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mm/damon/sysfs-schemes: add timeout for update_schemes_tried_regions
If a scheme is set to not applied to any monitoring target region for any
reasons including the target access pattern, quota, filters, or
watermarks, writing 'update_schemes_tried_regions' to 'state' DAMON sysfs
file can indefinitely hang. Fix the case by implementing a timeout for
the operation. The time limit is two apply intervals of each scheme.
Link: https://lkml.kernel.org/r/20231124213840.39157-1-sj@kernel.org
Fixes: 4d4e41b682
("mm/damon/sysfs-schemes: do not update tried regions more than one DAMON snapshot")
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
parent
854f2764b5
commit
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@ -139,6 +139,13 @@ static const struct kobj_type damon_sysfs_scheme_region_ktype = {
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* damon_sysfs_before_damos_apply() understands the situation by showing the
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* 'finished' status and do nothing.
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*
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* If DAMOS is not applied to any region due to any reasons including the
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* access pattern, the watermarks, the quotas, and the filters,
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* ->before_damos_apply() will not be called back. Until the situation is
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* changed, the update will not be finished. To avoid this,
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* damon_sysfs_after_sampling() set the status as 'finished' if more than two
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* apply intervals of the scheme is passed while the state is 'idle'.
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*
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* Finally, the tried regions request handling finisher function
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* (damon_sysfs_schemes_update_regions_stop()) unregisters the callbacks.
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*/
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@ -154,6 +161,7 @@ struct damon_sysfs_scheme_regions {
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int nr_regions;
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unsigned long total_bytes;
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enum damos_sysfs_regions_upd_status upd_status;
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unsigned long upd_timeout_jiffies;
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};
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static struct damon_sysfs_scheme_regions *
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@ -1854,7 +1862,9 @@ static int damon_sysfs_after_sampling(struct damon_ctx *ctx)
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for (i = 0; i < sysfs_schemes->nr; i++) {
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sysfs_regions = sysfs_schemes->schemes_arr[i]->tried_regions;
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if (sysfs_regions->upd_status ==
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DAMOS_TRIED_REGIONS_UPD_STARTED)
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DAMOS_TRIED_REGIONS_UPD_STARTED ||
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time_after(jiffies,
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sysfs_regions->upd_timeout_jiffies))
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sysfs_regions->upd_status =
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DAMOS_TRIED_REGIONS_UPD_FINISHED;
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}
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@ -1885,14 +1895,41 @@ int damon_sysfs_schemes_clear_regions(
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return 0;
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}
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static struct damos *damos_sysfs_nth_scheme(int n, struct damon_ctx *ctx)
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{
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struct damos *scheme;
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int i = 0;
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damon_for_each_scheme(scheme, ctx) {
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if (i == n)
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return scheme;
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i++;
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}
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return NULL;
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}
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static void damos_tried_regions_init_upd_status(
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struct damon_sysfs_schemes *sysfs_schemes)
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struct damon_sysfs_schemes *sysfs_schemes,
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struct damon_ctx *ctx)
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{
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int i;
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struct damos *scheme;
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struct damon_sysfs_scheme_regions *sysfs_regions;
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for (i = 0; i < sysfs_schemes->nr; i++)
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sysfs_schemes->schemes_arr[i]->tried_regions->upd_status =
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DAMOS_TRIED_REGIONS_UPD_IDLE;
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for (i = 0; i < sysfs_schemes->nr; i++) {
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sysfs_regions = sysfs_schemes->schemes_arr[i]->tried_regions;
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scheme = damos_sysfs_nth_scheme(i, ctx);
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if (!scheme) {
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sysfs_regions->upd_status =
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DAMOS_TRIED_REGIONS_UPD_FINISHED;
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continue;
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}
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sysfs_regions->upd_status = DAMOS_TRIED_REGIONS_UPD_IDLE;
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sysfs_regions->upd_timeout_jiffies = jiffies +
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2 * usecs_to_jiffies(scheme->apply_interval_us ?
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scheme->apply_interval_us :
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ctx->attrs.sample_interval);
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}
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}
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/* Called from damon_sysfs_cmd_request_callback under damon_sysfs_lock */
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@ -1902,7 +1939,7 @@ int damon_sysfs_schemes_update_regions_start(
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{
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damon_sysfs_schemes_clear_regions(sysfs_schemes, ctx);
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damon_sysfs_schemes_for_damos_callback = sysfs_schemes;
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damos_tried_regions_init_upd_status(sysfs_schemes);
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damos_tried_regions_init_upd_status(sysfs_schemes, ctx);
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damos_regions_upd_total_bytes_only = total_bytes_only;
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ctx->callback.before_damos_apply = damon_sysfs_before_damos_apply;
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ctx->callback.after_sampling = damon_sysfs_after_sampling;
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