mainline inclusion from mainline-v6.6-rc1 commit eead0056648cef49d7b15c07ae612fa217083165 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IAUKH4 CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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Currently, 'carryover_ios/bytes' is not handled in throtl_trim_slice(), for consequence, 'carryover_ios/bytes' will be used to throttle bio multiple times, for example:
1) set iops limit to 100, and slice start is 0, slice end is 100ms; 2) current time is 0, and 10 ios are dispatched, those io won't be throttled and io_disp is 10; 3) still at current time 0, update iops limit to 1000, carryover_ios is updated to (0 - 10) = -10; 4) in this slice(0 - 100ms), io_allowed = 100 + (-10) = 90, which means only 90 ios can be dispatched without waiting; 5) assume that io is throttled in slice(0 - 100ms), and throtl_trim_slice() update silce to (100ms - 200ms). In this case, 'carryover_ios/bytes' is not cleared and still only 90 ios can be dispatched between 100ms - 200ms.
Fix this problem by updating 'carryover_ios/bytes' in throtl_trim_slice().
Fixes: a880ae93e5b5 ("blk-throttle: fix io hung due to configuration updates") Reported-by: zhuxiaohui zhuxiaohui.400@bytedance.com Link: https://lore.kernel.org/all/20230812072116.42321-1-zhuxiaohui.400@bytedance.... Signed-off-by: Yu Kuai yukuai3@huawei.com Acked-by: Tejun Heo tj@kernel.org Link: https://lore.kernel.org/r/20230816012708.1193747-5-yukuai1@huaweicloud.com Signed-off-by: Jens Axboe axboe@kernel.dk --- block/blk-throttle.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-)
diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 91a22d49f5c3..f9aeaa2ce9e7 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -747,8 +747,9 @@ static u64 calculate_bytes_allowed(u64 bps_limit, unsigned long jiffy_elapsed) /* Trim the used slices and adjust slice start accordingly */ static inline void throtl_trim_slice(struct throtl_grp *tg, bool rw) { - unsigned long time_elapsed, io_trim; - u64 bytes_trim; + unsigned long time_elapsed; + long long bytes_trim; + int io_trim;
BUG_ON(time_before(tg->slice_end[rw], tg->slice_start[rw]));
@@ -776,17 +777,21 @@ static inline void throtl_trim_slice(struct throtl_grp *tg, bool rw) return;
bytes_trim = calculate_bytes_allowed(tg_bps_limit(tg, rw), - time_elapsed); - io_trim = calculate_io_allowed(tg_iops_limit(tg, rw), time_elapsed); - if (!bytes_trim && !io_trim) + time_elapsed) + + tg->carryover_bytes[rw]; + io_trim = calculate_io_allowed(tg_iops_limit(tg, rw), time_elapsed) + + tg->carryover_ios[rw]; + if (bytes_trim <= 0 && io_trim <= 0) return;
- if (tg->bytes_disp[rw] >= bytes_trim) + tg->carryover_bytes[rw] = 0; + if ((long long)tg->bytes_disp[rw] >= bytes_trim) tg->bytes_disp[rw] -= bytes_trim; else tg->bytes_disp[rw] = 0;
- if (tg->io_disp[rw] >= io_trim) + tg->carryover_ios[rw] = 0; + if ((int)tg->io_disp[rw] >= io_trim) tg->io_disp[rw] -= io_trim; else tg->io_disp[rw] = 0; @@ -794,7 +799,7 @@ static inline void throtl_trim_slice(struct throtl_grp *tg, bool rw) tg->slice_start[rw] += time_elapsed;
throtl_log(&tg->service_queue, - "[%c] trim slice nr=%lu bytes=%llu io=%lu start=%lu end=%lu jiffies=%lu", + "[%c] trim slice nr=%lu bytes=%lld io=%d start=%lu end=%lu jiffies=%lu", rw == READ ? 'R' : 'W', time_elapsed / tg->td->throtl_slice, bytes_trim, io_trim, tg->slice_start[rw], tg->slice_end[rw], jiffies);