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Sat, 06 Sep 2025 06:32:04 -0700 (PDT) MIME-Version: 1.0 References: <20250905191357.78298-1-ryncsn@gmail.com> <20250905191357.78298-2-ryncsn@gmail.com> In-Reply-To: From: Kairui Song Date: Sat, 6 Sep 2025 21:31:27 +0800 X-Gm-Features: AS18NWDELQkUGhXFIMgs5YM77ANpVCaP_i9mrVBu93dI7V9Pvwt8b0jXtcdeeYk Message-ID: Subject: Re: [PATCH v2 01/15] docs/mm: add document for swap table To: Chris Li Cc: linux-mm@kvack.org, Andrew Morton , Matthew Wilcox , Hugh Dickins , Barry Song , Baoquan He , Nhat Pham , Kemeng Shi , Baolin Wang , Ying Huang , Johannes Weiner , David Hildenbrand , Yosry Ahmed , Lorenzo Stoakes , Zi Yan , linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 315B0140015 X-Stat-Signature: b1mw5fgeguqz11fcqjpfwto1psoun4oq X-Rspam-User: X-HE-Tag: 1757165525-897530 X-HE-Meta: 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 i/wDeUxb xOoZeLIPwATWKAM8VfnhmsMyaESl9U8STg9KIJmIyhkRY76CORr7cS+H6OvyZFOJhQbHHDTg8rQVxiPN2D0qeox+OpnTaRrmib+zsnocxaZDymSx/VT4ekhvajMjH5u/nPwviA3piZmIq48xKBZeJzW2hjNRFMTMR8UewqFaYIBJz2oROCGKDOCAWB7Gp07s61re2PExufvFo/fy98lwGl7BzbfyXJCiRG8NL4vahWzNxxCDP0+FBomB3D9nZQd3ZlI3PGVkJOa2fFnBt8vXLi2IH+tNNyOYUvhVh95Qa3N5y9kiw0QuxifqqwzufrKznlFhFVF3Nixp57uMyWNq9CGpqZEpRQErWF8ZKiO2r96p7rguq4hjUjr4s5V4XLkcnZip1Rj3rpF1w9ZOp8T1T3FRr1fzlkXR1y2Zq8bGksm6Q0Kg= 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 Sat, Sep 6, 2025 at 8:05=E2=80=AFAM Chris Li wrote: > > On Fri, Sep 5, 2025 at 12:14=E2=80=AFPM Kairui Song wr= ote: > > > > From: Kairui Song > > > > From: Chris Li > > > > Swap table is the new swap cache. > > > > Signed-off-by: Chris Li > > Signed-off-by: Kairui Song > > --- > > Documentation/mm/swap-table.rst | 72 +++++++++++++++++++++++++++++++++ > > MAINTAINERS | 1 + > > 2 files changed, 73 insertions(+) > > create mode 100644 Documentation/mm/swap-table.rst > > > > diff --git a/Documentation/mm/swap-table.rst b/Documentation/mm/swap-ta= ble.rst > > new file mode 100644 > > index 000000000000..929cd91aa984 > > --- /dev/null > > +++ b/Documentation/mm/swap-table.rst > > @@ -0,0 +1,72 @@ > > +.. SPDX-License-Identifier: GPL-2.0 > > + > > +:Author: Chris Li , Kairui Song > > + > > +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > > +Swap Table > > +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > > + > > +Swap table implements swap cache as a per-cluster swap cache value arr= ay. > > + > > +Swap Entry > > +---------- > > + > > +A swap entry contains the information required to serve the anonymous = page > > +fault. > > + > > +Swap entry is encoded as two parts: swap type and swap offset. > > + > > +The swap type indicates which swap device to use. > > +The swap offset is the offset of the swap file to read the page data f= rom. > > + > > +Swap Cache > > +---------- > > + > > +Swap cache is a map to look up folios using swap entry as the key. The= result > > +value can have three possible types depending on which stage of this s= wap entry > > +was in. > > + > > +1. NULL: This swap entry is not used. > > + > > +2. folio: A folio has been allocated and bound to this swap entry. Thi= s is > > + the transient state of swap out or swap in. The folio data can be i= n > > + the folio or swap file, or both. > > + > > +3. shadow: The shadow contains the working set information of the swap > > I just noticed a typo here, should be "swapped out page" > > > + outed folio. This is the normal state for a swap outed page. > > Same here. "swap outed page" -> "swapped out page" Thanks, I used some grammar check tools and it seems they are not perfect with kernel terminologies. > > Chris >