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b=VJKVgeN3+Qn9GQFaBZQs61WHX/XKRIQzg+VY+N85N3T4lXGBLDHUw6/kFxaqHeTDt hSjbJ90rPOVOp/1M/6hIflDQN76PPxSyWqZO26rX6kvVtXrkviX6esW3Ecq/mKDDLn cak6LKA9nGH4Tv0CmidCuQGTFUSRm9puODoduSJpRCxbrrX+RTjitGDi/WMLLSd1hZ cGY0KNWr9a1qrorOJixlRykl4c5vVDjPs/yRFLYC8j0M6Nh1eh9HfMllpE2+979jlM zfRtDJ7ZASjMRh/bLGJyhfboi66TXhAI8LRbPq7B0TJIJ7V6uU+4wbZKE57By28zEr 22ICvS1YigYNw== From: SJ Park To: SJ Park Cc: Andrew Morton , stable@vger.kernel.org, damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] mm/damon/core: skip aging from repeated aggressive merging Date: Sun, 12 Jul 2026 10:23:34 -0700 Message-ID: <20260712172335.92448-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260712165432.87609-1-sj@kernel.org> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 9BFD0C0005 X-Stat-Signature: 99h4rq1pu5s14c5tyc6d9hxa8aqsyhn1 X-HE-Tag: 1783877019-474266 X-HE-Meta: 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 syLEsKyT UMqz6r2O/ulE1EHYKN/ST5Bg4iHZvt1nHHLCq0EFtX7Kk67nv52c33oaPcTSdueYndJQvkIGmQPiOh7QWHdzpnxnW6qALzAHey21kWcA+y7HokdPBsr+e9awykOVoFQCSCrGOyyOM0km4SIF0IUfVUo1TMWuoaYKfbo8vLNuRWX8XciCslyfsxH0gQUFB2lwSswxpfclTPup9vtJav5wI0AgGtdwRg10LvbggHLYgLhK7m6s= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sun, 12 Jul 2026 09:54:30 -0700 SJ Park wrote: > The number of DAMON regions could temporarily exceed the user-defined > maximum number of regions limit for corner cases. For example, users > could lower the limit via runtime parameters update. For such a case, > kdamond_merge_regions() repeats merging regions in the case doubling the > merge threshold. The repeated merge operation could update the age of > regions multiple times. This corrupts the monitoring results. Fix the > issue by asking the merge operation to skip aging for the corner case. > > The user impact is degradation of the monitoring quality. The impact > should be mild, since the degradation is only temporal, and it is not > common to happen in realistic setups. Sashiko found no blocker for this patch. Sashiko sent findings to damon@ mailing list [1], and I replied. Please read those for details. [1] https://lore.kernel.org/damon/ Thanks, SJ [...]