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AJvYcCXzqKS9PwrYecgFiuPxcehebDCDO5kkQa+BGfYmAdwqkT8vmK4RWsFQqQsqXZkZgSne3t/gT2iZoQ==@kvack.org X-Gm-Message-State: AOJu0YyB4XNDl5AD2KZbJzK3p4UDPH2+Pud1mqdWAcS3fqgehekNGqM3 cmrfdHy0gLUKT1zmqHmRPjFk/SJCx8CnpCXAIS7JS2hl25Rq86xlO58MLIcBYVpVfLj0isYQcWj h2ZJq1u7nCl/D8kNJz1bo2+IvOptnktfMaW29WBzf X-Gm-Gg: ATEYQzzkojOrvXCsmjg0v4DmiDFWSVyD9gn9mTYdQJMVLfHRBIrlRKBnnyV/G6w+02p Om7+9v69Uh/8KWa6LHPAyd5n77L3jPrN/pIP2xUIhMt1A/DC1Xts9szIZ+QMvXf6oRPTfSA+KyJ SOaxcQfiDzhz+RzdwZAKRlE1WyEVyGI63hCuRWfVFXOwJcTz9CA9zNAfWyEb2UzuzBpJ6iahcrU B8KopORqhO00JaXBQnZdSBwwaCKap3tzOCINxfpxv9TT8pKV3ZDxR7zdOwWt7b+W5Jief4US7E2 aFjquYC4 X-Received: by 2002:a05:6512:114e:b0:5a1:4c8:a632 with SMTP id 2adb3069b0e04-5a29b976dacmr321914e87.13.1774387464172; Tue, 24 Mar 2026 14:24:24 -0700 (PDT) MIME-Version: 1.0 References: <20260318141637.1870220-10-pasha.tatashin@soleen.com> <20260318141637.1870220-13-pasha.tatashin@soleen.com> In-Reply-To: <20260318141637.1870220-13-pasha.tatashin@soleen.com> From: David Matlack Date: Tue, 24 Mar 2026 14:23:56 -0700 X-Gm-Features: AaiRm52LXcc-C8LfZJHz0X5TGe6ipMfQUWo9odKChlYP9O7L9GCYExr5BHUEcbU Message-ID: Subject: Re: [PATCH v2 3/8] liveupdate: Remove file handler module refcounting To: Pasha Tatashin Cc: rppt@kernel.org, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, pratyush@kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 85909C000F X-Stat-Signature: 6eg3qucs1buuokrxy1cja4ebumigzus4 X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1774387466-936307 X-HE-Meta: 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 GRfRDqdh wJCKI8z7nXgGy6MFMvLkkYoa1gxdEoVG7aESAyOGjEScQeUOME5xugHoMwAq856TJSAE8g3q04pz89gt9hSu4KNaTPa9qRJy3FCgoy554pB37YHhFUhqEFGkqMjDcXPSimjS1XyYyt/aKl5GD0QFa092XJnZ5CgojH+4ZEXYU/7smnEXPjysxvE5LLlhwnGzIlT2SjIbNHSqXUdW55In7HBafyhJAUrpskw6RTbqCBIn89/U9R08F3V+OvxXcf793J1xEHxx9d38Kdg0mWYFSWdA3VcExJJIGHMqqLuqfuIkfEFM= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Mar 18, 2026 at 7:17=E2=80=AFAM Pasha Tatashin wrote: > > File handlers do not need to pin modules indefinitely or during active > live update sessions. The VFS 'struct file' pins the file handler's modul= e > via f_op->owner during active sessions, making dynamic reference counting > unnecessary for handlers. > > When a file is preserved, the live update core obtains a 'struct file' > via fdget(). As long as the file is kept open within the live update > session, the module is pinned by the VFS and cannot be unloaded. After invoking the file handler's retrieve(), LUO should probably check that the created file's owner matches the file handler's owner, since this scheme relies on that being true. If there is a mismatch, LUO can put the file that was just created, log a warning, and return an error up to the user.