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blk-cgroup: fix list corruption from resetting io stat

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Since commit 3b8cc62987 ("blk-cgroup: Optimize blkcg_rstat_flush()"),
each iostat instance is added to blkcg percpu list, so blkcg_reset_stats()
can't reset the stat instance by memset(), otherwise the llist may be
corrupted.

Fix the issue by only resetting the counter part.

Cc: Tejun Heo <tj@kernel.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Jay Shin <jaeshin@redhat.com>
Fixes: 3b8cc62987 ("blk-cgroup: Optimize blkcg_rstat_flush()")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Waiman Long <longman@redhat.com>
Link: https://lore.kernel.org/r/20240515013157.443672-2-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Ming Lei 2024-05-15 09:31:56 +08:00 committed by Jens Axboe
parent efb905aeb4
commit 6da6680632
1 changed files with 35 additions and 23 deletions
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58
block/blk-cgroup.c
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@ -618,12 +618,45 @@ static void blkg_destroy_all(struct gendisk *disk)
spin_unlock_irq(&q->queue_lock);
}
static void blkg_iostat_set(struct blkg_iostat *dst, struct blkg_iostat *src)
{
int i;
for (i = 0; i < BLKG_IOSTAT_NR; i++) {
dst->bytes[i] = src->bytes[i];
dst->ios[i] = src->ios[i];
}
}
static void __blkg_clear_stat(struct blkg_iostat_set *bis)
{
struct blkg_iostat cur = {0};
unsigned long flags;
flags = u64_stats_update_begin_irqsave(&bis->sync);
blkg_iostat_set(&bis->cur, &cur);
blkg_iostat_set(&bis->last, &cur);
u64_stats_update_end_irqrestore(&bis->sync, flags);
}
static void blkg_clear_stat(struct blkcg_gq *blkg)
{
int cpu;
for_each_possible_cpu(cpu) {
struct blkg_iostat_set *s = per_cpu_ptr(blkg->iostat_cpu, cpu);
__blkg_clear_stat(s);
}
__blkg_clear_stat(&blkg->iostat);
}
static int blkcg_reset_stats(struct cgroup_subsys_state *css,
struct cftype *cftype, u64 val)
{
struct blkcg *blkcg = css_to_blkcg(css);
struct blkcg_gq *blkg;
int i, cpu;
int i;
mutex_lock(&blkcg_pol_mutex);
spin_lock_irq(&blkcg->lock);
@ -634,18 +667,7 @@ static int blkcg_reset_stats(struct cgroup_subsys_state *css,
* anyway. If you get hit by a race, retry.
*/
hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
for_each_possible_cpu(cpu) {
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);
bis->blkg = blkg;
}
memset(&blkg->iostat, 0, sizeof(blkg->iostat));
u64_stats_init(&blkg->iostat.sync);
blkg_clear_stat(blkg);
for (i = 0; i < BLKCG_MAX_POLS; i++) {
struct blkcg_policy *pol = blkcg_policy[i];
@ -948,16 +970,6 @@ void blkg_conf_exit(struct blkg_conf_ctx *ctx)
}
EXPORT_SYMBOL_GPL(blkg_conf_exit);
static void blkg_iostat_set(struct blkg_iostat *dst, struct blkg_iostat *src)
{
int i;
for (i = 0; i < BLKG_IOSTAT_NR; i++) {
dst->bytes[i] = src->bytes[i];
dst->ios[i] = src->ios[i];
}
}
static void blkg_iostat_add(struct blkg_iostat *dst, struct blkg_iostat *src)
{
int i;