From: Andrew Morton <akpm@linux-foundation.org>
To: SeongJae Park <sj@kernel.org>
Cc: damon@lists.linux.dev, kernel-team@meta.com,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 0/7] mm/damon: define and use DAMON initialization check function
Date: Mon, 15 Sep 2025 21:33:12 -0700 [thread overview]
Message-ID: <20250915213312.12892156442f3a795a0a01f5@linux-foundation.org> (raw)
In-Reply-To: <20250916033511.116366-1-sj@kernel.org>
On Mon, 15 Sep 2025 20:35:04 -0700 SeongJae Park <sj@kernel.org> wrote:
> If DAMON is tried to be used by its API callers when it is not yet
> successfully initialized, the callers could be crashed. Such issues
> actually happened and were fixed [1]. DAMON API callers are therefore
> having their own hacks for seeing if it is safe to use DAMON or not.
> Those built on an untreliable assumption that DAMON should be ready to
> be used on module init time. DAMON initialization could fail if
> KMEM_CACHE() fails, though.
Wait. Is there any realistic expectation that KMEM_CACHE() will fail
when DAMON uses it? We do have the convention of assuming that
__init-time allocations do not fail. If they do, an oops or panic is
an acceptable response.
Are these problems actually real-world demonstrable things, or has
someone been playing with fault injection or, ...?
> Also those are basically duplications that
> make their maintenance difficult.
Unclear. This means that the client hacks are no longer necessary after
these changes?
next prev parent reply other threads:[~2025-09-16 4:33 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-16 3:35 SeongJae Park
2025-09-16 3:35 ` [PATCH 1/7] mm/damon/core: implement damon_initialized() function SeongJae Park
2025-09-16 3:35 ` [PATCH 2/7] mm/damon/stat: use damon_initialized() SeongJae Park
2025-09-16 3:35 ` [PATCH 3/7] mm/damon/reclaim: " SeongJae Park
2025-09-16 3:35 ` [PATCH 4/7] mm/damon/lru_sort: " SeongJae Park
2025-09-16 3:35 ` [PATCH 5/7] samples/damon/wsse: " SeongJae Park
2025-09-16 3:35 ` [PATCH 6/7] samples/damon/prcl: " SeongJae Park
2025-09-16 3:35 ` [PATCH 7/7] samples/damon/mtier: " SeongJae Park
2025-09-16 4:33 ` Andrew Morton [this message]
2025-09-16 5:54 ` [PATCH 0/7] mm/damon: define and use DAMON initialization check function SeongJae Park
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20250915213312.12892156442f3a795a0a01f5@linux-foundation.org \
--to=akpm@linux-foundation.org \
--cc=damon@lists.linux.dev \
--cc=kernel-team@meta.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=sj@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox