{"id":"CVE-2026-72132","summary":"NFS: Charge unstable writes by request size, not folio size","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nNFS: Charge unstable writes by request size, not folio size\n\nnfs_folio_mark_unstable() and nfs_folio_clear_commit() charge and\nuncharge NR_WRITEBACK/WB_WRITEBACK by folio_nr_pages(folio) once per\n*request* added to or removed from a commit list. This is correct only\nwhen a folio has a single associated request. When pg_test splits a\nfolio into N sub-folio requests (e.g. pNFS flexfiles striping with a\nstripe unit smaller than the folio size, or plain wsize-limited\nsplitting), each of the N requests independently charges the whole\nfolio's page count, inflating the accounting by a factor of N per\nfolio. With large folios and small stripe units this reaches multiple\norders of magnitude: a 2 MiB folio split into 512 4 KiB requests can\ncharge up to 512x its real size, pushing global dirty+writeback\naccounting past the system's dirty threshold and forcing every\nbuffered writer on the host into the hard-throttle path, including\nunrelated in-kernel NFS server threads sharing the box.\n\nCharge each request only for the pages it actually covers.","modified":"2026-08-18T03:31:04.692177448Z","published":"2026-08-15T05:53:08.096Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72132.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/0ffc032294a29601b1019dba91aa1a930d90df17"},{"type":"WEB","url":"https://git.kernel.org/stable/c/1f646e23372f3444dc5f0bcb5404a49d26756add"},{"type":"WEB","url":"https://git.kernel.org/stable/c/27934d02cbeb8a957dd11c985a579e58d30c5270"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a192b6c149c6ea10cc88869accb78165eb454456"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a442c258320b689f13d2205eaeeddf8b0e630288"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72132.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-72132"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"0c493b5cf16e28d761b6e77c7c32aa0e7af70813"},{"fixed":"a442c258320b689f13d2205eaeeddf8b0e630288"},{"fixed":"1f646e23372f3444dc5f0bcb5404a49d26756add"},{"fixed":"0ffc032294a29601b1019dba91aa1a930d90df17"},{"fixed":"a192b6c149c6ea10cc88869accb78165eb454456"},{"fixed":"27934d02cbeb8a957dd11c985a579e58d30c5270"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-72132.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.3.0"},{"fixed":"6.6.148"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.97"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.40"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.5"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-72132.json"}}],"schema_version":"1.9.0"}