From 561deb108ca412c2986afc6e7c0d4c2bc2072f62 Mon Sep 17 00:00:00 2001 From: "Dennis Zhou (Facebook)" Date: Fri, 31 Aug 2018 16:22:42 -0400 Subject: Revert "blk-throttle: fix race between blkcg_bio_issue_check() and cgroup_rmdir()" [ Upstream commit 6b06546206868f723f2061d703a3c3c378dcbf4c ] This reverts commit 4c6994806f708559c2812b73501406e21ae5dcd0. Destroying blkgs is tricky because of the nature of the relationship. A blkg should go away when either a blkcg or a request_queue goes away. However, blkg's pin the blkcg to ensure they remain valid. To break this cycle, when a blkcg is offlined, blkgs put back their css ref. This eventually lets css_free() get called which frees the blkcg. The above commit (4c6994806f70) breaks this order of events by trying to destroy blkgs in css_free(). As the blkgs still hold references to the blkcg, css_free() is never called. The race between blkcg_bio_issue_check() and cgroup_rmdir() will be addressed in the following patch by delaying destruction of a blkg until all writeback associated with the blkcg has been finished. Fixes: 4c6994806f70 ("blk-throttle: fix race between blkcg_bio_issue_check() and cgroup_rmdir()") Reviewed-by: Josef Bacik Signed-off-by: Dennis Zhou Cc: Jiufei Xue Cc: Joseph Qi Cc: Tejun Heo Cc: Jens Axboe Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- include/linux/blk-cgroup.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include') diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h index 0fce47d5acb1..5d46b83d4820 100644 --- a/include/linux/blk-cgroup.h +++ b/include/linux/blk-cgroup.h @@ -88,7 +88,6 @@ struct blkg_policy_data { /* the blkg and policy id this per-policy data belongs to */ struct blkcg_gq *blkg; int plid; - bool offline; }; /* -- cgit v1.2.3