With the recent gl_object fixes and an additional reference counting bug fixed in this patch queue, these four remaining shrinker deadlock avoidance patches now seem ready for mainline.
As explained in the previous posting of this patch queue, when inodes are evicted, GFS2 currently calls into DLM. Inode eviction can be triggered by memory pressure, in the context of a random user-space process. If DLM happens to block in the process in question (for example, it that process is a fence agent), GFS2 and DLM will deadlock. This patch queue stops GFS2 from calling into DLM on the inode evict path under memory pressure. It does so by first decoupling destroying inodes and putting their associated glocks, which is what ends up calling into DLM. Second, when under memory pressure, it moves putting glocks into work queue context where it cannot block DLM. Third, when gfs2_drop_inode determines that an inode's link count has hit zero under memory pressure, it puts that inode on the delete workqueue (and keeps the inode in the icache) instead of causing gfs2_evict_inode to delete the inode immediately. The delete workqueue will not be processed under memory pressure, so deleting inodes from there is safe. Thanks, Andreas Andreas Gruenbacher (4): gfs2: gfs2_glock_get: Wait on freeing glocks gfs2: Get rid of gfs2_set_nlink gfs2: gfs2_evict_inode: Put glocks asynchronously gfs2: Defer deleting inodes under memory pressure fs/gfs2/glock.c | 135 +++++++++++++++++++++++++++++++++++++++++++++++--------- fs/gfs2/glock.h | 2 + fs/gfs2/glops.c | 28 +----------- fs/gfs2/super.c | 43 +++++++++++++++++- 4 files changed, 157 insertions(+), 51 deletions(-) -- 2.13.3
