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b=UPvrCAz5ius3PvIltupEswBs5UZtH/0nmef6nzsW8CajXvksXVrEhJvlrEPpg8vRp i69Bz2BfpcWbo3WqgEBxwJ14pxRB/lZ5SWkB1T0XQrlI4payRRTajELbnWLKLzdMcA hc/5EexM4bzYCtmDnIT+cvNIMXxBt0WulCl1wd4KOqkwMPgsY46YnkCCBsnBvjvH1d xe+yVzrXIpj63tHcI7yfwLiIzc6i9dru3PDaeyaTNk2UItPTkG9b1FRrriNCJU6WBP Pyp6PcJlrtiflb1dv6hyDnuAicKlERHtgk5GnRVnUdaaPdHK3Dsw6/pKaUL5DdpwDX dCv73HAtlgK3A== From: SeongJae Park To: Enze Li Cc: SeongJae Park , akpm@linux-foundation.org, damon@lists.linux.dev, linux-mm@kvack.org, enze.li@gmx.com Subject: Re: [PATCH] mm/damon/core: delete damon_target when detected invalid Date: Tue, 9 Dec 2025 02:49:51 -0800 Message-ID: <20251209104952.43233-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <87v7igm2hq.fsf@> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: z3q6mwor4i8ixx1t19ujgrrzgzhbf8ci X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 1FFD61C0018 X-HE-Tag: 1765277396-91299 X-HE-Meta: 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 yPGnvHvr dL58n48LBxdf2ybBaK667/OLjTMTgPIavDGbC7+PfUwJDEYDOhxp/PmxPDgr4BBSEVQ15Mj1MssgvdQZOq/KHH1r+8sfI1NTdpIfO5z1zLGEJ8v05i1mE5lMv6hTw+5a75WCCrzKgos0QyWHB74EVobr0ZmL8jKG+48WUSmZ7NZH01tDt/uKNJC0L2zh59vMu03dE3ydMFhta4uyySc8zK5GyDtLmxSYiS/yIhLcXg3kOT4XXIvlWvt7W7/LZiJH3iwon X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, 09 Dec 2025 17:24:49 +0800 Enze Li wrote: > Hi SJ, > > On Mon, Dec 08 2025 at 11:21:45 PM -0800, SeongJae Park wrote: > > > On Tue, 9 Dec 2025 13:57:13 +0800 Enze Li wrote: > > > >> Currently, DAMON does not proactively clean up invalid monitoring > >> targets during its runtime. When some monitored targets exit, DAMON > >> still makes the following unnecessary function calls, > >> > >> --damon_for_each_target-- > >> --damon_for_each_region-- > >> damon_do_apply_schemes > >> damos_apply_scheme > >> damon_va_apply_scheme > >> damos_madvise > >> damon_get_mm > >> > >> and it is only in the damon_get_mm() that it may finally discover that > >> the monitoring target no longer exists. [...] > > So, from the beginning part of the patch description, I understand your concern > > is the unnecessary function calls in kdamond_apply_schemes(). What about > > checking the target validness using ctx->ops.target_valid() and avoid going > > deeper if it is invalid? Seems the damon_for_each_target() loop is a good > > point to do this. > > > > What do you think? > > Excellent suggestion! Moving the validity check to the > damon_for_each_target() loop via ctx->ops.target_valid() would indeed > prevent all unnecessary function calls, which is more efficient and > architecturally cleaner than my original approach. :) > > I will implement this change shortly. > > By the way, I'll add a "Suggested-by" tag to the commit message, if > that's okay with you. Surely that's okay and my honor :) Thanks, SJ [...]