From: Tejun Heo <tj@kernel.org> mainline inclusion from mainline-v5.16-rc1 commit 3c08b0931eedd04c530040499fadeccab50ed646 category: feature bugzilla: 185803 https://gitee.com/openeuler/kernel/issues/I4JOG9?from=project-issue CVE: NA Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------------------------------------- c3df5fb57fe8 ("cgroup: rstat: fix A-A deadlock on 32bit around u64_stats_sync") made u64_stats updates irq-safe to avoid A-A deadlocks. Unfortunately, the conversion missed one in blk_cgroup_bio_start(). Fix it. Fixes: 2d146aa3aa84 ("mm: memcontrol: switch to rstat") Cc: stable@vger.kernel.org # v5.13+ Reported-by: syzbot+9738c8815b375ce482a1@syzkaller.appspotmail.com Signed-off-by: Tejun Heo <tj@kernel.org> Link: https://lore.kernel.org/r/YWi7NrQdVlxD6J9W@slm.duckdns.org Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Lu Jialin <lujialin4@huawei.com> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> --- block/blk-cgroup.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 7f7d41236838..bd0c2bec05a8 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -1932,10 +1932,11 @@ void blk_cgroup_bio_start(struct bio *bio) { int rwd = blk_cgroup_io_type(bio), cpu; struct blkg_iostat_set *bis; + unsigned long flags; cpu = get_cpu(); bis = per_cpu_ptr(bio->bi_blkg->iostat_cpu, cpu); - u64_stats_update_begin(&bis->sync); + flags = u64_stats_update_begin_irqsave(&bis->sync); /* * If the bio is flagged with BIO_CGROUP_ACCT it means this is a split @@ -1947,7 +1948,7 @@ void blk_cgroup_bio_start(struct bio *bio) } bis->cur.ios[rwd]++; - u64_stats_update_end(&bis->sync); + u64_stats_update_end_irqrestore(&bis->sync, flags); if (cgroup_subsys_on_dfl(io_cgrp_subsys)) cgroup_rstat_updated(bio->bi_blkg->blkcg->css.cgroup, cpu); put_cpu(); -- 2.20.1