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From: SeongJae Park <sjpark@amazon.com>
To: SeongJae Park <sjpark@amazon.com>
Cc: <akpm@linux-foundation.org>, SeongJae Park <sjpark@amazon.de>,
	<Jonathan.Cameron@Huawei.com>, <aarcange@redhat.com>,
	<acme@kernel.org>, <alexander.shishkin@linux.intel.com>,
	<amit@kernel.org>, <benh@kernel.crashing.org>,
	<brendan.d.gregg@gmail.com>, <brendanhiggins@google.com>,
	<cai@lca.pw>, <colin.king@canonical.com>, <corbet@lwn.net>,
	<dwmw@amazon.com>, <foersleo@amazon.de>, <irogers@google.com>,
	<jolsa@redhat.com>, <kirill@shutemov.name>,
	<mark.rutland@arm.com>, <mgorman@suse.de>, <minchan@kernel.org>,
	<mingo@redhat.com>, <namhyung@kernel.org>, <peterz@infradead.org>,
	<rdunlap@infradead.org>, <riel@surriel.com>,
	<rientjes@google.com>, <rostedt@goodmis.org>, <sblbir@amazon.com>,
	<shakeelb@google.com>, <shuah@kernel.org>, <sj38.park@gmail.com>,
	<snu@amazon.de>, <vbabka@suse.cz>, <vdavydov.dev@gmail.com>,
	<yang.shi@linux.alibaba.com>, <ying.huang@intel.com>,
	<david@redhat.com>, <linux-damon@amazon.com>,
	<linux-mm@kvack.org>, <linux-doc@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v17 03/15] mm/damon: Implement region based sampling
Date: Tue, 7 Jul 2020 09:54:51 +0200
Message-ID: <20200707075451.24606-1-sjpark@amazon.com> (raw)
In-Reply-To: <20200706115322.29598-4-sjpark@amazon.com> (raw)

On Mon, 6 Jul 2020 13:53:10 +0200 SeongJae Park <sjpark@amazon.com> wrote:

> From: SeongJae Park <sjpark@amazon.de>
> 
> This commit implements DAMON's target address space independent high
> level logics for basic access check and region based sampling.  This
> doesn't work alone, but needs the target address space specific low
> level pritimives implementation for the monitoring target address ranges
> construction and the access check, though.  A reference implementation
> of those will be provided by a later commit.  Nevertheless, users can
> implement and use their own versions for their specific use cases.
>
[...]
> +/**
> + * damon_start() - Starts monitoring with given context.
> + * @ctx:	monitoring context
> + *
> + * Return: 0 on success, negative error code otherwise.
> + */
> +int damon_start(struct damon_ctx *ctx)
> +{
> +	int err = -EBUSY;
> +
> +	mutex_lock(&ctx->kdamond_lock);
> +	if (!ctx->kdamond) {
> +		err = 0;
> +		ctx->kdamond_stop = false;
> +		ctx->kdamond = kthread_run(kdamond_fn, ctx, "kdamond");

Oops, this means 'kdamond_fn' could see the unset '->kdamond'.  I will use
'kthread_create()' and 'wake_up_process()' in the next spin.

> +		if (IS_ERR(ctx->kdamond))
> +			err = PTR_ERR(ctx->kdamond);
> +	}
> +	mutex_unlock(&ctx->kdamond_lock);
> +
> +	return err;
> +}

So, the change would be something like below:

--- a/mm/damon.c
+++ b/mm/damon.c
@@ -1464,9 +1464,11 @@ int damon_start(struct damon_ctx *ctx)
        if (!ctx->kdamond) {
                err = 0;
                ctx->kdamond_stop = false;
-               ctx->kdamond = kthread_run(kdamond_fn, ctx, "kdamond");
+               ctx->kdamond = kthread_create(kdamond_fn, ctx, "kdamond");
                if (IS_ERR(ctx->kdamond))
                        err = PTR_ERR(ctx->kdamond);
+               else
+                       wake_up_process(ctx->kdamond);
        }
        mutex_unlock(&ctx->kdamond_lock);


Thanks,
SeongJae Park


  reply index

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-06 11:53 [PATCH v17 00/15] Introduce Data Access MONitor (DAMON) SeongJae Park
2020-07-06 11:53 ` [PATCH v17 01/15] mm/page_ext: Export lookup_page_ext() to GPL modules SeongJae Park
2020-07-06 11:53 ` [PATCH v17 02/15] mm: Introduce Data Access MONitor (DAMON) SeongJae Park
2020-07-06 11:53 ` [PATCH v17 03/15] mm/damon: Implement region based sampling SeongJae Park
2020-07-07  7:54   ` SeongJae Park [this message]
2020-07-06 11:53 ` [PATCH v17 04/15] mm/damon: Adaptively adjust regions SeongJae Park
2020-07-06 11:53 ` [PATCH v17 05/15] mm/damon: Track dynamic monitoring target regions update SeongJae Park
2020-07-06 11:53 ` [PATCH v17 06/15] mm/damon: Implement callbacks for the virtual memory address spaces SeongJae Park
2020-07-06 11:53 ` [PATCH v17 07/15] mm/damon: Implement access pattern recording SeongJae Park
2020-07-06 11:53 ` [PATCH v17 08/15] mm/damon: Add a tracepoint SeongJae Park
2020-07-06 11:53 ` [PATCH v17 09/15] mm/damon: Implement a debugfs interface SeongJae Park
2020-07-06 11:53 ` [PATCH v17 10/15] tools: Introduce a minimal user-space tool for DAMON SeongJae Park
2020-07-06 11:53 ` [PATCH v17 11/15] tools/damon/wss: Implement '--thres' option SeongJae Park
2020-07-06 15:04   ` SeongJae Park
2020-07-06 11:53 ` [PATCH v17 12/15] Documentation/admin-guide/mm: Add a document for DAMON SeongJae Park
2020-07-07  7:49   ` Mike Rapoport
2020-07-07  8:07     ` SeongJae Park
2020-07-06 11:53 ` [PATCH v17 13/15] mm/damon: Add kunit tests SeongJae Park
2020-07-06 11:53 ` [PATCH v17 14/15] mm/damon: Add user space selftests SeongJae Park
2020-07-06 11:53 ` [PATCH v17 15/15] MAINTAINERS: Update for DAMON SeongJae Park

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