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imf25.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=SR0lMN6f; spf=pass (imf25.hostedemail.com: domain of sj@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=sj@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1783267313; b=JoKwbBUasF/NzS0NA56EWBbeSvCtyLJTCj1ZwmWhwv8DgzyuHDpSExEBG4PhsVQm0kXWtd 90ogzGZOfD206XcxiHI8XRbTuiaenpZWD7Kdu0jMQyJSprR7l4a++8apAD+rmRxgU1iO+s fbng/QBCHEsFoOJI35nJoHHJfMwAxcU= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 4ED8840B6F; Sun, 5 Jul 2026 16:01:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 06A951F000E9; Sun, 5 Jul 2026 16:01:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783267312; bh=1W0z3ibNTBH982L2YdX0/4RM6hemskh9KnNpifQK0MI=; h=From:To:Cc:Subject:Date; b=SR0lMN6flT0EFxpBZ+36fDvNVXyyKnZiHs1cFMhGevOEAQItisttVNkv+hCDi2sB1 1QIKMFuyhQCnDomigvHYhGY/9qB6ZLJPb28KnkILt/bPc28v4Kq0i0QKZ+S5gVvavV DNbi0/qjtRSoEUxKgNkf16iiSDv9SZSlHkmD8IlOwm79itg2LlUn+GuNg0HBwzNRju HfyGNkPOqXrpR1K2RGRJPCEYqGDUjFPI6Jz5TtRZcgRHg1NhcwZKcj4QQyVs89hcKs YukTjrc8/izh557fMzIcOtwC16xblaHyQMY7god6HFUBodM3PajgMha8AXoA+NQrFT 6b6fvUeVlkgqw== From: SJ Park To: Cc: SJ Park , Andrew Morton , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [RFC PATCH v1.1 00/11] mm/damon: refactor damon_{start,stop,commit}() for simple error handling Date: Sun, 5 Jul 2026 09:01:27 -0700 Message-ID: <20260705160142.97308-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 07C7AA0016 X-Stat-Signature: 9bk691qr93kfzabxtrdiy4j1811u5wad X-HE-Tag: 1783267312-571924 X-HE-Meta: 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 VYgg6H6z OngWjOcEkVBcuTB0lPsTK7mVBYk3V6RH7/9BbzL/2vdH707SAv6XPhvf85sLDS2EjIE3CUZmZAjjcf9aNDZ+BHUJ2wittiJcmxMbD7V+OjJc/vcBfdaY2edZM0f+2EG9okyWYiLgmX7g8L/8gLrQD1WXp2kOTHNsTAAT2WP1Mu0/TlkR8lteppOdSB9Yay3m9dP9sfbkQb51nAc59u0WMx18U3jPJLxtJ1D82W3b605bqexZcBtBinYTjV2tVCyoUkGg9a6wVSGuOlw00K9e+9qYu1Q== 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 - 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: abe5b65a9c676375c3f118d453037f2f9ebbb7ac -- 2.47.3