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Mon, 13 Apr 2026 12:54:46 -0700 (PDT) From: Liew Rui Yan To: aethernet65535@gmail.com Cc: damon@lists.linux.dev, linux-mm@kvack.org, sj@kernel.org Subject: Re: (sashiko review) [PATCH v2 1/2] mm/damon/lru_sort: reset thread status parameters upon kdamond termination Date: Tue, 14 Apr 2026 03:54:51 +0800 Message-ID: <20260413195451.17184-1-aethernet65535@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260413185249.5921-2-aethernet65535@gmail.com> References: <20260413185249.5921-2-aethernet65535@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 063C68000B X-Stat-Signature: ikjuqr4tosyeydexgkyazchds3hs6y86 X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1776110087-719400 X-HE-Meta: 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 NDPYpQG2 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Sashiko found some issues, so I will send my comment for it soon. Forwarding sashiko review for doing discussions via mails. # review url: https://sashiko.dev/#/patchset/20260413185249.5921-2-aethernet65535@gmail.com # start of sashiko.dev inline review commit a943fcfe60e73956b72cad5a625120222653bdda Author: Liew Rui Yan mm/damon/lru_sort: reset thread status parameters upon kdamond termination This commit adds logic to reset thread status parameters when kdamond terminates unexpectedly or when context commit fails. This ensures the module does not get stuck in a state where it cannot be restarted via sysfs. > diff --git a/mm/damon/lru_sort.c b/mm/damon/lru_sort.c > index 554559d729760..96c8d0dfcafd2 100644 > --- a/mm/damon/lru_sort.c > +++ b/mm/damon/lru_sort.c > @@ -344,6 +344,10 @@ static int damon_lru_sort_apply_parameters(void) > if (err) > goto out; > err = damon_commit_ctx(ctx, param_ctx); > + if (err) { > + enabled = false; > + kdamond_pid = -1; > + } Does updating the module parameters here require holding kernel_param_lock? Since damon_lru_sort_apply_parameters() can be executed asynchronously by the kdamond thread when a user writes to the commit_inputs parameter, changing these variables locklessly might introduce a race condition. If enabled is set to false here while kdamond is still preparing to terminate, could a concurrent sysfs write (echo Y > enabled) read the false state and proceed to call damon_lru_sort_turn(true) because it incorrectly assumes the worker has completely stopped? If so, damon_lru_sort_turn(true) would call damon_commit_ctx(ctx, ...) and modify the shared ctx structures while the exiting kdamond worker thread is concurrently executing its cleanup block, such as damon_destroy_targets(ctx). Can this concurrent modification of the context lists lead to use-after-free issues or list corruption? [ ... ] # end of sashiko.dev inline review # review url: https://sashiko.dev/#/patchset/20260413185249.5921-2-aethernet65535@gmail.com # hkml [1] generated a draft of this mail. You can regenerate # this using below command: # # hkml patch sashiko_dev --for_forwarding \ # 20260413185249.5921-2-aethernet65535@gmail.com # # [1] https://github.com/sjp38/hackermail