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authorTejun Heo <tj@kernel.org>2019-06-13 15:30:41 -0700
committerJens Axboe <axboe@kernel.dk>2019-06-15 10:39:42 -0600
commit6631142229005e1b1c311a09efe9fb3cfdac8559 (patch)
tree26f8b21314b83d627d3d0354d1abf3638397832a /fs/fs-writeback.c
parent71c814077de60b2e7415dac6f5c4e98f59d521fd (diff)
blkcg, writeback: dead memcgs shouldn't contribute to writeback ownership arbitration
wbc_account_io() collects information on cgroup ownership of writeback pages to determine which cgroup should own the inode. Pages can stay associated with dead memcgs but we want to avoid attributing IOs to dead blkcgs as much as possible as the association is likely to be stale. However, currently, pages associated with dead memcgs contribute to the accounting delaying and/or confusing the arbitration. Fix it by ignoring pages associated with dead memcgs. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs/fs-writeback.c')
-rw-r--r--fs/fs-writeback.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index e41cbe8e81b9..9ebfb1b28430 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -715,6 +715,7 @@ void wbc_detach_inode(struct writeback_control *wbc)
void wbc_account_io(struct writeback_control *wbc, struct page *page,
size_t bytes)
{
+ struct cgroup_subsys_state *css;
int id;
/*
@@ -726,7 +727,12 @@ void wbc_account_io(struct writeback_control *wbc, struct page *page,
if (!wbc->wb)
return;
- id = mem_cgroup_css_from_page(page)->id;
+ css = mem_cgroup_css_from_page(page);
+ /* dead cgroups shouldn't contribute to inode ownership arbitration */
+ if (!(css->flags & CSS_ONLINE))
+ return;
+
+ id = css->id;
if (id == wbc->wb_id) {
wbc->wb_bytes += bytes;