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mm/damon: simplify stop mechanism
A kernel thread can exit gracefully with kthread_stop(). So we don't need a new flag 'kdamond_stop'. And to make sure the task struct is not freed when accessing it, get reference to it before termination. Link: https://lkml.kernel.org/r/20211027130517.4404-1-changbin.du@gmail.com Signed-off-by: Changbin Du <changbin.du@gmail.com> Reviewed-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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0d16cfd46b
commit
0f91d13366
2 changed files with 15 additions and 37 deletions
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@ -381,7 +381,6 @@ struct damon_ctx {
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/* public: */
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/* public: */
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struct task_struct *kdamond;
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struct task_struct *kdamond;
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bool kdamond_stop;
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struct mutex kdamond_lock;
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struct mutex kdamond_lock;
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struct damon_primitive primitive;
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struct damon_primitive primitive;
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@ -390,17 +390,6 @@ static unsigned long damon_region_sz_limit(struct damon_ctx *ctx)
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return sz;
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return sz;
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}
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}
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static bool damon_kdamond_running(struct damon_ctx *ctx)
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{
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bool running;
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mutex_lock(&ctx->kdamond_lock);
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running = ctx->kdamond != NULL;
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mutex_unlock(&ctx->kdamond_lock);
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return running;
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}
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static int kdamond_fn(void *data);
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static int kdamond_fn(void *data);
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/*
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/*
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@ -418,7 +407,6 @@ static int __damon_start(struct damon_ctx *ctx)
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mutex_lock(&ctx->kdamond_lock);
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mutex_lock(&ctx->kdamond_lock);
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if (!ctx->kdamond) {
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if (!ctx->kdamond) {
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err = 0;
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err = 0;
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ctx->kdamond_stop = false;
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ctx->kdamond = kthread_run(kdamond_fn, ctx, "kdamond.%d",
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ctx->kdamond = kthread_run(kdamond_fn, ctx, "kdamond.%d",
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nr_running_ctxs);
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nr_running_ctxs);
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if (IS_ERR(ctx->kdamond)) {
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if (IS_ERR(ctx->kdamond)) {
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@ -474,13 +462,15 @@ int damon_start(struct damon_ctx **ctxs, int nr_ctxs)
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*/
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*/
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static int __damon_stop(struct damon_ctx *ctx)
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static int __damon_stop(struct damon_ctx *ctx)
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{
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{
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struct task_struct *tsk;
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mutex_lock(&ctx->kdamond_lock);
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mutex_lock(&ctx->kdamond_lock);
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if (ctx->kdamond) {
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tsk = ctx->kdamond;
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ctx->kdamond_stop = true;
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if (tsk) {
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get_task_struct(tsk);
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mutex_unlock(&ctx->kdamond_lock);
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mutex_unlock(&ctx->kdamond_lock);
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while (damon_kdamond_running(ctx))
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kthread_stop(tsk);
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usleep_range(ctx->sample_interval,
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put_task_struct(tsk);
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ctx->sample_interval * 2);
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return 0;
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return 0;
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}
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}
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mutex_unlock(&ctx->kdamond_lock);
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mutex_unlock(&ctx->kdamond_lock);
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@ -925,12 +915,8 @@ static bool kdamond_need_update_primitive(struct damon_ctx *ctx)
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static bool kdamond_need_stop(struct damon_ctx *ctx)
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static bool kdamond_need_stop(struct damon_ctx *ctx)
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{
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{
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struct damon_target *t;
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struct damon_target *t;
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bool stop;
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mutex_lock(&ctx->kdamond_lock);
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if (kthread_should_stop())
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stop = ctx->kdamond_stop;
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mutex_unlock(&ctx->kdamond_lock);
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if (stop)
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return true;
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return true;
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if (!ctx->primitive.target_valid)
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if (!ctx->primitive.target_valid)
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@ -1021,13 +1007,6 @@ static int kdamond_wait_activation(struct damon_ctx *ctx)
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return -EBUSY;
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return -EBUSY;
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}
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}
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static void set_kdamond_stop(struct damon_ctx *ctx)
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{
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mutex_lock(&ctx->kdamond_lock);
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ctx->kdamond_stop = true;
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mutex_unlock(&ctx->kdamond_lock);
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}
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/*
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/*
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* The monitoring daemon that runs as a kernel thread
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* The monitoring daemon that runs as a kernel thread
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*/
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*/
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@ -1038,17 +1017,18 @@ static int kdamond_fn(void *data)
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struct damon_region *r, *next;
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struct damon_region *r, *next;
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unsigned int max_nr_accesses = 0;
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unsigned int max_nr_accesses = 0;
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unsigned long sz_limit = 0;
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unsigned long sz_limit = 0;
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bool done = false;
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pr_debug("kdamond (%d) starts\n", current->pid);
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pr_debug("kdamond (%d) starts\n", current->pid);
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if (ctx->primitive.init)
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if (ctx->primitive.init)
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ctx->primitive.init(ctx);
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ctx->primitive.init(ctx);
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if (ctx->callback.before_start && ctx->callback.before_start(ctx))
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if (ctx->callback.before_start && ctx->callback.before_start(ctx))
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set_kdamond_stop(ctx);
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done = true;
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sz_limit = damon_region_sz_limit(ctx);
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sz_limit = damon_region_sz_limit(ctx);
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while (!kdamond_need_stop(ctx)) {
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while (!kdamond_need_stop(ctx) && !done) {
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if (kdamond_wait_activation(ctx))
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if (kdamond_wait_activation(ctx))
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continue;
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continue;
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@ -1056,7 +1036,7 @@ static int kdamond_fn(void *data)
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ctx->primitive.prepare_access_checks(ctx);
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ctx->primitive.prepare_access_checks(ctx);
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if (ctx->callback.after_sampling &&
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if (ctx->callback.after_sampling &&
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ctx->callback.after_sampling(ctx))
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ctx->callback.after_sampling(ctx))
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set_kdamond_stop(ctx);
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done = true;
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usleep_range(ctx->sample_interval, ctx->sample_interval + 1);
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usleep_range(ctx->sample_interval, ctx->sample_interval + 1);
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@ -1069,7 +1049,7 @@ static int kdamond_fn(void *data)
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sz_limit);
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sz_limit);
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if (ctx->callback.after_aggregation &&
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if (ctx->callback.after_aggregation &&
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ctx->callback.after_aggregation(ctx))
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ctx->callback.after_aggregation(ctx))
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set_kdamond_stop(ctx);
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done = true;
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kdamond_apply_schemes(ctx);
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kdamond_apply_schemes(ctx);
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kdamond_reset_aggregated(ctx);
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kdamond_reset_aggregated(ctx);
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kdamond_split_regions(ctx);
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kdamond_split_regions(ctx);
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@ -1088,9 +1068,8 @@ static int kdamond_fn(void *data)
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damon_destroy_region(r, t);
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damon_destroy_region(r, t);
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}
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}
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if (ctx->callback.before_terminate &&
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if (ctx->callback.before_terminate)
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ctx->callback.before_terminate(ctx))
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ctx->callback.before_terminate(ctx);
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set_kdamond_stop(ctx);
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if (ctx->primitive.cleanup)
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if (ctx->primitive.cleanup)
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ctx->primitive.cleanup(ctx);
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ctx->primitive.cleanup(ctx);
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