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Wed, 27 Aug 2025 23:57:40 -0700 (PDT) MIME-Version: 1.0 References: <20250826071948.2618-1-laoar.shao@gmail.com> <20250826071948.2618-3-laoar.shao@gmail.com> <299e12dc-259b-45c2-8662-2f3863479939@lucifer.local> In-Reply-To: <299e12dc-259b-45c2-8662-2f3863479939@lucifer.local> From: Yafang Shao Date: Thu, 28 Aug 2025 14:57:03 +0800 X-Gm-Features: Ac12FXygvU0PTDWHH1nV9Tdj3y453lXYUAzGekUvEJHvbRAb7PUlo_2hu--qJCI Message-ID: Subject: Re: [PATCH v6 mm-new 02/10] mm: thp: add a new kfunc bpf_mm_get_mem_cgroup() To: Lorenzo Stoakes Cc: akpm@linux-foundation.org, david@redhat.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, hannes@cmpxchg.org, usamaarif642@gmail.com, gutierrez.asier@huawei-partners.com, willy@infradead.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, ameryhung@gmail.com, rientjes@google.com, corbet@lwn.net, bpf@vger.kernel.org, linux-mm@kvack.org, linux-doc@vger.kernel.org, Michal Hocko , Roman Gushchin , Shakeel Butt Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 2119CA0004 X-Rspam-User: X-Stat-Signature: m7u7ycxaotwbrd39rgpnykaq5ira45wj X-Rspamd-Server: rspam09 X-HE-Tag: 1756364261-586247 X-HE-Meta: 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 NPELcMHZ 7Tj6uKavrywCx1v5H9OGYFI70vNw3TXXIkzkMEda6XF/zSXF9j21ercKL44/1cWfYB8hvJdpfkK4Q3XJLXaZwkY49ckUZVF7jT8546ydTNjKGifN1gNRTSqRphBfBpR3taX6O2z8qJ/lOX6lFmQ8DpyOjTDLSCJmdW3YZ5sQH2Ad8MWX3ngJWpLFPg/4OSRGvX3wFmUxNHqpL+kkxvei9igNmHOBBn4wPzkbtZjsQAyvuge+6nK9b66LT1Kq6OqqWQURgJ35bScZl17Sp/q301Cdg8wfaZVjbiK+H/S7ikRU2AGbLQa3UqWzz07gteUxeuOnCW8hAFJmzI2lmo1/l+HUJ7k5t53XeToXa3q1NA4FqZbA1P3aoNd1qkMpOzvzN/I3ZWbDLiHCGrYKkCt6SlR+C73LbKahPIBlj2gLDxMhv7prn0m5yaG+FufRyMt7MZPQ1opl+a4BHQRtTsQ/PTd3IXL7TCbVkawE/x7ATmwDenpE= 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 Wed, Aug 27, 2025 at 11:34=E2=80=AFPM Lorenzo Stoakes wrote: > > +cc cgroup people, please do include them on this stuff. sure. > > BTW I see there is a BPF [STORAGE & CGROUPS] section in MAINTAINERS and > kernel/bpf/cgroup.c etc. anything useful there for us? BPF local storage can assist in implementing this feature. However, we still need to introduce a new helper, bpf_mm_get_mem_cgroup(), to retrieve the mem_cgroup from an mm_struct. > > On Tue, Aug 26, 2025 at 03:19:40PM +0800, Yafang Shao wrote: > > We will utilize this new kfunc bpf_mm_get_mem_cgroup() to retrieve the > > associated mem_cgroup from the given @mm. The obtained mem_cgroup must > > be released by calling bpf_put_mem_cgroup() as a paired operation. > > What locking guarantees do we have that this is all fine? As explained by Shakeel, no locking is needed for this stuff. > > > > > Signed-off-by: Yafang Shao > > --- > > mm/bpf_thp.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++++++- > > Also not to be nitty (but I'm going to be anyway :P) but I'm not in love = with > the filename here. > > So now we have > > - khugepaged.c > - huge_memory.c > - bpf_thp.c > > Let's maybe call it huge_memory_bpf.c for consistency? makes sense. > And obv as mentioned > before, add it to the MAINTAINERS in the THP section plz. will do it. --=20 Regards Yafang