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Mon, 14 Sep 2026 06:31:46 +0000 X-Mizu-Trace-ID: d8fd9943a3e500eb X-Migadu-Flow: FLOW_OUT Date: Mon, 14 Sep 2026 14:31:39 +0800 From: Baoquan He To: Andrew Morton Cc: Baoquan He , 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: References: <20260913063031.1689420-1-hebaoquan@kylinos.cn> <20260913005149.a28c21aaca165fa0255f8475@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260913005149.a28c21aaca165fa0255f8475@linux-foundation.org> X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 12DCE1A0002 X-Stat-Signature: mhzudd47ss9x15ztgk8wn3rfoxum6x8q X-HE-Tag: 1789367507-139599 X-HE-Meta: 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 cSJ0MT/h 8VLEu/yQL3mf4iQ6Q5PCL/5xlVDceTxh+jpICsqTxJh5ygf2va3d+M6o9mxbswxwbkFfbuIoH/9NIfSPGYGptDU3C1tBewanAcC4lY9TUkHOqoKbf1Vuxd9UXSJ9kyWxAjl+NmXl5TYT4GydhQ0HjACoOqHSJqRlVt8Eze78uhQeLPmiv4jJZIatEiBdlH7lU8z2xuVyuyWAajJ4LR4r1Wl6MxQr5q+iGDOfTuvHajm0edb5pk9X2ODoCmtatduYgh87AJhTB7Lx0cYA= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 09/13/26 at 12:51am, Andrew Morton wrote: > 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. > > > > ... > > > > --- a/mm/zswap.c > > +++ b/mm/zswap.c > > @@ -998,7 +998,7 @@ static int zswap_writeback_entry(struct zswap_entry *entry, > > /* try to allocate swap cache folio */ > > Comment was always lame ("say why, not what"). It now seems flat out wrong? Agree, the comment should be moved down to be cloe to "mpol = get_task_policy(current);" line. > > > si = get_swap_device(swpentry); > > if (!si) > > - return -EEXIST; > > + return -ENOENT; > > mm-new has changed. I made this Thanks. Does it need a v2? or just use ther version you tuned. By the way, which mm branch is suggested to take as a base for mm patches posting? I usually take mm-unstable branch, seems it's changed to mm-new now? > > > /* try to allocate swap cache folio */ > si = get_swap_device(swpentry); > if (IS_ERR_OR_NULL(si)) > return -ENOENT; > >