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Howlett" , Baoquan He , Pratyush Yadav , Pasha Tatashin , Jaroslav Kysela , Takashi Iwai , Lorenzo Stoakes , Michal Hocko , Mike Rapoport , Simona Vetter , Suren Baghdasaryan , Vlastimil Babka , Dave Young , linux-mm@kvack.org, linux-pci@vger.kernel.org, linux-sound@vger.kernel.org, kexec@lists.infradead.org, driver-core@lists.linux.dev Subject: Re: [PATCH v2 0/3] mm,kernfs,proc: Unmap mmaps of removed files via file->f_mapping Message-Id: <20260725143737.daa698b50289257fbaa9c6f1@linux-foundation.org> In-Reply-To: <20260725210549.3716546-1-kwilczynski@kernel.org> References: <20260725210549.3716546-1-kwilczynski@kernel.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: B05BE140005 X-Stat-Signature: p3mus31trksmqmt3sksgjexdnu56eok1 X-HE-Tag: 1785015460-683326 X-HE-Meta: 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 KwN7fIZ5 b/6cTEGDoVnMICHdm/X/GaUe3P5PqIShFoEKE8AOFMVBpa1BttZH71mgNaNmlrNqRlZZJouqeA/bJgLWNfDNN8ug8+sr1VgrPr7bIy/CQo5OX0l5s0WgMwsLwyfZaYY4ntKM0sW9gSPJdj2x99eqfsanzYgttbYzeIMxIP2lJvy/3ZX/N9kSBobBl/4adDxwtiTCG7w159LB6hzsMMCkjzmsKM63HVzhtPsKuG1l2bLzy2yam0FUqmiCT3G06fT1yZ1iILo7cpZ4UIaqfsonWseG/+xBvd6W1FyklthllCYiRko2Sz+j2FofvV8hDzPt2PApmvmkmUcaEpJiv2ozmSOv7S1up7BkY8jUw2NZtLgzcME8ti7xWwogANqEGcSXoZLZNgIG2vBWlViHRO8kQq5fyIg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sat, 25 Jul 2026 21:05:46 +0000 Krzysztof Wilczyński wrote: > Hello, > > The PCI resource files in sysfs and the /proc/bus/pci device files swap > their f_mapping to the shared iomem address space at open time, so that > revoke_iomem() can unmap userspace mappings when a driver claims a > region, see commit 636b21b50152 ("PCI: Revoke mappings like devmem"). > > Their VMAs are therefore attached to the shared address space, which > neither removal path reaches: kernfs_drain_open_files() unmaps the > sysfs inode's own mapping, which contains none of them, and > proc_entry_rundown() does not unmap anything at all. > > As a result, userspace mappings of PCI BARs survive device removal, > and also survive a BAR resize on the sysfs side, keeping stale PTEs > into physical address space that the kernel may have reassigned since. > A mapping made before the device is removed still returns the previous > register value after the device has been released, through both > interfaces. Thanks. Can we please have full description of the userspace-visible effects of this? AI review might have found a few things: https://sashiko.dev/#/patchset/20260725210549.3716546-1-kwilczynski@kernel.org