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b=uxwBBs63QYfX9q9Q+laXRdgI9HZDS7j1HcLVOBEDfGQk4vNQLhDbHP6jblsOFwMM3 l6zndEnCSF9c7pi2CQyxGstu8rhJHSbE8omXSak+0g3+ndGIolZL4lWbHMG/AugVc7 PK/Ro6cYPxWBAuffimQzFsx5e5GqKVdp0U38Dq3o= Date: Sun, 13 Sep 2026 00:51:49 -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: <20260913005149.a28c21aaca165fa0255f8475@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-Stat-Signature: j4wprgdc1awh61nui9t6msw33o3fx9jz X-Rspam-User: X-Rspamd-Queue-Id: 9AED01C0004 X-Rspamd-Server: rspam03 X-HE-Tag: 1789285910-676681 X-HE-Meta: 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 dJ7CapVG i0bPgPZxI5TLWe0P3qwRhLgrzvfG5yQyygaMvYrLPUfDNqExBs3YiW8MfOmBMT4EpgUI8/hhT073XSWQlJCqljAwvPkTlcV1IHNpsCsvsSNFpDdK3+ybTIKIMAf11YppxpXDUhXgaCZ2it30vxDnWFbtggGxvzjwPqqlL6XKui6uUeJldeA4A3P2xOFOAcsL9FJEhVDXUJiEPNrqqX0jwgDATiU5EmkMAHWLQ6vdvTf7h3jw6SEGYTrKFoA== 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. > > ... > > --- 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? > si = get_swap_device(swpentry); > if (!si) > - return -EEXIST; > + return -ENOENT; mm-new has changed. I made this /* try to allocate swap cache folio */ si = get_swap_device(swpentry); if (IS_ERR_OR_NULL(si)) return -ENOENT;