0/0x200
kernfs_fop_write_iter+0x17d/0x270
vfs_write+0x414/0x620
ksys_write+0x73/0x160
__x64_sys_write+0x1e/0x30
do_syscall_64+0x35/0x80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
calc_lcoefs() uses the input value of cost.model in DIV_ROUND_UP_ULL,
overflow would happen if bps plus IOC_PAGE_SIZE is greater than
ULLONG_MAX, it can cause divide by 0 error.
Fix the problem by setting basecost
Signed-off-by: Li Nan <linan122@huawei.com>
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230117070806.3857142-5-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-iocost.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/block/blk-iocost.c b/block/blk-iocost.c index ef287c33d6d9..4fdc8858a69a 100644 --- a/block/blk-iocost.c +++ b/block/blk-iocost.c @@ -785,9 +785,14 @@ static void calc_lcoefs(u64 bps, u64 seqiops, u64 randiops, *page = *seqio = *randio = 0; - if (bps) - *page = DIV64_U64_ROUND_UP(VTIME_PER_SEC, - DIV_ROUND_UP_ULL(bps, IOC_PAGE_SIZE)); + if (bps) { + u64 bps_pages = DIV_ROUND_UP_ULL(bps, IOC_PAGE_SIZE); + + if (bps_pages) + *page = DIV64_U64_ROUND_UP(VTIME_PER_SEC, bps_pages); + else + *page = 1; + } if (seqiops) { v = DIV64_U64_ROUND_UP(VTIME_PER_SEC, seqiops); |