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[109.81.29.22]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-488ee018b34sm28791895e9.13.2026.04.13.23.57.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 13 Apr 2026 23:57:58 -0700 (PDT) Date: Tue, 14 Apr 2026 08:57:57 +0200 From: Michal Hocko To: Minchan Kim Cc: akpm@linux-foundation.org, david@kernel.org, brauner@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, surenb@google.com, timmurray@google.com Subject: Re: [RFC 0/3] mm: process_mrelease: expedited reclaim and auto-kill support Message-ID: References: <20260413223948.556351-1-minchan@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260413223948.556351-1-minchan@kernel.org> X-Rspam-User: X-Stat-Signature: rgr9419zyjw13tr4dgsqbjp4z8nj6t4f X-Rspamd-Queue-Id: 7D912140011 X-Rspamd-Server: rspam09 X-HE-Tag: 1776149880-654921 X-HE-Meta: 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 6G+td1Ee 1U0+jUz2AUVAz2qi5d4rVkcHWmAks81lc3hoO1Fxy4R9gYpL+7m2C9a/M1QA/vOsnLNmui64aP2pIJnlHr0KDPF1fkHTIkCsfxsfg2B+U/9Srwu4A+Isu+zrZF6R8UeerJT8dsS1ijoezUNPt8ITpQO/KMCA0gsrbX5ceFs652ub0Z3Y2olDqaXsaQbXw0C4cd1aHshNs7sairpooPUsyrL2JXgDrkknfHJSBJExRxJx3+NBMlTqVBZwEUZWecEmreFKK62CpIoPOjQpwLiE3X3nfs2o4i2EUw1yP3G2hfMZx1JZhnk7GQrT9k+zE9dN9G3AXUi/rsf/g4TrMusl+JKuZWe0dxfBHAQJjF3M0WxTivz/VMAVje7FqU1BEX6Wu+kyTZx0r8beudc0YyCG1CNTBUoghxD0USKar0UF8HasjeaqTBqHK1PhmhSmBqWtzEIfXrUoEbunytwVQE8WcFMKWh9Bvdx0zH5Ou26qWVr9hyhI= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon 13-04-26 15:39:45, Minchan Kim wrote: > This patch series introduces optimizations to expedite memory reclamation > in process_mrelease() and provides a secure, race-free "auto-kill" > mechanism for efficient container shutdown and OOM handling. > > Currently, process_mrelease() unmaps pages but leaves clean file folios > on the LRU list, relying on standard memory reclaim to eventually free > them. Furthermore, requiring userspace to send a SIGKILL prior to > invoking process_mrelease() introduces scheduling race conditions where > the victim task may enter the exit path prematurely, bypassing expedited > reclamation hooks. > > This series addresses these limitations in three logical steps. > > Patch #1: mm: process_mrelease: expedite clean file folio reclaim via mmu_gather > Integrates clean file folio eviction directly into the low-level TLB > batching (mmu_gather) infrastructure. Symmetrically truncates clean file > folios alongside anonymous pages during the unmap loop. Why do we need to care about clean page cache? Is this a form of drop_caches? > Patch #2: mm: process_mrelease: skip LRU movement for exclusive file folios > Skips costly LRU marking (folio_mark_accessed) for exclusive file-backed > folios undergoing process_mrelease reclaim. Perf profiling reveals that > LRU movement accounts for ~55% of overhead during unmap. OK, but why is this not desirable behavior fir mrelease? > Patch #3: mm: process_mrelease: introduce PROCESS_MRELEASE_REAP_KILL flag > Adds an auto-kill flag supporting atomic teardown. Utilizes a dedicated > signal code (KILL_MRELEASE) to guarantee MMF_UNSTABLE is marked in the > signal delivery path, preventing scheduling races. Could you explain why those races are a real problem? -- Michal Hocko SUSE Labs