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b=jHSztCqNcZj5l1XY/Li9FJ51I+dsx9ENmMATmd3nYd+0ajUD5ZifB1uUJ9q4KamlW cPnXiBcj/QaYeQJXAeJMjWEBAj3fzm9z8t6C0wam9zU1sJGY+MPP0DqWFqX+3iPUmx 4SBO109ZVTumz4UAuIGT5Q1ivLHFzXak6Wdi3+6BJfMH3NsEj4yUozA97CkdeaMeeX fxJvwm9EOzQMajTkgSmlJomKTKjsjIUgNueiY/6T4FTtV752sp1oTetoK34IwHwcUs J6FFP+JXPFkxkc9YSQwWMqfcioCsuSe+9bWB16ILqHP1dCwKo0DfjMz++b/AZWNhtf vVwzU6cfNo94Q== Date: Tue, 7 Jul 2026 14:55:56 +0100 From: Lorenzo Stoakes To: Wandun Chen Cc: vbabka@kernel.org, david@kernel.org, rostedt@goodmis.org, mhiramat@kernel.org, Alexander.Krabler@kuka.com, hughd@google.com, fvdl@google.com, bigeasy@linutronix.de, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev, akpm@linux-foundation.org, surenb@google.com, mhocko@suse.com, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, riel@surriel.com, liam@infradead.org, harry@kernel.org, jannh@google.com, lance.yang@linux.dev, mathieu.desnoyers@efficios.com, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net, ying.huang@linux.alibaba.com, apopple@nvidia.com, pfalcato@suse.de Subject: Re: [PATCH v2 1/4] mm/migrate: do not migrate folios mapped into VM_LOCKED VMAs under compaction Message-ID: References: <20260707125925.3725177-1-chenwandun1@gmail.com> <20260707125925.3725177-2-chenwandun1@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: 37rfdgyqxqm7abiyqx6n5s7ppcwtoy8k X-Rspamd-Queue-Id: 320291C0004 X-Rspamd-Server: rspam01 X-Rspam-User: X-HE-Tag: 1783432572-727616 X-HE-Meta: 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 bvESkkcN vGKcLo311Y0eDri8NQNWk2Mf1QYdergTZeDQVE3f5ODWnzkU7JFqxT7m3JwoWY/sS7U0HgcgEcbXDQvI/GDTN+B9ZIqb+8HiPs6t1qZC1NfQKDU6uT1CaqcltMyCEF/38Rrr4hB28StlAL8YaEOvVPzYJfTdPb2rm4owPwkb5aR3Ny64SwEYUcj/qioYqG/Jk1VlMJBKvIaCvtH+A9B2gomYfGKvy/Vp/kW5nAPOt8CS/vsmxxHZI+TaoCRviv65AZdqS9fuLGA0HwgKwqRJFfC7SpE+FjN2+If8h2ZrgPMyA/9PO7JvYi/CboDY1VYEW6/gFlC0t22tvMc3Gz2ZKy+4iIVadC8RjtvQLm7knCppVhPFsNCqrf7lfKF+xuqqbG+pL2Ce1oJpGBObU7kKedKbs7A== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Jul 07, 2026 at 02:44:50PM +0100, Lorenzo Stoakes wrote: > See above about deduplicating. > > > + ttu |= TTU_RESPECT_MLOCK; > > Hmm. I don't love 'respect mlock'. I guess we only know about the reason > being compaction here. > > But I'm confused anyway. We have the folio, why aren't we just checking for > PG_mlocked() here instead of getting the rmap to see if it's mapped > anywhere with VMA_LOCKED_BIT? Also, since compaction_allow_unevictable() is a function that is accessible elsewhere, you could literally just have a TTU_MIGRATION here instead and have the rmap logic call compaction_allow_unevictable() instead rather than this. And then you could adapt the function I suggested before not to take a reason parameter but rather a 'is_migration' one instead possibly and then pass (ttu & TTU_MIGRATION) in. BUT. I still question whether this is at all needed since you have the folio you can check for PG_mlocked... Cheers, Lorenzo