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[174.91.117.149]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-506920071c4sm3288501cf.1.2026.02.11.12.01.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Feb 2026 12:01:10 -0800 (PST) Date: Wed, 11 Feb 2026 15:00:58 -0500 From: Peter Xu To: Mike Rapoport Cc: linux-mm@kvack.org, Andrea Arcangeli , Andrew Morton , Axel Rasmussen , Baolin Wang , David Hildenbrand , Hugh Dickins , James Houghton , "Liam R. Howlett" , Lorenzo Stoakes , Michal Hocko , Muchun Song , Nikita Kalyazin , Oscar Salvador , Paolo Bonzini , Sean Christopherson , Shuah Khan , Suren Baghdasaryan , Vlastimil Babka , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH RFC 10/17] shmem, userfaultfd: implement shmem uffd operations using vm_uffd_ops Message-ID: References: <20260127192936.1250096-1-rppt@kernel.org> <20260127192936.1250096-11-rppt@kernel.org> MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: Je53iKXNFChE6Q8MMjO6_sH5tpwo_5Vh4av_78b8OPo_1770840072 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 096BE1C000D X-Stat-Signature: b8zyg7xrxc1crwkyunzws93qfxeqwxjz X-Rspam-User: X-HE-Tag: 1770840073-601255 X-HE-Meta: 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 B0uGjnLj KbbzwB468F5B1Zh1j+Nep0KyIiYpyDNIoTEqln6ftFbzITJUOz5odaKiJp7YWSSbuAZw/EFungQUs8XKWNPe87pkd4mcX8tHmmtsCfH8+XMrMXU+n64mdljVpy2EgHMToLWWu64ojJSiD33fXReUt/JoLAxnvAagmYDLvzVEW5dPsyn34vg8X73+COyL0CoeWRwMrI70uWkxu8LbRV+8tQ074CbPALhhahpWMNHgu0zd74T/Eamj9Ni2agOiwZfeF+txm3492wPhV1ILfvbKwXA8l3wkQS+c1mAc+WeTonVoooDTSIg9HrcKfg4Y8hKfAdQjZiXb0STjJPh9tbqTGe32BtgL7/LpFUfyVYhKLyRJ70p2pZ0sEmXE3nv9/muobfS6PAELtn/Ijkw0Cw9qdr4rblIv4RGUEvGRmx5hjQgEAxcWPmtn+8STSpg== 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 Sun, Feb 08, 2026 at 12:35:43PM +0200, Mike Rapoport wrote: > > > +static void shmem_mfill_filemap_remove(struct folio *folio, > > > + struct vm_area_struct *vma) > > > +{ > > > + struct inode *inode = file_inode(vma->vm_file); > > > + > > > + filemap_remove_folio(folio); > > > + shmem_recalc_inode(inode, 0, 0); > > > folio_unlock(folio); > > > - folio_put(folio); > > > -out_unacct_blocks: > > > - shmem_inode_unacct_blocks(inode, 1); > > > > This looks wrong, or maybe I miss somewhere we did the unacct_blocks()? > > This is handled by shmem_recalc_inode(inode, 0, 0). IIUC shmem_recalc_inode() only does the fixup of shmem_inode_info over possiblly changing inode->i_mapping->nrpages. It's not for reverting the accounting in the failure paths here. OTOH, we still need to maintain accounting for the rest things with correctly invoke shmem_inode_unacct_blocks(). One thing we can try is testing this series against either shmem quota support (since 2023, IIUC it's relevant to "quota" mount option), or max_blocks accountings (IIUC, "size" mount option), etc. Any of those should reflect a difference if my understanding is correct. So IIUC we still need the unacct_blocks(), please kindly help double check. Thanks, -- Peter Xu