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Fri, 24 Nov 2023 21:38:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1700861923; bh=ptjkAte1QXNuW1BDKm99u+0k/U6sLZF2tFKHqkC6btM=; h=From:To:Cc:Subject:Date:From; b=WAWCwNsY1fMaMcr302PWbuf4doJ/cZNDDR46mMRellmvcqfw+AE1fBzUM+XKP6w/W ZTEckTXLa3jzw433vrk0ZUlXvUeOkH/CPYzyh5vb8chikffbn3v6+6Nx5SVVol9/AP ag9lC0u5aCFRoq8B8xkjd6BEaU6udnSrYJEZw+szeuWXzkcmf4AOwVbF87rODMKuXh H2HOlG2sZxp6+hgg8qkunGc7zQUlq+R5KeYEWWRyVITNe8SNeXMPpYGDAuy2BYaggl 0d0aeVp2TRE2toLmluzDNm+GUz05Ymczjp4ozq/TWMpMD1U0aRX15nA7ZG3UDc94j2 +FLkltKFRLS0w== From: SeongJae Park To: Andrew Morton Cc: SeongJae Park , damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH] mm/damon/sysfs-schemes: add timeout for update_schemes_tried_regions Date: Fri, 24 Nov 2023 21:38:40 +0000 Message-Id: <20231124213840.39157-1-sj@kernel.org> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 X-Rspamd-Queue-Id: 9B6921C0007 X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: epukziyfmzx6j7dp7tr4st9hyii7hkbn X-HE-Tag: 1700861924-243155 X-HE-Meta: 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 6DnSHUBX UvV+toWcZ/1mo2uGNeBnVHH7JdNJlicvNrqexngYqh4UE/XM6aAR/8WtWuokJeEhR8oTvkrYEzoAedaszEGrqtXtgTBOjlTU0g+ghiZCFn0XNlqX7KxVP0+PdSRNaaRIa2SVPfcNVG9djzGJOOqTyv8EZW71OkQrFNlL02nPOw2eT8f8udhTAD23CJLeQvqcCi/aSPO4+nv+QIXVlwsRlBcW4oklFwyqsBlfZAFdIhy50yJsHkq4cV+k4L4C7ojjjkHfYa7fpA421OcSjAImpEFGpWqv3OlkyOZ28 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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. Fixes: 4d4e41b68299 ("mm/damon/sysfs-schemes: do not update tried regions more than one DAMON snapshot") Signed-off-by: SeongJae Park --- The commit that fixed by this patch is merged in v6.7-rc1. Hence not Cc-ing stable@, but this patch would better to be treated as a hotfix that will be merged in the mainline before the v6.7 release. mm/damon/sysfs-schemes.c | 49 +++++++++++++++++++++++++++++++++++----- 1 file changed, 43 insertions(+), 6 deletions(-) diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c index be667236b8e6..fe0fe2562000 100644 --- a/mm/damon/sysfs-schemes.c +++ b/mm/damon/sysfs-schemes.c @@ -139,6 +139,13 @@ static const struct kobj_type damon_sysfs_scheme_region_ktype = { * damon_sysfs_before_damos_apply() understands the situation by showing the * 'finished' status and do nothing. * + * If DAMOS is not applied to any region due to any reasons including the + * access pattern, the watermarks, the quotas, and the filters, + * ->before_damos_apply() will not be called back. Until the situation is + * changed, the update will not be finished. To avoid this, + * damon_sysfs_after_sampling() set the status as 'finished' if more than two + * apply intervals of the scheme is passed while the state is 'idle'. + * * Finally, the tried regions request handling finisher function * (damon_sysfs_schemes_update_regions_stop()) unregisters the callbacks. */ @@ -154,6 +161,7 @@ struct damon_sysfs_scheme_regions { int nr_regions; unsigned long total_bytes; enum damos_sysfs_regions_upd_status upd_status; + unsigned long upd_timeout_jiffies; }; static struct damon_sysfs_scheme_regions * @@ -1854,7 +1862,9 @@ static int damon_sysfs_after_sampling(struct damon_ctx *ctx) for (i = 0; i < sysfs_schemes->nr; i++) { sysfs_regions = sysfs_schemes->schemes_arr[i]->tried_regions; if (sysfs_regions->upd_status == - DAMOS_TRIED_REGIONS_UPD_STARTED) + DAMOS_TRIED_REGIONS_UPD_STARTED || + time_after(jiffies, + sysfs_regions->upd_timeout_jiffies)) sysfs_regions->upd_status = DAMOS_TRIED_REGIONS_UPD_FINISHED; } @@ -1885,14 +1895,41 @@ int damon_sysfs_schemes_clear_regions( return 0; } +static struct damos *damos_sysfs_nth_scheme(int n, struct damon_ctx *ctx) +{ + struct damos *scheme; + int i = 0; + + damon_for_each_scheme(scheme, ctx) { + if (i == n) + return scheme; + i++; + } + return NULL; +} + static void damos_tried_regions_init_upd_status( - struct damon_sysfs_schemes *sysfs_schemes) + struct damon_sysfs_schemes *sysfs_schemes, + struct damon_ctx *ctx) { int i; + struct damos *scheme; + struct damon_sysfs_scheme_regions *sysfs_regions; - for (i = 0; i < sysfs_schemes->nr; i++) - sysfs_schemes->schemes_arr[i]->tried_regions->upd_status = - DAMOS_TRIED_REGIONS_UPD_IDLE; + for (i = 0; i < sysfs_schemes->nr; i++) { + sysfs_regions = sysfs_schemes->schemes_arr[i]->tried_regions; + scheme = damos_sysfs_nth_scheme(i, ctx); + if (!scheme) { + sysfs_regions->upd_status = + DAMOS_TRIED_REGIONS_UPD_FINISHED; + continue; + } + sysfs_regions->upd_status = DAMOS_TRIED_REGIONS_UPD_IDLE; + sysfs_regions->upd_timeout_jiffies = jiffies + + 2 * usecs_to_jiffies(scheme->apply_interval_us ? + scheme->apply_interval_us : + ctx->attrs.sample_interval); + } } /* Called from damon_sysfs_cmd_request_callback under damon_sysfs_lock */ @@ -1902,7 +1939,7 @@ int damon_sysfs_schemes_update_regions_start( { damon_sysfs_schemes_clear_regions(sysfs_schemes, ctx); damon_sysfs_schemes_for_damos_callback = sysfs_schemes; - damos_tried_regions_init_upd_status(sysfs_schemes); + damos_tried_regions_init_upd_status(sysfs_schemes, ctx); damos_regions_upd_total_bytes_only = total_bytes_only; ctx->callback.before_damos_apply = damon_sysfs_before_damos_apply; ctx->callback.after_sampling = damon_sysfs_after_sampling;