When a bio is split, the newly created bio must be associated with the same blkcg as the original bio (if BLK_CGROUP is enabled). If this operation is not performed, then the new bio is not associated with any group, and the group of the current task is returned when the group of the bio is requested. Depending on the frequency of splits, this may cause a large percentage of the bios belonging to a given group to be treated as if belonging to other groups (in most cases as if belonging to the root group). The expected group isolation may thereby be then broken. This commit adds the missing association in bio_split. Signed-off-by: Paolo Valente <paolo.valente@xxxxxxxxxx> --- block/bio.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/block/bio.c b/block/bio.c index 807d25e..c4a3834 100644 --- a/block/bio.c +++ b/block/bio.c @@ -1811,6 +1811,11 @@ struct bio *bio_split(struct bio *bio, int sectors, bio_advance(bio, split->bi_iter.bi_size); +#ifdef CONFIG_BLK_CGROUP + if (bio->bi_css) + bio_associate_blkcg(split, bio->bi_css); +#endif + return split; } EXPORT_SYMBOL(bio_split); -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html