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Tue, 17 Mar 2026 11:33:10 -0700 (PDT) MIME-Version: 1.0 References: <20260317025049.494931-1-pasha.tatashin@soleen.com> <20260317025049.494931-4-pasha.tatashin@soleen.com> In-Reply-To: From: Pasha Tatashin Date: Tue, 17 Mar 2026 14:32:34 -0400 X-Gm-Features: AaiRm52fq7oKmnbeu_WHYpCRKUQbscba7gVOBfphGRHbk0R5kyda8GX57LwnRgE Message-ID: Subject: Re: [PATCH 3/6] liveupdate: Defer file handler module refcounting to active sessions To: David Matlack Cc: rppt@kernel.org, pratyush@kernel.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: n6p1ejgakngkqjoz6w9k96h4tnhwh1r6 X-Rspam-User: X-Rspamd-Queue-Id: B821A40007 X-Rspamd-Server: rspam12 X-HE-Tag: 1773772392-388848 X-HE-Meta: U2FsdGVkX1+5c3a7p8sDF45XtpVtJtIhByRQUvFwUYQpkC8N5glJC1Zwbyc4w7KmmyIkpyyhDqV2ckDvw88zZBkowMeTqsfrjkyOzxVHKjtswMVyKDVZBrIAqt2r1ST9ugnBTi3XiL1677xmXziPM9J42ngL7xA/9rbxptIK82MvE5cH8zDnEOMkjhGgo9iJleZPmtGm5Es8Lgc2iRALfcLWz19GQCpybtHYMWcOFcy2s0o9S/m4+25uYzBPxifNREnh5Tsz8FfAruK5h2EoAivEpcOgnrdz3DE0d8oMZA7vW+XS3zcLSaZQT9Ym4mGgCXpVbZLkTw/Fmt0fH3dJ07C6ctlocnBfql3z5fLxKugZGgTqM/t5b0qI5OO1ouQ/6ZPkePPhJMq401WGegwF9qUWZ4i3I9KF3B2ru53sdpnqWhAHqT4OZYADF/faH3N48jJdwXyDGTM26TGM8FMhpViDkz/R44NxFhHoRIxGwMZ8GbT+Hvh3oyK9Tk3anChqzNhHuK9Yb5qXmuVoHywxq8u9pkW6K30Olku9704bhc2MezT4FtoPBIb1xcxFKDdrPOQjJsF2v//Kyi2gGGXuIYlBsEpt7cr0jhnz6DLTHeI/kjlcMP1q6h1K1+dfoxxqMF0aI2SGjt0aPlDWMd/2gTPRM+MY6ebmuEOH/g58tCB+oRgbBQYFbrq2Wp9umZBwG6eu/r/Pu69+wBUCCWH1JwJVxTkuQCDJip5pbU2uCFygmOkUR0Uhizm++JMkNFRQ8kFIhHumyzykuuvXKp3K1u1Hw6pb1wECuFOsOym1rqvNFqwmgxKlH7hWWtjP21ixM9d8h0G4/fHl3TQWh8QnGDKvMuYHoqJSWiomTYAnqbYRVQKaziCf7++DWNZB1qW0m76/Vc1rXIXV/ZinSYbCx7nmcKyhrdqf6agz1YwS+kylQOHSm14ZbUilyql5/7Jn3IUsbICjpi7VRVy1VtK NahFGsqE sVhB9ojwgESDmN7ofhQXNHummM4Cgazu0qqEalYYvpHnhMiAghMB2+7Mf+vlDuzpcXOT1bXkff2fRdi6/iMiVydsx8eBQGGkvD8pyemZdEn1kaScoADBDh/UqYy0kfM9cF5Jlhud4u9+0U3i0NXu9Tw2KARizkuPW4AWo0a8GfiCAkQKFdUl1y4puP0laOjdO2qd20Cv+qWO1L789mATxv4+mXgFD5l1k6Ugt4S21+I8A2ppSgT9MvRNq48WIBM58EWrjcBL1G53VvDEjltsyDvfLDbRivs4rv17vgsidotSHxcr2/Z/m4JL3WA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Mar 17, 2026 at 12:39=E2=80=AFPM David Matlack wrote: > > On Mon, Mar 16, 2026 at 7:50=E2=80=AFPM Pasha Tatashin > wrote: > > > @@ -281,7 +282,10 @@ int luo_preserve_file(struct luo_file_set *file_se= t, u64 token, int fd) > > scoped_guard(rwsem_read, &luo_file_handler_lock) { > > list_private_for_each_entry(fh, &luo_file_handler_list,= list) { > > if (fh->ops->can_preserve(fh, file)) { > > - err =3D 0; > > + if (try_module_get(fh->ops->owner)) > > + err =3D 0; > > + else > > + err =3D -ENODEV; > > break; > > } > > } > > Does LUO even need to take a reference to the file handler owner? > > LUO already takes a reference to the file, and the file should already > be holding a reference to the file's owner, which should (must?) be > the same as the file handler's owner. Hi David, Thanks for review. This is a very good point. I will remove taking file handler reference entirely. > > For FLB it makes more sense since the FLB's owner is likely not the > same as the file's owner. +1. Pasha