{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2025-21908",
  "modified": "2026-10-07T17:22:01Z",
  "upstream": [
    "CVE-2025-21908"
  ],
  "published": "2025-04-01T15:40:16Z",
  "summary": "NFS: fix nfs_release_folio() to not deadlock via kcompactd writeback",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFS: fix nfs_release_folio() to not deadlock via kcompactd writeback\n\nAdd PF_KCOMPACTD flag and current_is_kcompactd() helper to check for it so\nnfs_release_folio() can skip calling nfs_wb_folio() from kcompactd.\n\nOtherwise NFS can deadlock waiting for kcompactd enduced writeback which\nrecurses back to NFS (which triggers writeback to NFSD via NFS loopback\nmount on the same host, NFSD blocks waiting for XFS's call to\n__filemap_get_folio):\n\n6070.550357] INFO: task kcompactd0:58 blocked for more than 4435 seconds.\n\n{---\n[58] \"kcompactd0\"\n[<0>] folio_wait_bit+0xe8/0x200\n[<0>] folio_wait_writeback+0x2b/0x80\n[<0>] nfs_wb_folio+0x80/0x1b0 [nfs]\n[<0>] nfs_release_folio+0x68/0x130 [nfs]\n[<0>] split_huge_page_to_list_to_order+0x362/0x840\n[<0>] migrate_pages_batch+0x43d/0xb90\n[<0>] migrate_pages_sync+0x9a/0x240\n[<0>] migrate_pages+0x93c/0x9f0\n[<0>] compact_zone+0x8e2/0x1030\n[<0>] compact_node+0xdb/0x120\n[<0>] kcompactd+0x121/0x2e0\n[<0>] kthread+0xcf/0x100\n[<0>] ret_from_fork+0x31/0x40\n[<0>] ret_from_fork_asm+0x1a/0x30\n---}\n\n[akpm@linux-foundation.org: fix build]",
  "affected": [
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      "package": {
        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
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  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2025-21908"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/ab0727d6e2196682351c25c1dd112136f6991f11"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/5ae31c54cff745832b9bd5b32e71f3d1b607cd1e"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/8253ff29edcb429a9a6c75710941c6a16a9a34b1"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/ce6d9c1c2b5cc785016faa11b48b6cd317eb367e"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-05-12T04:54:46Z"
  }
}