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b=AQUAf4uFkNStZ1Tb45HwVwL+jD4BDOL1WJROlgROMNZxvnKJ+C58K3zQn90022Z22 5YKPPtJJ4vXOvkJPPwHpKa2lcbBb03d0cwLGDwnpOZwAwUjItS07Q3ueELNy/b7JNp Ac3EM806qvU69cwSlSAGYkBY7fvEsup5fnuhlPig= Date: Sun, 13 Sep 2026 00:48:31 -0700 From: Andrew Morton To: Baoquan He Cc: hannes@cmpxchg.org, yosry@kernel.org, nphamcs@gmail.com, chengming.zhou@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kasong@tencent.com, chrisl@kernel.org Subject: Re: [PATCH] mm: zswap: return -ENOENT when the swap device is gone Message-Id: <20260913004831.884d37afd92249d763b7f1da@linux-foundation.org> In-Reply-To: <20260913063031.1689420-1-hebaoquan@kylinos.cn> References: <20260913063031.1689420-1-hebaoquan@kylinos.cn> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 8A366C0003 X-Stat-Signature: qyh57ecx7p717ituhrm3qgboiqdep96a X-HE-Tag: 1789285713-227834 X-HE-Meta: U2FsdGVkX18FZRT0gevv+RkribYqRw0BrIrNorDJ6guA7VF/LxUf3wI4ucp7cU4iRf6pyvGlMc0/gIdT+6uebv+cjPa0V7I61xo4Q51/xptsZ9FCgsDHQuOBbj0Q6E9eKT0L/8s5bVyPBq131QFxXYqqOx0iQM4+LAMJBTR3HXx9Qb2/2aDmhG88I30f7xKODOsLwbU1glh8/r/Rz1JRn6VX17bWHGroNlhji6ANH8V+yQuwpGvisLi7xdolqc0ZyHbXCBN08uUOQ8dBQZRYm5Jj8GZdmq39VJZcTsR4Irs6nP8X5aKiDB36n57WnwMirJ/vdqBqrXexpeH13KqphIMwONkAapfhQVGGpIp1CEO3KxQYxUUkpT/CfWKPDXBSxNePDzmdhSwP/kiJK14j4cAU7cAmvAKyTBkGngf/knmeiEn6tAA6XxPFc7Uy0VLvLJ8rX1XrSRbVbI4//1yw/VevrxeSG3NQic63t1pqzyPW4q06KCjPbDtJyC+F/vZIxmMZtV5rvteWTKHL7HHKRq1LOY+VekPNUWwGa3v0zdfb4JIQsxK5CdzNw+xXxupPYFfIynG/umpMBLWOPWMPy7rK7wjrd8F/TdV/7KsgfheFFqx7Oe1d18pH9lfXi2XJTC+WoT5bK7YGFRcbYyDcQTi00EBjCwCdppDsIlMPjSRbCh2i7hdX3VXbp/Xnu/Kp8oW6HE2WB7zcWH+pw5YpilBSGvue0veKuBv1FVu8pVlsVynlllnl90tJvyi05D8TKFDMYlcEGruuX+qroY695fLMwSm8JDw020L+ETa7XSSJ/haqQ7Ycmj7e+Rc99xO0SDoMYf9CYZNyimeWKaHADpznfh+I99TZWMd0Q+usasnnZTibCn2u0rs6/GnIvZ5ujKDgShgrEPnzewbe/68agn8oBe6nX6TlIn4LIj73G0xqXNmBeEjkBcI1I3KBrwAPl3dW/lSuwSMxzsdu7+Y Y+i39NrN 1QsagMvdavKvjyYXpgMV8NEIZpJIVDvkoI2gBT+hx1kRA90bjtBnvzEbq2HrjeUtr+A2eqADJBQQJPzWiEC+cn1+rGzJKwxk2WvFTPPm7IjUeDKq9SEwwioEFp1NlcQDk2OEW7BKDrK7FG7aFJvBXfltMHorySe2dKPY8pdsCScduXyXH+RSZuFhyxY4Xyv0LZm/8JCD1kLJtIReHuJHu8+JTcEM8DDMNDHm8vRIvFHOHSTTibbzCzXxEIkZ1Lhb05IX3nKLx1G/IYc7dF2jkGq20rHbTmueWl1mu5IfyV5iP7ao= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sun, 13 Sep 2026 14:30:31 +0800 Baoquan He wrote: > zswap_writeback_entry() returns -EEXIST when get_swap_device() finds no > device. -EEXIST is the shrinker's "page already in swap cache" signal, > which makes zswap_shrinker_scan() stop shrinking entirely. A NULL > get_swap_device() instead means the device is being swapped off, so the > entry is simply stale. > > Return -ENOENT so the shrinker skips the stale entry and keeps scanning. > Independent of xswap; affects all swap devices. I'm struggling to understand the userspace-visible runtime effects of this. I see that reclaim will prematurely abort, but is this a once-off thing which will resolve on the next reclaim attempt, or will the reclaim failure persist for a significant period?