diff options
| author | Waiman Long <longman@redhat.com> | 2026-01-27 04:02:42 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-02-06 16:44:23 +0100 |
| commit | 892faa76be894d324bf48b12a55c7af7be2bad83 (patch) | |
| tree | 0c3d59720c2c2214ae0139299d8397ad66724c72 /block | |
| parent | a58e29849aef8d26554a982989a2190b49aaf8ed (diff) | |
blk-cgroup: Reinit blkg_iostat_set after clearing in blkcg_reset_stats()
[ Upstream commit 3d2af77e31ade05ff7ccc3658c3635ec1bea0979 ]
When blkg_alloc() is called to allocate a blkcg_gq structure
with the associated blkg_iostat_set's, there are 2 fields within
blkg_iostat_set that requires proper initialization - blkg & sync.
The former field was introduced by commit 3b8cc6298724 ("blk-cgroup:
Optimize blkcg_rstat_flush()") while the later one was introduced by
commit f73316482977 ("blk-cgroup: reimplement basic IO stats using
cgroup rstat").
Unfortunately those fields in the blkg_iostat_set's are not properly
re-initialized when they are cleared in v1's blkcg_reset_stats(). This
can lead to a kernel panic due to NULL pointer access of the blkg
pointer. The missing initialization of sync is less problematic and
can be a problem in a debug kernel due to missing lockdep initialization.
Fix these problems by re-initializing them after memory clearing.
Fixes: 3b8cc6298724 ("blk-cgroup: Optimize blkcg_rstat_flush()")
Fixes: f73316482977 ("blk-cgroup: reimplement basic IO stats using cgroup rstat")
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230606180724.2455066-1-longman@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
[ Remove this line: bis -> blkg = blkg for blkg was introduced by commit
3b8cc6298724 ("blk-cgroup: Optimize blkcg_rstat_flush()") since v6.2. ]
Signed-off-by: Alva Lan <alvalan9@foxmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-cgroup.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index ef596fc10465..f314192b6de8 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -531,8 +531,12 @@ static int blkcg_reset_stats(struct cgroup_subsys_state *css, struct blkg_iostat_set *bis = per_cpu_ptr(blkg->iostat_cpu, cpu); memset(bis, 0, sizeof(*bis)); + + /* Re-initialize the cleared blkg_iostat_set */ + u64_stats_init(&bis->sync); } memset(&blkg->iostat, 0, sizeof(blkg->iostat)); + u64_stats_init(&blkg->iostat.sync); for (i = 0; i < BLKCG_MAX_POLS; i++) { struct blkcg_policy *pol = blkcg_policy[i]; |