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b=PxS71KXE0XX8PS754fVKeQyfOKjd0DlyFHlzQV499NC9EF9mWn6RitGkA6KJ6Xq69 klgA63gHeLUh4euLHPdm9+JuBLjY3egpsqCJKVSnQ01dXgTB6BtEQcsgA5hh3I7ynQ K1MTPAm8crzd26gLRnUGS4TMAzk03ubqjrp5oCN0b40cv/X+IZMr4oN+yMRnkoOeA/ +UuOF0uzHC0ghsRehC28VqytsmxFJalU3LIc5LcdKvfQkY5yGhTLlWIbiuhfuGQELQ jqejgxUP8PuMBdnpO1HcxFiw/R5j8SgQKrPfiKu6JCOVkl1eXDaez9JemTzlqhGGBm kKajcaLOjVlLw== Received: by mail-yw1-f176.google.com with SMTP id 00721157ae682-790992528f6so43387007b3.1 for ; Mon, 02 Feb 2026 10:22:57 -0800 (PST) X-Gm-Message-State: AOJu0Yyt6QPyREViEmmikfJ0bmy4O5SWb07u7Vu8ExeuJk/BxmFNelu6 GysxONQo6VBWaCaXE45KEtQgBD/RjoEs1h8hP+MqsIVxIor+A8AsiUzl54T/G6Y+qh8V6D4Rrpg THv4fgyPPxr/U18NVImJd34zT+ptWldXVbUlmTbB/cQ== X-Received: by 2002:a05:690c:60c3:b0:794:70f6:a87f with SMTP id 00721157ae682-7949dec6ec3mr105333257b3.19.1770056576448; Mon, 02 Feb 2026 10:22:56 -0800 (PST) MIME-Version: 1.0 References: <20260202-zswap-syncio-cleanup-v1-1-86bb24a64521@tencent.com> In-Reply-To: <20260202-zswap-syncio-cleanup-v1-1-86bb24a64521@tencent.com> From: Chris Li Date: Mon, 2 Feb 2026 10:22:45 -0800 X-Gmail-Original-Message-ID: X-Gm-Features: AZwV_QiSj4eo8Mfc4E0Q1W-pDir9H_xKh1YofvGSFBSixKG-idrDQtrCmrSkD-U Message-ID: Subject: Re: [PATCH] mm/zswap: remove SWP_SYNCHRONOUS_IO swapcache bypass workaround To: Kairui Song Cc: linux-mm@kvack.org, Johannes Weiner , Yosry Ahmed , Nhat Pham , Chengming Zhou , Andrew Morton , Baoquan He , Barry Song , linux-kernel@vger.kernel.org, Kairui Song Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 507D3180002 X-Stat-Signature: 7emy1j9ozcdyhozur1gwkiybhcycaw7a X-Rspam-User: X-HE-Tag: 1770056578-957897 X-HE-Meta: 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 ArlHTGzX vsk9yJ/ZCR1OppZsVLAoZUi7b2MhfTf3HX0TX X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sun, Feb 1, 2026 at 9:47=E2=80=AFAM Kairui Song wrote= : > > From: Kairui Song > > Since commit f1879e8a0c60 ("mm, swap: never bypass the swap cache even > for SWP_SYNCHRONOUS_IO"), all swap-in operations go through the swap > cache, including those from SWP_SYNCHRONOUS_IO devices like > zram. Which means the workaround for swap cache bypassing > introduced by commit 25cd241408a2 ("mm: zswap: fix data loss on > SWP_SYNCHRONOUS_IO devices") is no longer needed. Remove it, but > keep the comments that are still helpful. Acked-by: Chris Li Chris > > Suggested-by: Yosry Ahmed > Signed-off-by: Kairui Song > --- > mm/zswap.c | 19 ++++++------------- > 1 file changed, 6 insertions(+), 13 deletions(-) > > diff --git a/mm/zswap.c b/mm/zswap.c > index 3d2d59ac3f9c..8cd61603ff79 100644 > --- a/mm/zswap.c > +++ b/mm/zswap.c > @@ -1589,11 +1589,11 @@ int zswap_load(struct folio *folio) > { > swp_entry_t swp =3D folio->swap; > pgoff_t offset =3D swp_offset(swp); > - bool swapcache =3D folio_test_swapcache(folio); > struct xarray *tree =3D swap_zswap_tree(swp); > struct zswap_entry *entry; > > VM_WARN_ON_ONCE(!folio_test_locked(folio)); > + VM_WARN_ON_ONCE(!folio_test_swapcache(folio)); > > if (zswap_never_enabled()) > return -ENOENT; > @@ -1624,22 +1624,15 @@ int zswap_load(struct folio *folio) > count_objcg_events(entry->objcg, ZSWPIN, 1); > > /* > - * When reading into the swapcache, invalidate our entry. The > - * swapcache can be the authoritative owner of the page and > + * We are reading into the swapcache, invalidate zswap entry. > + * The swapcache is the authoritative owner of the page and > * its mappings, and the pressure that results from having two > * in-memory copies outweighs any benefits of caching the > * compression work. > - * > - * (Most swapins go through the swapcache. The notable > - * exception is the singleton fault on SWP_SYNCHRONOUS_IO > - * files, which reads into a private page and may free it if > - * the fault fails. We remain the primary owner of the entry.) > */ > - if (swapcache) { > - folio_mark_dirty(folio); > - xa_erase(tree, offset); > - zswap_entry_free(entry); > - } > + folio_mark_dirty(folio); > + xa_erase(tree, offset); > + zswap_entry_free(entry); > > folio_unlock(folio); > return 0; > > --- > base-commit: 2c263046cbe6d9d5fce3dfeba063f199f7e6298f > change-id: 20251226-zswap-syncio-cleanup-a05b7fc6180f > > Best regards, > -- > Kairui Song >