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b=Aet7JhT/3Cg+XD7nELXupEFsMsvRiPNuvnx+JJTECPvjMrYt9Ru2s1iZRx3Hh4I4h odjxWCZ/Si7eLBYIi2tqfJ5ngyQNpMfp9QFki9LyCbTdyYfDv30ZSUyO5QElZFAEAs 7+in80aS55d9YsYrRIxf/C/BmAJyDwzh/uhyn4bnOe7DzZxQ0OarAmOPWfhUwkkNuW CbGISHcMbTPl4Xm8W1mLRGicvZbyD8rH9YTgebKA4IHJEE3XM2rIFC5I5nytloru2u 5+pXjJUI4JFyg1/1N52anhJgTpu10hHVOGXKnkAx/HGFnP0wPncdD2tZPrYXJ+dGvr lHIHF90J/Z8UQ== From: SeongJae Park To: Joshua Hahn Cc: SeongJae Park , Andrew Morton , Honggyu Kim , Hyeongtak Ji , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org, stable@vger.kernel.org Subject: Re: [PATCH] mm/damon/ops-common: ignore migration request to invalid nodes Date: Mon, 21 Jul 2025 09:30:37 -0700 Message-Id: <20250721163037.9920-1-sj@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250721152828.423605-1-joshua.hahnjy@gmail.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 8FF2E40007 X-Stat-Signature: ckgzde3fnetfqq8twrpkfr3oi1gjcsfx X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1753115442-900082 X-HE-Meta: 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 9VigFlEC Mjqhw3lq/JEsSQm9BFQxVOeI8B8ACT9zup17VqXlkzVrnRQJuzzaBDpb3IgKqyFeZkgRPJGH4fRNeLgVn9deqUoYwiwJW2JKmJlxksyavc0edDVhiOWoX3ih7gy2BqnyZgWn6DJTS21vTVdSjju+cztq2owtcHZy60Kqz520TLUjGEZSm8Ju4um8jes0eWDKr2qVZzT6bt1MCrxAeROKdqawXwf+lPtyKjO9uI0/DyyW3+silOXPmhIAg2Hqz9mR/mHAwwaltU6oZ92Vqz4/wx5lHypc/9nYTb+olOScGPSYzaTvz6e5MIysYCOpOLy84+yBacershvk3QJUlLjqduUhBNDfXnxjN77zdOhIeGZwS4y+wQqkn1t2XGd0c+2ueRMqmuHTPxdg/n/TMuY3MAVcfXw== 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 Mon, 21 Jul 2025 08:28:26 -0700 Joshua Hahn wrote: > On Sun, 20 Jul 2025 11:58:22 -0700 SeongJae Park wrote: > > > damon_migrate_pages() try migration even if the target node is invalid. > > If users mistakenly make such invalid requests via > > DAMOS_MIGRATE_{HOT,COLD} action, below kernel BUG can happen. [...] > > Add a target node validity check in damon_migrate_pages(). The validity > > check is stolen from that of do_pages_move(), which is being used for > > move_pages() system call. > > > > Fixes: b51820ebea65 ("mm/damon/paddr: introduce DAMOS_MIGRATE_COLD action for demotion") # 6.11.x > > Cc: stable@vger.kernel.org > > Cc: Honggyu Kim > > Signed-off-by: SeongJae Park > > --- > > LGTM, thank you SJ! > > On a side note... This seems like it would be a common check. However, doing a > (quick) search seems to return no function that checks whether a node is valid. > Perhaps it would make sense to look deeper and see how many other functions > make this check, and export this as a function? I can try spinning something > if it makes sense to you : -) My humble impression was that this check is short enough to be ok to be open-coded, but please don't be blocked on my opinion :) > > Reviewed-by: Joshua Hahn Thank you! > > Sent using hkml (https://github.com/sjp38/hackermail) Thanks, SJ