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fix: corrupted hmt_swap_ctrl->lock spinlock. #10

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fix: corrupted hmt_swap_ctrl->lock spinlock. #10

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2 changes: 2 additions & 0 deletions linux-5.14-rc5/include/linux/hermit_types.h
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,8 @@ struct hmt_work_struct {
* swap stats to control async swap out
*/
struct hmt_swap_ctrl {
// `lock` must be the first field in the struct to avoid breaking
// `hmt_clear_locked_swap_ctrl()`.
spinlock_t lock;
atomic_t sthd_cnt;
atomic_t active_sthd_cnt;
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11 changes: 9 additions & 2 deletions linux-5.14-rc5/mm/hermit_utils.c
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Original file line number Diff line number Diff line change
Expand Up @@ -179,13 +179,20 @@ static inline void hmt_update_low_watermark(struct mem_cgroup *memcg,
}
}

// Resets a locked `hmt_swap_ctrl` without dropping the lock.
// We assume `offsetof(hmt_swap_ctrl, lock) = 0`.
static void hmt_clear_locked_swap_ctrl(struct hmt_swap_ctrl *sc)
{
memset(sc + sizeof(sc->lock), 0, sizeof(*sc) - sizeof(sc->lock));
}

// must hold sc->lock
inline void hmt_update_swap_ctrl(struct mem_cgroup *memcg,
struct hmt_swap_ctrl *sc)
{
const int UPD_PERIOD = 1000; // update swap-in tput per UPD_PERIOD us
if (sc->swin_ts[0] == 0) {
memset(sc, 0, sizeof(struct hmt_swap_ctrl));
hmt_clear_locked_swap_ctrl(sc);
sc->swin_ts[0] = get_cycles_light();
sc->nr_pg_charged[0] = atomic64_read(&memcg->total_pg_charge);
return;
Expand Down Expand Up @@ -311,7 +318,7 @@ void hermit_init_memcg(struct mem_cgroup *memcg)
return;

memset(&memcg->hmt_sc, 0, sizeof(struct hmt_swap_ctrl));
memcg->hmt_sc.lock = __SPIN_LOCK_UNLOCKED(memcg->hmt_sc.lock);
spin_lock_init(&memcg->hmt_sc.lock);
for (i = 0; i < HMT_MAX_NR_STHDS; i++) {
INIT_WORK(&memcg->sthds[i].work, hermit_high_work_func);
memcg->sthds[i].id = i;
Expand Down