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Wed, 11 Mar 2026 20:05:10 -0700 (PDT) Received: from google.com ([2a00:79e0:2031:6:8bb8:36d7:daf6:bf85]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-35a02fc8465sm3647444a91.9.2026.03.11.20.05.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Mar 2026 20:05:09 -0700 (PDT) Date: Thu, 12 Mar 2026 12:05:05 +0900 From: Sergey Senozhatsky To: Matt Fleming Cc: Andrew Morton , Jens Axboe , Minchan Kim , Sergey Senozhatsky , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Barry Song , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , Zi Yan , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, kernel-team@cloudflare.com, Matt Fleming Subject: Re: [RFC PATCH 0/1] mm: Reduce direct reclaim stalls with RAM-backed swap Message-ID: References: <20260303115358.1323188-1-matt@readmodwrite.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260303115358.1323188-1-matt@readmodwrite.com> X-Rspamd-Queue-Id: B04ED40007 X-Rspamd-Server: rspam07 X-Stat-Signature: w11d937f639zwy3dj9axyz34jgukcfbh X-Rspam-User: X-HE-Tag: 1773284711-639698 X-HE-Meta: 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 co89x8Rn rW/gb1ySDMSUp9ejuGaxGC+vW5VyL0fA0wJe0ao6EQ57xXExMBekU+/DC5zuCx/dL9WV4zuukuXceJxOjWewvJqO/9QLTt+FWNlG8g29QESpV3loNc+LeGhfMuHtZed7Ohqrs5iH2iSEfYOyBb0xM6URskSGg6iV2e5gJ1GoQvj7qX1QkXlbPowjmgFCy7qWGSaKn0/hd90ltd7jpvlzsYl5crtfsxogjVqYaryTTjiYcY96PN6OG1YV+ViG92CovbUaNb5+FNK2l8A9902Ywmh8NOHOKSTRMXdsnPMCdxXngAU+eGCFqi353UsEsa6pdYOeo7nPtZYzqdb03I/9VKpxZqcHVX3dO6fFZfxuSgLbQQjY= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On (26/03/03 11:53), Matt Fleming wrote: > What about mixed swap configurations (zram + disk)? > > When at least one disk-backed swap device is active, > swap_all_ram_backed is false and the current behaviour is preserved. > Per-device reclaimable accounting is possible but it's a much larger > change, and mixed zram+disk configurations are uncommon in practice > AFAIK. There are also setups where zram is configured with a backing device (a real physical device) to which zram writeback pages, effectively releasing pool memory that they occupied.