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Wed, 10 Dec 2025 23:38:58 -0800 (PST) MIME-Version: 1.0 References: <20251211060413.60534-1-sj@kernel.org> In-Reply-To: <20251211060413.60534-1-sj@kernel.org> From: JaeJoon Jung Date: Thu, 11 Dec 2025 16:38:46 +0900 X-Gm-Features: AQt7F2qkI0dCCYHs9Len6GIYpErZ3A-Zu8QVXmNkIzVYVohQsczhTaiydbVhr4w Message-ID: Subject: Re: [PATCH] mm/damon: modified damon_call_control from static to kmalloc To: SeongJae Park Cc: damon@lists.linux.dev, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 3A5B22000D X-Stat-Signature: jnf5zp47m8856bcuek6hjjdwbt8wekma X-Rspam-User: X-HE-Tag: 1765438739-324748 X-HE-Meta: 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 nlIeO6hO zelM6aMT/Jtq4IE5vtSNdOkcXHXT/EWAush5iP4Ub9SJfFupZnODz9QIxJR+Bg1uVwwEPSpu/JrPKCkedC3jI4mlpAyM/I98FE5kGN7opUa/1ENfnPOzS5vXzkaYiAhDSZwVVsIEK/FUcn2QK2g9qRqzqcX+RLx00IyWxYiBULoNSKeO6BuSe7eKATE/MxY9Lf9hWmvfF7DYcZOIpEZrMK40ved1Q647HhkKi079vL0NQT+3SUEibRbv9DUYFp0puAmo4RfhE2lHzyhFkT/hzo73pgISBP3PKKE35oFCOy9XowDXrBkiHD0Qxy8F1hD3JgOuzTIabCemyoOOv5vCAExmijOFGFWeJggn5dAtpiUA6ZElp3tGr1OOQqgDMGAHCG9JapyNBRFEdX46lkNEsf1IfVg0dgVv1HfwQqfT+kO3UMZe7xbPJ+w94PIh+4qeDYfcL 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 Thu, 11 Dec 2025 at 15:04, SeongJae Park wrote: > > On Thu, 11 Dec 2025 12:29:59 +0900 JaeJoon Jung wrote: > > > On Wed, 10 Dec 2025 at 11:54, SeongJae Park wrote: > > > > > > On Tue, 9 Dec 2025 21:20:42 +0900 JaeJoon Jung wrote: > [...] > > I suggested removing the dealloc_on_cancel condition from the patch. > > When using the damon_call_control structure, if you only use kmalloc()/kfree() > > when canceled without dealloc_on_cancel. However, currently, in other modules, > > since it is static struct damon_call_control { ... }, kfree() is not allowed, > > so dealloc_on_cancel condition is additionally required. > > Because kmalloc()/kfree() and static are mixed together, > > dealloc_on_cancel condition is required. > > As you pointed out in the previous email, kmalloc()/kfree() has the burden of > > memory allocation and deallocation, and static has the disadvantage of > > increasing > > the code size. Both have their pros and cons. > > Among these, I proposed unifying them into kmalloc()/kfree() methods and > > removing the dealloc_on_cancel > > Thank you for kindly clarifying this, JeaJoon! > > > > > > > > > Meanwhile I find the feature might look complicated, or not well documented. > > > Specifically, dealloc_on_cancel should be set on only dynamic-allocated > > > damon_call_control object, but that is not well documented on the kernel-doc > > > comments. Are you saying removing it is an advantage because it makes reading > > > code easier? If that's the case, how about improving the documentation? > > > > > > > dealloc_on_cancel is only used in mm/damon/sysfs.c. Here, since kmalloc > > the damon_call_control structure, the dealloc_on_cancel=true condition is > > required. If you want to keep the current code as is and only change the > > comment, it would be clearer to comment it out like this: > > > > De-allocate when canceled. > > --> To perform kfree() if allocated with kmalloc() when canceled. > > Sounds good. Would you mind sending a patch for that? Would you like me to send you the patch with only the comments corrected? Thanks, JaeJoon > > > Thanks, > SJ > > [...]