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[172.10.233.147]) by smtp.gmail.com with ESMTPSA id 00721157ae682-717c61b4ccfsm26066777b3.59.2025.07.15.15.09.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Jul 2025 15:09:57 -0700 (PDT) Date: Tue, 15 Jul 2025 15:09:40 -0700 (PDT) From: Hugh Dickins To: Kairui Song , Andrew Morton cc: Baolin Wang , linux-mm@kvack.org, Hugh Dickins , Matthew Wilcox , Kemeng Shi , Chris Li , Nhat Pham , Baoquan He , Barry Song , linux-kernel@vger.kernel.org Subject: Re: [PATCH v5 6/8] mm/shmem, swap: simplify swapin path and result handling In-Reply-To: Message-ID: <7454d5b3-e8a4-29c2-ea00-435821ebfd37@google.com> References: <20250710033706.71042-1-ryncsn@gmail.com> <20250710033706.71042-7-ryncsn@gmail.com> <57e82add-b8d5-49cb-8a3e-58c7c65768d0@linux.alibaba.com> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="-1463770367-387016046-1752617397=:11996" X-Rspamd-Queue-Id: 1E75D180007 X-Stat-Signature: 7416s9tj75t4bxxpsn7euajutqb9isey X-Rspam-User: X-Rspamd-Server: rspam07 X-HE-Tag: 1752617399-465667 X-HE-Meta: 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 yjGomg// bBsOVsaGO7nK0ao4Tw2D193w2NJPc9Gs7JLU/rTkhHQ4yJ2fJ/zWqtIebzWtCMqbSCh3Ec7b8+VkrtzOx/8Hx1ltZPCxfEZEWzJtjqg5TK4sX/hFjbrDHRV5jHi+gT50fUGTLt6YgalIEp1a8vrvLJsoPB1333y7LPMBLvP1hKQILeXk3IMU5MlG1MMXqbwDpSTh3jw9KPxL/4yNlwYfySzzjGlwHKJUepsngTp01GQo+bpq95ohujv/5zg5nTZO9Up3wvXiTG3SLsE6yVcNbNlDjdB9FSUq3BPex4u3g/W6gGXCd6hIT8+GYdGpcN9Ttvxtv/E9vog6NGYXG+0q9V1aTvxMm/efz9qZBJ05rarN3AAcdUWNL0VsPomDMt1N7rdTaYpkqqNl2lergG2X9WOyzuIg64aUwhH80ZKQWdoVb8kIZEkWL+/TZ4Pwtpff2KPzXYtwdLiYoGL3Q8rCSYkilJ9XccV7xh3hq8mdmQl3RpYc= 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: This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. ---1463770367-387016046-1752617397=:11996 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE On Fri, 11 Jul 2025, Kairui Song wrote: > On Fri, Jul 11, 2025 at 2:23=E2=80=AFPM Baolin Wang > wrote: > > > > > > > > On 2025/7/10 11:37, Kairui Song wrote: > > > From: Kairui Song > > > > > > Slightly tidy up the different handling of swap in and error handling > > > for SWP_SYNCHRONOUS_IO and non-SWP_SYNCHRONOUS_IO devices. Now swapin > > > will always use either shmem_swap_alloc_folio or shmem_swapin_cluster= , > > > then check the result. > > > > > > Simplify the control flow and avoid a redundant goto label. > > > > > > Signed-off-by: Kairui Song > > > > LGTM, with a nit as follows. > > Reviewed-by: Baolin Wang > > > > > --- > > > mm/shmem.c | 45 +++++++++++++++++++-------------------------- > > > 1 file changed, 19 insertions(+), 26 deletions(-) > > > > > > diff --git a/mm/shmem.c b/mm/shmem.c > > > index 847e6f128485..80f5b8c73eb8 100644 > > > --- a/mm/shmem.c > > > +++ b/mm/shmem.c > > > @@ -2320,40 +2320,33 @@ static int shmem_swapin_folio(struct inode *i= node, pgoff_t index, > > > count_memcg_event_mm(fault_mm, PGMAJFAULT); > > > } > > > > > > - /* Skip swapcache for synchronous device. */ > > > if (data_race(si->flags & SWP_SYNCHRONOUS_IO)) { > > > + /* Direct mTHP swapin skipping swap cache & rea= dhaed */ > > > folio =3D shmem_swap_alloc_folio(inode, vma, in= dex, swap, order, gfp); > > > > Nit: the 'mTHP' word can be confusing, since we will skip swapcache for > > order 0 too. Please drop it. > > >=20 > Yes, thanks for the review. And a few words after that 'mTHP ', I keep wincing at 'readhaed': Andrew, you already did a fix to remove the 'mTHP ', I hope we can also persuade you to change 'readhaed' to 'readahead' there - thanks! Kairui, I'm a little uneasy about the way this series does arithmetic on swap.val, in the knowledge that swp_offset(entry) involves no shift. Perhaps I haven't noticed, but I think this is the first place to make that assumption; and a few years ago it was not true at all - swp_type() was down the bottom. Usually we would do it all with swp_entry(swp_type(x), arithmetic_on(swp_offset(x))). But I guess, let's just agree that it's easier to read and get right the way you have it, and make no change: if I try to "correct" you, or demand that you change it, we shall probably just bring in bugs. I'm particularly glad that you now avoid SWP_SYNCHRONOUS_IO readahead: that stupidity had very much annoyed me, once I realized it. Thanks, Hugh ---1463770367-387016046-1752617397=:11996--