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a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1783346799; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:references:dkim-signature; bh=YScqbvC2FcRD4fWbOctqhEtUzflD1TaDoeycdSdZYxo=; b=b4f+iDcp9WjCKyqdoi5NQOpjp5fRaNn7CR1DiWDoRiUbAI7SjZKTTYNJ4FXUu0FWamUXq0 zgvdy6gtVauOZlHh/fZ8gL3kCVuZZB/Ji9MHUecczfREXk9h+hmc6ynJ/6Mwy2UOAnDQ29 CQ/pvKdl6BwApUsDr48pAd3w3il6nGs= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 273E541895; Mon, 6 Jul 2026 14:06:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D88CC1F000E9; Mon, 6 Jul 2026 14:06:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783346798; bh=YScqbvC2FcRD4fWbOctqhEtUzflD1TaDoeycdSdZYxo=; h=From:To:Cc:Subject:Date; b=ES6uY66a/NoD6rtnEolVYYmqIPRmWM/XsrPcOny8u7cLT0mTMvEIEFk0WkipninKv elwfwCzrzdFI+2C+VrhaWJf+m+zywyPo8PTCkKU6FhnRCysQ2YvdxY3VN/F8DPFY1O v21tWpLhregnoQU5P9BInKlC5/1w7/H8O4T26pN97PCXTsLs+WfPRa4uGGPKTUZT35 LYDQtUr6wSSrguuiOBcNO2PunxUAlVVNAW4Vx260C0lhcjgmykujl5iiYNcJQ3lAof 3C7oisLt++4LFHNi1zJeQnWqXipuMUCQp5jKRH8eAwSDpy7Hs87OQ6LYY2wAZA+i1J Cc0zLvcZhmdJw== From: SJ Park To: Andrew Morton Cc: SJ Park , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 00/11] mm/damon: refactor damon_{start,stop,commit}() for simple error handling Date: Mon, 6 Jul 2026 07:06:15 -0700 Message-ID: <20260706140628.87414-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 4E83612000D X-Rspam-User: X-Stat-Signature: wcnccrpykyhgzbjsctnbu5zehbanjqmg X-Rspamd-Server: rspam03 X-HE-Tag: 1783346799-96113 X-HE-Meta: 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 prgj7z9O 7TgRxq4zbO2pM0d+9rXuFr6fmzhYiv3p8dbfuu+X1UaxQ6GoaISs1wwQ3tpw4EujBwMlEYWSLlZB5XIdrb0z9DX3FM0Ell/SOjRo3lsBczndwm9YGZurFMmHnlOBXbFt4ovMVXgnQ002rWs5hPVkqhFwEVR4cX1LXz+I+BWI6mB7QgDkBLcsDc8GYl4JQosmKsMp+g6lCJ78aQMps7zQAZZJFThYbAm7zIDlyWV4uxETGgjcuxUFGhPXYPnFGUd7P0rfnC2s3Qpd9xrqtvNQu8HqgWw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: damon_start() and damon_stop() could leave a few of requested DAMON contexts running when they return an error. damon_commit() failure stops the DAMON context, but in an asynchronous way. Callers should stop the left-over DAMON contexts. It is easy to make mistakes, and indeed a few bugs from such mistakes were found and fixed. Refactor the core API functions to guarantee contexts are completely stopped under failures. Remove the caller side error handlers that are no longer needed due to the refactoring. Patches Sequence ================ Patch 1 refactors damon_start() to ensure all contexts are stopped for failures. Patch 2 updates unnecessary damon_start() error handling from mtier sample module. Patch 3 refactors damon_stop() to always success. Patches 4-6 updates callers (damon_{sysfs,reclaim lru_sort}) to ignore the return value. Patch 7 update damon_stop() return value to void. Patch 8 simplifies damon_stop() error handling in mtier sample module. Patch 9 refactors damon_call() to return errors only after the context is completely stopped. Patches 10 and 11 remove unnecessary error handlings from callers (wsse and prcl sample modules). Changelog ========= Changes from RFC v1.1 - RFC v1.1: https://lore.kernel.org/20260705160142.97308-1-sj@kernel.org - Drop RFC tag. - Rebase to latest mm-new. Changes from RFC v1 - RFC v1: https://lore.kernel.org/20260704181135.132956-1-sj@kernel.org - Fix ABBA deadlock in damon_start(). - Wait instead of doing racy-stop in damon_call(). SJ Park (11): mm/damon/core: stop ctxs in damon_start() before returning an error samples/damon/mtier: do not stop first context for damon_start() failure mm/damon/core: make damon_stop() never fails mm/damon/sysfs: ignore damon_stop() return value mm/damon/reclaaim: ignore damon_stop() return value mm/damon/lru_sort: ignore damon_stop() return value mm/damon/core: change damon_stop() return type to void samples/damon/mtier: stop all contexts with single damon_stop() call mm/damon/core: wait ctx stop in damon_call() before reruning an error samples/damon/wsse: do not stop ctx for damon_call() failure samples/damon/prcl: do not stop DAMON for damon_call() failure include/linux/damon.h | 2 +- mm/damon/core.c | 37 +++++++++++++++++++------------------ mm/damon/lru_sort.c | 6 ++++-- mm/damon/reclaim.c | 6 ++++-- mm/damon/sysfs.c | 3 ++- samples/damon/mtier.c | 5 +---- samples/damon/prcl.c | 4 +--- samples/damon/wsse.c | 4 +--- 8 files changed, 33 insertions(+), 34 deletions(-) base-commit: 3fc9ce1db037091d433cb95dff0ce1cb6815fffe -- 2.47.3