From: Jan Kara jack@suse.cz
stable inclusion from stable-v5.10.121 commit 6b03dc67dde3811b11125b089bec876f1a9806b7 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5L6CQ
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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commit 22b106e5355d6e7a9c3b5cb5ed4ef22ae585ea94 upstream.
Commit d92c370a16cb ("block: really clone the block cgroup in bio_clone_blkg_association") changed bio_clone_blkg_association() to just clone bio->bi_blkg reference from source to destination bio. This is however wrong if the source and destination bios are against different block devices because struct blkcg_gq is different for each bdev-blkcg pair. This will result in IOs being accounted (and throttled as a result) multiple times against the same device (src bdev) while throttling of the other device (dst bdev) is ignored. In case of BFQ the inconsistency can even result in crashes in bfq_bic_update_cgroup(). Fix the problem by looking up correct blkcg_gq for the cloned bio.
Reported-by: Logan Gunthorpe logang@deltatee.com Reported-and-tested-by: Donald Buczek buczek@molgen.mpg.de Fixes: d92c370a16cb ("block: really clone the block cgroup in bio_clone_blkg_association") CC: stable@vger.kernel.org Reviewed-by: Christoph Hellwig hch@lst.de Signed-off-by: Jan Kara jack@suse.cz Link: https://lore.kernel.org/r/20220602081242.7731-1-jack@suse.cz Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com Acked-by: Xie XiuQi xiexiuqi@huawei.com --- block/blk-cgroup.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-)
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index cebcc00e30f8..bd13079d63f9 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -1925,12 +1925,8 @@ EXPORT_SYMBOL_GPL(bio_associate_blkg); */ void bio_clone_blkg_association(struct bio *dst, struct bio *src) { - if (src->bi_blkg) { - if (dst->bi_blkg) - blkg_put(dst->bi_blkg); - blkg_get(src->bi_blkg); - dst->bi_blkg = src->bi_blkg; - } + if (src->bi_blkg) + bio_associate_blkg_from_css(dst, &bio_blkcg(src)->css); } EXPORT_SYMBOL_GPL(bio_clone_blkg_association);