From: Chunguang Xu brookxu@tencent.com
mainline inclusion from mainline-v5.14-rc1 commit d80c228d44640f0b47b57a2ca4afa26ef87e16b0 category: bugfix bugzilla: 187475, https://gitee.com/openeuler/kernel/issues/I5ME0J CVE: NA
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On the IO submission path, blk_account_io_start() may interrupt the system interruption. When the interruption returns, the value of part->stamp may have been updated by other cores, so the time value collected before the interruption may be less than part-> stamp. So when this happens, we should do nothing to make io_ticks more accurate? For kernels less than 5.0, this may cause io_ticks to become smaller, which in turn may cause abnormal ioutil values.
Signed-off-by: Chunguang Xu brookxu@tencent.com Reviewed-by: Christoph Hellwig hch@lst.de Link: https://lore.kernel.org/r/1625521646-1069-1-git-send-email-brookxu.cn@gmail.... Signed-off-by: Jens Axboe axboe@kernel.dk
conflict: block/blk-core.c
Signed-off-by: Li Nan linan122@huawei.com Reviewed-by: Jason Yan yanaijie@huawei.com Signed-off-by: Yongqiang Liu liuyongqiang13@huawei.com --- block/bio.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/block/bio.c b/block/bio.c index 48092fe0c116..21c56c177b25 100644 --- a/block/bio.c +++ b/block/bio.c @@ -1673,7 +1673,7 @@ void update_io_ticks(int cpu, struct hd_struct *part, unsigned long now, bool en unsigned long stamp; again: stamp = READ_ONCE(part->stamp); - if (unlikely(stamp != now)) { + if (unlikely(time_after(now, stamp))) { if (likely(cmpxchg(&part->stamp, stamp, now) == stamp)) __part_stat_add(cpu, part, io_ticks, end ? now - stamp : 1); }